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Occurrence, Fate, and Transport of Contaminants in Indoor Air and Atmosphere

Observation-Based Diagnostics of Reactive Nitrogen Recycling through HONO Heterogenous Production: Divergent Implications for Ozone Production and Emission Control
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Cite this: Environ. Sci. Technol. 2024, 58, 26, 11554–11567
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https://doi.org/10.1021/acs.est.3c07967
Published June 17, 2024

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Abstract

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Understanding of nitrous acid (HONO) production is crucial to photochemical studies, especially in polluted environments like eastern China. In-situ measurements of gaseous and particulate compositions were conducted at a rural coastal site during the 2018 spring Ozone Photochemistry and Export from China Experiment (OPECE). This data set was applied to investigate the recycling of reactive nitrogen through daytime heterogeneous HONO production. Although HONO levels increase during agricultural burning, analysis of the observation data does not indicate more efficient HONO production by agricultural burning aerosols than other anthropogenic aerosols. Box and 1-D modeling analyses reveal the intrinsic relationships between nitrogen dioxide (NO2), particulate nitrate (pNO3), and nitric acid (HNO3), resulting in comparable agreement between observed and simulated HONO concentrations with any one of the three heterogeneous HONO production mechanisms, photosensitized NO2 conversion on aerosols, photolysis of pNO3, and conversion from HNO3. This finding underscores the uncertainties in the mechanistic understanding and quantitative parametrizations of daytime heterogeneous HONO production pathways. Furthermore, the implications for reactive nitrogen recycling, ozone (O3) production, and O3 control strategies vary greatly depending on the HONO production mechanism. On a regional scale, the conversion of HONO from pNO3 can drastically enhance O3 production, while the conversion from NO2 can reduce O3 sensitivity to NOx changes in polluted eastern China.

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Analysis of an extensive observation dataset reveals observation ambiguity in the underlying heterogeneous HONO production mechanism and divergent implications for ozone production and emission control.

1. Introduction

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Nitrous acid (HONO) is a crucial component in boundary layer photochemistry, playing a significant role in the production of the hydroxyl radical (OH) via fast photolysis. (1−4) Understanding HONO formation mechanisms advances our knowledge of photochemical processes to better predict and regulate regional air pollution, such as the formation of ozone (O3) and secondary organic aerosols. (5−8)
HONO is produced through the gas-phase reaction of nitric oxide (NO) and OH (R1). (9) Direct emissions from combustion activities, such as vehicle exhaust and biomass burning (BB) can also contribute to HONO levels. (10−15) In recent years, observations in a variety of locations have found other daytime HONO sources to be important. (16,17) Soil emissions of HONO have been found to be potentially important for regions with livestock farming or after fertilization, highlighting the need of detailed quantification in future studies. (18) Moreover, various HONO production pathways have been proposed based on field measurements and laboratory experiments, with heterogeneous reactions highlighted as crucial contributors. (19−22) For example, studies have demonstrated the importance of heterogeneous nitrogen dioxide (NO2) conversion on ground surfaces (eq S3) as an important nocturnal HONO source. (23) However, this source and gas-phase production still cannot explain observed daytime HONO losses. (24−27) Aerosol reactions were recognized as a contributor to HONO productions as early as the 1990s. (28) Research by Ammann et al. detected HONO production from NO2 on suspended soot particles, and highlighted the important role of aerosols in HONO production. (29) Since then, numerous observations have reported HONO production from heterogeneous reactions on aerosols, including photosensitized conversion of NO2 (Supporting Information eqs S4–S5), (30−38) conversion from adsorbed nitric acid (HNO3) (Supporting Information eq S9), (39−41) and photolysis of particulate nitrate (pNO3) (Supporting Information eqs S6–S8). (42−45) More details regarding these HONO sources will be discussed in Section 2.2.
OH+NO+M→HONO+M
(1)
Although the precise mechanism of aerosol-induced HONO production is still a subject of debate, (46−48) heterogeneous mechanisms have been included into atmospheric chemistry simulations and have shown promising agreement with observed levels of HONO. Various HONO budget analyses have been conducted, yet the prevailing mechanism responsible for daytime HONO production beyond R1 remains uncertain. (49−52) This is due in part to large uncertainties in key reaction parameters of heterogeneous daytime HONO production, such as the reactive uptake coefficient of NO2, the enhancement factor of pNO3 photolysis rate (jpNO3), and the HONO yield coefficient (YHONO) from HNO3 conversion, as well as variations in precursor concentrations observed in different campaigns.
Furthermore, environmental factors, such as BB (53−55) and aerosol acidity, (56,57) can impact HONO production. This provides additional challenges to characterize HONO sources. For example, Nie et al. (53) found that the conversion rate of NO2 to HONO in BB plumes is twice that in non-BB plumes, suggesting that BB aerosol composition can enhance NO2 conversion efficiencies of BB aerosols. Aerosol acidity can affect the volatility of aerosol components and gas-particle partitioning; and HONO heterogeneous production tends to increase with decreasing pH. (58−60)
In this study, we test these proposed HONO heterogeneous mechanisms, including photosensitized NO2 conversion on aerosols, photolysis of pNO3, and conversion from HNO3, using a comprehensive data set of gaseous and particulate compositions measured at a rural coastal site during the 2018 spring Ozone Photochemistry and Export from China Experiment (OPECE). (61) Observations at a remote location are ideal for diagnosing photochemical processes due in part to generally less-complex emission characteristics compared to urban regions. In this work we investigate the impact of BB and aerosol acidity on observed HONO concentrations. Focusing on the observations not affected by BB, we also analyze the intrinsic photochemical relationships between NO2, pNO3, and HNO3 in the remote boundary layer and how the relationships can obscure the diagnostics of HONO heterogeneous production mechanisms. Lagrangian box model simulations are used to demonstrate the utility of diagnosing O3 enhancements by the recycling of reactive nitrogen species through HONO production on aerosols. We also investigate the implications of the different HONO heterogeneous production mechanisms for O3 control strategy.

2. Materials and Methods

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2.1. Observations

The OPECE campaign was carried out at the Yellow River Delta Ecology Research Station of the Coastal Wetland in Dongying, Shandong, China. The rural coastal site (37.76°N, 118.98°E) is located in the Yellow River Delta region near the Shandong Yellow River Delta National Nature Reserve. (62) The closest urban area, Dongying, is located approximately 50 km southwest of the site. From 23 March to 22 April of 2018, surface concentrations of HONO were measured by a Long Path Absorption Photometer (LOPAP). (63−67) Additionally, measurements of NOx (NO+NO2), O3, acetonitrile (CH3CN), carbon monoxide (CO), volatile organic compounds (VOCs), aerosol size distribution, NO2 photolysis rate (jNO2), and meteorological parameters, including pressure, temperature, and relative humidity (RH) during this period were obtained. Detailed instrument information is provided in Supporting Information Table S1 and previous studies. (61)
Ambient aerosol surface area (SA) was derived using observation data and accounting for the hygroscopic effect, (68) using the observed RH to estimate the radius ratio of ambient to dry aerosols (Supporting Information Figure S1, eqs S1–S2). Aerosol chemical composition was measured by both an aerosol mass spectrometer (AMS) and PM2.5 filter samples. Comparisons of daily inorganic ion concentrations reported by the two instruments demonstrate reasonable agreement with p-values <0.05 and measurement ratios ranging from 0.83 to 1.1 (Supporting Information Figure S2). The AMS instrument samples particles with size <1 μm. Therefore, AMS data are generally lower than the filter measurements. In our study, we combined the two data sets to obtain pNO3 and other inorganic aerosol concentrations. Further details regarding data preparation, including the derivations of ambient aerosol surface area, pNO3 concentration, and aerosol pH and gas-particulate partitioning calculations, can be found in the Supporting Information Text S1.

2.2. Photochemical Models, Source Parameterizations, and Simulation Cases

In this study, we utilize the Regional chEmical trAnsport Model (REAM) in both one- and zero-dimensional configurations (69−71) to evaluate the recycling of reactive nitrogen species through heterogeneous HONO production and its impacts on O3 formation. The model incorporates 30 vertical layers in the troposphere, and the condensed chemistry mechanism from the GEOS-Chem model (v9–02) (72) for the Ox-NOx-VOCs photochemistry. For VOCs, ≥ 3C alkenes, ≥ 4C alkanes, and high reactivity aromatics are lumped while preserving the OH reactivities. Photolysis rates are calculated based on cloud fraction and optical depths simulated by the Weather Research and Forecasting (WRF) model and subsequently scaled using jNO2 observations. To ensure realistic meteorological conditions, observed data are used to constrain meteorological parameters such as temperature, RH, wind velocities and wind directions. Vertical mixing is included using eddy diffusion coefficient (Kzz) simulated by WRF. An averaged diurnal profile of mixing layer height diagnosed by Kzz (73) is shown in Supporting Information Figure S3. We constrain the model at a 1 min time step using surface observations of O3, NO2, NO, CO, and selected VOCs. Averaged midmorning to afternoon (10:00–15:00 LT) mixing ratios of VOCs are shown in Supporting Information Figure S4.
To investigate the relationship between HONO production and potential photoactive production pathways, we calculated the missing HONO source strength (pHONO) by
pHONO=d[HONO]+Lchem+Ltransport−POH+NO
(2)
where, d[HONO] represents the net change of HONO calculated from observations for each 1 min time step, Lchem denotes the chemical loss of HONO through photolysis and gas-phase reactions, Ltransport denotes the loss of HONO through vertical transport, and POH+NO denotes the production of HONO through the gas-phase reaction of NO and OH. Primary emissions are not considered for this rural coastal site. Since we focus on using pHONO to diagnose daytime HONO sources, the impact of regional transport is not considered either.
Hourly pHONO data are calculated in the baseline 1-D model simulation by constraining surface HONO and other chemical concentrations to the observations (same chemical setup as case B in Table 1) using eq 2. To explain observation-based pHONO, five additional 1-D model simulations were conducted (Table 1). In case S0, HONO production from NO2 conversion on ground surface upon dry deposition of NO2 was parametrized with a yield coefficient of HONO production (f) of 0.24 (Supporting Information eq S3) to reproduce nighttime HONO observations following Liu et al. (24) As in the previous study, an uptake coefficient of 10–6 of NO2 uptake to aerosol surfaces under dark conditions was assigned. (74)
Table 1. Simulation Cases in This Study
CasesConfiguration
BNO + OH + M → HONO + M
S0B + NO2 conversions on ground (f = 0.24) and on aerosols (γ = 10–6) (Supporting Information eq. S3)
S1S0 + photosensitized NO2 conversions on aerosol γ = max (5 × 10–7×SWR, 10–6) (Supporting Information Eqs. S4–S5)
S2–1S0 + photolysis of pNO3, jpNO3= 80 × jHNO3 (Supporting Information eqs. S6–S7)
S2–2S0 + photolysis of pNO3, jpNO3= EF(pNO3, a = 3 × 104)×jHNO3 (Supporting Information eqs. S6–S8)
S3S0 + HONO from HNO3, YHONO = 0.45 (Supporting Information Eq. S9)
F0Free-running S0
F1F0 + photosensitized NO2 conversions on aerosol γ = max (5 × 10–7×SWR, 10–6)
F2–1F0 + photolysis of pNO3, jpNO3= EF × jHNO3, EF = 80
F2–2F0 + photolysis of pNO3, jpNO3= EF(pNO3, 3 × 104)×jHNO3
F3F0 + HONO from HNO3, YHONO = 0.45
To reproduce daytime HONO observations, three photoactive HONO production mechanisms were implemented in model simulations (Supporting Information eqs S4–S9) on top of S0. The parameters were chosen by considering the values and uncertainties from previous studies and minimizing the simulation errors (root-mean-square error, RMSE) of midmorning to afternoon (10:00–15:00 LT) HONO simulations (see Section 3.2). In S1, we considered a first-order enhancement on aerosol uptake of NO2 from short wave radiation (SWR), (24) in which γ = 5 × 10–7 × SWR, to simulate daytime enhancements of pHONO. In S2, photolysis of pNO3 (42) was implemented in two subsets. In S2–1, the pNO3 photolysis rate (jpNO3) was scaled from the photolysis rate of gas-phase HNO3 (jHNO3) by a constant enhancement factor (EF) of 80. (50) However, a recent study by Andersen et al. (44) indicated that EF depends on bulk pNO3 concentrations and can be parametrized as a Langmuir function of pNO3. In S2–2, EF was computed as a function of the concentration of pNO3 (Supporting Information eq S8), (75) ranging from 20 to 3600 with a median value of 106. Photolysis of nitrate in coarse particles has been found to contribute to HONO production at coastal sites. (76) In our study, this mechanism is not included due to a lack of coarse particle measurements. This omission may lead to a high bias in the estimated EF. A recent experimental study (77) has reported HONO production proportional to the production of HNO3 (P(HNO3)) from photooxidation of NO2, and proposed HONO production involving adsorbed HNO3. Utilizing this proportional relationship, in S3, we parametrized HONO production with a yield coefficient (YHONO, Supporting Information eq S9) of 0.45. More details of HONO source parametrizations are available in Supporting Information Text S2. The RMSEs of the simulated HONO compared to observations are 0.031, 0.024, 0.019, and 0.019 for S1, S2–1, S2–2, and S3.
Ground sources of HONO have been recognized as potentially important contributors. (25,78) The HONO isotope observations in China show significant influences of fertilizer applications and livestock farms. (18) Ground conversion from NO2 is found to be a minor HONO source in that study. In our study, the Dongying site is not affected by fertilizer applications or livestock farms. The ground HONO source from NO2 is estimated based on nighttime HONO observations. If we assume that the ground source of HONO (in S0) with f having a first-order dependence on SWR, (79) the best fit of the observed HONO gives f = min(1, 0.24 + 0.76*SWR/800) since f cannot be physically larger than 100%. Under this scenario, f reaches 100% during 10:30 to 14:30, but the simulated HONO concentrations still have a low bias compared to the observations (Supporting Information Figure S5). A conversion efficiency of 100% poses stringent requirements for ground surface properties. Equivalent maximum f values reported in prior literature (33,80) are 20% to 40%, much less than 100%; their daily average f values are less than or comparable to the nonphotosensitive f value used in this study. In terms of simulating observed HONO concentrations and the effect of heterogeneous NO2 to HONO conversion on O3, the conversion of NO2 to HONO on aerosols is equivalent to the conversion on ground surface. Therefore, in this study, the aerosol conversion of NO2 to HONO can be thought as representing the combined photosensitized conversions from NO2 to HONO on both aerosol and ground surfaces. Similarly, potential photoactive conversions of HONO from HNO3 or pNO3 deposited on ground surfaces are included in the respective aerosol conversion. During our study period, HNO3 predominantly partitions into the particulate phase (25) (Supporting Information Figure S6) and dry deposition of particulates is slower compared to that of NO2. Considering that the dry deposition of HNO3 is much faster, (81) we acknowledge the possible contribution of deposited HNO3 on ground to HONO. (82,83) Since the observations are insufficient to diagnose this contribution and it is implicitly included in the respective aerosol conversion pathway, the effect of this contribution on O3 is not separately analyzed in this study.
A major chemical impact of heterogeneous HONO production in S1–S3 is the recycling of reactive nitrogen. To understand the effect of this recycling on PO3, we conducted a set of Lagrangian free-running box-model simulations (F0 – F3) to investigate the evolution of plume aging. F0 represents the control case using the same chemical reactions as S0 (case Control). F1 incorporates photosensitized uptake of NO2 on aerosol surfaces as in S1. F2–1 considers the photolysis of pNO3 with a constant EF as in S2–1 (EF = 80), while F2–2 incorporates a changing EF as in S2–2 (changing EF). Lastly, case F3 includes the production of HONO from HNO3 as in S3. The models are initialized with average concentrations of observed O3, NO, NO2, HONO, CO, and VOCs and started at midnight.

3. Results and Discussion

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3.1. pHONO Dependence on Biomass Burning and Aerosol Acidity

Supporting Information Figure S7 shows the time series of observed O3, NOx, HONO, pNO3, and SA during the OPECE campaign. The average HONO concentration was 0.39 ± 0.27 parts per billion by volume (ppbv) with a maximum of 1.54 ppbv recorded at the site. These HONO levels have been reported in measurements from other rural coastal sites in China, (84−86) and some urban/suburban areas in Europe, (17,87) much higher than those observed in clean coastal regions. (88) The average concentrations of pNO3 and SA were 8 ± 16.8 μg/m3 and 527 ± 382 μm2/cm3, respectively. The diurnal profiles of HONO and other species were also examined (Supporting Information Figure S8). The diurnal profile of HONO illustrates a nighttime accumulation followed by a sharp decrease in the early morning due to rapid photolysis. A slower decrease was observed at noon, indicating the presence of a photoactive daytime HONO source. The average NOx concentration was 13.6 ± 10.4 ppbv, consistent with levels observed at a background site in the North China Plain (NCP) region. (89) However, notably higher O3 levels, exceeding 100 ppbv at times, were observed, with an average peak concentration of 70 ppbv. This elevated O3 level underscores the need to gain a better understanding of springtime photochemistry in China. In this study, we focus on investigating the impact of photoactive HONO sources on O3 enhancements, as explained in more detail in Section 3.3.
BB can significantly contribute to regional air pollution, including HONO, through both direct emissions and secondary production. The long lifetime and source-specific characteristics of CH3CN make it a widely used tracer for BB. (90−93) During the measurement campaign, NOx, SA, and organic aerosols showed concurrent enhancements with CH3CN (Supporting Information Figure S9), indicating the representativeness of CH3CN as an indicator of BB impact at this site. For observations with elevated levels of CH3CN, we investigated BB impacts on mixing ratios and production pathways of HONO. A previous study reported increased HONO/NO2 ratios (2.8% to 6.6%) in BB affected plumes, (53) suggesting efficient secondary production of HONO on BB aerosols. In our study, we examined the daytime HONO/NO2 and HONO/pNO3 ratios, which served as indicators for NO2 and pNO3 conversion efficiencies to HONO, respectively. We analyzed correlations of HONO, HONO/NO2, and HONO/pNO3 with CH3CN (Supporting Information Table S2). Despite the significant positive correlation between HONO and CH3CN, consistent with previous studies, (12,13,92,94,95) we did not find a positive correlation between either ratio with CH3CN (Figure 1(a)). To further characterize BB-impacted air masses, we employed a threshold of 0.1 ppbv CH3CN to define BB-impacted and clean airmasses. (96,97) We compared the daytime (8:00–17:00) averaged HONO, HONO/NO2, and HONO/pNO3 between these two groups. The average HONO concentrations increased from 0.25 to 0.33 ppbv (Figure 1(c)) due to BB. However, the ratios did not show significant differences (Figure 1(d), (e)). We also analyzed data from an agricultural burning event near the site on 31 March 2018 (61,62) and compared the ratios in BB and clean airmasses (Supporting Information Figure S10). While HONO was significantly enhanced during the burning event, the median ratios still showed little difference from those of clean airmasses, except for a slightly higher averaged HONO/NO2 ratio than that of the clean airmasses. To minimize the impact of rapid photolysis loss of HONO, nighttime data was also investigated (Supporting Information Figure S11 (a)). A similar pattern emerged, showing a significant positive correlation between HONO and CH3CN, insignificant correlations between either HONO/NO2 or HONO/pNO3 ratio and CH3CN. As these ratios may be affected by the enhancements of NOx and pNO3 during BB, (98) it is difficult to conclude whether the increased HONO levels can be attributed to direct emissions or secondary production. Normalized excess mixing ratio (NEMR) has been utilized to quantify fire emissions. Here, we calculated NEMR for HONO relative to NO2, i.e., ΔHONO/ΔNO2=(HONOBB-HONOnBB)/(NO2BB-NO2nBB), and compared that with previous studies focusing on direct HONO emissions from biomass burning. The NEMR measured in our study ranges from 1.8% for daytime hours (8:00–17:00) to 4.2% during nighttime (20:00–05:00), much lower than the 20% to 140% reported in previous studies. (95) This result suggests that the effect of direct agricultural burning emissions of HONO at the OPECE site is much less than those found for forest fires in previous studies.

Figure 1

Figure 1. (a) Scatter plots of HONO (blue), HONO/NO2 (red), and HONO/pNO3 (yellow) as functions of CH3CN. (b) Same as (a) but as functions of aerosol pH. (c) Box plots of HONO concentrations for clean (CH3CN < 0.1) and BB (CH3CN > 0.1) airmasses, where the mean value is denoted by the red dot. And the median is denoted by black line. (d) and (e) are same as (c) but for HONO/NO2 and HONO/pNO3, respectively.

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In addition to BB, previous studies show that heterogeneous HONO production is affected by aerosol acidity through altering the partitioning between nitrite (NO2–) and HONO. (99) Here, we investigated the correlation between pH and heterogeneous HONO production using non-BB data. No statistically significant correlations are found during daytime (Figure 1(b), Supporting Information Table S3). At night (Supporting Information Figure S11(b), Table S3), HONO shows a weak negative correlation with aerosol pH. The negative correlation between pH and SA reflects in part higher sulfate concentrations in large particles in China. (100) This contributes to the negative correlation of HONO/NO2 with pH, as higher SA leads to more conversion of NO2 to HONO. The positive correlation between HONO/pNO3 and pH reflects in part the degassing of pNO3 at higher acidity. (101)

3.2. Recycling of Reactive Nitrogen through Photoactive Heterogeneous HONO Production

Here we address the question to see if a comprehensive in situ observation data set can be applied to test the validity of the proposed heterogeneous mechanisms, including photosensitized NO2 conversion on aerosol, photolysis of pNO3 and HONO yield from adsorbed HNO3. A caveat in this analysis is that NO2, HNO3, and pNO3 are all part of the reactive nitrogen family and they have dependent relationships, which are reflected in the correlation analysis. To avoid the impact of BB, we focus on the observations not affected by BB, which comprises 55% of the total available data (Supporting Information Figure S12).
We assess each production pathway by examining the correlations of pHONO with the corresponding production terms associated with each pathway. A strong positive correlation lends observational support to the existence of the source, whereas a lack of correlation can be considered observational evidence for excluding the production pathway as a major contributor. Figure 2(a) shows a significant positive correlation between pHONO and pNO3, with a correlation coefficient r = 0.83. This correlation strengthens to r = 0.87 when considering the case of pNO3 × jHNO3 (Figure 2(a)). Additionally, although the parametrization for the production pathway via HNO3 is based on a smog experiment, which requires further validation and investigation, a strong correlation between pHONO and P(HNO3) is found with r = 0.9 in our study. We also find a significant correlation between pHONO and the production terms of photosensitized NO2 conversion on aerosols, with r increasing from 0.82 between pHONO and NO2 to 0.90 for that with NO2 × SA × SWR (Figure 2(b)). Correlation statistics can be found in Supporting Information Table S4. These strong correlations reflect the intrinsic relationships among the precursors of heterogeneous HONO production. (102,103)

Figure 2

Figure 2. (a) Scatter plot of pHONO as functions of pNO3 (blue), pNO3 × jHNO3 (red), and P(HNO3) (green). The corresponding correlation coefficients are shown at the bottom right corner of the plot. (b) Scatter plot of pHONO as functions of NO2 (blue) and NO2 × SA × SWR (red), and the corresponding correlation coefficients. (c) Observed diurnal HONO (black dots) with standard deviation (black vertical lines) and simulated HONO under the six cases (B, S0–S3) as described in Table 1. (d) Mean diurnal profiles of pNO3 (orange) and NO2 (blue) during the measurement period. All panels show the non-BB data.

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To further assess the photoactive HONO production mechanisms, we conducted a set of constrained simulations (S0–S3, Table 1) incorporating additional HONO sources as described in Section 2. Consistent with previous studies, the observed HONO levels consistently exceed those predicted by R1 (Figure 2(c): B) throughout the day. Nocturnal HONO levels are explained by heterogeneous NO2 conversion on the ground surface with f = 0.24, while daytime HONO concentrations remain underestimated (Figure 2(c): S0).
After incorporating photoactive HONO production mechanisms (S1–S3), the model with any one of the mechanisms can reproduce the observed HONO levels within one standard deviation (Figure 2(c): S1–S3). A slightly higher bias of S1 in the morning hours (8:00–10:00) is seen, this is due to the fact that a constant scaling factor of 5 × 10–7 is used for γ, minimizing the 10:00–15:00 RMSE yields a higher bias in the morning when both NO2 and SA reach peak values. Importantly, the derived key parameters for HONO production, obtained by minimizing the simulation errors (i.e., scaling factor for γ (5 × 10–4), EF (80 or 106), and YHONO (0.45)), are comparable to those reported in previous experimental and modeling studies: [2 × 10–5, 1 × 10–3], [8, 700], and 0.53, respectively (Supporting Information Table S5). This agreement underscores the difficulty of assessing the underlying HONO heterogeneous production mechanism due to the intrinsic relationships among reactive nitrogen species. For example, higher HONO concentrations can promote pNO3 production, (25) and the photolysis of pNO3 can recycle reactive nitrogen from a reservoir species back into more reactive gaseous species, thereby sustaining atmospheric NO2 levels. (104−106) Moreover, as atmospheric HNO3 is produced through the reaction of OH and NO2, the production rate of HONO via this process is directly proportional to NO2. Given these intertwined relationships, it becomes challenging to establish a definitive causal relationship between HONO production and the proposed mechanisms solely through photochemical analysis of in situ observations.
However, these mechanisms have very different implications for the recycling of reactive nitrogen. The conversion from NO2 to HONO has the lowest impact since both species are short-lived. In springtime, the gas-particulate partitioning of nitrate strongly favors the formation of pNO3 from gaseous HNO3. (25) Therefore, the conversion of HNO3 to HONO reduces the lifetime of HNO3 and the formation of pNO3, effectively enhancing the recycling of reactive nitrogen. The photolysis of pNO3 significantly reduces the lifetime of the most long-lived reactive nitrogen reservoir and makes the entire inorganic reactive nitrogen family photochemically active, speeding up the recycling of reactive nitrogen the most.
We acknowledge that some reaction parameters derived in this study may appear larger than the values observed in laboratory experiments. For instance, the uptake coefficient for NO2 of 5 × 10–4 is greater than typical experimental results (Supporting Information Table S5). Two key points should be highlighted. First, the parameters were derived under the assumption that the unexplained daytime HONO is exclusively produced through the targeted mechanism. In the real atmosphere, multiple mechanisms may contribute to HONO simultaneously. Consequently, the parameters obtained in this study represent upper limits. Second, our primary focus is on understanding the implications for reactive nitrogen recycling and, consequently, O3 production. We are not aiming to establish the optimal kinetics parameters or identify the dominant mechanism, which cannot be accomplished through photochemical modeling of field observations as shown in our analysis. In the following section, we delve deeper into exploring the impact of HONO heterogeneous production on O3 production. It will become evident that, even if all these mechanisms yield the same amount of HONO, their effects on O3 production differ significantly due to varying efficiencies in reactive nitrogen recycling.

3.3. Sensitivity of O3 Production to the Heterogeneous Reactive Nitrogen Mechanism

The different implications of the heterogeneous HONO production mechanisms for the recycling of reactive nitrogen also strongly affect the production of O3. In this section, we investigate the changes of O3 chemistry by heterogeneous HONO production. The chemical analysis is isolated from meteorological impacts. As such, the box model simulations assume that the composition of an air mass is isolated from mixing and other meteorological processes. This analysis provides qualitative insights into the vastly different impacts of different heterogeneous HONO production pathways on O3 production.
We use Lagrangian box model simulations to analyze the chemical evolutions of isolated airmasses and investigate the consequences of the heterogeneous HONO production mechanisms (Table 1: F0 – F3). Figure 3(a) shows the divergent evolutions of O3, NOx, OH, and O3 production rate (PO3) among the HONO production mechanisms. Compared to the control case (F0) without HONO production from aerosols, the addition of photoactive conversion of NO2 (F1) or adsorbed HNO3 to HONO (F3) has a transient impact on reactive nitrogen, OH, and O3. In contrast, the impact from F2 cases via pNO3 photolysis is much larger and longer lasting. The difference lies in how the heterogeneous HONO production mechanism affects the recycling between NOx and pNO3. The conversion of NO2 to HONO on aerosols partitions reactive nitrogen into HONO, which effectively increases HONO/NO2 and HONO/pNO3 when compared to F0 (Figure 3(c), (d)), but does not significantly affect the ratio of NOx/pNO3 (Figure 3(e)). In the case of F3, the addition of HONO source reduces the production of HNO3 and hence the concentration of pNO3 by converting it to HONO and then to NOx, resulting in an increased NOx/pNO3 ratio (Figure 3(e)), (107) in addition to enhancing HONO/NO2 and HONO/pNO3 similar to F1. The photolysis of HONO adds a larger radical source and can speed up O3 production. (108) However, one O3 is lost for each conversion of NO2 to HONO. In contrast, the conversion from HNO3 to HONO does not incur this O3 loss and therefore produces more O3 than F1 (Figure 3(b)). These effects are most pronounced in the first day but diminish over time as NOx is converted to pNO3, which serves as a permanent sink for reactive nitrogen in these two cases.

Figure 3

Figure 3. (a) Simulated evolutions of O3, NOx, HONO, pNO3, OH, and PO3 in a Lagrangian box model for 7 days under cases F0 – F3. (b) O3 enhancement ratios, defined as the relative O3 increase from the initial O3 concentration for cases F0 – F3. (c), (d), and (e) are simulated HONO/NO2, HONO/pNO3 and NOx/pNO3 ratios. The dashed lines denote measured HONO/NO2, HONO/pNO3 and NOx/pNO3 values from Ye et al. (104)

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In cases F2–1 and F2–2, however, the conversion of pNO3 to HONO allows a full recycling of inorganic reactive nitrogen species, (106,109−111) thus the highest NOx/pNO3 ratio (Figure 3(e)). In some previous modeling studies, in addition to HONO, NO2 is also included as a product of pNO3 photolysis, this could lead to direct recycling from pNO3 to NOx, thus increasing NOx/pNO3 ratio and subsequent O3 production even more. Daytime HONO and NOx concentrations are sustained at significant levels, leading to high OH concentrations and O3 production and a tripling of O3 concentrations of >100 ppbv after a week (Figure 3(a)). The increase of O3 is twice as much in F2–1 and F2–2 as that of F0, F1 or F3 (Figure 3(b)). The difference between F2–1 and F2–2 is smaller compared to their differences from F1 and F3. A recent study (112) implementing HONO conversion from NO2 and pNO3 into a chemistry-climate model found a reduction effect on O3 driven by HONO conversion from NO2 and a strong enhancement of NOx caused by HONO conversion from pNO3. A necessary condition to simulate an O3 reduction is that NO from HONO photolysis can only produce a fractional (<1) O3 despite the additional OH from HONO photolysis. This could occur when OH reacts with O3 due to a lack of reactive VOCs. Figure 3 shows that it is not the case in a polluted boundary layer.
Ye et al. (104) reported rapid cycling of pNO3 to HONO from aircraft measurements over the North Atlantic Ocean in the marine boundary layer, based on observed high HONO production with low-level NOx present. We reexamined their observation data using the simulation results from OPECE. Following the observation-model comparison procedure by Ye et al., we used model outputs at 2:30 pm on the second diurnal cycle, which represents a 1.5-day airmass transport from the coastal site in the marine boundary layer, to be compared to their observations. The observed HOHO/NO2, HONO/pNO3, and NOx/pNO3 ratios reported by Ye et al. are much higher than our simulation results (Figure 3 (c) - (e)), although our observations during OPECE are more comparable to the observed values reported by other ground-based studies (Supporting Information Table S6). Therefore, the marine observations by Ye et al. appear to suggest a chemical environment of extremely fast recycling of reactive nitrogen not seen over polluted land areas. (88,113)
Figure 3(b) shows that O3 production rate can be much higher from the pNO3 conversion mechanism (F2–1 and F2–2) than the two other mechanisms (F1 and F3) in comparison to the case of no heterogeneous HONO production (F0). However, the effects depend on the amount of reactive nitrogen. To understand how the relationship between O3 and NOx responds to these different mechanisms, (114,115) we conducted box model simulations for 3 h under noontime conditions with initial NOx mixing ratios in the range of 1–25 ppbv. Similar results are obtained when longer integration hours are used, but the differences of F2–1 and F2–2 from the other cases increase with time.
A few features emerge from the modeling analysis. Figure 4(a) shows the cumulative PO3 first increases with NOx and then starts to decrease with increasing NOx. The NOx concentration at which the cumulative PO3 maximizes is the transition from NOx-limited to VOC-limited O3 production. (71,108) The critical initial NOx concentration for this transition increases when heterogeneous HONO production is introduced (Figure 4). The largest increase occurs with the NO2 conversion mechanism (F1) because the OH production from HONO photolysis speeds up the conversion of NOx to its reservoir, HNO3. In F2 and F3 cases, HNO3 can be effectively recycled back to NOx but not in F1. Consequently, the reduction of NOx is fastest in F1 due to HONO production. In a polluted urban environment, where O3 production decreases as NOx increases, this faster NOx reduction and increased OH production tends to increase PO3. Previous modeling studies have also shown elevated O3 levels via F1 in high-NOx regions. (116) As the urban plume ages and is transported regionally to low-NOx areas, however, this mechanism could lead to significant NOx reductions. (112) It is therefore expected that pNO3 recycling (F2) will increase PO3 much more than NO2 recycling (F1) on a regional scale. Supporting Information Figure S13 shows the ozone production efficiency (OPE), defined as the cumulative PO3 in a three-hour period (ΔO3) per NOx consumed (ΔNOx) as a function of initial NOx concentration. The NO2 conversion case (F1) is slightly higher than the case without heterogeneous HONO production (F0) under high-NOx conditions. The pNO3 conversion case (F2–1 and F2–2) increases OPE by a factor of 2–4 compared to F0. The HNO3 conversion case (F3) is more similar to (and higher than) the NO2 conversion case (F1) under low NOx conditions and approaches the pNO3 conversion cases (F2–1 and F2–2) under high NOx conditions.

Figure 4

Figure 4. (a) Cumulative PO3 as a function of initial NOx for cases F0 - F3. The dashed lines denote NOx levels at which cumulative PO3 reaches its peak values. (b) Loss of NOx (ΔNOx) as a function of initial NOx.

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3.4. Implications

Observed HONO levels are enhanced with increasing aerosol acidity and agricultural burning. However, analysis of the observation data does not indicate more efficient HONO production by agricultural burning aerosols. The NEMR of HONO over NO2 for agricultural burning in our study ranges from 1.8% in daytime to 4.2% at night, which is much lower than those reported for forest fires. Aerosol acidity is not found to enhance the non-BB aerosol HONO production efficiency in daytime data. The analysis of nighttime data is inconclusive since other factors may also lead to the observed correlations of aerosol acidity with HONO/NO2 and HONO/pNO3 ratios at night.
Modeling analysis of the OPECE gaseous and particulate measurements shows clear evidence for daytime heterogeneous production of HONO on aerosols in agreement with previous studies. By incorporating either photosensitized NO2 conversion on aerosols, photolysis of pNO3, or conversion from HNO3, the model can reproduce the observed HONO concentrations when other reactive nitrogen and chemical species are constrained by the observations. This modeling equivalency reflects the intrinsic relationships between NO2, pNO3, and HNO3 in the chemical system, indicating that inland in situ observations may not provide sufficient constraints to investigate the underlying mechanism of heterogeneous HONO production. This finding highlights the uncertainties in both the mechanistic understanding and quantitative parametrizations of daytime heterogeneous HONO production pathways. It appears necessary to conduct Lagrangian experiments away from sources such as in the marine boundary layer since the three mechanisms have drastically different predictions of HONO/NO2, HONO/pNO3, and NOx/pNO3 ratios (Figure 3(c)-(e)) after 1–2 days of chemical aging. Being able to follow the evolutions of these ratios can provide more information on the underlying mechanism.
The maritime observations by Ye et al. (104) are not as ideal as a Lagrangian experiment but can be carried out more easily. Their observations suggest a chemical environment with much faster reactive nitrogen recycling than the one found in OPECE or other inland data sets, indicating that additional processes may contribute to efficient reactive nitrogen recycling through HONO production over the ocean. However, it also implies much higher O3 production in offshore regions than in current model predictions. A survey of OPECE observations did not provide evidence for high O3 airmass transport from offshore regions, which may be related to prevailing westerly conditions during OPECE.
Quantifying the mechanism of heterogeneous HONO production on aerosols has profound implications for understanding O3 pollution and is important to formulating effective mitigation strategies on a regional scale. The conversion of HONO from pNO3 can drastically increase the lifetime of NOx and the cumulative O3 production during aging (Figures 3 and 4) compared to the other two mechanisms. It has the potential to substantially elevate O3 concentrations in regions located downwind from emission sources and to amplify O3 levels even in distant marine environments, potentially exerting a global influence.
On the other hand, the conversion of HONO from NO2 on aerosols can move the transition regime, when O3 production becomes insensitive to NOx, into higher NOx conditions and significantly flatten the PO3 decrease as NOx increases under high-NOx conditions (Figure 4(a)). The faster removal of NOx (Figure 4(b)) also implies a lower effect of background O3 production in downwind regions compared to the other cases since the OPEs of case F1 are among the lowest under low NOx conditions (Supporting Information Figure S13). The net effect is to reduce O3 sensitivity to NOx changes. It may help explain the observations that O3 concentrations in China have not changed much over the past decade (Supporting Information Figure S14) despite a ∼ 50% reduction in NOx (Supporting Information Figure S15) (117−120)
Despite the increasingly recognized significance of HONO over the years, the underlying production mechanisms of HONO are not understood and have considerable uncertainties. The kinetics parameters for heterogeneous HONO production have large uncertainties, and future laboratory studies are needed for improving the accuracy of these parameters. This study focuses on understanding their impacts on O3 production on a regional scale. Previous modeling studies have incorporated various HONO sources to address the underestimation of daytime HONO and to understand their corresponding impacts on photochemical pollutants. However, the simulated impacts on reactive nitrogen recycling and O3 are tied to the parametrizations of these sources in the models, which can introduce large uncertainties. Hence caution is warranted in the incoproration of HONO sources into models, as different production pathways can have vastly different implications, as found in this study.

Supporting Information

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The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.est.3c07967.

  • Details on the instrument used, preparation of observational data, and parametrizations of HONO sources; summary of the observed pollutant concentrations; detailed statistical test results for analyses on biomass burning impact, aerosol acidity impact, and HONO source evaluations; comparisons with previous studies on key kinetic parameters, and HONO/NO2/pNO3 measurements; O3 production efficiency with changing NO2 concentration; observed O3 and NO2 levels in eastern China from 2014 to 2022 (PDF)

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Author Information

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  • Corresponding Authors
  • Authors
    • Kezhen Chong - School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332, United States;  Orcidhttps://orcid.org/0000-0001-8799-3305
    • Mingming Zheng - School of Chemical and Environmental Engineering, Wuhan Polytechnic University, Wuhan 430024, China
    • Hang Qu - School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332, United States;  Orcidhttps://orcid.org/0000-0002-2924-2826
    • Ruixiong Zhang - School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
    • Young Ro Lee - School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
    • Yi Ji - School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
    • Lewis Gregory Huey - School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332, United States;  Orcidhttps://orcid.org/0000-0002-0518-7690
    • Hua Fang - Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China;  Present Address: (H. F.): School of Ecology and Environment, Anhui Normal University, Wuhu 241000, China
    • Wei Song - Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
    • Zheng Fang - Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China;  Present Address: (Z. F.): Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot 76100, Israel;  Orcidhttps://orcid.org/0000-0003-2355-5618
    • Cheng Liu - University of Science and Technology of China, Hefei 230026, China;  Orcidhttps://orcid.org/0000-0002-3759-9219
    • Yang Gao - Key Laboratory of Marine Environment and Ecology, Ministry of Education of China, Ocean University of China, Qingdao 266100, China;  Orcidhttps://orcid.org/0000-0001-6444-6544
    • Jianhui Tang - Yantai Institute of Coast Zone Research, CAS, Yantai 264003, China;  Orcidhttps://orcid.org/0000-0002-9006-263X
  • Notes
    The authors declare no competing financial interest.

Acknowledgments

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This work is supported by the National Science Foundation Atmospheric Chemistry Program (grant 1743401). The authors thank the science teams of the OPECE 2018 campaign.

References

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This article references 120 other publications.

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    Nitrous acid measurements were carried out during the MEGAPOLI summer and winter field campaigns at SIRTA observatory in Paris surroundings. Highly variable HONO levels were obsd. during the campaigns, ranging from 10 ppt to 500 ppt in summer and from 10 ppt to 1.7 ppb in winter. Significant HONO mixing ratios have also been measured during daytime hours, comprised between some tenth of ppt and 200 ppt for the summer campaign and between few ppt and 1 ppb for the winter campaign. Ancillary measurements, such as NOx, O3, photolysis frequencies, meteorol. parameters (pressure, temp., relative humidity, wind speed and wind direction), black carbon concn., total aerosol surface area, boundary layer height and soil moisture, were conducted during both campaigns. In addn., for the summer period, OH radical measurements were made with a CIMS (Chem. Ionisation Mass Spectrometer). This large dataset has been used to investigate the HONO budget in a suburban environment. To do so, calcns. of HONO concns. using PhotoStationary State (PSS) approach have been performed, for daytime hours. The comparison of these calcns. with measured HONO concns. revealed an underestimation of the calcns. making evident a missing source term for both campaigns. This unknown HONO source exhibits a bell-shaped like av. diurnal profile with a max. around noon of approx. 0.7 ppb h-1 and 0.25 ppb h-1, during summer and winter resp. This source is the main HONO source during daytime hours for both campaigns. In both cases, this source shows a slight pos. correlation with J(NO2) and the product between J(NO2) and soil moisture. This original approach had, thus, indicated that this missing source is photolytic and might be heterogeneous occurring at ground surface and involving water content available on the ground.
  18. 18
    Zhang, Q.; Liu, P.; Wang, Y.; George, C.; Chen, T.; Ma, S.; Ren, Y.; Mu, Y.; Song, M.; Herrmann, H.; Mellouki, A.; Chen, J.; Yue, Y.; Zhao, X.; Wang, S.; Zeng, Y. Unveiling the underestimated direct emissions of nitrous acid (HONO). Proc. Natl. Acad. Sci. U. S. A. 2023, 120 (35), e2302048120  DOI: 10.1073/pnas.2302048120
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    Lammel, G.; Cape, J. N. Nitrous acid and nitrite in the atmosphere. Chem. Soc. Rev. 1996, 25 (5), 361– 369,  DOI: 10.1039/cs9962500361
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    Nitrous acid and nitrite in the atmosphere
    Lammel, Gerhard; Cape, J. Neil
    Chemical Society Reviews (1996), 25 (5), 361-370CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)
    A review with 42 refs., investigates the evidence from lab. and field studies on the occurrence of HNO2 in the atm. boundary layer.
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    Finlayson-Pitts, B. J.; Wingen, L. M.; Sumner, A. L.; Syomin, D.; Ramazan, K. A. The heterogeneous hydrolysis of NO2 in laboratory systems and in outdoor and indoor atmospheres: An integrated mechanism. Phys. Chem. Chem. Phys. 2003, 5 (2), 223– 242,  DOI: 10.1039/b208564j
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    The heterogeneous hydrolysis of NO2 in laboratory systems and in outdoor and indoor atmospheres: An integrated mechanism
    Finlayson-Pitts, B. J.; Wingen, L. M.; Sumner, A. L.; Syomin, D.; Ramazan, K. A.
    Physical Chemistry Chemical Physics (2003), 5 (2), 223-242CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)
    The heterogeneous reaction of NO2 with water on the surface of lab. systems has been known for decades to generate HONO, a major source of OH that drives the formation of ozone and other air pollutants in urban areas and possibly in snowpacks. Previous studies have shown that the reaction is first order in NO2 and in water vapor, and the formation of a complex between NO2 and water at the air-water interface has been hypothesized as being the key step in the mechanism. We report data from long path FTIR studies in borosilicate glass reaction chambers of the loss of gaseous NO2 and the formation of the products HONO, NO and N2O. Further FTIR studies were carried out to measure species generated on the surface during the reaction, including HNO3, N2O4 and NO2+. We propose a new reaction mechanism in which we hypothesize that the sym. form of the NO2 dimer, N2O4, is taken up on the surface and isomerizes to the asym. form, ONONO2. The latter autoionizes to NO+NO3-, and it is this intermediate that reacts with water to generate HONO and surface-adsorbed HNO3. Nitric oxide is then generated by secondary reactions of HONO on the highly acidic surface. This new mechanism is discussed in the context of our exptl. data and those of previous studies, as well as the chem. of such intermediates as NO+ and NO2+ that is known to occur in soln. Implications for the formation of HONO both outdoors and indoors in real and simulated polluted atmospheres, as well as on airborne particles and in snowpacks, are discussed. A key aspect of this chem. is that in the atm. boundary layer where human exposure occurs and many measurements of HONO and related atm. constituents such as ozone are made, a major substrate for this heterogeneous chem. is the surface of buildings, roads, soils, vegetation and other materials. This area of reactions in thin films on surfaces (SURFACE = Surfaces, Urban and Remote: Films As a Chem. Environment) has received relatively little attention compared to reactions in the gas and liq. phases, but in fact may be quite important in the chem. of the boundary layer in urban areas.
  21. 21
    Kleffmann, J.; Becker, K.; Wiesen, P. Heterogeneous NO2 conversion processes on acid surfaces: possible atmospheric implications. Atmos. Environ. 1998, 32 (16), 2721– 2729,  DOI: 10.1016/S1352-2310(98)00065-X
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    Heterogeneous NO2 conversion processes acid surfaces: possible atmospheric implications
    Kleffmann, J.; Becker, K. H.; Wiesen, P.
    Atmospheric Environment (1998), 32 (16), 2721-2729CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Science Ltd.)
    The heterogeneous conversion of NO2 on water/H2SO4 surfaces was studied in a quartz reactor and a bubbler system. NO2 decay and the HONO formation are first order in [NO2] and are limited by an uptake coeff., γ ≈ 10-6. It was obsd. that HONO formation on acid/water surfaces of moderate acidity only occurs via the reaction 2 NO2 + H2O → HNO3. Involvement of NO on the HONO formation is of minor importance. HONO formation rates calcd. from results of this study at high aerosol load are of the same order of magnitude as obsd. HONO formation rates in the troposphere. Possible HONO formation on stratospheric aerosol by the parallel reaction of NO2 with H2SO4 (cH2SO4 >60 wt. percent) could explain, at least in part, obsd. stratospheric OH radical formation in the morning shortly after sunrise.
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    Reisinger, A. R. Observations of HNO2 in the polluted winter atmosphere: possible heterogeneous production on aerosols. Atmos. Environ. 2000, 34 (23), 3865– 3874,  DOI: 10.1016/S1352-2310(00)00179-5
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    Tuite, K.; Thomas, J. L.; Veres, P. R.; Roberts, J. M.; Stevens, P. S.; Griffith, S. M.; Dusanter, S.; Flynn, J. H.; Ahmed, S.; Emmons, L.; Kim, S.-W.; Washenfelder, R.; Young, C.; Tsai, C.; Pikelnaya, O.; Stutz, J. Quantifying Nitrous Acid Formation Mechanisms Using Measured Vertical Profiles During the CalNex 2010 Campaign and 1D Column Modeling. Journal of Geophysical Research: Atmospheres 2021, 126 (13), e2021JD034689  DOI: 10.1029/2021JD034689
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    Liu, Z.; Wang, Y.; Costabile, F.; Amoroso, A.; Zhao, C.; Huey, L. G.; Stickel, R.; Liao, J.; Zhu, T. Evidence of aerosols as a media for rapid daytime HONO production over China. Environ. Sci. Technol. 2014, 48 (24), 14386– 14391,  DOI: 10.1021/es504163z
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    Xue, C.; Zhang, C.; Ye, C.; Liu, P.; Catoire, V.; Krysztofiak, G.; Chen, H.; Ren, Y.; Zhao, X.; Wang, J.; Zhang, F.; Zhang, C.; Zhang, J.; An, J.; Wang, T.; Chen, J.; Kleffmann, J.; Mellouki, A.; Mu, Y. HONO Budget and Its Role in Nitrate Formation in the Rural North China Plain. Environ. Sci. Technol. 2020, 54 (18), 11048– 11057,  DOI: 10.1021/acs.est.0c01832
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    HONO budget and its role in nitrate formation in the rural North China Plain
    Xue, Chaoyang; Zhang, Chenglong; Ye, Can; Liu, Pengfei; Catoire, Valery; Krysztofiak, Gisele; Chen, Hui; Ren, Yangang; Zhao, Xiaoxi; Wang, Jinhe; Zhang, Fei; Zhang, Chongxu; Zhang, Jingwei; An, Junling; Wang, Tao; Chen, Jianmin; Kleffmann, Jorg; Mellouki, Abdelwahid; Mu, Yujing
    Environmental Science & Technology (2020), 54 (18), 11048-11057CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    Nitrous acid (HONO) is a major precursor of tropospheric hydroxyl radical (OH) that accelerates the formation of secondary pollutants. The HONO sources, however, are not well understood, esp. in polluted areas. Based on a comprehensive winter field campaign conducted at a rural site of the North China Plain, a box model (MCM v3.3.1) was used to simulate the daytime HONO budget and nitrate formation. We found that HONO photolysis acted as the dominant source for primary OH with a contribution of more than 92%. The obsd. daytime HONO could be well explained by the known sources in the model. The heterogeneous conversion of NO2 on ground surfaces and the homogeneous reaction of NO with OH were the dominant HONO sources with contributions of more than 36 and 34% to daytime HONO, resp. The contribution from the photolysis of particle nitrate and the reactions of NO2 on aerosol surfaces was found to be negligible in clean periods (2%) and slightly higher during polluted periods (8%). The relatively high OH levels due to fast HONO photolysis at the rural site remarkably accelerated gas-phase reactions, resulting in the fast formation of nitrate as well as other secondary pollutants in the daytime.
  26. 26
    Zheng, J.; Shi, X.; Ma, Y.; Ren, X.; Jabbour, H.; Diao, Y.; Wang, W.; Ge, Y.; Zhang, Y.; Zhu, W. Contribution of nitrous acid to the atmospheric oxidation capacity in an industrial zone in the Yangtze River Delta region of China. Atmospheric Chemistry and Physics 2020, 20 (9), 5457– 5475,  DOI: 10.5194/acp-20-5457-2020
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    Stutz, J.; Alicke, B.; Neftel, A. Nitrous acid formation in the urban atmosphere: Gradient measurements of NO2 and HONO over grass in Milan, Italy. Journal of Geophysical Research: Atmospheres 2002, 107 (D22), LOP 5-1– LOP 5-15,  DOI: 10.1029/2001JD000390
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    Notholt, J.; Hjorth, J.; Raes, F. Formation of HNO2 on aerosol surfaces during foggy periods in the presence of NO and NO2. Atmospheric Environment. Part A. General Topics 1992, 26 (2), 211– 217,  DOI: 10.1016/0960-1686(92)90302-2
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    Ammann, M.; Kalberer, M.; Jost, D. T.; Tobler, L.; Rossler, E.; Piguet, D.; W, G. H.; Baltensperger, U. Heterogeneous production of nitrous acid on soot in polluted air masses. Nature 1998, 395, 157,  DOI: 10.1038/25965
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    Heterogeneous production of nitrous acid on soot in polluted air masses
    Ammann, M.; Kalberer, M.; Jost, D. T.; Tobler, L.; Rossler, E.; Piguet, D.; Gaggeler, H. W.; Baltensperger, U.
    Nature (London) (1998), 395 (6698), 157-160CODEN: NATUAS; ISSN:0028-0836. (Macmillan Magazines)
    Polluted air masses are characterized by high concns. of oxidized nitrogen compds. which are involved in photochem. smog and ozone formation. The OH radical is a key species in these oxidn. processes. The photolysis of nitrous acid (HNO2), in the morning, leads to the direct formation of the OH radical and may therefore contribute significantly to the initiation of the daytime photochem. in the polluted planetary boundary layer. But the formation of nitrous acid remains poorly understood: exptl. studies imply that a suggested heterogeneous formation process involving NO2 is not efficient enough to explain the obsd. night-time build-up of HNO2 in polluted air masses. Here we describe kinetic investigations which indicate that the heterogeneous prodn. of HNO2 from NO2 on suspended soot particles proceeds 105 to 107 times faster than on previously studied surfaces. We therefore propose that the interaction between NO2 and soot particles may account for the high concns. of HNO2 in air masses where combustion sources contribute to air pollution by soot and NOx emissions. We believe that the obsd. HNO2 formation results from the redn. of NO2 in the presence of water by C-O and C-H groups in the soot. Although prolonged exposure to oxidizing agents in the atm. is likely to affect the chem. activity of these groups, our observations nevertheless suggest that fresh soot may have a considerable effect on the chem. reactions occurring in polluted air.
  30. 30
    George, C.; Strekowski, R. S.; Kleffmann, J.; Stemmler, K.; Ammann, M. Photoenhanced uptake of gaseous NO2 on solid organic compounds: a photochemical source of HONO?. Faraday Discuss. 2005, 130, 195– 210,  DOI: 10.1039/b417888m
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    Photoenhanced uptake of gaseous NO2 on solid organic compounds: A photochemical source of HONO?
    George, C.; Strekowski, R. S.; Kleffmann, J.; Stemmler, K.; Ammann, M.
    Faraday Discussions (2005), 130 (Atmospheric Chemistry), 195-210CODEN: FDISE6; ISSN:1359-6640. (Royal Society of Chemistry)
    In several recent field campaigns the existence of a strong daytime source of nitrous acid was demonstrated. The mechanism of this source remains unclear. Accordingly, in the present lab. study, the effect of light (in the range 300-500 nm) on the uptake kinetics of NO2 on various surfaces taken as proxies for org. surfaces encountered in the troposphere (as org. aerosol but also ground surfaces) was investigated. In this collaborative study, the uptake kinetics and product formation rate were measured by different flow tube reactors in combination with a sensitive HONO instrument. Uptake on light absorbing arom. compds. was significantly enhanced when irradiated with light of 300-420 nm, and HONO was formed with high yield when the gas was humidified. Esp. org. substrates contg. a combination of electron donors, such as phenols, and of compds. yielding excited triplet states, such as arom. ketones, showed a high reactivity towards NO2. Based on the results reported a mechanism is suggested, in which photosensitized electron transfer is occurring. The results show that HONO can be efficiently formed during the day in the atm. at much longer wavelengths compared to the recently proposed nitrate photolysis.

    discussion 241–164, 519–124

  31. 31
    Ramazan, K. A.; Syomin, D.; Finlayson-Pitts, B. J. The photochemical production of HONO during the heterogeneous hydrolysis of NO2. Phys. Chem. Chem. Phys. 2004, 6 (14), 3836– 3843,  DOI: 10.1039/b402195a
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    The photochemical production of HONO during the heterogeneous hydrolysis of NO2
    Ramazan, Kevin A.; Syomin, Dennis; Finlayson-Pitts, Barbara J.
    Physical Chemistry Chemical Physics (2004), 6 (14), 3836-3843CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)
    The heterogeneous hydrolysis of NO2 in thin water films, a major source of HONO and hence OH radicals in polluted urban atmospheres, has been previously reported to be photoenhanced (H. Akimoto, H. Takagi and F. Sakamaki, Int. J. Chem. Kinet., 1987, 19, 539, ref. 1) which has important implications for OH prodn. both in environmental chambers and in the lower atm. We report here studies of the impact of 320-400 nm radiation on HONO formation during the heterogeneous NO2 hydrolysis at 296 K. The expts. were carried out in a borosilicate glass cell using long path Fourier transform IR (FTIR) spectroscopy with three initial NO2 concns. (20, 46, and 54 ppm) at relative humidities of 33, 39, and 57%, resp. Nitrous acid was first allowed to accumulate from NO2 hydrolysis in the dark, and then the mixt. of reactants and products was irradiated. The measured concn.-time profiles of the gases were compared to the predictions of a kinetics model developed for this system. The initial loss of HONO upon irradn. was consistent with its photolysis and known secondary gas phase chem. without any photoenhancement. While the fundamental NO2 heterogeneous hydrolysis is not itself photoenhanced, there is clear evidence in these expts. for the generation of gas phase HONO by photolysis of adsorbed HNO3 formed during the heterogeneous hydrolysis. The mechanisms and atm. implications of HONO as well as NO2 formation by the photolysis of surface-adsorbed HNO3 are discussed.
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    Gustafsson, R. J.; Orlov, A.; Griffiths, P. T.; Cox, R. A.; Lambert, R. M. Reduction of NO2 to nitrous acid on illuminated titanium dioxide aerosol surfaces: implications for photocatalysis and atmospheric chemistry. Chem. Commun. 2006, (37), 3936– 3938,  DOI: 10.1039/b609005b
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    Stemmler, K.; Ammann, M.; Donders, C.; Kleffmann, J.; George, C. Photosensitized reduction of nitrogen dioxide on humic acid as a source of nitrous acid. Nature 2006, 440 (7081), 195– 198,  DOI: 10.1038/nature04603
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    Photosensitized reduction of nitrogen dioxide on humic acid as a source of nitrous acid
    Stemmler, Konrad; Ammann, Markus; Donders, Chantal; Kleffmann, Joerg; George, Christian
    Nature (London, United Kingdom) (2006), 440 (7081), 195-198CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)
    Nitrous acid is a significant photochem. precursor of the hydroxyl radical, the key oxidant in the degrdn. of most air pollutants in the troposphere. The sources of nitrous acid in the troposphere, however, are still poorly understood. Recent atm. measurements revealed a strongly enhanced formation of nitrous acid during daytime via unknown mechanisms. Here we expose humic acid films to nitrogen dioxide in an irradiated tubular gas flow reactor and find that redn. of nitrogen dioxide on light-activated humic acids is an important source of gaseous nitrous acid. Our findings indicate that soil and other surfaces contg. humic acid exhibit an org. surface photochem. that produces reductive surface species, which react selectively with nitrogen dioxide. The obsd. rate of nitrous acid formation could explain the recently obsd. high daytime concns. of nitrous acid in the boundary layer, the photolysis of which accounts for up to 60% of the integrated hydroxyl radical source strengths. We suggest that this photo-induced nitrous acid prodn. on humic acid could have a potentially significant impact on the chem. of the lowermost troposphere.
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    Ndour, M.; D’Anna, B.; George, C.; Ka, O.; Balkanski, Y.; Kleffmann, J.; Stemmler, K.; Ammann, M. Photoenhanced uptake of NO2 on mineral dust: Laboratory experiments and model simulations. Geophys. Res. Lett. 2008, 35 (5), L05812,  DOI: 10.1029/2007GL032006
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    Photoenhanced uptake of NO2 on mineral dust: laboratory experiments and model simulations
    Ndour, Marieme; D'Anna, Barbara; George, Christian; Ka, Oumar; Balkanski, Yves; Kleffmann, Joerg; Stemmler, Konrad; Ammann, Markus
    Geophysical Research Letters (2008), 35 (5), L05812/1-L05812/5CODEN: GPRLAJ; ISSN:0094-8276. (American Geophysical Union)
    Mineral dust contains material such as TiO2 that is well known to have photocatalytic activity. In this lab. study, mixed TiO2-SiO2, Saharan dust and Arizona Test Dust were exposed to NO2 in a coated wall flow tube reactor. While uptake in the dark was negligible, photoenhanced uptake of NO2 was obsd. on all samples. For the mixed TiO2-SiO2, the uptake coeffs. increased with increasing TiO2 mass fraction, with BET uptake coeffs. ranging from 0.12 to 1.9 × 10-6. HONO was obsd. from all samples, with varying yields, e.g., 80% for Saharan dust. Three-dimensional modeling indicates that photochem. of dust may reduce the NO2 level up to 37% and ozone up to 5% during a dust event in the free troposphere.
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    Wang, S.; Ackermann, R.; Spicer, C. W.; Fast, J. D.; Schmeling, M.; Stutz, J. Atmospheric observations of enhanced NO2-HONO conversion on mineral dust particles. Geophys. Res. Lett. 2003, 30 (11), 1595,  DOI: 10.1029/2003GL017014
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    Jiang, Y.; Xue, L.; Gu, R.; Jia, M.; Zhang, Y.; Wen, L.; Zheng, P.; Chen, T.; Li, H.; Shan, Y.; Zhao, Y.; Guo, Z.; Bi, Y.; Liu, H.; Ding, A.; Zhang, Q.; Wang, W. Sources of nitrous acid (HONO) in the upper boundary layer and lower free troposphere of North China Plain: insights from the Mount Tai Observatory. Atmos. Chem. Phys. 2020, 20, 12115,  DOI: 10.5194/acp-20-12115-2020
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    Colussi, A. J.; Enami, S.; Yabushita, A.; Hoffmann, M. R.; Liu, W. G.; Mishra, H.; Goddard, W. A., 3rd. Tropospheric aerosol as a reactive intermediate. Faraday Discuss. 2013, 165, 407– 420,  DOI: 10.1039/c3fd00040k
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    Tropospheric aerosol as a reactive intermediate
    Colussi, Agustin J.; Enami, Shinichi; Yabushita, Akihiro; Hoffmann, Michael R.; Liu, Wei-Guang; Mishra, Himanshu; Goddard, William A., III
    Faraday Discussions (2013), 165 (), 407-420CODEN: FDISE6; ISSN:1359-6640. (Royal Society of Chemistry)
    In tropospheric chem., secondary org. aerosol (SOA) is deemed an end product. Here, on the basis of new evidence, we make the case that SOA is a key reactive intermediate. We present lab. results on the catalysis by carboxylate anions of the disproportionation of NO2 'on water': 2NO2 + H2O = HONO + NO3- + H+ (R1), and supporting quantum chem. calcns., which we apply to reinterpret recent reports on (i) HONO daytime source strengths vis-a-vis SOA anion loadings and (ii) the weak seasonal and latitudinal dependences of NOx decay kinetics over several megacities. HONO daytime generation via R1 should track sunlight because it is generally catalyzed by the anions produced during the photochem. oxidn. of pervasive gaseous pollutants. Furthermore, by proceeding on the ever present substrate of airborne particulates, R1 can eventually overtake the photolysis of NO2: NO2 + hν = NO + O(3P) (R2), at large zenith angles. Thus, since R1 leads directly to *OH-radical generation via HONO photolysis: HONO + hν = NO + *OH, whereas the path initiated by R2 is more circuitous and actually controlled by the slower photolysis of O3: O3 + hν (+H2O) = O2 + 2*OH, the competition between R1 and R2 provides a mechanistic switch that buffers *OH concns. and NO2 decay (via R1 and/or NO2 + *OH = HNO3) from actinic flux variations.
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    Ricker, H. M.; Leonardi, A.; Navea, J. G. Reduction and Photoreduction of NO2 in Humic Acid Films as a Source of HONO, ClNO, N2O, NOX, and Organic Nitrogen. ACS Earth and Space Chemistry 2022, 6 (12), 3066– 3077,  DOI: 10.1021/acsearthspacechem.2c00282
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    Jiang, Y.; Hoffmann, E. H.; Tilgner, A.; Aiyuk, M. B. E.; Andersen, S. T.; Wen, L.; van Pinxteren, M.; Shen, H.; Xue, L.; Wang, W.; Herrmann, H. Insights Into NOx and HONO Chemistry in the Tropical Marine Boundary Layer at Cape Verde During the MarParCloud Campaign. Journal of Geophysical Research: Atmospheres 2023, 128 (16), e2023JD038865  DOI: 10.1029/2023JD038865
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    Tsai, C.; Spolaor, M.; Colosimo, S. F.; Pikelnaya, O.; Cheung, R.; Williams, E.; Gilman, J. B.; Lerner, B. M.; Zamora, R. J.; Warneke, C.; Roberts, J. M.; Ahmadov, R.; de Gouw, J.; Bates, T.; Quinn, P. K.; Stutz, J. Nitrous acid formation in a snow-free wintertime polluted rural area. Atmos. Chem. Phys. 2018, 18 (3), 1977– 1996,  DOI: 10.5194/acp-18-1977-2018
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    Laufs, S.; Kleffmann, J. Investigations on HONO formation from photolysis of adsorbed HNO3 on quartz glass surfaces. Phys. Chem. Chem. Phys. 2016, 18 (14), 9616– 9625,  DOI: 10.1039/C6CP00436A
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    Investigations on HONO formation from photolysis of adsorbed HNO3 on quartz glass surfaces
    Laufs, Sebastian; Kleffmann, Joerg
    Physical Chemistry Chemical Physics (2016), 18 (14), 9616-9625CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)
    During the last few decades, nitrous acid (HONO) has attracted significant attention as a major source of the OH radical, the detergent of the atm. However, the different daytime sources identified in the lab. are still the subject of controversial discussion. In the present study, one of these postulated HONO sources, the heterogeneous photolysis of nitric acid (HNO3), was studied on quartz glass surfaces in a photo flow-reactor under atmospherically relevant conditions. In contrast to other investigations, a very low HNO3 photolysis frequency for HONO formation of J(HNO3 → HONO) = 2.4 × 10-7 s-1 (0° SZA, 50% r.h.) was detd. If these results can be translated to atm. surfaces, HNO3 photolysis cannot explain the significant HONO levels in the daytime atm. In addn., it is demonstrated that even the small measured yields of HONO did not result from the direct photolysis of HNO3 but rather from the consecutive heterogeneous conversion of the primary photolysis product NO2 on the humid surfaces. The secondary NO2 conversion was not photo-enhanced on pure quartz glass surfaces in good agreement with former studies. A photolysis frequency for the primary reaction product NO2 of J(HNO3 → NO2) = 1.1 × 10-6 s-1 has been calcd. (0° SZA, 50% r.h.), which indicates that renoxification by photolysis of adsorbed HNO3 on non-reactive surfaces is also a minor process in the atm.
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    Ye, C.; Zhang, N.; Gao, H.; Zhou, X. Photolysis of Particulate Nitrate as a Source of HONO and NOx. Environ. Sci. Technol. 2017, 51 (12), 6849– 6856,  DOI: 10.1021/acs.est.7b00387
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    Photolysis of Particulate Nitrate as a Source of HONO and NOx
    Ye, Chunxiang; Zhang, Ning; Gao, Honglian; Zhou, Xianliang
    Environmental Science & Technology (2017), 51 (12), 6849-6856CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    Photolysis of HNO3 on surfaces was recently detd. to be greatly enhanced vs. gaseous HNO3. Yet photolysis of particulate nitrate (pNO3) assocd. with atm. aerosols is relatively unknown. Aerosol filter samples were collected near the ground surface and throughout the troposphere on-board an NSF/NACR C-130 aircraft. Photolysis rate consts. of pNO3 were detd. from these samples by directly monitoring HONO and NO2 prodn. rates under UV irradn. (>290 nm). Scaled to ground level tropical noon-time conditions (0° solar zenith angle), normalized photolysis rate consts. (jNpNO3) were 6.2 × 10-6/s to 5.0 × 10-4/s with a median of 8.3 × 10-5/s and a mean (±1 std. deviation) of (1.3 ± 1.2) × 10-4/s. Chem. compns., specifically NO3 loads and org. matter, affect the photolysis rate. Extrapolated to ambient pNO3 load conditions, e.g. ≤10 nmol/m3, the mean jNpNO3 value was >1.8 × 10-4/s in suburban, rural, and remote environments. Hence, pNO3 photolysis is a tropospheric source of HONO and NO2.
  43. 43
    Zhou, X.; Zhang, N.; TerAvest, M.; Tang, D.; Hou, J.; Bertman, S.; Alaghmand, M.; Shepson, P. B.; Carroll, M. A.; Griffith, S.; Dusanter, S.; Stevens, P. S. Nitric acid photolysis on forest canopy surface as a source for tropospheric nitrous acid. Nature Geoscience 2011, 4 (7), 440– 443,  DOI: 10.1038/ngeo1164
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    Nitric acid photolysis on forest canopy surface as a source for tropospheric nitrous acid
    Zhou, Xianliang; Zhang, Ning; TerAvest, Michaela; Tang, David; Hou, Jian; Bertman, Steve; Alaghmand, Marjan; Shepson, Paul B.; Carroll, Mary Anne; Griffith, Stephen; Dusanter, Sebastien; Stevens, Philip S.
    Nature Geoscience (2011), 4 (7), 440-443CODEN: NGAEBU; ISSN:1752-0894. (Nature Publishing Group)
    Photolysis of nitrous acid generates hydroxyl radicals-a key atm. oxidant-in the lower atm. Significant concns. of nitrous acid have been reported in the rural atm. boundary layer during the day, where photolysis of nitrous acid accounts for up to 42% of sunlight-induced radical prodn. The obsd. concns. of nitrous acid are thought to be sustained by heterogeneous reactions involving precursors such as nitrogen oxides and nitric acid. Here, we present direct measurements of nitrous acid flux over a rural forest canopy in Michigan, together with surface nitrate loading at the top of the canopy. We report a significant upward flux of nitrous acid during the day, with a peak around noontime. Daytime nitrous acid flux was pos. correlated with the product of leaf surface nitrate loading and the rate const. of nitrate photolysis. We suggest that the photolysis of nitric acid on forest canopies is a significant daytime source of nitrous acid to the lower atm. in rural environments, and could serve as an important pathway for the remobilization of deposited nitric acid.
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    Andersen, S. T.; Carpenter, L. J.; Reed, C.; Lee, J. D.; Chance, R.; Sherwen, T.; Vaughan, A. R.; Stewart, J.; Edwards, P. M.; Bloss, W. J.; Sommariva, R.; Crilley, L. R.; Nott, G. J.; Neves, L.; Read, K.; Heard, D. E.; Seakins, P. W.; Whalley, L. K.; Boustead, G. A.; Fleming, L. T.; Stone, D.; Fomba, K. W. Extensive field evidence for the release of HONO from the photolysis of nitrate aerosols. Science Advances 2023, 9 (3), eadd6266  DOI: 10.1126/sciadv.add6266
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    Ye, C.; Zhou, X.; Pu, D.; Stutz, J.; Festa, J.; Spolaor, M.; Tsai, C.; Cantrell, C.; Mauldin Iii, R. L.; Weinheimer, A.; Hornbrook, R. S.; Apel, E. C.; Guenther, A.; Kaser, L.; Yuan, B.; Karl, T.; Haggerty, J.; Hall, S.; Ullmann, K.; Smith, J.; Ortega, J. Tropospheric HONO distribution and chemistry in the southeastern US. Atmos. Chem. Phys. 2018, 18 (12), 9107– 9120,  DOI: 10.5194/acp-18-9107-2018
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    Chai, J.; Dibb, J. E.; Anderson, B. E.; Bekker, C.; Blum, D. E.; Heim, E.; Jordan, C. E.; Joyce, E. E.; Kaspari, J. H.; Munro, H.; Walters, W. W.; Hastings, M. G. Isotopic constraints on wildfire derived HONO. Atmospheric Chemistry and Physics Discussion 2021,  DOI: 10.5194/acp-2021-225
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    Romer, P. S.; Wooldridge, P. J.; Crounse, J. D.; Kim, M. J.; Wennberg, P. O.; Dibb, J. E.; Scheuer, E.; Blake, D. R.; Meinardi, S.; Brosius, A. L.; Thames, A. B.; Miller, D. O.; Brune, W. H.; Hall, S. R.; Ryerson, T. B.; Cohen, R. C. Constraints on Aerosol Nitrate Photolysis as a Potential Source of HONO and NO x. Environ. Sci. Technol. 2018, 52 (23), 13738– 13746,  DOI: 10.1021/acs.est.8b03861
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    Constraints on Aerosol Nitrate Photolysis as a Potential Source of HONO and NOx
    Romer, Paul S.; Wooldridge, Paul J.; Crounse, John D.; Kim, Michelle J.; Wennberg, Paul O.; Dibb, Jack E.; Scheuer, Eric; Blake, Donald R.; Meinardi, Simone; Brosius, Alexandra L.; Thames, Alexander B.; Miller, David O.; Brune, William H.; Hall, Samuel R.; Ryerson, Thomas B.; Cohen, Ronald C.
    Environmental Science & Technology (2018), 52 (23), 13738-13746CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    The concn. of nitrogen oxides (NOx) plays a central role in controlling air quality. On a global scale, the primary sink of NOx is oxidn. to form HNO3. Gas-phase HNO3 photolyses slowly with a lifetime in the troposphere of 10 days or more. However, several recent studies examg. HONO chem. have proposed that particle-phase HNO3 undergoes photolysis 10-300 times more rapidly than gas-phase HNO3. We present here constraints on the rate of particle-phase HNO3 photolysis based on observations of NOx and HNO3 collected over the Yellow Sea during the KORUS-AQ study in summer 2016. The fastest proposed photolysis rates are inconsistent with the obsd. NOx to HNO3 ratios. Negligible to moderate enhancements of the HNO3 photolysis rate in particles, 1-30 times faster than in the gas phase, are most consistent with the observations. Small or moderate enhancement of particle-phase HNO3 photolysis would not significantly affect the HNO3 budget but could help explain observations of HONO and NOx in highly aged air.
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    Pusede, S. E.; VandenBoer, T. C.; Murphy, J. G.; Markovic, M. Z.; Young, C. J.; Veres, P. R.; Roberts, J. M.; Washenfelder, R. A.; Brown, S. S.; Ren, X.; Tsai, C.; Stutz, J.; Brune, W. H.; Browne, E. C.; Wooldridge, P. J.; Graham, A. R.; Weber, R.; Goldstein, A. H.; Dusanter, S.; Griffith, S. M.; Stevens, P. S.; Lefer, B. L.; Cohen, R. C. An Atmospheric Constraint on the NO2 Dependence of Daytime Near-Surface Nitrous Acid (HONO). Environ. Sci. Technol. 2015, 49 (21), 12774– 12781,  DOI: 10.1021/acs.est.5b02511
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    An Atmospheric Constraint on the NO2 Dependence of Daytime Near-Surface Nitrous Acid (HONO)
    Pusede, Sally E.; Vanden Boer, Trevor C.; Murphy, Jennifer G.; Markovic, Milos Z.; Young, Cora J.; Veres, Patrick R.; Roberts, James M.; Washenfelder, Rebecca A.; Brown, Steven S.; Ren, Xinrong; Tsai, Catalina; Stutz, Jochen; Brune, William H.; Browne, Eleanor C.; Wooldridge, Paul J.; Graham, Ashley R.; Weber, Robin; Goldstein, Allen H.; Dusanter, Sebastien; Griffith, Stephen M.; Stevens, Philip S.; Lefer, Barry L.; Cohen, Ronald C.
    Environmental Science & Technology (2015), 49 (21), 12774-12781CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    Recent observations suggest a large and unknown daytime source of nitrous acid (HONO) to the atm. Multiple mechanisms have been proposed, many of which involve chem. that reduces nitrogen dioxide (NO2) on some time scale. To examine the NO2 dependence of the daytime HONO source, we compare weekday and weekend measurements of NO2 and HONO in two U.S. cities. We find that daytime HONO does not increase proportionally to increases in same-day NO2, i.e., the local NO2 concn. at that time and several hours earlier. We discuss various published HONO formation pathways in the context of this constraint.
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    Yang, Y.; Li, X.; Zu, K.; Lian, C.; Chen, S.; Dong, H.; Feng, M.; Liu, H.; Liu, J.; Lu, K.; Lu, S.; Ma, X.; Song, D.; Wang, W.; Yang, S.; Yang, X.; Yu, X.; Zhu, Y.; Zeng, L.; Tan, Q.; Zhang, Y. Elucidating the effect of HONO on O3 pollution by a case study in southwest China. Sci. Total Environ. 2021, 756, 144127  DOI: 10.1016/j.scitotenv.2020.144127
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    Elucidating the effect of HONO on O3 pollution by a case study in southwest China
    Yang, Yiming; Li, Xin; Zu, Kexin; Lian, Chaofan; Chen, Shiyi; Dong, Huabin; Feng, Miao; Liu, Hefan; Liu, Jingwei; Lu, Keding; Lu, Sihua; Ma, Xuefei; Song, Danlin; Wang, Weigang; Yang, Suding; Yang, Xinping; Yu, Xuena; Zhu, Yuan; Zeng, Limin; Tan, Qinwen; Zhang, Yuanhang
    Science of the Total Environment (2021), 756 (), 144127CODEN: STENDL; ISSN:0048-9697. (Elsevier B.V.)
    Photolysis of nitrous acid (HONO) is one of the major sources for atm. hydroxyl radicals (OH), playing significant role in initiating tropospheric photochem. reactions for ozone (O3) prodn. However, scarce field investigations were conducted to elucidate this effect. In this study, a field campaign was conducted at a suburban site in southwest China. The whole observation was classified into three periods based on O3 levels and data coverage: the serious O3 pollution period (Aug 13-18 as P1), the O3 pollution period (Aug 22-28 as P2) and the clean period (Sep 3-12 as P3), with av. O3 peak values of 96 ppb, 82 ppb and 44 ppb, resp. There was no significant difference of the levels of O3 precursors (VOCs and NOx) between P1 and P2, and thus the evident elevation of OH peak values in P1 was suspected to be the most possible explanation for the higher O3 peak values. Considering the larger contribution of HONO photolysis to HOX primary prodn. than photolysis of HCHO, O3 and ozonolysis of Alkenes, sensitivity tests of HONO redn. on O3 prodn. rate in P1 are conducted by a 0-dimension model. Reduced HONO concn. effectively slows the O3 prodn. in the morning, and such effect correlates with the calcd. prodn. rate of OH radicals from HONO photolysis. Higher HONO level supplying for OH radical initiation in the early morning might be the main reason for the higher O3 peak values in P1, which explained the correlation (R2 = 0.51) between av. O3 value during daytime (10:00-19:00 LT) and av. HONO value during early morning (00:00-05:00 LT). For nighttime accumulation, a suitable range of relative humidity that favored NO2 conversion within P1 was assumed to be the reason for the higher HONO concn. in the following early morning which promoted O3 peak values.
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    Liu, Y.; Lu, K.; Li, X.; Dong, H.; Tan, Z.; Wang, H.; Zou, Q.; Wu, Y.; Zeng, L.; Hu, M.; Min, K. E.; Kecorius, S.; Wiedensohler, A.; Zhang, Y. A Comprehensive Model Test of the HONO Sources Constrained to Field Measurements at Rural North China Plain. Environ. Sci. Technol. 2019, 53 (7), 3517– 3525,  DOI: 10.1021/acs.est.8b06367
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    A Comprehensive Model Test of the HONO Sources Constrained to Field Measurements at Rural North China Plain
    Liu, Yuhan; Lu, Keding; Li, Xin; Dong, Huabin; Tan, Zhaofeng; Wang, Haichao; Zou, Qi; Wu, Yusheng; Zeng, Limin; Hu, Min; Min, Kyung-Eun; Kecorius, Simonas; Wiedensohler, Alfred; Zhang, Yuanhang
    Environmental Science & Technology (2019), 53 (7), 3517-3525CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    Since HONO photolysis is an important source of OH-, apportionment of ambient HONO sources is necessary to better understand atm. oxidn. Based on data HONO-related species and various parameters measured during a one-month campaign at Wangdu rural site on the North China Plain in summer 2014, a box model was adopted, including current literature parametrization inputs for various HONO sources (NO2 heterogeneous conversion, photo-enhanced conversion, photolysis of adsorbed HNO3 and particulate NO3-, acid displacement, soil emissions) to show the relative importance of each source at this rural site. Simulation results reproduced obsd. HONO prodn. rates at noon in general, but with large uncertainty from prodn. and destruction terms. NO2 photo-enhanced conversion and particulate NO3- photolysis were the major mechanisms with large potential of HONO formation, but the assocd. uncertainty may reduce their importance to be nearly negligible. Soil NP2- were an important HONO source during fertilization periods, accounting for 80±6% of simulation HONO at noon. For some biomass burning episodes, only NO2 heterogeneously converted to HONO was significantly promoted. In summary, the HONO budget is still far from closed, which would require a significant effort to accurately measure HONO and det. related kinetic parameters for its prodn. pathways.
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    Ge, Y.; Shi, X.; Ma, Y.; Zhang, W.; Ren, X.; Zheng, J.; Zhang, Y. Seasonality of nitrous acid near an industry zone in the Yangtze River Delta region of China: Formation mechanisms and contribution to the atmospheric oxidation capacity. Atmos. Environ. 2021, 254, 118420,  DOI: 10.1016/j.atmosenv.2021.118420
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    Shi, X.; Ge, Y.; Zheng, J.; Ma, Y.; Ren, X.; Zhang, Y. Budget of nitrous acid and its impacts on atmospheric oxidative capacity at an urban site in the central Yangtze River Delta region of China. Atmos. Environ. 2020, 238, 117725,  DOI: 10.1016/j.atmosenv.2020.117725
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    Budget of nitrous acid and its impacts on atmospheric oxidative capacity at an urban site in the central Yangtze River Delta region of China
    Shi, Xiaowen; Ge, Yifeng; Zheng, Jun; Ma, Yan; Ren, Xinrong; Zhang, Yuchan
    Atmospheric Environment (2020), 238 (), 117725CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Ltd.)
    In this study, we used a wet chem. based long-path absorption spectroscopy method to measure HONO in Changzhou, in the central Yangtze River Delta region (YRD) of China, from Apr. 3-24, 2017. During the observation period, the av. HONO mixing ratio was 1.55 ± 1.21 ppbv. In addn., the av. OH formation rates of the photolysis of HONO, O3, HCHO and H2O2 along with ozonolysis of alkenes were 7.84 x 106, 2.02 x 107, 7.41 x 105, 3.79 x 105 and 1.51 x 106 mols. cm-3 s-1, resp. At nighttime, the av. conversion rate from NO2 to HONO was detd. to be ∼0.018 h-1. In this work, the primary emission rate of HONO was detd. by the ratios of HONO to nitrogen oxides (NOx = NO + NO2) within freshly emitted plumes (NO/NOx > 0.85) and a value of ∼0.69% was obtained. The sources of HONO were further investigated through a box model utilizing the Master Chem. Mechanism. The simulation results show that primary emissions contributed only ∼12.3% of the total HONO budget during daytime but a substantial portion (31.4%) at night. Comparing to heterogeneous HONO sources, the gas-phase NO + OH reaction was the less important HONO source, with a contribution of 14.2% at night and 28.7% during the daytime. Overall, nighttime HONO can be reasonably explained by aforementioned mechanisms.
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    Nie, W.; Ding, A. J.; Xie, Y. N.; Xu, Z.; Mao, H.; Kerminen, V. M.; Zheng, L. F.; Qi, X. M.; Huang, X.; Yang, X. Q.; Sun, J. N.; Herrmann, E.; Petäjä, T.; Kulmala, M.; Fu, C. B. Influence of biomass burning plumes on HONO chemistry in eastern China. Atmospheric Chemistry and Physics 2015, 15 (3), 1147– 1159,  DOI: 10.5194/acp-15-1147-2015
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    Peng, Q.; Palm, B. B.; Fredrickson, C. D.; Lee, B. H.; Hall, S. R.; Ullmann, K.; Weinheimer, A. J.; Levin, E.; DeMott, P.; Garofalo, L. A.; Pothier, M. A.; Farmer, D. K.; Fischer, E. V.; Thornton, J. A. Direct Constraints on Secondary HONO Production in Aged Wildfire Smoke From Airborne Measurements Over the Western US. Geophys. Res. Lett. 2022, 49 (15), e2022GL098704  DOI: 10.1029/2022GL098704
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    Chai, J.; Miller, D. J.; Scheuer, E.; Dibb, J.; Selimovic, V.; Yokelson, R.; Zarzana, K. J.; Brown, S. S.; Koss, A. R.; Warneke, C.; Hastings, M. Isotopic characterization of nitrogen oxides (NOx), nitrous acid (HONO), and nitrate (pNO3−) from laboratory biomass burning during FIREX. Atmos. Meas. Technol. 2019, 12 (12), 6303– 6317,  DOI: 10.5194/amt-12-6303-2019
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    Scharko, N. K.; Berke, A. E.; Raff, J. D. Release of nitrous acid and nitrogen dioxide from nitrate photolysis in acidic aqueous solutions. Environ. Sci. Technol. 2014, 48 (20), 11991– 12001,  DOI: 10.1021/es503088x
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    Release of Nitrous Acid and Nitrogen Dioxide from Nitrate Photolysis in Acidic Aqueous Solutions
    Scharko, Nicole K.; Berke, Andrew E.; Raff, Jonathan D.
    Environmental Science & Technology (2014), 48 (20), 11991-12001CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    Nitrate (NO3‾) is an abundant component of aerosols, boundary layer surface films, and surface water. Photolysis of NO3‾ leads to NO2 and HONO, both of which play important roles in tropospheric ozone and OH prodn. Field and lab. studies suggest that NO3‾ photochem. is a more important source of HONO than once thought, although a mechanistic understanding of the variables controlling this process is lacking. We present results of cavity-enhanced absorption spectroscopy measurements of NO2 and HONO emitted during photodegrdn. of aq. NO3‾ under acidic conditions. Nitrous acid is formed in higher quantities at pH 2-4 than expected based on consideration of primary photochem. channels alone. Both exptl. and modeled results indicate that the addnl. HONO is not due to enhanced NO3‾ absorption cross sections or effective quantum yields, but rather to secondary reactions of NO2 in soln. We find that NO2 is more efficiently hydrolyzed in soln. when it is generated in situ during NO3‾ photolysis than for the heterogeneous system where mass transfer of gaseous NO2 into bulk soln. is prohibitively slow. The presence of nonchromophoric OH scavengers that are naturally present in the environment increases HONO prodn. 4-fold, and therefore play an important role in enhancing daytime HONO formation from NO3‾ photochem.
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    Shi, X.; Nenes, A.; Xiao, Z.; Song, S.; Yu, H.; Shi, G.; Zhao, Q.; Chen, K.; Feng, Y.; Russell, A. G. High-Resolution Data Sets Unravel the Effects of Sources and Meteorological Conditions on Nitrate and Its Gas-Particle Partitioning. Environ. Sci. Technol. 2019, 53 (6), 3048– 3057,  DOI: 10.1021/acs.est.8b06524
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    High-Resolution Data Sets Unravel the Effects of Sources and Meteorological Conditions on Nitrate and Its Gas-Particle Partitioning
    Shi, Xurong; Nenes, Athanasios; Xiao, Zhimei; Song, Shaojie; Yu, Haofei; Shi, Guoliang; Zhao, Qianyu; Chen, Kui; Feng, Yinchang; Russell, Armistead G.
    Environmental Science & Technology (2019), 53 (6), 3048-3057CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    Nitrate is 1 of the most abundant inorg. H2O-sol. ions in fine particulate matter (PM2.5). However, the formation mechanism of nitrate in the ambient atm., esp. the impacts of its semivolatility and the various existing forms of N, remain under-studied. Hourly ambient observations of speciated PM2.5 components (NO3-, SO42-, etc.) were collected in Tianjin, China. Source contributions were analyzed by PMF/ME2 (Pos. Matrix Factorization using the Multilinear Engine 2) program, and pH were estd. by ISORROPIA-II, to study the relation between pH and nitrate. Five sources (factors) were resolved: secondary sulfate (SS), secondary nitrate (SN), dust, vehicle and coal combustion. SN and pH showed a triangle-shaped relation. When SS was high, the fraction of nitrate partitioning into the aerosol phase exhibits a characteristic S-curve relation with pH for different seasons. An index (ITL) is developed and combined with pH to explore the sensitive regions of S-curve. Controlling the emissions of (SO42-, Cl-), cations (Ca2+, Mg2+, etc.) and gases (NOx, NH3, SO2, etc.) will change pH, potentially reducing or increasing SN. The findings of this work provide an effective approach for exploring the formation mechanisms of nitrate under different influencing factors (sources, pH, and IRL).
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    Park, J. Y.; Lee, Y. N. Solubility and decomposition kinetics of nitrous acid in aqueous solution. J. Phys. Chem. 1988, 92 (22), 6294– 6302,  DOI: 10.1021/j100333a025
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    Solubility and decomposition kinetics of nitrous acid in aqueous solution
    Park, Jong Yoon; Lee, Yin Nan
    Journal of Physical Chemistry (1988), 92 (22), 6294-302CODEN: JPCHAX; ISSN:0022-3654.
    The Henry's law soly. and the decompn. reaction kinetics of HNO2 in aq. solns. were studied by measuring the distribution of species between the gas and liq. phases by using a bubbler-type gas-liq. reactor in conjunction with a high-sensitivity chemiluminescence NOx detector. The pH-dependent soly. of N(III) (≡HNO2 + NO2-) was measured at pH 2.13-3.33. The Henry's law coeff. and the acid dissocn. const. of HNO2 at 25° 49 ± 3 M/atm and (5.3 ± 0.4) × 10-4 M, resp. The temp. dependence of the soly. at 0-30° yields ΔH°soln. = -9.7 ± 0.3 kcal/mol and ΔS°soln. = -24.8 ± 0.7 cal/mol.K. The rate consts. of the aq.-phase reactions, 2HNO2 ↹ NO + NO2 + H2O and 2NO2 + H2O → H+ + NO3- + HNO2 at 22.0 ± 0.1° were detd. The present ΔG°soln. and ΔS°soln. for HNO2 dissoln. are at variance with the latest values recommended by the National Bureau of Stds., essentially identical with the previously selected set of values. The rather limited soly. of HNO2, in combination with its low atm. concn., suggest that HNO2 by itself contributes insignificantly to the acidification of atm. water, e.g., cloud water. However, aq.-phase reactions that produce HNO2 followed by degassing remain a plausible route for the prodn. of atm. HNO2.
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    Mora Garcia, S. L.; Pandit, S.; Navea, J. G.; Grassian, V. H. Nitrous Acid (HONO) Formation from the Irradiation of Aqueous Nitrate Solutions in the Presence of Marine Chromophoric Dissolved Organic Matter: Comparison to Other Organic Photosensitizers. ACS Earth and Space Chemistry 2021, 5 (11), 3056– 3064,  DOI: 10.1021/acsearthspacechem.1c00292
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    Nitrous Acid (HONO) Formation from the Irradiation of Aqueous Nitrate Solutions in the Presence of Marine Chromophoric Dissolved Organic Matter: Comparison to Other Organic Photosensitizers
    Mora Garcia, Stephanie L.; Pandit, Shubhrangshu; Navea, Juan G.; Grassian, Vicki H.
    ACS Earth and Space Chemistry (2021), 5 (11), 3056-3064CODEN: AESCCQ; ISSN:2472-3452. (American Chemical Society)
    Nitrous acid (HONO), a highly reactive trace atm. gas, is often underestimated in global atm. models due to the poor understanding of its sources and sinks, esp. in the marine boundary layer (MBL). Herein, we have investigated HONO formation from the irradn. of nitrate solns. in the presence of increasingly complex photosensitizers including marine dissolved org. matter (m-DOM), which contains chromophoric org. matter, collected from a large-scale mesocosm expt. In particular, aq. nitrate solns. in the presence of m-DOM, humic acid (HA), and 4-benzoylbenzoic acid (4-BBA) as well as ethylene glycol (EG) were irradiated with a solar simulator. Gas-phase HONO and NO2 produced during the irradn. of these samples were detected using incoherent broad band cavity enhanced absorption spectroscopy (IBBCEAS). The relative amts. of HONO and NO2 formation varied for the different samples. The addn. of all of these different org. contg. samples (m-DOM, HA, 4-BBA, and EG) to nitrate solns. caused an enhancement in HONO formation, with m-DOM showing the greatest total amt. over a 6 h time period. Mechanisms for this enhancement are discussed as well as the strong pH dependence, with the greatest amt. of HONO at a low pH. Overall, HONO formation from nitrate photolysis in the presence of m-DOM provides insights into the HONO formation pathway in the MBL and ultimately contributes to improving atm. models.
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    VandenBoer, T. C.; Markovic, M. Z.; Sanders, J. E.; Ren, X.; Pusede, S. E.; Browne, E. C.; Cohen, R. C.; Zhang, L.; Thomas, J.; Brune, W. H.; Murphy, J. G. Evidence for a nitrous acid (HONO) reservoir at the ground surface in Bakersfield, CA, during CalNex 2010. Journal of Geophysical Research: Atmospheres 2014, 119 (14), 9093– 9106,  DOI: 10.1002/2013JD020971
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    Lee, Y.; Huey, L. G.; Wang, Y.; Qu, H.; Zhang, R.; Ji, Y.; Tanner, D. J.; Wang, X.; Tang, J.; Song, W.; Hu, W.; Zhang, Y. Photochemistry of Volatile Organic Compounds in the Yellow River Delta, China: Formation of O3 and Peroxyacyl Nitrates. Journal of Geophysical Research: Atmospheres 2021, 126 (23), e2021JD035296  DOI: 10.1029/2021JD035296
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    Chong, K.; Wang, Y.; Liu, C.; Gao, Y.; Boersma, K. F.; Tang, J.; Wang, X. Remote Sensing Measurements at a Rural Site in China: Implications for Satellite NO2 and HCHO Measurement Uncertainty and Emissions From Fires. Journal of Geophysical Research: Atmospheres 2024, 129 (2), e2023JD039310  DOI: 10.1029/2023JD039310
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    Kleffmann, J.; Heland, J.; Kurtenbach, R.; Lörzer, J. C.; Wiesen, P. A new instrument (LOPAP) for the detection of nitrous acid (HONO). Environ. Sci. Pollut. Res. 2002, 9, 48– 54
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    Heland, J.; Kleffmann, J.; Kurtenbach, R.; Wiesen, P. A New Instrument To Measure Gaseous Nitrous Acid (HONO) in the Atmosphere. Environ. Sci. Technol. 2001, 35 (15), 3207– 3212,  DOI: 10.1021/es000303t
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    A New Instrument To Measure Gaseous Nitrous Acid (HONO) in the Atmosphere
    Heland, Joerg; Kleffmann, Joerg; Kurtenbach, Ralf; Wiesen, Peter
    Environmental Science and Technology (2001), 35 (15), 3207-3212CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    A new in situ instrument (LOPAP: long path absorption photometer) to measure gaseous nitrous acid (HONO) using wet chem. sampling and photometric detection was developed. This instrument is aimed to overcome the known problems with current HONO measurement techniques and was designed to be a cheap, sensitive, compact, and continuously working HONO monitor for ambient air measurements in the troposphere or for measurements of higher concns. e.g. in smog chambers, in exhaust gases, and in indoor environments. Lab. studies were carried out to characterize the instrument components with respect to collection efficiency, optimum dye formation, optimum detection, and interfering species. Detection limits ranging from ∼3 to 50 pptV were obtained with response times from 4 to 1.5 min, resp., using different instrument parameters. The accuracy of the measurements is in the range between ±(10-15)%. The validation of the instrument was performed in the lab. for HONO concns. of 3 and 30 ppbV using ion chromatog. and with a DOAS (differential optical absorption spectrometer) instrument in a large outdoor smog chamber at 0.1-20 ppbV. The deviations were well within the errors of the measurements; however, when comparing the data with the DOAS instrument systematically higher values were found with the LOPAP instrument.
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    Kleffmann, J.; Lörzer, J. C.; Wiesen, P.; Kern, C.; Trick, S.; Volkamer, R.; Rodenas, M.; Wirtz, K. Intercomparison of the DOAS and LOPAP techniques for the detection of nitrous acid (HONO). Atmos. Environ. 2006, 40 (20), 3640– 3652,  DOI: 10.1016/j.atmosenv.2006.03.027
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    Intercomparison of the DOAS and LOPAP techniques for the detection of nitrous acid (HONO)
    Kleffmann, J.; Loerzer, J. C.; Wiesen, P.; Kern, C.; Trick, S.; Volkamer, R.; Rodenas, M.; Wirtz, K.
    Atmospheric Environment (2006), 40 (20), 3640-3652CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Ltd.)
    Recent studies demonstrated HNO2 is a source of OH- in the atm. boundary layer early in the morning and throughout the day. Despite its importance, all known instruments to detect HNO2 in the atm. suffer from great exptl. effort necessary or the possibility of significant interferences. Also, only a few instruments are sensitive enough to detect low HNO2 concns. during the day. Validated, sensitive HNO2 measurements are of paramount importance to describe the oxidn. capacity of the atm. Until now, inter-comparisons of these chem. detectors with the well-accepted DOAS (differential optical absorption spectroscopy) method exhibited significantly higher concns. in the day; the discrepancy was attributed to interferences. In this work, a recently developed HNO2 long-path absorption photometer instrument (LOPAP) was validated against the DOAS method in the field and in a large smog chamber under various conditions. Since sample artifacts were minimized and interferences were measured and cor. for by the LOPAP instrument, excellent agreement was obtained between these methods during the day and at night. It was demonstrated that chem. instruments, which do not measure and do not correct interferences, may significantly overestimate daytime HNO2 concns. caused by unknown interferences, particularly important during the day, when HNO2 concns. are low. Using the DOAS method, the possibility of HNO2 impurities in the NO2 ref. spectra used for the spectral anal. must be treated actively during the evaluation to avoid a potential neg. interference at low HNO2:NO2 ratios. A simple procedure is presented to eliminate this possible error source in atm. HNO2 DOAS measurements.
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    Reed, C.; Brumby, C. A.; Crilley, L. R.; Kramer, L. J.; Bloss, W. J.; Seakins, P. W.; Lee, J. D.; Carpenter, L. J. HONO measurement by differential photolysis. Atmos. Meas. Technol. 2016, 9 (6), 2483– 2495,  DOI: 10.5194/amt-9-2483-2016
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    Liu, Z.; Wang, Y.; Gu, D.; Zhao, C.; HUEY, L. G.; STICKEL, R.; LIAO, J.; Shao, M.; Zhu, T.; Zeng, L.; Liu, S.-C.; CHANG, C.-C.; AMOROSO, A.; COSTABILE, F. Evidence of Reactive Aromatics As a Major Source of Peroxy Acetyl Nitrate over China. Environ. Sci. Technol. 2010, 44, 7017,  DOI: 10.1021/es1007966
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    Evidence of Reactive Aromatics As a Major Source of Peroxy Acetyl Nitrate over China
    Liu, Zhen; Wang, Yuhang; Gu, Dasa; Zhao, Chun; Huey, L. Gregory; Stickel, Robert; Liao, Jin; Shao, Min; Zhu, Tong; Zeng, Limin; Liu, Shaw-Chen; Chang, Chih-Chung; Amoroso, Antonio; Costabile, Francesca
    Environmental Science & Technology (2010), 44 (18), 7017-7022CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    Observations of near-surface peroxy acetyl nitrate (PAN) and its precursor compds. in air over Beijing, China, Aug. 2007 were analyzed. PAN concns. were remarkably high (≤14 ppbv), surpassing those measured over other urban regions in recent years. Analyses using a 1-dimensional version of a chem. transport model (REAM, regional chem. and transport model) indicated arom. non-methane hydrocarbons (NMHC) were the dominant (55-75%) PAN source. The major arom. oxidn. product which produces acetyl peroxy radicals was methylglyoxal (MGLY). Obsd. PAN and O3 concns. were correlated in the daytime; arom. NMHC appeared to play an important role in O3 photochem. Previous NMHC measurements indicated the presence of reactive aroms. at high concns. over broad polluted regions in China. Aroms. are often ignored in global and, to a lesser degree, regional 3-dimensional photochem. transport models; their emissions and photochem. over China are quite uncertain. Results suggested crit. assessments of arom. emissions and chem., e.g., MGLY yields, are necessary to understand and assess O3 photochem. and regional pollution export over China.
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    Zhang, Y.; Wang, Y.; Chen, G.; Smeltzer, C.; Crawford, J.; Olson, J.; Szykman, J.; Weinheimer, A. J.; Knapp, D. J.; Montzka, D. D.; Wisthaler, A.; Mikoviny, T.; Fried, A.; Diskin, G. Large vertical gradient of reactive nitrogen oxides in the boundary layer: Modeling analysis of DISCOVER-AQ 2011 observations. Journal of Geophysical Research: Atmospheres 2016, 121 (4), 1922– 1934,  DOI: 10.1002/2015JD024203
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    Li, J.; Wang, Y.; Zhang, R.; Smeltzer, C.; Weinheimer, A.; Herman, J.; Boersma, K. F.; Celarier, E. A.; Long, R. W.; Szykman, J. J.; Delgado, R.; Thompson, A. M.; Knepp, T. N.; Lamsal, L. N.; Janz, S. J.; Kowalewski, M. G.; Liu, X.; Nowlan, C. R. Comprehensive evaluations of diurnal NO2 measurements during DISCOVER-AQ 2011: effects of resolution-dependent representation of NOx emissions. Atmos. Chem. Phys. 2021, 21 (14), 11133– 11160,  DOI: 10.5194/acp-21-11133-2021
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    Heterogeneous NO2 conversion processes acid surfaces: possible atmospheric implications
    Kleffmann, J.; Becker, K. H.; Wiesen, P.
    Atmospheric Environment (1998), 32 (16), 2721-2729CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Science Ltd.)
    The heterogeneous conversion of NO2 on water/H2SO4 surfaces was studied in a quartz reactor and a bubbler system. NO2 decay and the HONO formation are first order in [NO2] and are limited by an uptake coeff., γ ≈ 10-6. It was obsd. that HONO formation on acid/water surfaces of moderate acidity only occurs via the reaction 2 NO2 + H2O → HNO3. Involvement of NO on the HONO formation is of minor importance. HONO formation rates calcd. from results of this study at high aerosol load are of the same order of magnitude as obsd. HONO formation rates in the troposphere. Possible HONO formation on stratospheric aerosol by the parallel reaction of NO2 with H2SO4 (cH2SO4 >60 wt. percent) could explain, at least in part, obsd. stratospheric OH radical formation in the morning shortly after sunrise.
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    Wang, Y.; Wang, J.; Wang, Y.; Zhang, Y.; Woodward-Massey, R.; Zhang, C.; Kuang, Y.; Zhu, J.; Shang, J.; Li, X.; Zeng, L.; Lin, W.; Ye, C. Experimental and kinetic model evaluation of HONO production from surface nitrate photolysis. Atmos. Environ. 2023, 296, 119568  DOI: 10.1016/j.atmosenv.2022.119568
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    Tang, M.-X.; He, L.-Y.; Xia, S.-Y.; Jiang, Z.; He, D.-Y.; Guo, S.; Hu, R.-Z.; Zeng, H.; Huang, X.-F. Coarse particles compensate for missing daytime sources of nitrous acid and enhance atmospheric oxidation capacity in a coastal atmosphere. Science of The Total Environment 2024, 915, 170037  DOI: 10.1016/j.scitotenv.2024.170037
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    Song, M.; Zhao, X.; Liu, P.; Mu, J.; He, G.; Zhang, C.; Tong, S.; Xue, C.; Zhao, X.; Ge, M.; Mu, Y. Atmospheric NOx oxidation as major sources for nitrous acid (HONO). npj Climate and Atmospheric Science 2023, 6 (1), 30,  DOI: 10.1038/s41612-023-00357-8
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    Stemmler, K.; Ndour, M.; Elshorbany, Y.; Kleffmann, J.; D’Anna, B.; George, C.; Bohn, B.; Ammann, M. Light induced conversion of nitrogen dioxide into nitrous acid on submicron humic acid aerosol. Atmos. Chem. Phys. 2007, 7 (16), 4237– 4248,  DOI: 10.5194/acp-7-4237-2007
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    Light induced conversion of nitrogen dioxide into nitrous acid on submicron humic acid aerosol
    Stemmler, K.; Ndour, M.; Elshorbany, Y.; Kleffmann, J.; D'Anna, B.; George, C.; Bohn, B.; Ammann, M.
    Atmospheric Chemistry and Physics (2007), 7 (16), 4237-4248CODEN: ACPTCE; ISSN:1680-7316. (Copernicus Publications)
    The interactions of aerosols consisting of humic acids with gaseous NO2 were investigated under different light conditions in aerosol flow tube expts. at ambient pressure and temp. The results show that NO2 is converted on the humic acid aerosol into HONO, which is released from the aerosol and can be detected in the gas phase at the reactor exit. The formation of HONO on the humic acid aerosol is strongly activated by light: in the dark, the HONO-formation was below the detection limit, but it was increasing with the intensity of the irradn. with visible light. Under simulated atm. conditions with respect to the actinic flux, relative humidity and NO2-concn., reactive uptake coeffs. γrxn for the NO2 → HONO conversion on the aerosol between γrxn <10-7 (in the dark) and γrxn = 6 × 10-6 were obsd. The obsd. uptake coeffs. decreased with increasing NO2-concn. in the range from 2.7 to 280 ppb and were dependent on the relative humidity (RH) with slightly reduced values at low humidity (<20% RH) and high humidity (>60% RH). The measured uptake coeffs. for the NO2 → HONO conversion are too low to explain the HONO-formation rates obsd. near the ground in rural and urban environments by the conversion of NO2 → HONO on org. aerosol surfaces, even if one would assume that all aerosols consist of humic acid only. It is concluded that the processes leading to HONO formation on the Earth surface will have a much larger impact on the HONO-formation in the lowermost layer of the troposphere than humic materials potentially occurring in airborne particles.
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    Zhang, J.; Lian, C.; Wang, W.; Ge, M.; Guo, Y.; Ran, H.; Zhang, Y.; Zheng, F.; Fan, X.; Yan, C.; Daellenbach, K. R.; Liu, Y.; Kulmala, M.; An, J. Amplified role of potential HONO sources in O3 formation in North China Plain during autumn haze aggravating processes. Atmos. Chem. Phys. 2022, 22 (5), 3275– 3302,  DOI: 10.5194/acp-22-3275-2022
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    Amplified role of potential HONO sources in O3 formation in North China Plain during autumn haze aggravating processes
    Zhang, Jingwei; Lian, Chaofan; Wang, Weigang; Ge, Maofa; Guo, Yitian; Ran, Haiyan; Zhang, Yusheng; Zheng, Feixue; Fan, Xiaolong; Yan, Chao; Daellenbach, Kaspar R.; Liu, Yongchun; Kulmala, Markku; An, Junling
    Atmospheric Chemistry and Physics (2022), 22 (5), 3275-3302CODEN: ACPTCE; ISSN:1680-7324. (Copernicus Publications)
    Co-occurrences of high concns. of PM2.5 and ozone (O3) have been frequently obsd. in haze-aggravating processes in the North China Plain (NCP) over the past few years. Higher O3 concns. on hazy days were hypothesized to be related to nitrous acid (HONO), but the key sources of HONO enhancing O3 during haze-aggravating processes remain unclear. We added six potential HONO sources, i.e., four ground-based (traffic, soil, and indoor emissions, and the NO2 heterogeneous reaction on ground surface (Hetground)) sources, and two aerosol-related (the NO2 heterogeneous reaction on aerosol surfaces (Hetaerosol) and nitrate photolysis (Photnitrate)) sources into the WRF-Chem model and designed 23 simulation scenarios to explore the unclear key sources. The results indicate that ground-based HONO sources producing HONO enhancements showed a rapid decrease with height, while the NO + OH reaction and aerosol-related HONO sources decreased slowly with height. Photnitrate contributions to HONO concns. were enhanced with aggravated pollution levels. The enhancement of HONO due to Photnitrate on hazy days was about 10 times greater than on clean days and Photnitrate dominated daytime HONO sources (~ 30%-70% when the ratio of the photolysis frequency of nitrate (Jnitrate) to gas nitric acid (JHNO3) equals 30) at higher layers (>800 m). Compared with that on clean days, the Photnitrate contribution to the enhanced daily max. 8 h averaged (DMA8) O3was increased by over 1 magnitude during the haze-aggravating process. Photnitrate contributed only ∼ 5% of the surface HONO in the daytime with a Jnitrate/JHNO3 ratio of 30 but contributed ∼ 30%-50% of the enhanced O3near the surface in NCP on hazy days. Surface O3was dominated by volatile org. compd.-sensitive chem., while O3at higher altitudes (>800 m) was dominated by NOx-sensitive chem. Photnitrate had a limited impact on nitrate concns. (<15%) even with a Jnitrate/JHNO3 ratio of 120. These results suggest the potential but significant impact of Photnitrate on O3formation, and that more comprehensive studies on Photnitrate in the atm. are still needed.
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    Han, C.; Yang, W.; Wu, Q.; Yang, H.; Xue, X. Heterogeneous Photochemical Conversion of NO2 to HONO on the Humic Acid Surface under Simulated Sunlight. Environ. Sci. Technol. 2016, 50 (10), 5017– 5023,  DOI: 10.1021/acs.est.5b05101
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    Heterogeneous Photochemical Conversion of NO2 to HONO on the Humic Acid Surface under Simulated Sunlight
    Han, Chong; Yang, Wangjin; Wu, Qianqian; Yang, He; Xue, Xiangxin
    Environmental Science & Technology (2016), 50 (10), 5017-5023CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    The poor understanding of HONO sources in the daytime highlights the importance of the heterogeneous photochem. reaction of NO2 with aerosol or soil surfaces. The conversion of NO2 to HONO on humic acid (HA) under simulated sunlight was investigated using a flow tube reactor at ambient pressure. The uptake coeff. (γ) of NO2 linearly increased with irradn. intensity and HA mass in the range of 0-2.0 μg/cm2, while it decreased with the NO2 concn. The HONO yield was found to be independent of irradn. intensity, HA mass, and NO2 concn. The temp. (278-308 K) had little influence on both γ and HONO yield. Addnl., γ increased continuously with relative humidity (RH, 7-70%), and a max. HONO yield was obsd. at 40% RH. The heterogeneous photochem. reaction of NO2 with HA was explained by the Langmuir-Hinshelwood mechanism.
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    Li, X.; Brauers, T.; Häseler, R.; Bohn, B.; Fuchs, H.; Hofzumahaus, A.; Holland, F.; Lou, S.; Lu, K. D.; Rohrer, F.; Hu, M.; Zeng, L. M.; Zhang, Y. H.; Garland, R. M.; Su, H.; Nowak, A.; Wiedensohler, A.; Takegawa, N.; Shao, M.; Wahner, A. Exploring the atmospheric chemistry of nitrous acid (HONO) at a rural site in Southern China. Atmospheric Chemistry and Physics 2012, 12 (3), 1497– 1513,  DOI: 10.5194/acp-12-1497-2012
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    Gu, R.; Zheng, P.; Chen, T.; Dong, C.; Wang, Y. n; Liu, Y.; Liu, Y.; Luo, Y.; Han, G.; Wang, X.; Zhou, X.; Wang, T.; Wang, W.; Xue, L. Atmospheric nitrous acid (HONO) at a rural coastal site in North China: Seasonal variations and effects of biomass burning. Atmos. Environ. 2020, 229, 117429,  DOI: 10.1016/j.atmosenv.2020.117429
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    Atmospheric nitrous acid (HONO) at a rural coastal site in North China: Seasonal variations and effects of biomass burning
    Gu, Rongrong; Zheng, Penggang; Chen, Tianshu; Dong, Can; Wang, Ya'nan; Liu, Yiming; Liu, Yuhong; Luo, Yuanyuan; Han, Guangxuan; Wang, Xinfeng; Zhou, Xuehua; Wang, Tao; Wang, Wenxing; Xue, Likun
    Atmospheric Environment (2020), 229 (), 117429CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Ltd.)
    Nitrous acid (HONO) plays a significant role in atm. chem. due to its contribution to hydroxyl radical (OH). However, no scientific consensus has been achieved about the daytime HONO formation mechanisms. To identify the seasonal variations of HONO chem. and the impacts of biomass burning (BB), we performed a two-phased field study in winter-spring and summer (covering a harvest season) in 2017 at a rural coastal site in North China. Though the mean HONO concn. in winter-spring (0.26 ± 0.28 ppbv) was higher than in summer (0.17 ± 0.19 ppbv), the max. HONO concns. were comparable (∼2 ppbv) in the two campaigns. Both the HONO/NOx ratio and nocturnal heterogeneous conversion efficiency of HONO (CHONO) in summer were over twice of that in winter-spring. The daytime budget anal. also revealed that the strength of Pother (i.e., the HONO sources apart from the reaction of OH + NO) in summer was double of that in winter-spring. BB affected the HONO concn. by enhancing the contribution of heterogeneous HONO prodn. on the aerosol surface but weakening the role of photo-related HONO formation. HONO photolysis was a significant source of OH in both winter-spring and summer, and its contribution could be further enhanced during the BB episode in summer.
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    Yang, J.; Shen, H.; Guo, M.-Z.; Zhao, M.; Jiang, Y.; Chen, T.; Liu, Y.; Li, H.; Zhu, Y.; Meng, H.; Wang, W.; Xue, L. Strong marine-derived nitrous acid (HONO) production observed in the coastal atmosphere of northern China. Atmos. Environ. 2021, 244, 117948,  DOI: 10.1016/j.atmosenv.2020.117948
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    Strong marine-derived nitrous acid (HONO) production observed in the coastal atmosphere of northern China
    Yang, Juan; Shen, Hengqing; Guo, Ming-Zhi; Zhao, Min; Jiang, Ying; Chen, Tianshu; Liu, Yuhong; Li, Hongyong; Zhu, Yujiao; Meng, He; Wang, Wenxing; Xue, Likun
    Atmospheric Environment (2021), 244 (), 117948CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Ltd.)
    Despite its important roles in the formation of hydroxyl radical (OH) and ozone (O3), the characteristics and sources of nitrous acid (HONO) in the marine atm. are still poorly understood. In this study, the HONO prodn. in maritime air masses was explored based on a field observation conducted at a coastal site in Qingdao, China in the summer of 2019. The "sea case" and the "land case" were carefully distinguished according to wind direction and backward air mass trajectory. About four times larger nocturnal NO2-to-HONO conversion rate and ∼60% larger daytime Pother (prodn. rate of HONO other than gas-phase OH + NO reaction) at noon were obsd. in the "sea case" compared to the "land case" (0.045 ± 0.014 h-1 vs. 0.012 ± 0.007 h-1, and 1.83± 0.02 ppbv h-1 vs. 1.14 ± 0.07 ppbv h-1, resp.). Correlation anal. implied that heterogeneous conversion of NO2 and photolysis of nitrogen-contg. compds. were potentially important sources of marine atm. HONO in the nocturnal and daytime, resp., though alk. oceans are previously considered as sinks of HONO. The impacts of these marine-derived HONO on OH and O3 were comparable to or larger than that of the "land case". These results suggest that strong marine-derived HONO prodn. may have been overlooked previously, and more studies are required to explore its detailed formation mechanisms in the marine atm.
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    Cui, L.; Li, R.; Fu, H.; Li, Q.; Zhang, L.; George, C.; Chen, J. Formation features of nitrous acid in the offshore area of the East China Sea. Sci. Total Environ. 2019, 682, 138– 150,  DOI: 10.1016/j.scitotenv.2019.05.004
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    Cui, Lulu; Li, Rui; Fu, Hongbo; Li, Qing; Zhang, Liwu; George, Christian; Chen, Jianmin
    Science of the Total Environment (2019), 682 (), 138-150CODEN: STENDL; ISSN:0048-9697. (Elsevier B.V.)
    Nitrous acid (HONO) is an important precursor of hydroxyl radical (OH), which plays a key role in atm. chem. A shipboard-based measurement of HONO and related species in the offshore area of the East China Sea (ECS) was performed during June 2017. The HONO concn. ranged from 35 ppt to 1.95 ppb, with an av. value of 0.44 ± 0.25 ppb during the entire campaign. HONO displayed a relatively higher level (0.48 ± 0.21 ppb) in the area within 30 km from the coastline (S1), whereas a lower level (0.40 ± 0.18 ppb) in the area between 30 km and 100 km from the coastline (S2). Five distinct hotspots of HONO were identified, including Ningbo Port, Yangshan Port, the Yangtze River estuary, northwest of the Zhoushan city, and the area adjacent to Jinshan Chem. Industry Park, suggesting the impact of local vessel emissions and land industrial emissions on HONO formation. During the nighttime, the direct vessel emissions contributed on av. 18% of the HONO concn. The averaged conversion frequency of NO2-to-HONO (khet) estd. from 6 nighttime cases was 1.18 × 10-2 h-1. Daytime budget anal. showed that the unknown HONO prodn. rate (Punknown) in S1 and S2 was 1.52 ppb h-1 and 1.14 ppb h-1, resp. Punknown was related to a light-induced HONO source from NO2 on the sea surface and particulate nitrate. During the cruise campaign, the averaged daytime OH prodn. rate from HONO photolysis was 1.35 ± 0.69 ppb h-1, ∼1.6 times higher than that from the O3 photolysis (0.87 ± 0.55 ppb h-1), which suggested an important role of HONO in the atm. chem. of the offshore area of ECS.
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    Lee, J. D.; Whalley, L. K.; Heard, D. E.; Stone, D.; Dunmore, R. E.; Hamilton, J. F.; Young, D. E.; Allan, J. D.; Laufs, S.; Kleffmann, J. Detailed budget analysis of HONO in central London reveals a missing daytime source. Atmospheric Chemistry and Physics 2016, 16 (5), 2747– 2764,  DOI: 10.5194/acp-16-2747-2016
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    Detailed budget analysis of HONO in central London reveals a missing daytime source
    Lee, J. D.; Whalley, L. K.; Heard, D. E.; Stone, D.; Dunmore, R. E.; Hamilton, J. F.; Young, D. E.; Allan, J. D.; Laufs, S.; Kleffmann, J.
    Atmospheric Chemistry and Physics (2016), 16 (5), 2747-2764CODEN: ACPTCE; ISSN:1680-7324. (Copernicus Publications)
    Measurements of HONO were carried out at an urban background site near central London as part of the Clean air for London (ClearfLo) project in summer 2012. Data were collected from 22 July to 18 August 2014, with peak values of up to 1.8 ppbV at night and non-zero values of between 0.2 and 0.6 ppbV seen during the day. A wide range of other gas phase, aerosol, radiation, and meteorol. measurements were made concurrently at the same site, allowing a detailed anal. of the chem. to be carried out. The peak HONO=NOx ratio of 0.04 is seen at ∼02:00 UTC, with the presence of a second, daytime, peak in HONO=NOx of similar magnitude to the night-time peak, suggesting a significant secondary daytime HONO source. A photostationary state calcn. of HONO involving formation from the reaction of OH and NO and loss from photolysis, reaction with OH, and dry deposition shows a significant underestimation during the day, with calcd. values being close to 0, compared to the measurement av. of 0.4 ppbV at midday. The addn. of further HONO sources from the literature, including dark conversion of NOx on surfaces, direct emission, photolysis of ortho-substituted nitrophenols, the postulated formation from the reaction of HO2 × H2O with NO2, photolysis of adsorbed HNO3 on ground and aerosols, and HONO produced by photosensitized conversion of NO2 on the surface increases the daytime modelled HONO to 0.1 ppbV, still leaving a significant missing daytime source. The missing HONO is plotted against a series of parameters including NO2 and OH reactivity (used as a proxy for org. material), with little correlation seen. Much better correlation is obsd. with the product of these species with j(NO2), in particular NO2 and the product of NO2 with OH reactivity. This suggests the missing HONO source is in some way related to NO2 and also requires sunlight. Increasing the photo-sensitized surface conversion rate of NO2 by a factor of 10 to a mean daytime first-order loss of ∼6 × 10-5 s-1 (but which varies as a function of j(NO2)) closes the daytime HONO budget at all times (apart from the late afternoon), suggesting that urban surfaces may enhance this photosensitized source. The effect of the missing HONO to OH radical prodn. is also investigated and it is shown that the model needs to be constrained to measured HONO in order to accurately reproduce the OH radical measurements.
  88. 88
    Zha, Q.; Xue, L.; Wang, T.; Xu, Z.; Yeung, C.; Louie, P. K. K.; Luk, C. W. Y. Large conversion rates of NO2 to HNO2 observed in air masses from the South China Sea: Evidence of strong production at sea surface?. Geophys. Res. Lett. 2014, 41 (21), 7710– 7715,  DOI: 10.1002/2014GL061429
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    88
    Large conversion rates of NO2 to HNO2 observed in air masses from the South China Sea: Evidence of strong production at sea surface?
    Zha, Qiaozhi; Xue, Likun; Wang, Tao; Xu, Zheng; Yeung, Chungpong; Louie, Peter K. K.; Luk, Connie W. Y.
    Geophysical Research Letters (2014), 41 (21), 7710-7715CODEN: GPRLAJ; ISSN:1944-8007. (Wiley-Blackwell)
    Nitrous acid (HONO) plays important roles in tropospheric chem., but its source(s) are not completely understood. Here, we analyze measurements of HONO, nitrogen dioxide (NO2), and related parameters at a coastal site in Hong Kong during Sept.-Dec. 2012. The nocturnal NO2-to-HONO conversion rates were estd. in air masses passing over land and sea surfaces. The conversion rates in the "sea cases" (3.17-3.36 × 10-2 h-1) were significantly higher than those in the "land cases" in our study (1.20-1.30 × 10-2 h-1) and in previous studies by others. These results suggest that air-sea interactions may be a significant source of atm. HONO and need to be considered in chem. transport models.
  89. 89
    Liu, X.; Ran, L.; Lin, W.; Xu, X.; Ma, Z.; Dong, F.; He, D.; Zhou, L.; Shi, Q.; Wang, Y. Measurement report: Variations in surface SO2 and NOx mixing ratios from 2004 to 2016 at a background site in the North China Plain. Atmos. Chem. Phys. 2022, 22 (10), 7071– 7085,  DOI: 10.5194/acp-22-7071-2022
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    Chen, J.; Li, C.; Ristovski, Z.; Milic, A.; Gu, Y.; Islam, M. S.; Wang, S.; Hao, J.; Zhang, H.; He, C.; Guo, H.; Fu, H.; Miljevic, B.; Morawska, L.; Thai, P.; Lam, Y. F.; Pereira, G.; Ding, A.; Huang, X.; Dumka, U. C. A review of biomass burning: Emissions and impacts on air quality, health and climate in China. Sci. Total Environ. 2017, 579, 1000– 1034,  DOI: 10.1016/j.scitotenv.2016.11.025
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    90
    A review of biomass burning: Emissions and impacts on air quality, health and climate in China
    Chen, Jianmin; Li, Chunlin; Ristovski, Zoran; Milic, Andelija; Gu, Yuantong; Islam, Mohammad S.; Wang, Shuxiao; Hao, Jiming; Zhang, Hefeng; He, Congrong; Guo, Hai; Fu, Hongbo; Miljevic, Branka; Morawska, Lidia; Thai, Phong; Lam, Yun Fat; Pereira, Gavin; Ding, Aijun; Huang, Xin; Dumka, Umesh C.
    Science of the Total Environment (2017), 579 (), 1000-1034CODEN: STENDL; ISSN:0048-9697. (Elsevier B.V.)
    A comprehensive review of biomass burning (BB) emissions and their impacts on air quality, human health, and climate in China is given. including literature concerning field measurements, lab. studies and the impacts of BB indoors and outdoors in China. It attempted to provide a basis for policy-makers to formulate policies and regulations. Topics discussed include: introduction; BB monitoring (field observations, satellite remote sensing, lab. studies, BB campaigns); BB types (forest fire, agricultural straw open burning, wood and straw combustion as fuel, misc.); BB pollutants (particulate matter [carbonaceous, other important components], smoke particle phys. properties [size distribution, hygroscopicity, d., volatility, optical properties], morphol. and mixing state, gaseous pollutants, polycyclic arom. hydrocarbons, emission trends and control); BB plumes (transport, atm. aging [transmission electron microscopy plus energy-dispersive x-ray spectroscopy, and aerosol mass spectrometry approaches, O3 formation from BB emissions]); BB impacts (severe haze episodes, air quality impacts [annual and seasonal properties, BB episode impact assessment], health, climate and weather); research priorities and insights (field campaigns, aging, health and climate).
  91. 91
    Yuan, B.; Liu, Y.; Shao, M.; Lu, S.; Streets, D. G. Biomass Burning Contributions to Ambient VOCs Species at a Receptor Site in the Pearl River Delta (PRD), China. Environ. Sci. Technol. 2010, 44 (12), 4577– 4582,  DOI: 10.1021/es1003389
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    91
    Biomass burning contributions to ambient VOCs species at a receptor site in the Pearl River Delta (PRD), China
    Yuan, Bin; Liu, Ying; Shao, Min; Lu, Sihua; Streets, David G.
    Environmental Science & Technology (2010), 44 (12), 4577-4582CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    Ambient VOCs were measured by a proton transfer reaction-mass spectrometer (PTR-MS) at a receptor site in the Pearl River Delta (PRD), China during Oct. 19-Nov. 18, 2008. Biomass burning plumes are identified by using acetonitrile as tracer, and enhancement ratios of 9 VOCs species relative to acetonitrile are obtained from linear regression anal. and the source-tracer-ratio method. Enhancement ratios detd. by the 2 different methods show good agreement for most VOCs species. Biomass burning contributions are investigated by using the source-tracer-ratio method. Biomass burning contributed 9.5%-17.7% to mixing ratios of the 9 VOCs. The estd. biomass burning contributions are compared with local emission inventories. Large discrepancies are obsd. between our results and the ests. in 2 emission inventories. Though biomass burning emissions in TRACE-P inventory agree well with our results, the VOCs speciation for arom. compds. may be not appropriate for Guangdong.
  92. 92
    Juncosa Calahorrano, J. F.; Lindaas, J.; O’Dell, K.; Palm, B. B.; Peng, Q.; Flocke, F.; Pollack, I. B.; Garofalo, L. A.; Farmer, D. K.; Pierce, J. R.; Collett, J. L.; Weinheimer, A.; Campos, T.; Hornbrook, R. S.; Hall, S. R.; Ullmann, K.; Pothier, M. A.; Apel, E. C.; Permar, W.; Hu, L.; Hills, A. J.; Montzka, D.; Tyndall, G.; Thornton, J. A.; Fischer, E. V. Daytime Oxidized Reactive Nitrogen Partitioning in Western U.S. Wildfire Smoke Plumes. Journal of Geophysical Research: Atmospheres 2021, 126 (4), e2020JD033484,  DOI: 10.1029/2020JD033484
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    Hughes, D. D.; Christiansen, M. B.; Milani, A.; Vermeuel, M. P.; Novak, G. A.; Alwe, H. D.; Dickens, A. F.; Pierce, R. B.; Millet, D. B.; Bertram, T. H.; Stanier, C. O.; Stone, E. A. PM2.5 chemistry, organosulfates, and secondary organic aerosol during the 2017 Lake Michigan Ozone Study. Atmos. Environ. 2021, 244, 117939,  DOI: 10.1016/j.atmosenv.2020.117939
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    93
    PM2.5 chemistry, organosulfates, and secondary organic aerosol during the 2017 Lake Michigan Ozone Study
    Hughes, Dagen D.; Christiansen, Megan B.; Milani, Alissa; Vermeuel, Michael P.; Novak, Gordon A.; Alwe, Hariprasad D.; Dickens, Angela F.; Pierce, R. Bradley; Millet, Dylan B.; Bertram, Timothy H.; Stanier, Charles O.; Stone, Elizabeth A.
    Atmospheric Environment (2021), 244 (), 117939CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Ltd.)
    The Lake Michigan Ozone Study from 21 May to 23 June 2017 (LMOS 2017) aimed to better understand the anthropogenic and biogenic sources that contribute to ozone and fine particles (PM2.5) along the coast of Lake Michigan. Here, we focus on the chem. compn. of daytime and nighttime PM2.5-esp. org. carbon, inorg. ions and organosulfates-at a ground-based supersite in Zion, Illinois. PM2.5 mass concns. ranged from 1.5 to 12.9 μg m-3 with an av. (±std. error) of 5.2 ± 0.4 μg m-3. The most significant contributor to PM2.5 mass was org. matter (OM; calcd. as 1.7 x org. carbon [OC]; contributing an av. of 59 ± 2%), followed by sulfate (17± 1%), ammonium (6.3 ± 0.3%), nitrate (3.5 ± 0.4%), and elemental carbon (EC; 3.4± 0.2%). During each of the three periods of high ozone, PM2.5 had different regional characteristics. Period A (2-3 June) was impacted by lake breeze and south-easterly air masses that travelled over major urban areas. Period A had the highest daily PM2.5 mass concns. (11.4 ± 1.5 μg m-3) and EC with a relatively low OC:EC ratio of 7.0, indicating the influence of sources with low OC:EC ratios, which includes the anthropogenic combustion of fossil fuels and biomass. Period B (10-13 June) was impacted by air masses traveling from the southern US. It had a relatively high OC:EC ratio of 18, the highest PM2.5 sulfate concns. and aerosol acidity, and elevated mixing ratios of isoprene along with its oxidn. products Me vinyl ketone (MVK) and methacrolein (MACR). Peak concns. of organosulfates, including methyltetrol sulfate (m/z 215; C5H11SO-7), were also obsd. throughout period B. Period C (13-17 June) followed a change to northerly winds. PM2.5 concns. decreased along with decreases in sulfate, acidity, and most organosulfates. Throughout the study, organosulfates accounted for an av. of 4% of OM and up to 15% of OM in Period B. Organosulfates were largely isoprene-derived, with lessor contributions from monoterpenes (0.3%) and anthropogenic sources (0.5%). Through these measurements of organosulfates in the Great Lakes region, we demonstrate the importance of anthropogenic sulfate emissions and aerosol acidity on SOA formation, and establish that isoprene-derived organosulfates, in particular, contribute significantly to PM2.5. With other LMOS observations, the chem. signatures of PM2.5, and back trajectories show that ozone episodes cooccur with localized lake-breeze meteorol. within air masses that vary from episode to episode in chem. history and source region.
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    Lindaas, J.; Pollack, I. B.; Garofalo, L. A.; Pothier, M. A.; Farmer, D. K.; Kreidenweis, S. M.; Campos, T. L.; Flocke, F.; Weinheimer, A. J.; Montzka, D. D.; Tyndall, G. S.; Palm, B. B.; Peng, Q.; Thornton, J. A.; Permar, W.; Wielgasz, C.; Hu, L.; Ottmar, R. D.; Restaino, J. C.; Hudak, A. T.; Ku, I. T.; Zhou, Y.; Sive, B. C.; Sullivan, A.; Collett, J. L.; Fischer, E. V. Emissions of Reactive Nitrogen From Western U.S. Wildfires During Summer 2018. Journal of Geophysical Research: Atmospheres 2021, 126 (2), e2020JD032657,  DOI: 10.1029/2020JD032657
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    Peng, Q.; Palm, B. B.; Melander, K. E.; Lee, B. H.; Hall, S. R.; Ullmann, K.; Campos, T.; Weinheimer, A. J.; Apel, E. C.; Hornbrook, R. S.; Hills, A. J.; Montzka, D. D.; Flocke, F.; Hu, L.; Permar, W.; Wielgasz, C.; Lindaas, J.; Pollack, I. B.; Fischer, E. V.; Bertram, T. H.; Thornton, J. A. HONO Emissions from Western U.S. Wildfires Provide Dominant Radical Source in Fresh Wildfire Smoke. Environ. Sci. Technol. 2020, 54, 5954,  DOI: 10.1021/acs.est.0c00126
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    95
    HONO Emissions from Western U.S. Wildfires Provide Dominant Radical Source in Fresh Wildfire Smoke
    Peng, Qiaoyun; Palm, Brett B.; Melander, Kira E.; Lee, Ben H.; Hall, Samuel R.; Ullmann, Kirk; Campos, Teresa; Weinheimer, Andrew J.; Apel, Eric C.; Hornbrook, Rebecca S.; Hills, Alan J.; Montzka, Denise D.; Flocke, Frank; Hu, Lu; Permar, Wade; Wielgasz, Catherine; Lindaas, Jakob; Pollack, Ilana B.; Fischer, Emily V.; Bertram, Timothy H.; Thornton, Joel A.
    Environmental Science & Technology (2020), 54 (10), 5954-5963CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    Wildfires are an important source of HONO, a photo-labile radical precursor, yet in-situ measurements and quantification of primary HONO emissions from open wildfires are scarce. Airborne observations of HONO within wildfire plumes sampled during the Western Wildfire Expt. for Cloud Chem., Aerosol Absorption and Nitrogen (WE-CAN) campaign were obsd. ΔHONO:ΔCO ratios close to fire locations were 0.7-17 pptv/ppbv, using a max. enhancement method, with a median similar to previous observations of temperate forest fire plumes. Measured HONO:NOx enhancement ratios were generally factors of 2 or higher at early plume ages vs. previous studies. Enhancement ratios scaled with modified combustion efficiency and certain nitrogenous trace gases, which may be useful to est. HONO release when HONO observations are lacking or plumes have photochem. exposures >1 h, since emitted HONO is rapidly photolyzed. HONO photolysis was the dominant contributor to hydrogen oxide radicals (HOx = OH- + HO2) in the early stage (<3 h) wildfire plume evolution. Results highlighted the HONO role as a major component of reactive N emissions from wildfires and the main driver of initial photochem. oxidn.
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    Xu, R.; Li, X.; Dong, H.; Wu, Z.; Chen, S.; Xin, F.; Gao, J.; Guo, S.; Hu, M.; Li, D.; Liu, Y.; Liu, Y.; Lou, S.; Lu, K.; Meng, X.; Wang, H.; Zeng, L.; Zong, T.; Hu, J.; Zhang, Y. Measurement of gaseous and particulate formaldehyde in the Yangtze River Delta, China. Atmos. Environ. 2020, 224, 117114  DOI: 10.1016/j.atmosenv.2019.117114
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    Brock, C. A.; Cozic, J.; Bahreini, R.; Froyd, K. D.; Middlebrook, A. M.; McComiskey, A.; Brioude, J.; Cooper, O. R.; Stohl, A.; Aikin, K. C.; de Gouw, J. A.; Fahey, D. W.; Ferrare, R. A.; Gao, R. S.; Gore, W.; Holloway, J. S.; Hübler, G.; Jefferson, A.; Lack, D. A.; Lance, S.; Moore, R. H.; Murphy, D. M.; Nenes, A.; Novelli, P. C.; Nowak, J. B.; Ogren, J. A.; Peischl, J.; Pierce, R. B.; Pilewskie, P.; Quinn, P. K.; Ryerson, T. B.; Schmidt, K. S.; Schwarz, J. P.; Sodemann, H.; Spackman, J. R.; Stark, H.; Thomson, D. S.; Thornberry, T.; Veres, P.; Watts, L. A.; Warneke, C.; Wollny, A. G. Characteristics, sources, and transport of aerosols measured in spring 2008 during the aerosol, radiation, and cloud processes affecting Arctic Climate (ARCPAC) Project. Atmospheric Chemistry and Physics 2011, 11 (6), 2423– 2453,  DOI: 10.5194/acp-11-2423-2011
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    Hecobian, A.; Liu, Z.; Hennigan, C. J.; Huey, L. G.; Jimenez, J. L.; Cubison, M. J.; Vay, S.; Diskin, G. S.; Sachse, G. W.; Wisthaler, A.; Mikoviny, T.; Weinheimer, A. J.; Liao, J.; Knapp, D. J.; Wennberg, P. O.; Kürten, A.; Crounse, J. D.; Clair, J. S.; Wang, Y.; Weber, R. J. Comparison of chemical characteristics of 495 biomass burning plumes intercepted by the NASA DC-8 aircraft during the ARCTAS/CARB-2008 field campaign. Atmos. Chem. Phys. 2011, 11 (24), 13325– 13337,  DOI: 10.5194/acp-11-13325-2011
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    Comparison of chemical characteristics of 495 biomass burning plumes intercepted by the NASA DC-8 aircraft during the ARCTAS/CARB-2008 field campaign
    Hecobian, A.; Liu, Z.; Hennigan, C. J.; Huey, L. G.; Jimenez, J. L.; Cubison, M. J.; Vay, S.; Diskin, G. S.; Sachse, G. W.; Wisthaler, A.; Mikoviny, T.; Weinheimer, A. J.; Liao, J.; Knapp, D. J.; Wennberg, P. O.; Kurten, A.; Crounse, J. D.; St. Clair, J.; Wang, Y.; Weber, R. J.
    Atmospheric Chemistry and Physics (2011), 11 (24, Pt. 2), 13325-13337CODEN: ACPTCE; ISSN:1680-7316. (Copernicus Publications)
    This paper compares measurements of gaseous and particulate emissions from a wide range of biomass-burning plumes intercepted by the NASA DC-8 research aircraft during the three phases of the ARCTAS-2008 expt.: ARCTAS-A, based out of Fairbanks, Alaska, USA (3 Apr. to 19 Apr. 2008); ARCTAS-B based out of Cold Lake, Alberta, Canada (29 June to 13 July 2008); and ARCTAS-CARB, based out of Palmdale, California, USA (18 June to 24 June 2008). Approx. 500 smoke plumes from biomass burning emissions that varied in age from minutes to days were segregated by fire source region and urban emission influences. The normalized excess mixing ratios (NEMR) of gaseous (carbon dioxide, acetonitrile, hydrogen cyanide, toluene, benzene, methane, oxides of nitrogen and ozone) and fine aerosol particulate components (nitrate, sulfate, ammonium, chloride, org. aerosols and water sol. org. carbon) of these plumes were compared. A detailed statistical anal. of the different plume categories for different gaseous and aerosol species is presented in this paper. The comparison of NEMR values showed that CH4 concns. were higher in air-masses that were influenced by urban emissions. Fresh biomass burning plumes mixed with urban emissions showed a higher degree of oxidative processing in comparison with fresh biomass burning only plumes. This was evident in higher concns. of inorg. aerosol components such as sulfate, nitrate and ammonium, but not reflected in the org. components. Lower NOx NEMRs combined with high sulfate, nitrate and ammonium NEMRs in aerosols of plumes subject to long-range transport, when comparing all plume categories, provided evidence of advanced processing of these plumes.
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    Pandit, S.; Grassian, V. H. Gas-Phase Nitrous Acid (HONO) Is Controlled by Surface Interactions of Adsorbed Nitrite (NO2−) on Common Indoor Material Surfaces. Environ. Sci. Technol. 2022, 56 (17), 12045– 12054,  DOI: 10.1021/acs.est.2c02042
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    Zhang, Q.; Wang, Y.; Liu, M.; Zheng, M.; Yuan, L.; Liu, J.; Tao, S.; Wang, X. Wintertime Formation of Large Sulfate Particles in China and Implications for Human Health. Environ. Sci. Technol. 2023, 57, 20010,  DOI: 10.1021/acs.est.3c05645
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    Zheng, M.; Wang, Y.; Bao, J.; Yuan, L.; Zheng, H.; Yan, Y.; Liu, D.; Xie, M.; Kong, S. Initial Cost Barrier of Ammonia Control in Central China. Geophys. Res. Lett. 2019, 46 (23), 14175– 14184,  DOI: 10.1029/2019GL084351
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    Zhang, W.; Tong, S.; Jia, C.; Wang, L.; Liu, B.; Tang, G.; Ji, D.; Hu, B.; Liu, Z.; Li, W.; Wang, Z.; Liu, Y.; Wang, Y.; Ge, M. Different HONO Sources for Three Layers at the Urban Area of Beijing. Environ. Sci. Technol. 2020, 54 (20), 12870– 12880,  DOI: 10.1021/acs.est.0c02146
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    Different HONO sources for three layers at the urban area of Beijing
    Zhang, Wenqian; Tong, Shengrui; Jia, Chenhui; Wang, Lili; Liu, Baoxian; Tang, Guiqian; Ji, Dongsheng; Hu, Bo; Liu, Zirui; Li, Weiran; Wang, Zhen; Liu, Yang; Wang, Yuesi; Ge, Maofa
    Environmental Science & Technology (2020), 54 (20), 12870-12880CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    Gaseous nitrous acid (HONO) is a crucial precursor of the hydroxyl (OH) radical, which is a "detergent" in the atm. Nowadays, HONO formation mechanisms at polluted urban areas are controversial, which restricts the understanding of atm. oxidative capacity and radical cycling. Herein, multiday vertical observation of HONO and NOx was simultaneously performed at three heights at the urban area of Beijing for the first time. The vertical distribution of HONO was often unexpected, and it had the highest HONO concn. at 120 m, followed by those at 8 and 240 m. 0D box model simulations suggest that ground and aerosol surfaces might play similar roles in NO2 conversion at 8 m during the whole measurement. NO2 conversion on aerosol surfaces was the most important HONO source aloft during haze days. At daytime, a strong missing HONO source unexpectedly existed in the urban aloft, and it was relevant to solar radiation and consumed OH.
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    Jiang, Y.; Xue, L.; Shen, H.; Dong, C.; Xiao, Z.; Wang, W. Dominant Processes of HONO Derived from Multiple Field Observations in Contrasting Environments. Environmental Science & Technology Letters 2022, 9 (4), 258– 264,  DOI: 10.1021/acs.estlett.2c00004
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    Ye, C.; Zhou, X.; Pu, D.; Stutz, J.; Festa, J.; Spolaor, M.; Tsai, C.; Cantrell, C.; Mauldin, R. L., 3rd; Campos, T.; Weinheimer, A.; Hornbrook, R. S.; Apel, E. C.; Guenther, A.; Kaser, L.; Yuan, B.; Karl, T.; Haggerty, J.; Hall, S.; Ullmann, K.; Smith, J. N.; Ortega, J.; Knote, C. Rapid cycling of reactive nitrogen in the marine boundary layer. Nature 2016, 532 (7600), 489– 491,  DOI: 10.1038/nature17195
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    Rapid cycling of reactive nitrogen in the marine boundary layer
    Ye, Chunxiang; Zhou, Xianliang; Pu, Dennis; Stutz, Jochen; Festa, James; Spolaor, Max; Tsai, Catalina; Cantrell, Christopher; Mauldin, Roy L.; Campos, Teresa; Weinheimer, Andrew; Hornbrook, Rebecca S.; Apel, Eric C.; Guenther, Alex; Kaser, Lisa; Yuan, Bin; Karl, Thomas; Haggerty, Julie; Hall, Samuel; Ullmann, Kirk; Smith, James N.; Ortega, John; Knote, Christoph
    Nature (London, United Kingdom) (2016), 532 (7600), 489-491CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)
    NOx are essential for the formation of secondary atm. aerosols and of atm. oxidants such as ozone and the hydroxyl radical, which controls the self-cleansing capacity of the atm. Nitric acid, a major oxidn. product of NOx, has traditionally been considered to be a permanent sink of NOx. However, model studies predict higher ratios of nitric acid to NOx in the troposphere than are obsd. A renoxification process that recycles nitric acid into NOx has been proposed to reconcile observations with model studies, but the mechanisms responsible for this process remain uncertain. We present data from an aircraft measurement campaign over the North Atlantic Ocean and find evidence for rapid recycling of nitric acid to nitrous acid and NOx in the clean marine boundary layer via particulate nitrate photolysis. Lab. expts. further demonstrate the photolysis of particulate nitrate collected on filters at a rate >2 orders of magnitude greater than that of gaseous nitric acid, with nitrous acid as the main product. Box model calcns. based on the Master Chem. Mechanism suggest that particulate nitrate photolysis mainly sustains the obsd. levels of nitrous acid and NOx at midday under typical marine boundary layer conditions. Given that oceans account for >70% of Earth's surface, we propose that particulate nitrate photolysis could be a substantial tropospheric NOx source. Recycling of NOx in remote oceanic regions with minimal direct NOx emissions could increase the formation of tropospheric oxidants and secondary atm. aerosols on a global scale.
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    Ramazan, K. A.; Wingen, L. M.; Miller, Y.; Chaban, G. M.; Gerber, R. B.; Xantheas, S. S.; Finlayson-Pitts, B. J. New Experimental and Theoretical Approach to the Heterogeneous Hydrolysis of NO2: Key Role of Molecular Nitric Acid and Its Complexes. J. Phys. Chem. A 2006, 110 (21), 6886– 6897,  DOI: 10.1021/jp056426n
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    105
    New Experimental and Theoretical Approach to the Heterogeneous Hydrolysis of NO2: Key Role of Molecular Nitric Acid and Its Complexes
    Ramazan, K. A.; Wingen, L. M.; Miller, Y.; Chaban, G. M.; Gerber, R. B.; Xantheas, S. S.; Finlayson-Pitts, B. J.
    Journal of Physical Chemistry A (2006), 110 (21), 6886-6897CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
    Although heterogeneous chem. on surfaces in the troposphere is known to be important, there are currently only a few techniques available to study the nature of surface-adsorbed species and their chem. and photochem. under atm. conditions of 1 atm pressure and in the presence of water vapor. A lab. approach using a combination of long path Fourier transform IR spectroscopy (FTIR) and attenuated total reflectance (ATR) FTIR which allows simultaneous observation and measurement of gases and surface species is reported. Theory identified surface-adsorbed intermediates and products and estd. their relative concns. At intermediate relative humidity typical of the tropospheric boundary layer, HNO3 formed during NO2 heterogeneous hydrolysis was shown to exist as NO3- from dissocn. of HNO3 formed on the surface and as mol. HNO3. In both cases, ions and HNO3 are complexed to water mols. Upon pumping, water is selectively removed, shifting the NO3--HNO3(water)y equil. toward more dehydrated forms of HNO3 and ultimately to HNO3 dimers. Irradiating the HNO3-water film using 300-400 nm radiation generated gaseous NO; irradn. at 254 nm generated NO and HNO2, resulting in conversion of surface-adsorbed NOx into photochem.-active NOx. Results which suggest the assumption that HNO3 deposition or formation provides a permanent removal mechanism from the atm. may not be correct. A potential role of surface-adsorbed HNO3 and other species formed during heterogeneous hydrolysis of NO2 during oxidn. of orgs. on surfaces, and in the generation of gas-phase HNO2 on local to global scales, should be considered.
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    Zhou, X.; Gao, H.; He, Y.; Huang, G.; Bertman, S. B.; Civerolo, K.; Schwab, J. Nitric acid photolysis on surfaces in low-NOx environments: Significant atmospheric implications. Geophys. Res. Lett. 2003, 30 (23), 2217,  DOI: 10.1029/2003GL018620
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    HNO3/NOx Ratio in the remote troposphere during MLOPEX 2: Evidence for nitric acid reduction on carbonaceous aerosols?
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    Geophysical Research Letters (1996), 23 (19), 2609-2612CODEN: GPRLAJ; ISSN:0094-8276. (American Geophysical Union)
    The [HNO3]/[NOx] ratio is generally over-estd. by a factor of 5-10 in photochem. models in comparison to tropospheric measurements. In this study, the heterogeneous redn. of HNO3 into NO on carbonaceous aerosols [Lary et al., 1996] has been introduced in a photochem. box-model on the basis of black carbon mass densities measured during MLOPEX 2. This recycling to NOx decreases the [HNO3]/[NOx] ratio close to obsd. values. The concomitant increase in modeled NOx concn. is also in better agreement with the observations, and has substantial implications for the ozone budget in the remote atm. Large uncertainties in the est. of black carbon surface area and of accommodation coeffs. preclude definitive conclusions until more detailed measurements are carried out.
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    Evidence for renoxification in the tropical marine boundary layer
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    Atmospheric Chemistry and Physics (2017), 17 (6), 4081-4092CODEN: ACPTCE; ISSN:1680-7324. (Copernicus Publications)
    We present 2 years of NOx observations from the Cape Verde Atm. Observatory located in the tropical Atlantic boundary layer. We find that NOx mixing ratios peak around solar noon (at 20-30 pptV depending on season), which is counter to box model simulations that show a midday min. due to OH conversion of NO2 to HNO3. Prodn. of NOx via decompn. of org. nitrogen species and the photolysis of HNO3 appear insufficient to provide the obsd. noontime max. A rapid photolysis of nitrate aerosol to produce HONO and NO2, however, is able to simulate the obsd. diurnal cycle. This would make it the dominant source of NOx at this remote marine boundary layer site, overturning the previous paradigm according to which the transport of org. nitrogen species, such as PAN, is the dominant source. We show that obsd. mixing ratios (Nov.-Dec. 2015) of HONO at Cape Verde (∼3.5 pptV peak at solar noon) are consistent with this route for NOx prodn. Reactions between the nitrate radical and halogen hydroxides which have been postulated in the literature appear to improve the box model simulation of NOx. This rapid conversion of aerosol phase nitrate to NOx changes our perspective of the NOx cycling chem. in the tropical marine boundary layer, suggesting a more chem. complex environment than previously thought.
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    Kasibhatla, P.; Sherwen, T.; Evans, M. J.; Carpenter, L. J.; Reed, C.; Alexander, B.; Chen, Q.; Sulprizio, M. P.; Lee, J. D.; Read, K. A.; Bloss, W.; Crilley, L. R.; Keene, W. C.; Pszenny, A. A. P.; Hodzic, A. Global impact of nitrate photolysis in sea-salt aerosol on NOx, OH, and O3 in the marine boundary layer. Atmospheric Chemistry and Physics 2018, 18 (15), 11185– 11203,  DOI: 10.5194/acp-18-11185-2018
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    Ha, P. T. M.; Kanaya, Y.; Taketani, F.; Andrés Hernández, M. D.; Schreiner, B.; Pfeilsticker, K.; Sudo, K. Implementation of HONO into the chemistry–climate model CHASER (V4.0): roles in tropospheric chemistry. Geosci. Model Dev. 2023, 16 (3), 927– 960,  DOI: 10.5194/gmd-16-927-2023
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    Crilley, L. R.; Kramer, L. J.; Pope, F. D.; Reed, C.; Lee, J. D.; Carpenter, L. J.; Hollis, L. D. J.; Ball, S. M.; Bloss, W. J. Is the ocean surface a source of nitrous acid (HONO) in the marine boundary layer?. Atmos. Chem. Phys. 2021, 21 (24), 18213– 18225,  DOI: 10.5194/acp-21-18213-2021
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    113
    Is the ocean surface a source of nitrous acid (HONO) in the marine boundary layer?
    Crilley, Leigh R.; Kramer, Louisa J.; Pope, Francis D.; Reed, Chris; Lee, James D.; Carpenter, Lucy J.; Hollis, Lloyd D. J.; Ball, Stephen M.; Bloss, William J.
    Atmospheric Chemistry and Physics (2021), 21 (24), 18213-18225CODEN: ACPTCE; ISSN:1680-7324. (Copernicus Publications)
    Nitrous acid, HONO, is a key net photolytic precursor to OH radicals in the atm. boundary layer. As OH is the dominant atm. oxidant, driving the removal of many primary pollutants and the formation of secondary species, a quant. understanding of HONO sources is important to predict atm. oxidising capacity. While a no. of HONO formation mechanisms have been identified, recent work has ascribed significant importance to the dark, ocean-surface-mediated conversion of NO2 to HONO in the coastal marine boundary layer. In order to evaluate the role of this mechanism, here we analyze measurements of HONO and related species obtained at two contrasting coastal locations - Cabo Verde (Atlantic Ocean, denoted Cape Verde herein), representative of the clean remote tropical marine boundary layer, and Weybourne (United Kingdom), representative of semi-polluted northern European coastal waters. As expected, higher av. concns. of HONO (70 ppt) were obsd. in marine air for the more anthropogenically influenced Weybourne location compared to Cape Verde (HONO < 5 ppt). At both sites, the approx. const. HONO/NO2 ratio at night pointed to a low importance for the dark, ocean-surface-mediated conversion of NO2 into HONO, whereas the midday max. in the HONO/NO2 ratios indicated significant contributions from photo-enhanced HONO formation mechanisms (or other sources). We obtained an upper limit to the rate coeff. of dark, ocean-surface HONO-to-NO2 conversion of CHONO = 0.0011 ppb h-1 from the Cape Verde observations; this is a factor of 5 lower than the slowest rate reported previously. These results point to significant geog. variation in the predominant HONO formation mechanisms in marine environments and indicate that caution is required when extrapolating the importance of such mechanisms from individual study locations to assess regional and/or global impacts on oxidising capacity. As a significant fraction of atm. processing occurs in the marine boundary layer, particularly in the tropics, better constraint of the possible ocean surface source of HONO is important for a quant. understanding of chem. processing of primary trace gases in the global atm. boundary layer and assocd. impacts upon air pollution and climate.
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    Wang, P.; Chen, Y.; Hu, J.; Zhang, H.; Ying, Q. Attribution of Tropospheric Ozone to NOx and VOC Emissions: Considering Ozone Formation in the Transition Regime. Environ. Sci. Technol. 2019, 53 (3), 1404– 1412,  DOI: 10.1021/acs.est.8b05981
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    Attribution of Tropospheric Ozone to NOx and VOC Emissions: Considering Ozone Formation in the Transition Regime
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    An improved, three-regime (3R) O3 attribution technique for O3 source apportionment in regional chem. transport models was developed to divide the entire range of VOC-NOx-O3 formation sensitivity to VOC-limited, transition, and NOx-limited regimes, based on the value of a regime indicator, R. Threshold R values to mark the start (Rts) and end (Rte) of the transition regime are defined at the point where O3-NOx sensitivity turns from neg. to pos., and where O3-NOx sensitivity is 10 times higher than O3-VOC sensitivity. Rts and Rte are detd. using NOx and VOC sensitivity simulations in a box model with a modified SAPRC-11 mechanism. For the widely used indicator ration R = (PH2O2 + PROOH)/PHNO3, based on H2O2, HNO3 and org. hydroperoxides (ROOH) prodn. rates, recommended Rts and Rte values are 0.047 and 5.142, resp. Parameterized attribution functions, depending only on R values, were developed to apportion modeled in-situ O3 formation in the transition regime to NOx and VOC. New 3R and the traditional two-regime (2R) schemes are incorporated into the Community Multiscale Air Quality model to quantify NOx and VOC contributions to regional O3 concns. in China in Aug. 2013. The 3R approach predicted ∼5-10 ppb and up to 15 ppb higher NOx contributions to 8-h O3 over the North China Plain, Yangtze River Delta, and the Pearl River Delta vs. the 2R approach. Large differences in O3 attribution between 2R and 3R can have significant policy implications for air pollution emission controls.
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    Ye, C.; Zhou, X.; Zhang, Y.; Wang, Y.; Wang, J.; Zhang, C.; Woodward-Massey, R.; Cantrell, C.; Mauldin, R. L.; Campos, T.; Hornbrook, R. S.; Ortega, J.; Apel, E. C.; Haggerty, J.; Hall, S.; Ullmann, K.; Weinheimer, A.; Stutz, J.; Karl, T.; Smith, J. N.; Guenther, A.; Song, S. Synthesizing evidence for the external cycling of NOx in high- to low-NOx atmospheres. Nat. Commun. 2023, 14 (1), 7995,  DOI: 10.1038/s41467-023-43866-z
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    Tang, Y.; An, J.; Wang, F.; Li, Y.; Qu, Y.; Chen, Y.; Lin, J. Impacts of an unknown daytime HONO source on the mixing ratio and budget of HONO, and hydroxyl, hydroperoxyl, and organic peroxy radicals, in the coastal regions of China. Atmos. Chem. Phys. 2015, 15 (16), 9381– 9398,  DOI: 10.5194/acp-15-9381-2015
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    116
    Impacts of an unknown daytime HONO source on the mixing ratio and budget of HONO, and hydroxyl, hydroperoxyl, and organic peroxy radicals, in the coastal regions of China
    Tang, Y.; An, J.; Wang, F.; Li, Y.; Qu, Y.; Chen, Y.; Lin, J.
    Atmospheric Chemistry and Physics (2015), 15 (16), 9381-9398CODEN: ACPTCE; ISSN:1680-7324. (Copernicus Publications)
    Many field expts. have found high nitrous acid (HONO) mixing ratios in both urban and rural areas during daytime, but these high daytime HONO mixing ratios cannot be explained well by gas-phase prodn., HONO emissions, and nighttime hydrolysis conversion of nitrogen dioxide (NO2) on aerosols, suggesting that an unknown daytime HONO source (Punknown) could exist. The formula Punknown ≈ 19.60[NO2] · J(NO2) was obtained using obsd. data from 13 field expts. across the globe. The three addnl. HONO sources (i.e., the Punknown, nighttime hydrolysis conversion of NO2 on aerosols, and HONO emissions) were coupled into the WRF-Chem model (Weather Research and Forecasting model coupled with Chem.) to assess the Punknown impacts on the concns. and budgets of HONO and peroxy (hydroxyl, hydroperoxyl, and org. peroxy) radicals (ROx) (= OH + HO2 + RO2) in the coastal regions of China. Results indicated that the addnl. HONO sources produced a significant improvement in HONO and OH simulations, particularly in the daytime. High daytime av. Punknown values were found in the coastal regions of China, with a max. of 2.5 ppb h-1 in the Beijing-Tianjin-Hebei region. The Punknown produced a 60-250% increase of OH, HO2, and RO2 near the ground in the major cities of the coastal regions of China, and a 5-48% increase of OH, HO2, and RO2 in the daytime meridionalmean mixing ratios within 1000m above the ground. When the three addnl. HONO sources were included, the photolysis of HONO was the second most important source in the OH prodn. rate in Beijing, Shanghai, and Guangzhou before 10:00 LST with a max. of 3.72 ppb h-1 and a corresponding Punknown contribution of 3.06 ppb h-1 in Beijing, whereas the reaction of HO2 + NO (nitric oxide) was dominant after 10:00 LST with a max. of 9.38 ppb h-1 and a corresponding Punknown contribution of 7.23 ppb h-1 in Beijing. The whole ROx cycle was accelerated by the three addnl. HONO sources, esp. the Punknown. The daytime av. OH prodn. rate was enhanced by 0.67 due to the three addnl. HONO sources; [0.64], due to the Punknown, to 4.32 [3.86] ppb h-1, via the reaction of HO2 + NO, and by 0.49 [0.47] to 1.86 [1.86] ppb h-1, via the photolysis of HONO. The OH daytime av. loss rate was enhanced by 0.58 [0.55] to 2.03 [1.92] ppb h-1, via the reaction of OH + NO2, and by 0.31 [0.28] to 1.78 [1.64] ppb h-1, via the reaction of OH + CO (carbon monoxide) in Beijing, Shanghai, and Guangzhou. Similarly, the three addnl. HONO sources produced an increase of 0.31 [0.28] (with a corresponding Punknown contribution) to 1.78 [1.64] ppb h-1, via the reaction of OH + CO, and 0.10 [0.09] to 0.63 [0.59] ppb h-1, via the reaction of CH3O2 (methylperoxy radical) + NO in the daytime av. HO2 prodn. rate, and 0.67 [0.61] to 4.32 [4.27] ppb h-1, via the reaction of HO2 + NO in the daytime av. HO2 loss rate in Beijing, Shanghai, and Guangzhou. The above results suggest that the Punknown considerably enhanced the ROx concns. and accelerated ROx cycles in the coastal regions of China, and could produce significant increases in concns. of in-org. aerosols and secondary org. aerosols and further aggrava haze events in these regions.
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    Wang, W.; Parrish, D. D.; Wang, S.; Bao, F.; Ni, R.; Li, X.; Yang, S.; Wang, H.; Cheng, Y.; Su, H. Long-term trend of ozone pollution in China during 2014–2020: distinct seasonal and spatial characteristics and ozone sensitivity. Atmos. Chem. Phys. 2022, 22 (13), 8935– 8949,  DOI: 10.5194/acp-22-8935-2022
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    117
    Long-term trend of ozone pollution in China during 2014-2020: distinct seasonal and spatial characteristics and ozone sensitivity
    Wang, Wenjie; Parrish, David D.; Wang, Siwen; Bao, Fengxia; Ni, Ruijing; Li, Xin; Yang, Suding; Wang, Hongli; Cheng, Yafang; Su, Hang
    Atmospheric Chemistry and Physics (2022), 22 (13), 8935-8949CODEN: ACPTCE; ISSN:1680-7324. (Copernicus Publications)
    In the past decade, ozone (O3) pollution has become a severe environmental problem in China's major cities. Here, based on available observational records, we investigated the long-term trend of O3 pollution in China during 2014-2020. The O3 concns. were slightly higher in urban areas than in non-urban areas. During these 7 years, the highest O3 concns. primarily occurred during summer in northern China, and during autumn or spring in southern China. Although O3 precursors, including nitrogen oxides (NOx) and carbon monoxide (CO), continuously decreased, O3 concns. generally increased throughout the 7 years with a slower increasing rate after 2017. The long-term trend of O3 concns. differed across seasons, esp. from 2019 to 2020, when O3 concns. decreased in summer and increased in winter. To analyze the causes of this obsd. trend, a photochem. box model was used to investigate the change in the O3 sensitivity regime in two representative cities - Beijing and Shanghai. Our model simulations suggest that the summertime O3 sensitivity regime in urban areas of China has changed from a VOC-limited regime to a transition regime during 2014-2020. By 2020, the urban photochem. was in a transition regime in summer but in a VOC-limited regime in winter. This study helps to understand the distinct trends of O3 in China and provides insights into efficient future O3 control strategies in different regions and seasons.
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    Yin, H.; Lu, X.; Sun, Y.; Li, K.; Gao, M.; Zheng, B.; Liu, C. Unprecedented decline in summertime surface ozone over eastern China in 2020 comparably attributable to anthropogenic emission reductions and meteorology. Environmental Research Letters 2021, 16 (12), 124069  DOI: 10.1088/1748-9326/ac3e22
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    Unprecedented decline in summertime surface ozone over eastern China in 2020 comparably attributable to anthropogenic emission reductions and meteorology
    Yin, Hao; Lu, Xiao; Sun, Youwen; Li, Ke; Gao, Meng; Zheng, Bo; Liu, Cheng
    Environmental Research Letters (2021), 16 (12), 124069CODEN: ERLNAL; ISSN:1748-9326. (IOP Publishing Ltd.)
    China's nationwide monitoring network initiated in 2013 has witnessed continuous increases of urban summertime surface ozone to 2019 by about 5% year-1, among the fastest ozone trends in the recent decade reported in the Tropospheric ozone assessment report. Here we report that surface ozone levels averaged over cities in eastern China cities decrease by 5.5 ppbv in May-August 2020 compared to the 2019 levels, representing an unprecedented ozone redn. since 2013. We combine the high-resoln. GEOS-Chem chem. model and the eXtreme Gradient Boosting (XGBoost) machine learning model to quantify the drivers of this redn. We est. that changes in anthropogenic emissions alone decrease ozone by 3.2 (2.9-3.6) ppbv (57% of the total 5.5 ppbv redn.) averaged over cities in eastern China and by 2.5 ∼ 3.2 ppbv in the three key city clusters for ozone mitigation. These redns. appear to be driven by decreases in anthropogenic emissions of both nitrogen oxides (NOx) and volatile org. compds., likely reflecting the stringent emission control measures implemented by The Chinese Ministry of Environmental and Ecol. in summer 2020, as supported by obsd. decline in tropospheric formaldehyde (HCHO) and nitrogen dioxides (NO2) from satellite and by bottom-up emission ests. Comparable to the emission-driven ozone redn., the wetter and cooler weather conditions in 2020 decrease ozone by 2.3 (1.9-2.6) ppbv (43%). Our analyses indicate that the current emission control strategies can be effective for ozone mitigation in China yet tracking future ozone changes is essential for further evaluation. Our study also reveals important potential to combine the mechanism-based, state-of-art atm. chem. models with machine learning model to improve the attribution of ozone drivers.
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    Xu, J.; Huang, X.; Wang, N.; Li, Y.; Ding, A. Understanding ozone pollution in the Yangtze River Delta of eastern China from the perspective of diurnal cycles. Science of The Total Environment 2021, 752, 141928  DOI: 10.1016/j.scitotenv.2020.141928
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    Li, K.; Jacob, D. J.; Shen, L.; Lu, X.; De Smedt, I.; Liao, H. Increases in surface ozone pollution in China from 2013 to 2019: anthropogenic and meteorological influences. Atmos. Chem. Phys. 2020, 20 (19), 11423– 11433,  DOI: 10.5194/acp-20-11423-2020
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    Increases in surface ozone pollution in China from 2013 to 2019: anthropogenic and meteorological influences
    Li, Ke; Jacob, Daniel J.; Shen, Lu; Lu, Xiao; De Smedt, Isabelle; Liao, Hong
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    Surface ozone data from the Chinese Ministry of Ecol. and Environment (MEE) network show sustained increases across the country over the 2013-2019 period. Despite Phase 2 of the Clean Air Action Plan targeting ozone pollution, ozone was higher in 2018-2019 than in previous years. The mean summer 2013-2019 trend in max. 8 h av. (MDA8) ozone was 1.9 ppb a-1 (p < 0.01) across China and 3.3 ppb a-1 (p < 0.01) over the North China Plain (NCP). Fitting ozone to meteorol. variables with a multiple linear regression model shows that meteorol. played a significant but not dominant role in the 2013-2019 ozone trend, contributing 0.70 ppb a-1 (p < 0.01) across China and 1.4 ppb a-1 (p = 0.02) over the NCP. Rising June-July temps. over the NCP were the main meteorol. driver, particularly in recent years (2017-2019), and were assocd. with increased foehn winds. NCP data for 2017-2019 show a 15% decrease in fine particulate matter (PM2.5) that may be driving the continued anthropogenic increase in ozone, as well as unmitigated emissions of volatile org. compds. (VOCs). VOC emission redns., as targeted by Phase 2 of the Chinese Clean Air Action Plan, are needed to reverse the increase in ozone.

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  • Abstract

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    Figure 1

    Figure 1. (a) Scatter plots of HONO (blue), HONO/NO2 (red), and HONO/pNO3 (yellow) as functions of CH3CN. (b) Same as (a) but as functions of aerosol pH. (c) Box plots of HONO concentrations for clean (CH3CN < 0.1) and BB (CH3CN > 0.1) airmasses, where the mean value is denoted by the red dot. And the median is denoted by black line. (d) and (e) are same as (c) but for HONO/NO2 and HONO/pNO3, respectively.

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    Figure 2

    Figure 2. (a) Scatter plot of pHONO as functions of pNO3 (blue), pNO3 × jHNO3 (red), and P(HNO3) (green). The corresponding correlation coefficients are shown at the bottom right corner of the plot. (b) Scatter plot of pHONO as functions of NO2 (blue) and NO2 × SA × SWR (red), and the corresponding correlation coefficients. (c) Observed diurnal HONO (black dots) with standard deviation (black vertical lines) and simulated HONO under the six cases (B, S0–S3) as described in Table 1. (d) Mean diurnal profiles of pNO3 (orange) and NO2 (blue) during the measurement period. All panels show the non-BB data.

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    Figure 3

    Figure 3. (a) Simulated evolutions of O3, NOx, HONO, pNO3, OH, and PO3 in a Lagrangian box model for 7 days under cases F0 – F3. (b) O3 enhancement ratios, defined as the relative O3 increase from the initial O3 concentration for cases F0 – F3. (c), (d), and (e) are simulated HONO/NO2, HONO/pNO3 and NOx/pNO3 ratios. The dashed lines denote measured HONO/NO2, HONO/pNO3 and NOx/pNO3 values from Ye et al. (104)

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    Figure 4

    Figure 4. (a) Cumulative PO3 as a function of initial NOx for cases F0 - F3. The dashed lines denote NOx levels at which cumulative PO3 reaches its peak values. (b) Loss of NOx (ΔNOx) as a function of initial NOx.

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  • References

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      Kim, Saewung; Vanden Boer, Trevor C.; Young, Cora J.; Riedel, Theran P.; Thornton, Joel A.; Swarthout, Bob; Sive, Barkley; Lerner, Brian; Gilman, Jessica B.; Warneke, Carsten; Roberts, James M.; Guenther, Alex; Wagner, Nicholas L.; Dube, William P.; Williams, Eric; Brown, Steven S.
      Journal of Geophysical Research: Atmospheres (2014), 119 (11), 6886-6896CODEN: JGRDE3; ISSN:2169-8996. (Wiley-Blackwell)
      We present OH observations from Nitrogen, Aerosol Compn., and Halogens on a Tall Tower 2011 (NACHTT-11) held at the Boulder Atm. Observatory in Weld County, Colorado. Av. OH levels at noon were ∼ 2.7 × 106 mols. cm-3 at 2 m above ground level. Nitrous acid (HONO) photolysis was the dominant OH source (80.4%) during this campaign, while alkene ozonolysis (4.9%) and ozone photolysis (14.7%) were smaller contributions to OH prodn. To evaluate recycling sources of OH from HO2 and RO2, an observationally constrained University of Washington Chem. Mechanism (UWCM) box model (version 2.1) was employed to simulate ambient OH levels over several scenarios. For the base run, not constrained by obsd. HONO, the model significantly underestimated OH by a factor of 5.3 in the morning (9:00-11:00) and by a factor of 3.2 in the afternoon (13:00-15:00). The results suggest that known chem. cannot constrain HONO and, subsequently, OH during the observational period. When HONO is constrained in the model by observations (< 50 m), the discrepancy between observation and model simulation improves to a factor of 1.3 in the morning and a factor 1.1 in the afternoon, within the 35% estd. instrumental uncertainty. However, the model produces both a morning and afternoon max. in OH, in contrast to the observations, which show strong evidence for morning OH prodn. but no distinct morning max. Two addnl. OH sources were also considered, although they do not improve the differences in modeled and measured temporal OH profiles. First, the impact of daytime HONO gradients near the ground surface (< 20 m) was evaluated. Strong HONO gradients were obsd. between 06:00 and 09:00 MST (mountain std. time), esp. within 20 m of the surface. When constrained to HONO obsd. below 20 m (rather than 50 m), the model produced an even larger morning OH max., in contrast to the observations. Second, Cl atoms from ClNO2 photolysis producing RO2 from reaction with alkanes, while significant, produced steady state Cl atom levels (∼ 103 atoms cm-3) that were too low to significantly perturb measured OH through reactions of org. peroxy radicals produced from Cl reactions with volatile org. compds.
    4. 4
      Alicke, B.; Platt, U.; Stutz, J. Impact of nitrous acid photolysis on the total hydroxyl radical budget during the Limitation of Oxidant Production/Pianura Padana Produzione di Ozono study in Milan. Journal of Geophysical Research: Atmospheres 2002, 107 (D22), LOP 9-1– LOP 9-17,  DOI: 10.1029/2000JD000075
      There is no corresponding record for this reference.
    5. 5
      Lu, X.; Wang, Y.; Li, J.; Shen, L.; Fung, J. C. H. Evidence of heterogeneous HONO formation from aerosols and the regional photochemical impact of this HONO source. Environmental Research Letters 2018, 13 (11), 114002,  DOI: 10.1088/1748-9326/aae492
      There is no corresponding record for this reference.
    6. 6
      Xing, L.; Wu, J.; Elser, M.; Tong, S.; Liu, S.; Li, X.; Liu, L.; Cao, J.; Zhou, J.; El-Haddad, I.; Huang, R.; Ge, M.; Tie, X.; Prévôt, A. S. H.; Li, G. Wintertime secondary organic aerosol formation in Beijing–Tianjin–Hebei (BTH): contributions of HONO sources and heterogeneous reactions. Atmospheric Chemistry and Physics 2019, 19 (4), 2343– 2359,  DOI: 10.5194/acp-19-2343-2019
      There is no corresponding record for this reference.
    7. 7
      Liu, P.; Xue, C.; Ye, C.; Liu, C.; Zhang, C.; Wang, J.; Zhang, Y.; Liu, J.; Mu, Y. The Lack of HONO Measurement May Affect the Accurate Diagnosis of Ozone Production Sensitivity. ACS Environmental Au 2023, 3 (1), 18– 23,  DOI: 10.1021/acsenvironau.2c00048
      There is no corresponding record for this reference.
    8. 8
      Li, Q.; Zhang, L.; Wang, T.; Wang, Z.; Fu, X.; Zhang, Q. ″New″ Reactive Nitrogen Chemistry Reshapes the Relationship of Ozone to Its Precursors. Environ. Sci. Technol. 2018, 52 (5), 2810– 2818,  DOI: 10.1021/acs.est.7b05771
      8
      "New" Reactive Nitrogen Chemistry Reshapes the Relationship of Ozone to Its Precursors
      Li, Qinyi; Zhang, Li; Wang, Tao; Wang, Zhe; Fu, Xiao; Zhang, Qiang
      Environmental Science & Technology (2018), 52 (5), 2810-2818CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      Tropospheric ozone pollution has been a major environmental issue, and mitigation of this persistent problem requires a comprehensive understanding of the sensitivity of ozone to its precursors, i.e., nitrogen oxides (NOx) and volatile org. compds. (VOCs). Recent studies have proposed several "new" reactive nitrogen chem. processes, including addnl. sources of nitrous acid, heterogeneous uptake of dinitrogen pentoxide, and prodn. of nitryl chloride. These processes significantly affect the budgets of radicals and NOx and hence the formation of ozone. In present study, we aim to investigate to what extent these processes alter the relationships between ozone and its precursors. A revised Weather Research and Forecasting model coupled with Chem. incorporating the "new" nitrogen chem. was adopted to simulate the ozone sensitivity regime in China in summer. The results showed that nitrogen chem. changed the ozone sensitivity regime for approx. 40% of the simulated area with human influence, mostly from VOC-sensitive or NOx-sensitive regimes to mixed-sensitive regime. The nitrogen chem. changed the isopleth plots of the ozone peak values for major cities, suggesting a different strategy for controlling ozone pollution. This study underscores the need to consider unconventional nitrogen chem. in air quality models used in the design of ozone control strategies.
    9. 9
      Pagsberg, P.; Bjergbakke, E.; Ratajczak, E.; Sillesen, A. Kinetics of the gas phase reaction OH + NO(+ M) HONO(+ M) and the determination of the UV absorption cross sections of HONO. Chem. Phys. Lett. 1997, 272, 383,  DOI: 10.1016/S0009-2614(97)00576-9
      There is no corresponding record for this reference.
    10. 10
      Burling, I. R.; Yokelson, R. J.; Griffith, D. W. T.; Johnson, T. J.; Veres, P.; Roberts, J. M.; Warneke, C.; Urbanski, S. P.; Reardon, J.; Weise, D. R.; Hao, W. M.; de Gouw, J. Laboratory measurements of trace gas emissions from biomass burning of fuel types from the southeastern and southwestern United States. Atmospheric Chemistry and Physics 2010, 10 (22), 11115– 11130,  DOI: 10.5194/acp-10-11115-2010
      There is no corresponding record for this reference.
    11. 11
      Veres, P.; Roberts, J. M.; Burling, I. R.; Warneke, C.; de Gouw, J.; Yokelson, R. J. Measurements of gas-phase inorganic and organic acids from biomass fires by negative-ion proton-transfer chemical-ionization mass spectrometry. Journal of Geophysical Research: Atmospheres 2010, 115 (D23), D23302,  DOI: 10.1029/2010JD014033
      There is no corresponding record for this reference.
    12. 12
      Neuman, J. A.; Trainer, M.; Brown, S. S.; Min, K. E.; Nowak, J. B.; Parrish, D. D.; Peischl, J.; Pollack, I. B.; Roberts, J. M.; Ryerson, T. B.; Veres, P. R. HONO emission and production determined from airborne measurements over the Southeast U.S. Journal of Geophysical Research: Atmospheres 2016, 121 (15), 9237– 9250,  DOI: 10.1002/2016JD025197
      There is no corresponding record for this reference.
    13. 13
      Theys, N.; Volkamer, R.; Müller, J. F.; Zarzana, K. J.; Kille, N.; Clarisse, L.; De Smedt, I.; Lerot, C.; Finkenzeller, H.; Hendrick, F.; Koenig, T. K.; Lee, C. F.; Knote, C.; Yu, H.; Van Roozendael, M. Global nitrous acid emissions and levels of regional oxidants enhanced by wildfires. Nature Geoscience 2020, 13 (10), 681– 686,  DOI: 10.1038/s41561-020-0637-7
      There is no corresponding record for this reference.
    14. 14
      Roberts, J. M.; Stockwell, C. E.; Yokelson, R. J.; de Gouw, J.; Liu, Y.; Selimovic, V.; Koss, A. R.; Sekimoto, K.; Coggon, M. M.; Yuan, B.; Zarzana, K. J.; Brown, S. S.; Santin, C.; Doerr, S. H.; Warneke, C. The nitrogen budget of laboratory-simulated western US wildfires during the FIREX 2016 Fire Lab study. Atmos. Chem. Phys. 2020, 20 (14), 8807– 8826,  DOI: 10.5194/acp-20-8807-2020
      There is no corresponding record for this reference.
    15. 15
      Xu, L.; Crounse, J. D.; Vasquez, K. T.; Allen, H.; Wennberg, P. O.; Bourgeois, I.; Brown, S. S.; Campuzano-Jost, P.; Coggon, M. M.; Crawford, J. H.; DiGangi, J. P.; Diskin, G. S.; Fried, A.; Gargulinski, E. M.; Gilman, J. B.; Gkatzelis, G. I.; Guo, H.; Hair, J. W.; Hall, S. R.; Halliday, H. A.; Hanisco, T. F.; Hannun, R. A.; Holmes, C. D.; Huey, L. G.; Jimenez, J. L.; Lamplugh, A.; Lee, Y. R.; Liao, J.; Lindaas, J.; Neuman, J. A.; Nowak, J. B.; Peischl, J.; Peterson, D. A.; Piel, F.; Richter, D.; Rickly, P. S.; Robinson, M. A.; Rollins, A. W.; Ryerson, T. B.; Sekimoto, K.; Selimovic, V.; Shingler, T.; Soja, A. J.; St. Clair, J. M.; Tanner, D. J.; Ullmann, K.; Veres, P. R.; Walega, J.; Warneke, C.; Washenfelder, R. A.; Weibring, P.; Wisthaler, A.; Wolfe, G. M.; Womack, C. C.; Yokelson, R. J. Ozone chemistry in western U.S. wildfire plumes. Science Advances 2021, 7 (50), eabl3648  DOI: 10.1126/sciadv.abl3648
      There is no corresponding record for this reference.
    16. 16
      Li, X.; Rohrer, F.; Hofzumahaus, A.; Brauers, T.; Häseler, R.; Bohn, B.; Broch, S.; Fuchs, H.; Gomm, S.; Holland, F.; Jäger, J.; Kaiser, J.; Keutsch, F. N.; Lohse, I.; Lu, K.; Tillmann, R.; Wegener, R.; Wolfe, G. M.; Mentel, T. F.; Kiendler-Scharr, A.; Wahner, A. Missing Gas-Phase Source of HONO Inferred from Zeppelin Measurements in the Troposphere. Science 2014, 344 (6181), 292– 296,  DOI: 10.1126/science.1248999
      16
      Missing Gas-Phase Source of HONO Inferred from Zeppelin Measurements in the Troposphere
      Li, Xin; Rohrer, Franz; Hofzumahaus, Andreas; Brauers, Theo; Haeseler, Rolf; Bohn, Birger; Broch, Sebastian; Fuchs, Hendrik; Gomm, Sebastian; Holland, Frank; Jaeger, Julia; Kaiser, Jennifer; Keutsch, Frank N.; Lohse, Insa; Lu, Keding; Tillmann, Ralf; Wegener, Robert; Wolfe, Glenn M.; Mentel, Thomas F.; Kiendler-Scharr, Astrid; Wahner, Andreas
      Science (Washington, DC, United States) (2014), 344 (6181), 292-296CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)
      Gaseous nitrous acid (HONO) is an important precursor of tropospheric hydroxyl radicals (OH). OH is responsible for atm. self-cleansing and controls the concns. of greenhouse gases like methane and ozone. Due to lack of measurements, vertical distributions of HONO and its sources in the troposphere remain unclear. Here, a set of observations of HONO and its budget made onboard a Zeppelin airship is presented. In a sunlit layer sepd. from Earth's surface processes by temp. inversion, high HONO concns. were found providing evidence for a strong gas-phase source of HONO consuming nitrogen oxides and potentially hydrogen oxide radicals. The obsd. properties of this prodn. process suggest that the generally assumed impact of HONO on the abundance of OH in the troposphere is substantially overestimated.
    17. 17
      Michoud, V.; Colomb, A.; Borbon, A.; Miet, K.; Beekmann, M.; Camredon, M.; Aumont, B.; Perrier, S.; Zapf, P.; Siour, G.; Ait-Helal, W.; Afif, C.; Kukui, A.; Furger, M.; Dupont, J. C.; Haeffelin, M.; Doussin, J. F. Study of the unknown HONO daytime source at a European suburban site during the MEGAPOLI summer and winter field campaigns. Atmos. Chem. Phys. 2014, 14 (6), 2805– 2822,  DOI: 10.5194/acp-14-2805-2014
      17
      Study of the unknown HONO daytime source at a European suburban site during the MEGAPOLI summer and winter field campaigns
      Michoud, V.; Colomb, A.; Borbon, A.; Miet, K.; Beekmann, M.; Camredon, M.; Aumont, B.; Perrier, S.; Zapf, P.; Siour, G.; Ait-Helal, W.; Afif, C.; Kukui, A.; Furger, M.; Dupont, J. C.; Haeffelin, M.; Doussin, J. F.
      Atmospheric Chemistry and Physics (2014), 14 (6), 2805-2822, 18 pp.CODEN: ACPTCE; ISSN:1680-7324. (Copernicus Publications)
      Nitrous acid measurements were carried out during the MEGAPOLI summer and winter field campaigns at SIRTA observatory in Paris surroundings. Highly variable HONO levels were obsd. during the campaigns, ranging from 10 ppt to 500 ppt in summer and from 10 ppt to 1.7 ppb in winter. Significant HONO mixing ratios have also been measured during daytime hours, comprised between some tenth of ppt and 200 ppt for the summer campaign and between few ppt and 1 ppb for the winter campaign. Ancillary measurements, such as NOx, O3, photolysis frequencies, meteorol. parameters (pressure, temp., relative humidity, wind speed and wind direction), black carbon concn., total aerosol surface area, boundary layer height and soil moisture, were conducted during both campaigns. In addn., for the summer period, OH radical measurements were made with a CIMS (Chem. Ionisation Mass Spectrometer). This large dataset has been used to investigate the HONO budget in a suburban environment. To do so, calcns. of HONO concns. using PhotoStationary State (PSS) approach have been performed, for daytime hours. The comparison of these calcns. with measured HONO concns. revealed an underestimation of the calcns. making evident a missing source term for both campaigns. This unknown HONO source exhibits a bell-shaped like av. diurnal profile with a max. around noon of approx. 0.7 ppb h-1 and 0.25 ppb h-1, during summer and winter resp. This source is the main HONO source during daytime hours for both campaigns. In both cases, this source shows a slight pos. correlation with J(NO2) and the product between J(NO2) and soil moisture. This original approach had, thus, indicated that this missing source is photolytic and might be heterogeneous occurring at ground surface and involving water content available on the ground.
    18. 18
      Zhang, Q.; Liu, P.; Wang, Y.; George, C.; Chen, T.; Ma, S.; Ren, Y.; Mu, Y.; Song, M.; Herrmann, H.; Mellouki, A.; Chen, J.; Yue, Y.; Zhao, X.; Wang, S.; Zeng, Y. Unveiling the underestimated direct emissions of nitrous acid (HONO). Proc. Natl. Acad. Sci. U. S. A. 2023, 120 (35), e2302048120  DOI: 10.1073/pnas.2302048120
      There is no corresponding record for this reference.
    19. 19
      Lammel, G.; Cape, J. N. Nitrous acid and nitrite in the atmosphere. Chem. Soc. Rev. 1996, 25 (5), 361– 369,  DOI: 10.1039/cs9962500361
      19
      Nitrous acid and nitrite in the atmosphere
      Lammel, Gerhard; Cape, J. Neil
      Chemical Society Reviews (1996), 25 (5), 361-370CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)
      A review with 42 refs., investigates the evidence from lab. and field studies on the occurrence of HNO2 in the atm. boundary layer.
    20. 20
      Finlayson-Pitts, B. J.; Wingen, L. M.; Sumner, A. L.; Syomin, D.; Ramazan, K. A. The heterogeneous hydrolysis of NO2 in laboratory systems and in outdoor and indoor atmospheres: An integrated mechanism. Phys. Chem. Chem. Phys. 2003, 5 (2), 223– 242,  DOI: 10.1039/b208564j
      20
      The heterogeneous hydrolysis of NO2 in laboratory systems and in outdoor and indoor atmospheres: An integrated mechanism
      Finlayson-Pitts, B. J.; Wingen, L. M.; Sumner, A. L.; Syomin, D.; Ramazan, K. A.
      Physical Chemistry Chemical Physics (2003), 5 (2), 223-242CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)
      The heterogeneous reaction of NO2 with water on the surface of lab. systems has been known for decades to generate HONO, a major source of OH that drives the formation of ozone and other air pollutants in urban areas and possibly in snowpacks. Previous studies have shown that the reaction is first order in NO2 and in water vapor, and the formation of a complex between NO2 and water at the air-water interface has been hypothesized as being the key step in the mechanism. We report data from long path FTIR studies in borosilicate glass reaction chambers of the loss of gaseous NO2 and the formation of the products HONO, NO and N2O. Further FTIR studies were carried out to measure species generated on the surface during the reaction, including HNO3, N2O4 and NO2+. We propose a new reaction mechanism in which we hypothesize that the sym. form of the NO2 dimer, N2O4, is taken up on the surface and isomerizes to the asym. form, ONONO2. The latter autoionizes to NO+NO3-, and it is this intermediate that reacts with water to generate HONO and surface-adsorbed HNO3. Nitric oxide is then generated by secondary reactions of HONO on the highly acidic surface. This new mechanism is discussed in the context of our exptl. data and those of previous studies, as well as the chem. of such intermediates as NO+ and NO2+ that is known to occur in soln. Implications for the formation of HONO both outdoors and indoors in real and simulated polluted atmospheres, as well as on airborne particles and in snowpacks, are discussed. A key aspect of this chem. is that in the atm. boundary layer where human exposure occurs and many measurements of HONO and related atm. constituents such as ozone are made, a major substrate for this heterogeneous chem. is the surface of buildings, roads, soils, vegetation and other materials. This area of reactions in thin films on surfaces (SURFACE = Surfaces, Urban and Remote: Films As a Chem. Environment) has received relatively little attention compared to reactions in the gas and liq. phases, but in fact may be quite important in the chem. of the boundary layer in urban areas.
    21. 21
      Kleffmann, J.; Becker, K.; Wiesen, P. Heterogeneous NO2 conversion processes on acid surfaces: possible atmospheric implications. Atmos. Environ. 1998, 32 (16), 2721– 2729,  DOI: 10.1016/S1352-2310(98)00065-X
      21
      Heterogeneous NO2 conversion processes acid surfaces: possible atmospheric implications
      Kleffmann, J.; Becker, K. H.; Wiesen, P.
      Atmospheric Environment (1998), 32 (16), 2721-2729CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Science Ltd.)
      The heterogeneous conversion of NO2 on water/H2SO4 surfaces was studied in a quartz reactor and a bubbler system. NO2 decay and the HONO formation are first order in [NO2] and are limited by an uptake coeff., γ ≈ 10-6. It was obsd. that HONO formation on acid/water surfaces of moderate acidity only occurs via the reaction 2 NO2 + H2O → HNO3. Involvement of NO on the HONO formation is of minor importance. HONO formation rates calcd. from results of this study at high aerosol load are of the same order of magnitude as obsd. HONO formation rates in the troposphere. Possible HONO formation on stratospheric aerosol by the parallel reaction of NO2 with H2SO4 (cH2SO4 >60 wt. percent) could explain, at least in part, obsd. stratospheric OH radical formation in the morning shortly after sunrise.
    22. 22
      Reisinger, A. R. Observations of HNO2 in the polluted winter atmosphere: possible heterogeneous production on aerosols. Atmos. Environ. 2000, 34 (23), 3865– 3874,  DOI: 10.1016/S1352-2310(00)00179-5
      There is no corresponding record for this reference.
    23. 23
      Tuite, K.; Thomas, J. L.; Veres, P. R.; Roberts, J. M.; Stevens, P. S.; Griffith, S. M.; Dusanter, S.; Flynn, J. H.; Ahmed, S.; Emmons, L.; Kim, S.-W.; Washenfelder, R.; Young, C.; Tsai, C.; Pikelnaya, O.; Stutz, J. Quantifying Nitrous Acid Formation Mechanisms Using Measured Vertical Profiles During the CalNex 2010 Campaign and 1D Column Modeling. Journal of Geophysical Research: Atmospheres 2021, 126 (13), e2021JD034689  DOI: 10.1029/2021JD034689
      There is no corresponding record for this reference.
    24. 24
      Liu, Z.; Wang, Y.; Costabile, F.; Amoroso, A.; Zhao, C.; Huey, L. G.; Stickel, R.; Liao, J.; Zhu, T. Evidence of aerosols as a media for rapid daytime HONO production over China. Environ. Sci. Technol. 2014, 48 (24), 14386– 14391,  DOI: 10.1021/es504163z
      There is no corresponding record for this reference.
    25. 25
      Xue, C.; Zhang, C.; Ye, C.; Liu, P.; Catoire, V.; Krysztofiak, G.; Chen, H.; Ren, Y.; Zhao, X.; Wang, J.; Zhang, F.; Zhang, C.; Zhang, J.; An, J.; Wang, T.; Chen, J.; Kleffmann, J.; Mellouki, A.; Mu, Y. HONO Budget and Its Role in Nitrate Formation in the Rural North China Plain. Environ. Sci. Technol. 2020, 54 (18), 11048– 11057,  DOI: 10.1021/acs.est.0c01832
      25
      HONO budget and its role in nitrate formation in the rural North China Plain
      Xue, Chaoyang; Zhang, Chenglong; Ye, Can; Liu, Pengfei; Catoire, Valery; Krysztofiak, Gisele; Chen, Hui; Ren, Yangang; Zhao, Xiaoxi; Wang, Jinhe; Zhang, Fei; Zhang, Chongxu; Zhang, Jingwei; An, Junling; Wang, Tao; Chen, Jianmin; Kleffmann, Jorg; Mellouki, Abdelwahid; Mu, Yujing
      Environmental Science & Technology (2020), 54 (18), 11048-11057CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      Nitrous acid (HONO) is a major precursor of tropospheric hydroxyl radical (OH) that accelerates the formation of secondary pollutants. The HONO sources, however, are not well understood, esp. in polluted areas. Based on a comprehensive winter field campaign conducted at a rural site of the North China Plain, a box model (MCM v3.3.1) was used to simulate the daytime HONO budget and nitrate formation. We found that HONO photolysis acted as the dominant source for primary OH with a contribution of more than 92%. The obsd. daytime HONO could be well explained by the known sources in the model. The heterogeneous conversion of NO2 on ground surfaces and the homogeneous reaction of NO with OH were the dominant HONO sources with contributions of more than 36 and 34% to daytime HONO, resp. The contribution from the photolysis of particle nitrate and the reactions of NO2 on aerosol surfaces was found to be negligible in clean periods (2%) and slightly higher during polluted periods (8%). The relatively high OH levels due to fast HONO photolysis at the rural site remarkably accelerated gas-phase reactions, resulting in the fast formation of nitrate as well as other secondary pollutants in the daytime.
    26. 26
      Zheng, J.; Shi, X.; Ma, Y.; Ren, X.; Jabbour, H.; Diao, Y.; Wang, W.; Ge, Y.; Zhang, Y.; Zhu, W. Contribution of nitrous acid to the atmospheric oxidation capacity in an industrial zone in the Yangtze River Delta region of China. Atmospheric Chemistry and Physics 2020, 20 (9), 5457– 5475,  DOI: 10.5194/acp-20-5457-2020
      There is no corresponding record for this reference.
    27. 27
      Stutz, J.; Alicke, B.; Neftel, A. Nitrous acid formation in the urban atmosphere: Gradient measurements of NO2 and HONO over grass in Milan, Italy. Journal of Geophysical Research: Atmospheres 2002, 107 (D22), LOP 5-1– LOP 5-15,  DOI: 10.1029/2001JD000390
      There is no corresponding record for this reference.
    28. 28
      Notholt, J.; Hjorth, J.; Raes, F. Formation of HNO2 on aerosol surfaces during foggy periods in the presence of NO and NO2. Atmospheric Environment. Part A. General Topics 1992, 26 (2), 211– 217,  DOI: 10.1016/0960-1686(92)90302-2
      There is no corresponding record for this reference.
    29. 29
      Ammann, M.; Kalberer, M.; Jost, D. T.; Tobler, L.; Rossler, E.; Piguet, D.; W, G. H.; Baltensperger, U. Heterogeneous production of nitrous acid on soot in polluted air masses. Nature 1998, 395, 157,  DOI: 10.1038/25965
      29
      Heterogeneous production of nitrous acid on soot in polluted air masses
      Ammann, M.; Kalberer, M.; Jost, D. T.; Tobler, L.; Rossler, E.; Piguet, D.; Gaggeler, H. W.; Baltensperger, U.
      Nature (London) (1998), 395 (6698), 157-160CODEN: NATUAS; ISSN:0028-0836. (Macmillan Magazines)
      Polluted air masses are characterized by high concns. of oxidized nitrogen compds. which are involved in photochem. smog and ozone formation. The OH radical is a key species in these oxidn. processes. The photolysis of nitrous acid (HNO2), in the morning, leads to the direct formation of the OH radical and may therefore contribute significantly to the initiation of the daytime photochem. in the polluted planetary boundary layer. But the formation of nitrous acid remains poorly understood: exptl. studies imply that a suggested heterogeneous formation process involving NO2 is not efficient enough to explain the obsd. night-time build-up of HNO2 in polluted air masses. Here we describe kinetic investigations which indicate that the heterogeneous prodn. of HNO2 from NO2 on suspended soot particles proceeds 105 to 107 times faster than on previously studied surfaces. We therefore propose that the interaction between NO2 and soot particles may account for the high concns. of HNO2 in air masses where combustion sources contribute to air pollution by soot and NOx emissions. We believe that the obsd. HNO2 formation results from the redn. of NO2 in the presence of water by C-O and C-H groups in the soot. Although prolonged exposure to oxidizing agents in the atm. is likely to affect the chem. activity of these groups, our observations nevertheless suggest that fresh soot may have a considerable effect on the chem. reactions occurring in polluted air.
    30. 30
      George, C.; Strekowski, R. S.; Kleffmann, J.; Stemmler, K.; Ammann, M. Photoenhanced uptake of gaseous NO2 on solid organic compounds: a photochemical source of HONO?. Faraday Discuss. 2005, 130, 195– 210,  DOI: 10.1039/b417888m
      30
      Photoenhanced uptake of gaseous NO2 on solid organic compounds: A photochemical source of HONO?
      George, C.; Strekowski, R. S.; Kleffmann, J.; Stemmler, K.; Ammann, M.
      Faraday Discussions (2005), 130 (Atmospheric Chemistry), 195-210CODEN: FDISE6; ISSN:1359-6640. (Royal Society of Chemistry)
      In several recent field campaigns the existence of a strong daytime source of nitrous acid was demonstrated. The mechanism of this source remains unclear. Accordingly, in the present lab. study, the effect of light (in the range 300-500 nm) on the uptake kinetics of NO2 on various surfaces taken as proxies for org. surfaces encountered in the troposphere (as org. aerosol but also ground surfaces) was investigated. In this collaborative study, the uptake kinetics and product formation rate were measured by different flow tube reactors in combination with a sensitive HONO instrument. Uptake on light absorbing arom. compds. was significantly enhanced when irradiated with light of 300-420 nm, and HONO was formed with high yield when the gas was humidified. Esp. org. substrates contg. a combination of electron donors, such as phenols, and of compds. yielding excited triplet states, such as arom. ketones, showed a high reactivity towards NO2. Based on the results reported a mechanism is suggested, in which photosensitized electron transfer is occurring. The results show that HONO can be efficiently formed during the day in the atm. at much longer wavelengths compared to the recently proposed nitrate photolysis.

      discussion 241–164, 519–124

    31. 31
      Ramazan, K. A.; Syomin, D.; Finlayson-Pitts, B. J. The photochemical production of HONO during the heterogeneous hydrolysis of NO2. Phys. Chem. Chem. Phys. 2004, 6 (14), 3836– 3843,  DOI: 10.1039/b402195a
      31
      The photochemical production of HONO during the heterogeneous hydrolysis of NO2
      Ramazan, Kevin A.; Syomin, Dennis; Finlayson-Pitts, Barbara J.
      Physical Chemistry Chemical Physics (2004), 6 (14), 3836-3843CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)
      The heterogeneous hydrolysis of NO2 in thin water films, a major source of HONO and hence OH radicals in polluted urban atmospheres, has been previously reported to be photoenhanced (H. Akimoto, H. Takagi and F. Sakamaki, Int. J. Chem. Kinet., 1987, 19, 539, ref. 1) which has important implications for OH prodn. both in environmental chambers and in the lower atm. We report here studies of the impact of 320-400 nm radiation on HONO formation during the heterogeneous NO2 hydrolysis at 296 K. The expts. were carried out in a borosilicate glass cell using long path Fourier transform IR (FTIR) spectroscopy with three initial NO2 concns. (20, 46, and 54 ppm) at relative humidities of 33, 39, and 57%, resp. Nitrous acid was first allowed to accumulate from NO2 hydrolysis in the dark, and then the mixt. of reactants and products was irradiated. The measured concn.-time profiles of the gases were compared to the predictions of a kinetics model developed for this system. The initial loss of HONO upon irradn. was consistent with its photolysis and known secondary gas phase chem. without any photoenhancement. While the fundamental NO2 heterogeneous hydrolysis is not itself photoenhanced, there is clear evidence in these expts. for the generation of gas phase HONO by photolysis of adsorbed HNO3 formed during the heterogeneous hydrolysis. The mechanisms and atm. implications of HONO as well as NO2 formation by the photolysis of surface-adsorbed HNO3 are discussed.
    32. 32
      Gustafsson, R. J.; Orlov, A.; Griffiths, P. T.; Cox, R. A.; Lambert, R. M. Reduction of NO2 to nitrous acid on illuminated titanium dioxide aerosol surfaces: implications for photocatalysis and atmospheric chemistry. Chem. Commun. 2006, (37), 3936– 3938,  DOI: 10.1039/b609005b
      There is no corresponding record for this reference.
    33. 33
      Stemmler, K.; Ammann, M.; Donders, C.; Kleffmann, J.; George, C. Photosensitized reduction of nitrogen dioxide on humic acid as a source of nitrous acid. Nature 2006, 440 (7081), 195– 198,  DOI: 10.1038/nature04603
      33
      Photosensitized reduction of nitrogen dioxide on humic acid as a source of nitrous acid
      Stemmler, Konrad; Ammann, Markus; Donders, Chantal; Kleffmann, Joerg; George, Christian
      Nature (London, United Kingdom) (2006), 440 (7081), 195-198CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)
      Nitrous acid is a significant photochem. precursor of the hydroxyl radical, the key oxidant in the degrdn. of most air pollutants in the troposphere. The sources of nitrous acid in the troposphere, however, are still poorly understood. Recent atm. measurements revealed a strongly enhanced formation of nitrous acid during daytime via unknown mechanisms. Here we expose humic acid films to nitrogen dioxide in an irradiated tubular gas flow reactor and find that redn. of nitrogen dioxide on light-activated humic acids is an important source of gaseous nitrous acid. Our findings indicate that soil and other surfaces contg. humic acid exhibit an org. surface photochem. that produces reductive surface species, which react selectively with nitrogen dioxide. The obsd. rate of nitrous acid formation could explain the recently obsd. high daytime concns. of nitrous acid in the boundary layer, the photolysis of which accounts for up to 60% of the integrated hydroxyl radical source strengths. We suggest that this photo-induced nitrous acid prodn. on humic acid could have a potentially significant impact on the chem. of the lowermost troposphere.
    34. 34
      Ndour, M.; D’Anna, B.; George, C.; Ka, O.; Balkanski, Y.; Kleffmann, J.; Stemmler, K.; Ammann, M. Photoenhanced uptake of NO2 on mineral dust: Laboratory experiments and model simulations. Geophys. Res. Lett. 2008, 35 (5), L05812,  DOI: 10.1029/2007GL032006
      34
      Photoenhanced uptake of NO2 on mineral dust: laboratory experiments and model simulations
      Ndour, Marieme; D'Anna, Barbara; George, Christian; Ka, Oumar; Balkanski, Yves; Kleffmann, Joerg; Stemmler, Konrad; Ammann, Markus
      Geophysical Research Letters (2008), 35 (5), L05812/1-L05812/5CODEN: GPRLAJ; ISSN:0094-8276. (American Geophysical Union)
      Mineral dust contains material such as TiO2 that is well known to have photocatalytic activity. In this lab. study, mixed TiO2-SiO2, Saharan dust and Arizona Test Dust were exposed to NO2 in a coated wall flow tube reactor. While uptake in the dark was negligible, photoenhanced uptake of NO2 was obsd. on all samples. For the mixed TiO2-SiO2, the uptake coeffs. increased with increasing TiO2 mass fraction, with BET uptake coeffs. ranging from 0.12 to 1.9 × 10-6. HONO was obsd. from all samples, with varying yields, e.g., 80% for Saharan dust. Three-dimensional modeling indicates that photochem. of dust may reduce the NO2 level up to 37% and ozone up to 5% during a dust event in the free troposphere.
    35. 35
      Wang, S.; Ackermann, R.; Spicer, C. W.; Fast, J. D.; Schmeling, M.; Stutz, J. Atmospheric observations of enhanced NO2-HONO conversion on mineral dust particles. Geophys. Res. Lett. 2003, 30 (11), 1595,  DOI: 10.1029/2003GL017014
      There is no corresponding record for this reference.
    36. 36
      Jiang, Y.; Xue, L.; Gu, R.; Jia, M.; Zhang, Y.; Wen, L.; Zheng, P.; Chen, T.; Li, H.; Shan, Y.; Zhao, Y.; Guo, Z.; Bi, Y.; Liu, H.; Ding, A.; Zhang, Q.; Wang, W. Sources of nitrous acid (HONO) in the upper boundary layer and lower free troposphere of North China Plain: insights from the Mount Tai Observatory. Atmos. Chem. Phys. 2020, 20, 12115,  DOI: 10.5194/acp-20-12115-2020
      There is no corresponding record for this reference.
    37. 37
      Colussi, A. J.; Enami, S.; Yabushita, A.; Hoffmann, M. R.; Liu, W. G.; Mishra, H.; Goddard, W. A., 3rd. Tropospheric aerosol as a reactive intermediate. Faraday Discuss. 2013, 165, 407– 420,  DOI: 10.1039/c3fd00040k
      37
      Tropospheric aerosol as a reactive intermediate
      Colussi, Agustin J.; Enami, Shinichi; Yabushita, Akihiro; Hoffmann, Michael R.; Liu, Wei-Guang; Mishra, Himanshu; Goddard, William A., III
      Faraday Discussions (2013), 165 (), 407-420CODEN: FDISE6; ISSN:1359-6640. (Royal Society of Chemistry)
      In tropospheric chem., secondary org. aerosol (SOA) is deemed an end product. Here, on the basis of new evidence, we make the case that SOA is a key reactive intermediate. We present lab. results on the catalysis by carboxylate anions of the disproportionation of NO2 'on water': 2NO2 + H2O = HONO + NO3- + H+ (R1), and supporting quantum chem. calcns., which we apply to reinterpret recent reports on (i) HONO daytime source strengths vis-a-vis SOA anion loadings and (ii) the weak seasonal and latitudinal dependences of NOx decay kinetics over several megacities. HONO daytime generation via R1 should track sunlight because it is generally catalyzed by the anions produced during the photochem. oxidn. of pervasive gaseous pollutants. Furthermore, by proceeding on the ever present substrate of airborne particulates, R1 can eventually overtake the photolysis of NO2: NO2 + hν = NO + O(3P) (R2), at large zenith angles. Thus, since R1 leads directly to *OH-radical generation via HONO photolysis: HONO + hν = NO + *OH, whereas the path initiated by R2 is more circuitous and actually controlled by the slower photolysis of O3: O3 + hν (+H2O) = O2 + 2*OH, the competition between R1 and R2 provides a mechanistic switch that buffers *OH concns. and NO2 decay (via R1 and/or NO2 + *OH = HNO3) from actinic flux variations.
    38. 38
      Ricker, H. M.; Leonardi, A.; Navea, J. G. Reduction and Photoreduction of NO2 in Humic Acid Films as a Source of HONO, ClNO, N2O, NOX, and Organic Nitrogen. ACS Earth and Space Chemistry 2022, 6 (12), 3066– 3077,  DOI: 10.1021/acsearthspacechem.2c00282
      There is no corresponding record for this reference.
    39. 39
      Jiang, Y.; Hoffmann, E. H.; Tilgner, A.; Aiyuk, M. B. E.; Andersen, S. T.; Wen, L.; van Pinxteren, M.; Shen, H.; Xue, L.; Wang, W.; Herrmann, H. Insights Into NOx and HONO Chemistry in the Tropical Marine Boundary Layer at Cape Verde During the MarParCloud Campaign. Journal of Geophysical Research: Atmospheres 2023, 128 (16), e2023JD038865  DOI: 10.1029/2023JD038865
      There is no corresponding record for this reference.
    40. 40
      Tsai, C.; Spolaor, M.; Colosimo, S. F.; Pikelnaya, O.; Cheung, R.; Williams, E.; Gilman, J. B.; Lerner, B. M.; Zamora, R. J.; Warneke, C.; Roberts, J. M.; Ahmadov, R.; de Gouw, J.; Bates, T.; Quinn, P. K.; Stutz, J. Nitrous acid formation in a snow-free wintertime polluted rural area. Atmos. Chem. Phys. 2018, 18 (3), 1977– 1996,  DOI: 10.5194/acp-18-1977-2018
      There is no corresponding record for this reference.
    41. 41
      Laufs, S.; Kleffmann, J. Investigations on HONO formation from photolysis of adsorbed HNO3 on quartz glass surfaces. Phys. Chem. Chem. Phys. 2016, 18 (14), 9616– 9625,  DOI: 10.1039/C6CP00436A
      41
      Investigations on HONO formation from photolysis of adsorbed HNO3 on quartz glass surfaces
      Laufs, Sebastian; Kleffmann, Joerg
      Physical Chemistry Chemical Physics (2016), 18 (14), 9616-9625CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)
      During the last few decades, nitrous acid (HONO) has attracted significant attention as a major source of the OH radical, the detergent of the atm. However, the different daytime sources identified in the lab. are still the subject of controversial discussion. In the present study, one of these postulated HONO sources, the heterogeneous photolysis of nitric acid (HNO3), was studied on quartz glass surfaces in a photo flow-reactor under atmospherically relevant conditions. In contrast to other investigations, a very low HNO3 photolysis frequency for HONO formation of J(HNO3 → HONO) = 2.4 × 10-7 s-1 (0° SZA, 50% r.h.) was detd. If these results can be translated to atm. surfaces, HNO3 photolysis cannot explain the significant HONO levels in the daytime atm. In addn., it is demonstrated that even the small measured yields of HONO did not result from the direct photolysis of HNO3 but rather from the consecutive heterogeneous conversion of the primary photolysis product NO2 on the humid surfaces. The secondary NO2 conversion was not photo-enhanced on pure quartz glass surfaces in good agreement with former studies. A photolysis frequency for the primary reaction product NO2 of J(HNO3 → NO2) = 1.1 × 10-6 s-1 has been calcd. (0° SZA, 50% r.h.), which indicates that renoxification by photolysis of adsorbed HNO3 on non-reactive surfaces is also a minor process in the atm.
    42. 42
      Ye, C.; Zhang, N.; Gao, H.; Zhou, X. Photolysis of Particulate Nitrate as a Source of HONO and NOx. Environ. Sci. Technol. 2017, 51 (12), 6849– 6856,  DOI: 10.1021/acs.est.7b00387
      42
      Photolysis of Particulate Nitrate as a Source of HONO and NOx
      Ye, Chunxiang; Zhang, Ning; Gao, Honglian; Zhou, Xianliang
      Environmental Science & Technology (2017), 51 (12), 6849-6856CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      Photolysis of HNO3 on surfaces was recently detd. to be greatly enhanced vs. gaseous HNO3. Yet photolysis of particulate nitrate (pNO3) assocd. with atm. aerosols is relatively unknown. Aerosol filter samples were collected near the ground surface and throughout the troposphere on-board an NSF/NACR C-130 aircraft. Photolysis rate consts. of pNO3 were detd. from these samples by directly monitoring HONO and NO2 prodn. rates under UV irradn. (>290 nm). Scaled to ground level tropical noon-time conditions (0° solar zenith angle), normalized photolysis rate consts. (jNpNO3) were 6.2 × 10-6/s to 5.0 × 10-4/s with a median of 8.3 × 10-5/s and a mean (±1 std. deviation) of (1.3 ± 1.2) × 10-4/s. Chem. compns., specifically NO3 loads and org. matter, affect the photolysis rate. Extrapolated to ambient pNO3 load conditions, e.g. ≤10 nmol/m3, the mean jNpNO3 value was >1.8 × 10-4/s in suburban, rural, and remote environments. Hence, pNO3 photolysis is a tropospheric source of HONO and NO2.
    43. 43
      Zhou, X.; Zhang, N.; TerAvest, M.; Tang, D.; Hou, J.; Bertman, S.; Alaghmand, M.; Shepson, P. B.; Carroll, M. A.; Griffith, S.; Dusanter, S.; Stevens, P. S. Nitric acid photolysis on forest canopy surface as a source for tropospheric nitrous acid. Nature Geoscience 2011, 4 (7), 440– 443,  DOI: 10.1038/ngeo1164
      43
      Nitric acid photolysis on forest canopy surface as a source for tropospheric nitrous acid
      Zhou, Xianliang; Zhang, Ning; TerAvest, Michaela; Tang, David; Hou, Jian; Bertman, Steve; Alaghmand, Marjan; Shepson, Paul B.; Carroll, Mary Anne; Griffith, Stephen; Dusanter, Sebastien; Stevens, Philip S.
      Nature Geoscience (2011), 4 (7), 440-443CODEN: NGAEBU; ISSN:1752-0894. (Nature Publishing Group)
      Photolysis of nitrous acid generates hydroxyl radicals-a key atm. oxidant-in the lower atm. Significant concns. of nitrous acid have been reported in the rural atm. boundary layer during the day, where photolysis of nitrous acid accounts for up to 42% of sunlight-induced radical prodn. The obsd. concns. of nitrous acid are thought to be sustained by heterogeneous reactions involving precursors such as nitrogen oxides and nitric acid. Here, we present direct measurements of nitrous acid flux over a rural forest canopy in Michigan, together with surface nitrate loading at the top of the canopy. We report a significant upward flux of nitrous acid during the day, with a peak around noontime. Daytime nitrous acid flux was pos. correlated with the product of leaf surface nitrate loading and the rate const. of nitrate photolysis. We suggest that the photolysis of nitric acid on forest canopies is a significant daytime source of nitrous acid to the lower atm. in rural environments, and could serve as an important pathway for the remobilization of deposited nitric acid.
    44. 44
      Andersen, S. T.; Carpenter, L. J.; Reed, C.; Lee, J. D.; Chance, R.; Sherwen, T.; Vaughan, A. R.; Stewart, J.; Edwards, P. M.; Bloss, W. J.; Sommariva, R.; Crilley, L. R.; Nott, G. J.; Neves, L.; Read, K.; Heard, D. E.; Seakins, P. W.; Whalley, L. K.; Boustead, G. A.; Fleming, L. T.; Stone, D.; Fomba, K. W. Extensive field evidence for the release of HONO from the photolysis of nitrate aerosols. Science Advances 2023, 9 (3), eadd6266  DOI: 10.1126/sciadv.add6266
      There is no corresponding record for this reference.
    45. 45
      Ye, C.; Zhou, X.; Pu, D.; Stutz, J.; Festa, J.; Spolaor, M.; Tsai, C.; Cantrell, C.; Mauldin Iii, R. L.; Weinheimer, A.; Hornbrook, R. S.; Apel, E. C.; Guenther, A.; Kaser, L.; Yuan, B.; Karl, T.; Haggerty, J.; Hall, S.; Ullmann, K.; Smith, J.; Ortega, J. Tropospheric HONO distribution and chemistry in the southeastern US. Atmos. Chem. Phys. 2018, 18 (12), 9107– 9120,  DOI: 10.5194/acp-18-9107-2018
      There is no corresponding record for this reference.
    46. 46
      Chai, J.; Dibb, J. E.; Anderson, B. E.; Bekker, C.; Blum, D. E.; Heim, E.; Jordan, C. E.; Joyce, E. E.; Kaspari, J. H.; Munro, H.; Walters, W. W.; Hastings, M. G. Isotopic constraints on wildfire derived HONO. Atmospheric Chemistry and Physics Discussion 2021,  DOI: 10.5194/acp-2021-225
      There is no corresponding record for this reference.
    47. 47
      Romer, P. S.; Wooldridge, P. J.; Crounse, J. D.; Kim, M. J.; Wennberg, P. O.; Dibb, J. E.; Scheuer, E.; Blake, D. R.; Meinardi, S.; Brosius, A. L.; Thames, A. B.; Miller, D. O.; Brune, W. H.; Hall, S. R.; Ryerson, T. B.; Cohen, R. C. Constraints on Aerosol Nitrate Photolysis as a Potential Source of HONO and NO x. Environ. Sci. Technol. 2018, 52 (23), 13738– 13746,  DOI: 10.1021/acs.est.8b03861
      47
      Constraints on Aerosol Nitrate Photolysis as a Potential Source of HONO and NOx
      Romer, Paul S.; Wooldridge, Paul J.; Crounse, John D.; Kim, Michelle J.; Wennberg, Paul O.; Dibb, Jack E.; Scheuer, Eric; Blake, Donald R.; Meinardi, Simone; Brosius, Alexandra L.; Thames, Alexander B.; Miller, David O.; Brune, William H.; Hall, Samuel R.; Ryerson, Thomas B.; Cohen, Ronald C.
      Environmental Science & Technology (2018), 52 (23), 13738-13746CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      The concn. of nitrogen oxides (NOx) plays a central role in controlling air quality. On a global scale, the primary sink of NOx is oxidn. to form HNO3. Gas-phase HNO3 photolyses slowly with a lifetime in the troposphere of 10 days or more. However, several recent studies examg. HONO chem. have proposed that particle-phase HNO3 undergoes photolysis 10-300 times more rapidly than gas-phase HNO3. We present here constraints on the rate of particle-phase HNO3 photolysis based on observations of NOx and HNO3 collected over the Yellow Sea during the KORUS-AQ study in summer 2016. The fastest proposed photolysis rates are inconsistent with the obsd. NOx to HNO3 ratios. Negligible to moderate enhancements of the HNO3 photolysis rate in particles, 1-30 times faster than in the gas phase, are most consistent with the observations. Small or moderate enhancement of particle-phase HNO3 photolysis would not significantly affect the HNO3 budget but could help explain observations of HONO and NOx in highly aged air.
    48. 48
      Pusede, S. E.; VandenBoer, T. C.; Murphy, J. G.; Markovic, M. Z.; Young, C. J.; Veres, P. R.; Roberts, J. M.; Washenfelder, R. A.; Brown, S. S.; Ren, X.; Tsai, C.; Stutz, J.; Brune, W. H.; Browne, E. C.; Wooldridge, P. J.; Graham, A. R.; Weber, R.; Goldstein, A. H.; Dusanter, S.; Griffith, S. M.; Stevens, P. S.; Lefer, B. L.; Cohen, R. C. An Atmospheric Constraint on the NO2 Dependence of Daytime Near-Surface Nitrous Acid (HONO). Environ. Sci. Technol. 2015, 49 (21), 12774– 12781,  DOI: 10.1021/acs.est.5b02511
      48
      An Atmospheric Constraint on the NO2 Dependence of Daytime Near-Surface Nitrous Acid (HONO)
      Pusede, Sally E.; Vanden Boer, Trevor C.; Murphy, Jennifer G.; Markovic, Milos Z.; Young, Cora J.; Veres, Patrick R.; Roberts, James M.; Washenfelder, Rebecca A.; Brown, Steven S.; Ren, Xinrong; Tsai, Catalina; Stutz, Jochen; Brune, William H.; Browne, Eleanor C.; Wooldridge, Paul J.; Graham, Ashley R.; Weber, Robin; Goldstein, Allen H.; Dusanter, Sebastien; Griffith, Stephen M.; Stevens, Philip S.; Lefer, Barry L.; Cohen, Ronald C.
      Environmental Science & Technology (2015), 49 (21), 12774-12781CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      Recent observations suggest a large and unknown daytime source of nitrous acid (HONO) to the atm. Multiple mechanisms have been proposed, many of which involve chem. that reduces nitrogen dioxide (NO2) on some time scale. To examine the NO2 dependence of the daytime HONO source, we compare weekday and weekend measurements of NO2 and HONO in two U.S. cities. We find that daytime HONO does not increase proportionally to increases in same-day NO2, i.e., the local NO2 concn. at that time and several hours earlier. We discuss various published HONO formation pathways in the context of this constraint.
    49. 49
      Yang, Y.; Li, X.; Zu, K.; Lian, C.; Chen, S.; Dong, H.; Feng, M.; Liu, H.; Liu, J.; Lu, K.; Lu, S.; Ma, X.; Song, D.; Wang, W.; Yang, S.; Yang, X.; Yu, X.; Zhu, Y.; Zeng, L.; Tan, Q.; Zhang, Y. Elucidating the effect of HONO on O3 pollution by a case study in southwest China. Sci. Total Environ. 2021, 756, 144127  DOI: 10.1016/j.scitotenv.2020.144127
      49
      Elucidating the effect of HONO on O3 pollution by a case study in southwest China
      Yang, Yiming; Li, Xin; Zu, Kexin; Lian, Chaofan; Chen, Shiyi; Dong, Huabin; Feng, Miao; Liu, Hefan; Liu, Jingwei; Lu, Keding; Lu, Sihua; Ma, Xuefei; Song, Danlin; Wang, Weigang; Yang, Suding; Yang, Xinping; Yu, Xuena; Zhu, Yuan; Zeng, Limin; Tan, Qinwen; Zhang, Yuanhang
      Science of the Total Environment (2021), 756 (), 144127CODEN: STENDL; ISSN:0048-9697. (Elsevier B.V.)
      Photolysis of nitrous acid (HONO) is one of the major sources for atm. hydroxyl radicals (OH), playing significant role in initiating tropospheric photochem. reactions for ozone (O3) prodn. However, scarce field investigations were conducted to elucidate this effect. In this study, a field campaign was conducted at a suburban site in southwest China. The whole observation was classified into three periods based on O3 levels and data coverage: the serious O3 pollution period (Aug 13-18 as P1), the O3 pollution period (Aug 22-28 as P2) and the clean period (Sep 3-12 as P3), with av. O3 peak values of 96 ppb, 82 ppb and 44 ppb, resp. There was no significant difference of the levels of O3 precursors (VOCs and NOx) between P1 and P2, and thus the evident elevation of OH peak values in P1 was suspected to be the most possible explanation for the higher O3 peak values. Considering the larger contribution of HONO photolysis to HOX primary prodn. than photolysis of HCHO, O3 and ozonolysis of Alkenes, sensitivity tests of HONO redn. on O3 prodn. rate in P1 are conducted by a 0-dimension model. Reduced HONO concn. effectively slows the O3 prodn. in the morning, and such effect correlates with the calcd. prodn. rate of OH radicals from HONO photolysis. Higher HONO level supplying for OH radical initiation in the early morning might be the main reason for the higher O3 peak values in P1, which explained the correlation (R2 = 0.51) between av. O3 value during daytime (10:00-19:00 LT) and av. HONO value during early morning (00:00-05:00 LT). For nighttime accumulation, a suitable range of relative humidity that favored NO2 conversion within P1 was assumed to be the reason for the higher HONO concn. in the following early morning which promoted O3 peak values.
    50. 50
      Liu, Y.; Lu, K.; Li, X.; Dong, H.; Tan, Z.; Wang, H.; Zou, Q.; Wu, Y.; Zeng, L.; Hu, M.; Min, K. E.; Kecorius, S.; Wiedensohler, A.; Zhang, Y. A Comprehensive Model Test of the HONO Sources Constrained to Field Measurements at Rural North China Plain. Environ. Sci. Technol. 2019, 53 (7), 3517– 3525,  DOI: 10.1021/acs.est.8b06367
      50
      A Comprehensive Model Test of the HONO Sources Constrained to Field Measurements at Rural North China Plain
      Liu, Yuhan; Lu, Keding; Li, Xin; Dong, Huabin; Tan, Zhaofeng; Wang, Haichao; Zou, Qi; Wu, Yusheng; Zeng, Limin; Hu, Min; Min, Kyung-Eun; Kecorius, Simonas; Wiedensohler, Alfred; Zhang, Yuanhang
      Environmental Science & Technology (2019), 53 (7), 3517-3525CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      Since HONO photolysis is an important source of OH-, apportionment of ambient HONO sources is necessary to better understand atm. oxidn. Based on data HONO-related species and various parameters measured during a one-month campaign at Wangdu rural site on the North China Plain in summer 2014, a box model was adopted, including current literature parametrization inputs for various HONO sources (NO2 heterogeneous conversion, photo-enhanced conversion, photolysis of adsorbed HNO3 and particulate NO3-, acid displacement, soil emissions) to show the relative importance of each source at this rural site. Simulation results reproduced obsd. HONO prodn. rates at noon in general, but with large uncertainty from prodn. and destruction terms. NO2 photo-enhanced conversion and particulate NO3- photolysis were the major mechanisms with large potential of HONO formation, but the assocd. uncertainty may reduce their importance to be nearly negligible. Soil NP2- were an important HONO source during fertilization periods, accounting for 80±6% of simulation HONO at noon. For some biomass burning episodes, only NO2 heterogeneously converted to HONO was significantly promoted. In summary, the HONO budget is still far from closed, which would require a significant effort to accurately measure HONO and det. related kinetic parameters for its prodn. pathways.
    51. 51
      Ge, Y.; Shi, X.; Ma, Y.; Zhang, W.; Ren, X.; Zheng, J.; Zhang, Y. Seasonality of nitrous acid near an industry zone in the Yangtze River Delta region of China: Formation mechanisms and contribution to the atmospheric oxidation capacity. Atmos. Environ. 2021, 254, 118420,  DOI: 10.1016/j.atmosenv.2021.118420
      There is no corresponding record for this reference.
    52. 52
      Shi, X.; Ge, Y.; Zheng, J.; Ma, Y.; Ren, X.; Zhang, Y. Budget of nitrous acid and its impacts on atmospheric oxidative capacity at an urban site in the central Yangtze River Delta region of China. Atmos. Environ. 2020, 238, 117725,  DOI: 10.1016/j.atmosenv.2020.117725
      52
      Budget of nitrous acid and its impacts on atmospheric oxidative capacity at an urban site in the central Yangtze River Delta region of China
      Shi, Xiaowen; Ge, Yifeng; Zheng, Jun; Ma, Yan; Ren, Xinrong; Zhang, Yuchan
      Atmospheric Environment (2020), 238 (), 117725CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Ltd.)
      In this study, we used a wet chem. based long-path absorption spectroscopy method to measure HONO in Changzhou, in the central Yangtze River Delta region (YRD) of China, from Apr. 3-24, 2017. During the observation period, the av. HONO mixing ratio was 1.55 ± 1.21 ppbv. In addn., the av. OH formation rates of the photolysis of HONO, O3, HCHO and H2O2 along with ozonolysis of alkenes were 7.84 x 106, 2.02 x 107, 7.41 x 105, 3.79 x 105 and 1.51 x 106 mols. cm-3 s-1, resp. At nighttime, the av. conversion rate from NO2 to HONO was detd. to be ∼0.018 h-1. In this work, the primary emission rate of HONO was detd. by the ratios of HONO to nitrogen oxides (NOx = NO + NO2) within freshly emitted plumes (NO/NOx > 0.85) and a value of ∼0.69% was obtained. The sources of HONO were further investigated through a box model utilizing the Master Chem. Mechanism. The simulation results show that primary emissions contributed only ∼12.3% of the total HONO budget during daytime but a substantial portion (31.4%) at night. Comparing to heterogeneous HONO sources, the gas-phase NO + OH reaction was the less important HONO source, with a contribution of 14.2% at night and 28.7% during the daytime. Overall, nighttime HONO can be reasonably explained by aforementioned mechanisms.
    53. 53
      Nie, W.; Ding, A. J.; Xie, Y. N.; Xu, Z.; Mao, H.; Kerminen, V. M.; Zheng, L. F.; Qi, X. M.; Huang, X.; Yang, X. Q.; Sun, J. N.; Herrmann, E.; Petäjä, T.; Kulmala, M.; Fu, C. B. Influence of biomass burning plumes on HONO chemistry in eastern China. Atmospheric Chemistry and Physics 2015, 15 (3), 1147– 1159,  DOI: 10.5194/acp-15-1147-2015
      There is no corresponding record for this reference.
    54. 54
      Peng, Q.; Palm, B. B.; Fredrickson, C. D.; Lee, B. H.; Hall, S. R.; Ullmann, K.; Weinheimer, A. J.; Levin, E.; DeMott, P.; Garofalo, L. A.; Pothier, M. A.; Farmer, D. K.; Fischer, E. V.; Thornton, J. A. Direct Constraints on Secondary HONO Production in Aged Wildfire Smoke From Airborne Measurements Over the Western US. Geophys. Res. Lett. 2022, 49 (15), e2022GL098704  DOI: 10.1029/2022GL098704
      There is no corresponding record for this reference.
    55. 55
      Chai, J.; Miller, D. J.; Scheuer, E.; Dibb, J.; Selimovic, V.; Yokelson, R.; Zarzana, K. J.; Brown, S. S.; Koss, A. R.; Warneke, C.; Hastings, M. Isotopic characterization of nitrogen oxides (NOx), nitrous acid (HONO), and nitrate (pNO3−) from laboratory biomass burning during FIREX. Atmos. Meas. Technol. 2019, 12 (12), 6303– 6317,  DOI: 10.5194/amt-12-6303-2019
      There is no corresponding record for this reference.
    56. 56
      Scharko, N. K.; Berke, A. E.; Raff, J. D. Release of nitrous acid and nitrogen dioxide from nitrate photolysis in acidic aqueous solutions. Environ. Sci. Technol. 2014, 48 (20), 11991– 12001,  DOI: 10.1021/es503088x
      56
      Release of Nitrous Acid and Nitrogen Dioxide from Nitrate Photolysis in Acidic Aqueous Solutions
      Scharko, Nicole K.; Berke, Andrew E.; Raff, Jonathan D.
      Environmental Science & Technology (2014), 48 (20), 11991-12001CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      Nitrate (NO3‾) is an abundant component of aerosols, boundary layer surface films, and surface water. Photolysis of NO3‾ leads to NO2 and HONO, both of which play important roles in tropospheric ozone and OH prodn. Field and lab. studies suggest that NO3‾ photochem. is a more important source of HONO than once thought, although a mechanistic understanding of the variables controlling this process is lacking. We present results of cavity-enhanced absorption spectroscopy measurements of NO2 and HONO emitted during photodegrdn. of aq. NO3‾ under acidic conditions. Nitrous acid is formed in higher quantities at pH 2-4 than expected based on consideration of primary photochem. channels alone. Both exptl. and modeled results indicate that the addnl. HONO is not due to enhanced NO3‾ absorption cross sections or effective quantum yields, but rather to secondary reactions of NO2 in soln. We find that NO2 is more efficiently hydrolyzed in soln. when it is generated in situ during NO3‾ photolysis than for the heterogeneous system where mass transfer of gaseous NO2 into bulk soln. is prohibitively slow. The presence of nonchromophoric OH scavengers that are naturally present in the environment increases HONO prodn. 4-fold, and therefore play an important role in enhancing daytime HONO formation from NO3‾ photochem.
    57. 57
      Shi, X.; Nenes, A.; Xiao, Z.; Song, S.; Yu, H.; Shi, G.; Zhao, Q.; Chen, K.; Feng, Y.; Russell, A. G. High-Resolution Data Sets Unravel the Effects of Sources and Meteorological Conditions on Nitrate and Its Gas-Particle Partitioning. Environ. Sci. Technol. 2019, 53 (6), 3048– 3057,  DOI: 10.1021/acs.est.8b06524
      57
      High-Resolution Data Sets Unravel the Effects of Sources and Meteorological Conditions on Nitrate and Its Gas-Particle Partitioning
      Shi, Xurong; Nenes, Athanasios; Xiao, Zhimei; Song, Shaojie; Yu, Haofei; Shi, Guoliang; Zhao, Qianyu; Chen, Kui; Feng, Yinchang; Russell, Armistead G.
      Environmental Science & Technology (2019), 53 (6), 3048-3057CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      Nitrate is 1 of the most abundant inorg. H2O-sol. ions in fine particulate matter (PM2.5). However, the formation mechanism of nitrate in the ambient atm., esp. the impacts of its semivolatility and the various existing forms of N, remain under-studied. Hourly ambient observations of speciated PM2.5 components (NO3-, SO42-, etc.) were collected in Tianjin, China. Source contributions were analyzed by PMF/ME2 (Pos. Matrix Factorization using the Multilinear Engine 2) program, and pH were estd. by ISORROPIA-II, to study the relation between pH and nitrate. Five sources (factors) were resolved: secondary sulfate (SS), secondary nitrate (SN), dust, vehicle and coal combustion. SN and pH showed a triangle-shaped relation. When SS was high, the fraction of nitrate partitioning into the aerosol phase exhibits a characteristic S-curve relation with pH for different seasons. An index (ITL) is developed and combined with pH to explore the sensitive regions of S-curve. Controlling the emissions of (SO42-, Cl-), cations (Ca2+, Mg2+, etc.) and gases (NOx, NH3, SO2, etc.) will change pH, potentially reducing or increasing SN. The findings of this work provide an effective approach for exploring the formation mechanisms of nitrate under different influencing factors (sources, pH, and IRL).
    58. 58
      Park, J. Y.; Lee, Y. N. Solubility and decomposition kinetics of nitrous acid in aqueous solution. J. Phys. Chem. 1988, 92 (22), 6294– 6302,  DOI: 10.1021/j100333a025
      58
      Solubility and decomposition kinetics of nitrous acid in aqueous solution
      Park, Jong Yoon; Lee, Yin Nan
      Journal of Physical Chemistry (1988), 92 (22), 6294-302CODEN: JPCHAX; ISSN:0022-3654.
      The Henry's law soly. and the decompn. reaction kinetics of HNO2 in aq. solns. were studied by measuring the distribution of species between the gas and liq. phases by using a bubbler-type gas-liq. reactor in conjunction with a high-sensitivity chemiluminescence NOx detector. The pH-dependent soly. of N(III) (≡HNO2 + NO2-) was measured at pH 2.13-3.33. The Henry's law coeff. and the acid dissocn. const. of HNO2 at 25° 49 ± 3 M/atm and (5.3 ± 0.4) × 10-4 M, resp. The temp. dependence of the soly. at 0-30° yields ΔH°soln. = -9.7 ± 0.3 kcal/mol and ΔS°soln. = -24.8 ± 0.7 cal/mol.K. The rate consts. of the aq.-phase reactions, 2HNO2 ↹ NO + NO2 + H2O and 2NO2 + H2O → H+ + NO3- + HNO2 at 22.0 ± 0.1° were detd. The present ΔG°soln. and ΔS°soln. for HNO2 dissoln. are at variance with the latest values recommended by the National Bureau of Stds., essentially identical with the previously selected set of values. The rather limited soly. of HNO2, in combination with its low atm. concn., suggest that HNO2 by itself contributes insignificantly to the acidification of atm. water, e.g., cloud water. However, aq.-phase reactions that produce HNO2 followed by degassing remain a plausible route for the prodn. of atm. HNO2.
    59. 59
      Mora Garcia, S. L.; Pandit, S.; Navea, J. G.; Grassian, V. H. Nitrous Acid (HONO) Formation from the Irradiation of Aqueous Nitrate Solutions in the Presence of Marine Chromophoric Dissolved Organic Matter: Comparison to Other Organic Photosensitizers. ACS Earth and Space Chemistry 2021, 5 (11), 3056– 3064,  DOI: 10.1021/acsearthspacechem.1c00292
      59
      Nitrous Acid (HONO) Formation from the Irradiation of Aqueous Nitrate Solutions in the Presence of Marine Chromophoric Dissolved Organic Matter: Comparison to Other Organic Photosensitizers
      Mora Garcia, Stephanie L.; Pandit, Shubhrangshu; Navea, Juan G.; Grassian, Vicki H.
      ACS Earth and Space Chemistry (2021), 5 (11), 3056-3064CODEN: AESCCQ; ISSN:2472-3452. (American Chemical Society)
      Nitrous acid (HONO), a highly reactive trace atm. gas, is often underestimated in global atm. models due to the poor understanding of its sources and sinks, esp. in the marine boundary layer (MBL). Herein, we have investigated HONO formation from the irradn. of nitrate solns. in the presence of increasingly complex photosensitizers including marine dissolved org. matter (m-DOM), which contains chromophoric org. matter, collected from a large-scale mesocosm expt. In particular, aq. nitrate solns. in the presence of m-DOM, humic acid (HA), and 4-benzoylbenzoic acid (4-BBA) as well as ethylene glycol (EG) were irradiated with a solar simulator. Gas-phase HONO and NO2 produced during the irradn. of these samples were detected using incoherent broad band cavity enhanced absorption spectroscopy (IBBCEAS). The relative amts. of HONO and NO2 formation varied for the different samples. The addn. of all of these different org. contg. samples (m-DOM, HA, 4-BBA, and EG) to nitrate solns. caused an enhancement in HONO formation, with m-DOM showing the greatest total amt. over a 6 h time period. Mechanisms for this enhancement are discussed as well as the strong pH dependence, with the greatest amt. of HONO at a low pH. Overall, HONO formation from nitrate photolysis in the presence of m-DOM provides insights into the HONO formation pathway in the MBL and ultimately contributes to improving atm. models.
    60. 60
      VandenBoer, T. C.; Markovic, M. Z.; Sanders, J. E.; Ren, X.; Pusede, S. E.; Browne, E. C.; Cohen, R. C.; Zhang, L.; Thomas, J.; Brune, W. H.; Murphy, J. G. Evidence for a nitrous acid (HONO) reservoir at the ground surface in Bakersfield, CA, during CalNex 2010. Journal of Geophysical Research: Atmospheres 2014, 119 (14), 9093– 9106,  DOI: 10.1002/2013JD020971
      There is no corresponding record for this reference.
    61. 61
      Lee, Y.; Huey, L. G.; Wang, Y.; Qu, H.; Zhang, R.; Ji, Y.; Tanner, D. J.; Wang, X.; Tang, J.; Song, W.; Hu, W.; Zhang, Y. Photochemistry of Volatile Organic Compounds in the Yellow River Delta, China: Formation of O3 and Peroxyacyl Nitrates. Journal of Geophysical Research: Atmospheres 2021, 126 (23), e2021JD035296  DOI: 10.1029/2021JD035296
      There is no corresponding record for this reference.
    62. 62
      Chong, K.; Wang, Y.; Liu, C.; Gao, Y.; Boersma, K. F.; Tang, J.; Wang, X. Remote Sensing Measurements at a Rural Site in China: Implications for Satellite NO2 and HCHO Measurement Uncertainty and Emissions From Fires. Journal of Geophysical Research: Atmospheres 2024, 129 (2), e2023JD039310  DOI: 10.1029/2023JD039310
      There is no corresponding record for this reference.
    63. 63
      Kleffmann, J.; Heland, J.; Kurtenbach, R.; Lörzer, J. C.; Wiesen, P. A new instrument (LOPAP) for the detection of nitrous acid (HONO). Environ. Sci. Pollut. Res. 2002, 9, 48– 54
      There is no corresponding record for this reference.
    64. 64
      Heland, J.; Kleffmann, J.; Kurtenbach, R.; Wiesen, P. A New Instrument To Measure Gaseous Nitrous Acid (HONO) in the Atmosphere. Environ. Sci. Technol. 2001, 35 (15), 3207– 3212,  DOI: 10.1021/es000303t
      64
      A New Instrument To Measure Gaseous Nitrous Acid (HONO) in the Atmosphere
      Heland, Joerg; Kleffmann, Joerg; Kurtenbach, Ralf; Wiesen, Peter
      Environmental Science and Technology (2001), 35 (15), 3207-3212CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      A new in situ instrument (LOPAP: long path absorption photometer) to measure gaseous nitrous acid (HONO) using wet chem. sampling and photometric detection was developed. This instrument is aimed to overcome the known problems with current HONO measurement techniques and was designed to be a cheap, sensitive, compact, and continuously working HONO monitor for ambient air measurements in the troposphere or for measurements of higher concns. e.g. in smog chambers, in exhaust gases, and in indoor environments. Lab. studies were carried out to characterize the instrument components with respect to collection efficiency, optimum dye formation, optimum detection, and interfering species. Detection limits ranging from ∼3 to 50 pptV were obtained with response times from 4 to 1.5 min, resp., using different instrument parameters. The accuracy of the measurements is in the range between ±(10-15)%. The validation of the instrument was performed in the lab. for HONO concns. of 3 and 30 ppbV using ion chromatog. and with a DOAS (differential optical absorption spectrometer) instrument in a large outdoor smog chamber at 0.1-20 ppbV. The deviations were well within the errors of the measurements; however, when comparing the data with the DOAS instrument systematically higher values were found with the LOPAP instrument.
    65. 65
      Kleffmann, J.; Lörzer, J. C.; Wiesen, P.; Kern, C.; Trick, S.; Volkamer, R.; Rodenas, M.; Wirtz, K. Intercomparison of the DOAS and LOPAP techniques for the detection of nitrous acid (HONO). Atmos. Environ. 2006, 40 (20), 3640– 3652,  DOI: 10.1016/j.atmosenv.2006.03.027
      65
      Intercomparison of the DOAS and LOPAP techniques for the detection of nitrous acid (HONO)
      Kleffmann, J.; Loerzer, J. C.; Wiesen, P.; Kern, C.; Trick, S.; Volkamer, R.; Rodenas, M.; Wirtz, K.
      Atmospheric Environment (2006), 40 (20), 3640-3652CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Ltd.)
      Recent studies demonstrated HNO2 is a source of OH- in the atm. boundary layer early in the morning and throughout the day. Despite its importance, all known instruments to detect HNO2 in the atm. suffer from great exptl. effort necessary or the possibility of significant interferences. Also, only a few instruments are sensitive enough to detect low HNO2 concns. during the day. Validated, sensitive HNO2 measurements are of paramount importance to describe the oxidn. capacity of the atm. Until now, inter-comparisons of these chem. detectors with the well-accepted DOAS (differential optical absorption spectroscopy) method exhibited significantly higher concns. in the day; the discrepancy was attributed to interferences. In this work, a recently developed HNO2 long-path absorption photometer instrument (LOPAP) was validated against the DOAS method in the field and in a large smog chamber under various conditions. Since sample artifacts were minimized and interferences were measured and cor. for by the LOPAP instrument, excellent agreement was obtained between these methods during the day and at night. It was demonstrated that chem. instruments, which do not measure and do not correct interferences, may significantly overestimate daytime HNO2 concns. caused by unknown interferences, particularly important during the day, when HNO2 concns. are low. Using the DOAS method, the possibility of HNO2 impurities in the NO2 ref. spectra used for the spectral anal. must be treated actively during the evaluation to avoid a potential neg. interference at low HNO2:NO2 ratios. A simple procedure is presented to eliminate this possible error source in atm. HNO2 DOAS measurements.
    66. 66
      Reed, C.; Brumby, C. A.; Crilley, L. R.; Kramer, L. J.; Bloss, W. J.; Seakins, P. W.; Lee, J. D.; Carpenter, L. J. HONO measurement by differential photolysis. Atmos. Meas. Technol. 2016, 9 (6), 2483– 2495,  DOI: 10.5194/amt-9-2483-2016
      There is no corresponding record for this reference.
    67. 67
      Crilley, L. R.; Kramer, L. J.; Ouyang, B.; Duan, J.; Zhang, W.; Tong, S.; Ge, M.; Tang, K.; Qin, M.; Xie, P.; Shaw, M. D.; Lewis, A. C.; Mehra, A.; Bannan, T. J.; Worrall, S. D.; Priestley, M.; Bacak, A.; Coe, H.; Allan, J.; Percival, C. J.; Popoola, O. A. M.; Jones, R. L.; Bloss, W. J. Intercomparison of nitrous acid (HONO) measurement techniques in a megacity (Beijing). Atmospheric Measurement Techniques 2019, 12 (12), 6449– 6463,  DOI: 10.5194/amt-12-6449-2019
      There is no corresponding record for this reference.
    68. 68
      Lewis, E. R. An examination of Köhler theory resulting in an accurate expression for the equilibrium radius ratio of a hygroscopic aerosol particle valid up to and including relative humidity 100%. Journal of Geophysical Research 2008, 113 (D3), D03205,  DOI: 10.1029/2007JD008590
      There is no corresponding record for this reference.
    69. 69
      Liu, Z.; Wang, Y.; Gu, D.; Zhao, C.; HUEY, L. G.; STICKEL, R.; LIAO, J.; Shao, M.; Zhu, T.; Zeng, L.; Liu, S.-C.; CHANG, C.-C.; AMOROSO, A.; COSTABILE, F. Evidence of Reactive Aromatics As a Major Source of Peroxy Acetyl Nitrate over China. Environ. Sci. Technol. 2010, 44, 7017,  DOI: 10.1021/es1007966
      69
      Evidence of Reactive Aromatics As a Major Source of Peroxy Acetyl Nitrate over China
      Liu, Zhen; Wang, Yuhang; Gu, Dasa; Zhao, Chun; Huey, L. Gregory; Stickel, Robert; Liao, Jin; Shao, Min; Zhu, Tong; Zeng, Limin; Liu, Shaw-Chen; Chang, Chih-Chung; Amoroso, Antonio; Costabile, Francesca
      Environmental Science & Technology (2010), 44 (18), 7017-7022CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      Observations of near-surface peroxy acetyl nitrate (PAN) and its precursor compds. in air over Beijing, China, Aug. 2007 were analyzed. PAN concns. were remarkably high (≤14 ppbv), surpassing those measured over other urban regions in recent years. Analyses using a 1-dimensional version of a chem. transport model (REAM, regional chem. and transport model) indicated arom. non-methane hydrocarbons (NMHC) were the dominant (55-75%) PAN source. The major arom. oxidn. product which produces acetyl peroxy radicals was methylglyoxal (MGLY). Obsd. PAN and O3 concns. were correlated in the daytime; arom. NMHC appeared to play an important role in O3 photochem. Previous NMHC measurements indicated the presence of reactive aroms. at high concns. over broad polluted regions in China. Aroms. are often ignored in global and, to a lesser degree, regional 3-dimensional photochem. transport models; their emissions and photochem. over China are quite uncertain. Results suggested crit. assessments of arom. emissions and chem., e.g., MGLY yields, are necessary to understand and assess O3 photochem. and regional pollution export over China.
    70. 70
      Zhang, Y.; Wang, Y.; Chen, G.; Smeltzer, C.; Crawford, J.; Olson, J.; Szykman, J.; Weinheimer, A. J.; Knapp, D. J.; Montzka, D. D.; Wisthaler, A.; Mikoviny, T.; Fried, A.; Diskin, G. Large vertical gradient of reactive nitrogen oxides in the boundary layer: Modeling analysis of DISCOVER-AQ 2011 observations. Journal of Geophysical Research: Atmospheres 2016, 121 (4), 1922– 1934,  DOI: 10.1002/2015JD024203
      There is no corresponding record for this reference.
    71. 71
      Qu, H.; Wang, Y.; Zhang, R.; Liu, X.; Huey, L. G.; Sjostedt, S.; Zeng, L.; Lu, K.; Wu, Y.; Shao, M.; Hu, M.; Tan, Z.; Fuchs, H.; Broch, S.; Wahner, A.; Zhu, T.; Zhang, Y. Chemical Production of Oxygenated Volatile Organic Compounds Strongly Enhances Boundary-Layer Oxidation Chemistry and Ozone Production. Environ. Sci. Technol. 2021, 55 (20), 13718– 13727,  DOI: 10.1021/acs.est.1c04489
      There is no corresponding record for this reference.
    72. 72
      Wang, Y.; Logan, J. A.; Jacob, D. J. Global simulation of tropospheric O3-NOx-hydrocarbon chemistry: 2. Model evaluation and global ozone budget. Journal of Geophysical Research: Atmospheres 1998, 103 (D9), 10727– 10755,  DOI: 10.1029/98JD00157
      There is no corresponding record for this reference.
    73. 73
      Li, J.; Wang, Y.; Zhang, R.; Smeltzer, C.; Weinheimer, A.; Herman, J.; Boersma, K. F.; Celarier, E. A.; Long, R. W.; Szykman, J. J.; Delgado, R.; Thompson, A. M.; Knepp, T. N.; Lamsal, L. N.; Janz, S. J.; Kowalewski, M. G.; Liu, X.; Nowlan, C. R. Comprehensive evaluations of diurnal NO2 measurements during DISCOVER-AQ 2011: effects of resolution-dependent representation of NOx emissions. Atmos. Chem. Phys. 2021, 21 (14), 11133– 11160,  DOI: 10.5194/acp-21-11133-2021
      There is no corresponding record for this reference.
    74. 74
      Kleffmann, J.; Becker, K. H.; Wiesen, P. Heterogeneous NO2 conversion processes on acid surfaces: possible atmospheric implications. Atmos. Environ. 1998, 32 (16), 2721– 2729,  DOI: 10.1016/S1352-2310(98)00065-X
      74
      Heterogeneous NO2 conversion processes acid surfaces: possible atmospheric implications
      Kleffmann, J.; Becker, K. H.; Wiesen, P.
      Atmospheric Environment (1998), 32 (16), 2721-2729CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Science Ltd.)
      The heterogeneous conversion of NO2 on water/H2SO4 surfaces was studied in a quartz reactor and a bubbler system. NO2 decay and the HONO formation are first order in [NO2] and are limited by an uptake coeff., γ ≈ 10-6. It was obsd. that HONO formation on acid/water surfaces of moderate acidity only occurs via the reaction 2 NO2 + H2O → HNO3. Involvement of NO on the HONO formation is of minor importance. HONO formation rates calcd. from results of this study at high aerosol load are of the same order of magnitude as obsd. HONO formation rates in the troposphere. Possible HONO formation on stratospheric aerosol by the parallel reaction of NO2 with H2SO4 (cH2SO4 >60 wt. percent) could explain, at least in part, obsd. stratospheric OH radical formation in the morning shortly after sunrise.
    75. 75
      Wang, Y.; Wang, J.; Wang, Y.; Zhang, Y.; Woodward-Massey, R.; Zhang, C.; Kuang, Y.; Zhu, J.; Shang, J.; Li, X.; Zeng, L.; Lin, W.; Ye, C. Experimental and kinetic model evaluation of HONO production from surface nitrate photolysis. Atmos. Environ. 2023, 296, 119568  DOI: 10.1016/j.atmosenv.2022.119568
      There is no corresponding record for this reference.
    76. 76
      Tang, M.-X.; He, L.-Y.; Xia, S.-Y.; Jiang, Z.; He, D.-Y.; Guo, S.; Hu, R.-Z.; Zeng, H.; Huang, X.-F. Coarse particles compensate for missing daytime sources of nitrous acid and enhance atmospheric oxidation capacity in a coastal atmosphere. Science of The Total Environment 2024, 915, 170037  DOI: 10.1016/j.scitotenv.2024.170037
      There is no corresponding record for this reference.
    77. 77
      Song, M.; Zhao, X.; Liu, P.; Mu, J.; He, G.; Zhang, C.; Tong, S.; Xue, C.; Zhao, X.; Ge, M.; Mu, Y. Atmospheric NOx oxidation as major sources for nitrous acid (HONO). npj Climate and Atmospheric Science 2023, 6 (1), 30,  DOI: 10.1038/s41612-023-00357-8
      There is no corresponding record for this reference.
    78. 78
      Stemmler, K.; Ndour, M.; Elshorbany, Y.; Kleffmann, J.; D’Anna, B.; George, C.; Bohn, B.; Ammann, M. Light induced conversion of nitrogen dioxide into nitrous acid on submicron humic acid aerosol. Atmos. Chem. Phys. 2007, 7 (16), 4237– 4248,  DOI: 10.5194/acp-7-4237-2007
      78
      Light induced conversion of nitrogen dioxide into nitrous acid on submicron humic acid aerosol
      Stemmler, K.; Ndour, M.; Elshorbany, Y.; Kleffmann, J.; D'Anna, B.; George, C.; Bohn, B.; Ammann, M.
      Atmospheric Chemistry and Physics (2007), 7 (16), 4237-4248CODEN: ACPTCE; ISSN:1680-7316. (Copernicus Publications)
      The interactions of aerosols consisting of humic acids with gaseous NO2 were investigated under different light conditions in aerosol flow tube expts. at ambient pressure and temp. The results show that NO2 is converted on the humic acid aerosol into HONO, which is released from the aerosol and can be detected in the gas phase at the reactor exit. The formation of HONO on the humic acid aerosol is strongly activated by light: in the dark, the HONO-formation was below the detection limit, but it was increasing with the intensity of the irradn. with visible light. Under simulated atm. conditions with respect to the actinic flux, relative humidity and NO2-concn., reactive uptake coeffs. γrxn for the NO2 → HONO conversion on the aerosol between γrxn <10-7 (in the dark) and γrxn = 6 × 10-6 were obsd. The obsd. uptake coeffs. decreased with increasing NO2-concn. in the range from 2.7 to 280 ppb and were dependent on the relative humidity (RH) with slightly reduced values at low humidity (<20% RH) and high humidity (>60% RH). The measured uptake coeffs. for the NO2 → HONO conversion are too low to explain the HONO-formation rates obsd. near the ground in rural and urban environments by the conversion of NO2 → HONO on org. aerosol surfaces, even if one would assume that all aerosols consist of humic acid only. It is concluded that the processes leading to HONO formation on the Earth surface will have a much larger impact on the HONO-formation in the lowermost layer of the troposphere than humic materials potentially occurring in airborne particles.
    79. 79
      Zhang, J.; Lian, C.; Wang, W.; Ge, M.; Guo, Y.; Ran, H.; Zhang, Y.; Zheng, F.; Fan, X.; Yan, C.; Daellenbach, K. R.; Liu, Y.; Kulmala, M.; An, J. Amplified role of potential HONO sources in O3 formation in North China Plain during autumn haze aggravating processes. Atmos. Chem. Phys. 2022, 22 (5), 3275– 3302,  DOI: 10.5194/acp-22-3275-2022
      79
      Amplified role of potential HONO sources in O3 formation in North China Plain during autumn haze aggravating processes
      Zhang, Jingwei; Lian, Chaofan; Wang, Weigang; Ge, Maofa; Guo, Yitian; Ran, Haiyan; Zhang, Yusheng; Zheng, Feixue; Fan, Xiaolong; Yan, Chao; Daellenbach, Kaspar R.; Liu, Yongchun; Kulmala, Markku; An, Junling
      Atmospheric Chemistry and Physics (2022), 22 (5), 3275-3302CODEN: ACPTCE; ISSN:1680-7324. (Copernicus Publications)
      Co-occurrences of high concns. of PM2.5 and ozone (O3) have been frequently obsd. in haze-aggravating processes in the North China Plain (NCP) over the past few years. Higher O3 concns. on hazy days were hypothesized to be related to nitrous acid (HONO), but the key sources of HONO enhancing O3 during haze-aggravating processes remain unclear. We added six potential HONO sources, i.e., four ground-based (traffic, soil, and indoor emissions, and the NO2 heterogeneous reaction on ground surface (Hetground)) sources, and two aerosol-related (the NO2 heterogeneous reaction on aerosol surfaces (Hetaerosol) and nitrate photolysis (Photnitrate)) sources into the WRF-Chem model and designed 23 simulation scenarios to explore the unclear key sources. The results indicate that ground-based HONO sources producing HONO enhancements showed a rapid decrease with height, while the NO + OH reaction and aerosol-related HONO sources decreased slowly with height. Photnitrate contributions to HONO concns. were enhanced with aggravated pollution levels. The enhancement of HONO due to Photnitrate on hazy days was about 10 times greater than on clean days and Photnitrate dominated daytime HONO sources (~ 30%-70% when the ratio of the photolysis frequency of nitrate (Jnitrate) to gas nitric acid (JHNO3) equals 30) at higher layers (>800 m). Compared with that on clean days, the Photnitrate contribution to the enhanced daily max. 8 h averaged (DMA8) O3was increased by over 1 magnitude during the haze-aggravating process. Photnitrate contributed only ∼ 5% of the surface HONO in the daytime with a Jnitrate/JHNO3 ratio of 30 but contributed ∼ 30%-50% of the enhanced O3near the surface in NCP on hazy days. Surface O3was dominated by volatile org. compd.-sensitive chem., while O3at higher altitudes (>800 m) was dominated by NOx-sensitive chem. Photnitrate had a limited impact on nitrate concns. (<15%) even with a Jnitrate/JHNO3 ratio of 120. These results suggest the potential but significant impact of Photnitrate on O3formation, and that more comprehensive studies on Photnitrate in the atm. are still needed.
    80. 80
      Han, C.; Yang, W.; Wu, Q.; Yang, H.; Xue, X. Heterogeneous Photochemical Conversion of NO2 to HONO on the Humic Acid Surface under Simulated Sunlight. Environ. Sci. Technol. 2016, 50 (10), 5017– 5023,  DOI: 10.1021/acs.est.5b05101
      80
      Heterogeneous Photochemical Conversion of NO2 to HONO on the Humic Acid Surface under Simulated Sunlight
      Han, Chong; Yang, Wangjin; Wu, Qianqian; Yang, He; Xue, Xiangxin
      Environmental Science & Technology (2016), 50 (10), 5017-5023CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      The poor understanding of HONO sources in the daytime highlights the importance of the heterogeneous photochem. reaction of NO2 with aerosol or soil surfaces. The conversion of NO2 to HONO on humic acid (HA) under simulated sunlight was investigated using a flow tube reactor at ambient pressure. The uptake coeff. (γ) of NO2 linearly increased with irradn. intensity and HA mass in the range of 0-2.0 μg/cm2, while it decreased with the NO2 concn. The HONO yield was found to be independent of irradn. intensity, HA mass, and NO2 concn. The temp. (278-308 K) had little influence on both γ and HONO yield. Addnl., γ increased continuously with relative humidity (RH, 7-70%), and a max. HONO yield was obsd. at 40% RH. The heterogeneous photochem. reaction of NO2 with HA was explained by the Langmuir-Hinshelwood mechanism.
    81. 81
      Williams, R. M. A model for the dry deposition of particles to natural water surfaces. Atmospheric Environment (1967) 1982, 16 (8), 1933– 1938,  DOI: 10.1016/0004-6981(82)90464-4
      There is no corresponding record for this reference.
    82. 82
      Li, X.; Brauers, T.; Häseler, R.; Bohn, B.; Fuchs, H.; Hofzumahaus, A.; Holland, F.; Lou, S.; Lu, K. D.; Rohrer, F.; Hu, M.; Zeng, L. M.; Zhang, Y. H.; Garland, R. M.; Su, H.; Nowak, A.; Wiedensohler, A.; Takegawa, N.; Shao, M.; Wahner, A. Exploring the atmospheric chemistry of nitrous acid (HONO) at a rural site in Southern China. Atmospheric Chemistry and Physics 2012, 12 (3), 1497– 1513,  DOI: 10.5194/acp-12-1497-2012
      There is no corresponding record for this reference.
    83. 83
      Zhou, X.; Huang, G.; Civerolo, K.; Roychowdhury, U.; Demerjian, K. L. Summertime observations of HONO, HCHO, and O3 at the summit of Whiteface Mountain, New York. Journal of Geophysical Research: Atmospheres 2007, 112 (D8), D08311,  DOI: 10.1029/2006JD007256
      There is no corresponding record for this reference.
    84. 84
      Gu, R.; Zheng, P.; Chen, T.; Dong, C.; Wang, Y. n; Liu, Y.; Liu, Y.; Luo, Y.; Han, G.; Wang, X.; Zhou, X.; Wang, T.; Wang, W.; Xue, L. Atmospheric nitrous acid (HONO) at a rural coastal site in North China: Seasonal variations and effects of biomass burning. Atmos. Environ. 2020, 229, 117429,  DOI: 10.1016/j.atmosenv.2020.117429
      84
      Atmospheric nitrous acid (HONO) at a rural coastal site in North China: Seasonal variations and effects of biomass burning
      Gu, Rongrong; Zheng, Penggang; Chen, Tianshu; Dong, Can; Wang, Ya'nan; Liu, Yiming; Liu, Yuhong; Luo, Yuanyuan; Han, Guangxuan; Wang, Xinfeng; Zhou, Xuehua; Wang, Tao; Wang, Wenxing; Xue, Likun
      Atmospheric Environment (2020), 229 (), 117429CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Ltd.)
      Nitrous acid (HONO) plays a significant role in atm. chem. due to its contribution to hydroxyl radical (OH). However, no scientific consensus has been achieved about the daytime HONO formation mechanisms. To identify the seasonal variations of HONO chem. and the impacts of biomass burning (BB), we performed a two-phased field study in winter-spring and summer (covering a harvest season) in 2017 at a rural coastal site in North China. Though the mean HONO concn. in winter-spring (0.26 ± 0.28 ppbv) was higher than in summer (0.17 ± 0.19 ppbv), the max. HONO concns. were comparable (∼2 ppbv) in the two campaigns. Both the HONO/NOx ratio and nocturnal heterogeneous conversion efficiency of HONO (CHONO) in summer were over twice of that in winter-spring. The daytime budget anal. also revealed that the strength of Pother (i.e., the HONO sources apart from the reaction of OH + NO) in summer was double of that in winter-spring. BB affected the HONO concn. by enhancing the contribution of heterogeneous HONO prodn. on the aerosol surface but weakening the role of photo-related HONO formation. HONO photolysis was a significant source of OH in both winter-spring and summer, and its contribution could be further enhanced during the BB episode in summer.
    85. 85
      Yang, J.; Shen, H.; Guo, M.-Z.; Zhao, M.; Jiang, Y.; Chen, T.; Liu, Y.; Li, H.; Zhu, Y.; Meng, H.; Wang, W.; Xue, L. Strong marine-derived nitrous acid (HONO) production observed in the coastal atmosphere of northern China. Atmos. Environ. 2021, 244, 117948,  DOI: 10.1016/j.atmosenv.2020.117948
      85
      Strong marine-derived nitrous acid (HONO) production observed in the coastal atmosphere of northern China
      Yang, Juan; Shen, Hengqing; Guo, Ming-Zhi; Zhao, Min; Jiang, Ying; Chen, Tianshu; Liu, Yuhong; Li, Hongyong; Zhu, Yujiao; Meng, He; Wang, Wenxing; Xue, Likun
      Atmospheric Environment (2021), 244 (), 117948CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Ltd.)
      Despite its important roles in the formation of hydroxyl radical (OH) and ozone (O3), the characteristics and sources of nitrous acid (HONO) in the marine atm. are still poorly understood. In this study, the HONO prodn. in maritime air masses was explored based on a field observation conducted at a coastal site in Qingdao, China in the summer of 2019. The "sea case" and the "land case" were carefully distinguished according to wind direction and backward air mass trajectory. About four times larger nocturnal NO2-to-HONO conversion rate and ∼60% larger daytime Pother (prodn. rate of HONO other than gas-phase OH + NO reaction) at noon were obsd. in the "sea case" compared to the "land case" (0.045 ± 0.014 h-1 vs. 0.012 ± 0.007 h-1, and 1.83± 0.02 ppbv h-1 vs. 1.14 ± 0.07 ppbv h-1, resp.). Correlation anal. implied that heterogeneous conversion of NO2 and photolysis of nitrogen-contg. compds. were potentially important sources of marine atm. HONO in the nocturnal and daytime, resp., though alk. oceans are previously considered as sinks of HONO. The impacts of these marine-derived HONO on OH and O3 were comparable to or larger than that of the "land case". These results suggest that strong marine-derived HONO prodn. may have been overlooked previously, and more studies are required to explore its detailed formation mechanisms in the marine atm.
    86. 86
      Cui, L.; Li, R.; Fu, H.; Li, Q.; Zhang, L.; George, C.; Chen, J. Formation features of nitrous acid in the offshore area of the East China Sea. Sci. Total Environ. 2019, 682, 138– 150,  DOI: 10.1016/j.scitotenv.2019.05.004
      86
      Formation features of nitrous acid in the offshore area of the East China Sea
      Cui, Lulu; Li, Rui; Fu, Hongbo; Li, Qing; Zhang, Liwu; George, Christian; Chen, Jianmin
      Science of the Total Environment (2019), 682 (), 138-150CODEN: STENDL; ISSN:0048-9697. (Elsevier B.V.)
      Nitrous acid (HONO) is an important precursor of hydroxyl radical (OH), which plays a key role in atm. chem. A shipboard-based measurement of HONO and related species in the offshore area of the East China Sea (ECS) was performed during June 2017. The HONO concn. ranged from 35 ppt to 1.95 ppb, with an av. value of 0.44 ± 0.25 ppb during the entire campaign. HONO displayed a relatively higher level (0.48 ± 0.21 ppb) in the area within 30 km from the coastline (S1), whereas a lower level (0.40 ± 0.18 ppb) in the area between 30 km and 100 km from the coastline (S2). Five distinct hotspots of HONO were identified, including Ningbo Port, Yangshan Port, the Yangtze River estuary, northwest of the Zhoushan city, and the area adjacent to Jinshan Chem. Industry Park, suggesting the impact of local vessel emissions and land industrial emissions on HONO formation. During the nighttime, the direct vessel emissions contributed on av. 18% of the HONO concn. The averaged conversion frequency of NO2-to-HONO (khet) estd. from 6 nighttime cases was 1.18 × 10-2 h-1. Daytime budget anal. showed that the unknown HONO prodn. rate (Punknown) in S1 and S2 was 1.52 ppb h-1 and 1.14 ppb h-1, resp. Punknown was related to a light-induced HONO source from NO2 on the sea surface and particulate nitrate. During the cruise campaign, the averaged daytime OH prodn. rate from HONO photolysis was 1.35 ± 0.69 ppb h-1, ∼1.6 times higher than that from the O3 photolysis (0.87 ± 0.55 ppb h-1), which suggested an important role of HONO in the atm. chem. of the offshore area of ECS.
    87. 87
      Lee, J. D.; Whalley, L. K.; Heard, D. E.; Stone, D.; Dunmore, R. E.; Hamilton, J. F.; Young, D. E.; Allan, J. D.; Laufs, S.; Kleffmann, J. Detailed budget analysis of HONO in central London reveals a missing daytime source. Atmospheric Chemistry and Physics 2016, 16 (5), 2747– 2764,  DOI: 10.5194/acp-16-2747-2016
      87
      Detailed budget analysis of HONO in central London reveals a missing daytime source
      Lee, J. D.; Whalley, L. K.; Heard, D. E.; Stone, D.; Dunmore, R. E.; Hamilton, J. F.; Young, D. E.; Allan, J. D.; Laufs, S.; Kleffmann, J.
      Atmospheric Chemistry and Physics (2016), 16 (5), 2747-2764CODEN: ACPTCE; ISSN:1680-7324. (Copernicus Publications)
      Measurements of HONO were carried out at an urban background site near central London as part of the Clean air for London (ClearfLo) project in summer 2012. Data were collected from 22 July to 18 August 2014, with peak values of up to 1.8 ppbV at night and non-zero values of between 0.2 and 0.6 ppbV seen during the day. A wide range of other gas phase, aerosol, radiation, and meteorol. measurements were made concurrently at the same site, allowing a detailed anal. of the chem. to be carried out. The peak HONO=NOx ratio of 0.04 is seen at ∼02:00 UTC, with the presence of a second, daytime, peak in HONO=NOx of similar magnitude to the night-time peak, suggesting a significant secondary daytime HONO source. A photostationary state calcn. of HONO involving formation from the reaction of OH and NO and loss from photolysis, reaction with OH, and dry deposition shows a significant underestimation during the day, with calcd. values being close to 0, compared to the measurement av. of 0.4 ppbV at midday. The addn. of further HONO sources from the literature, including dark conversion of NOx on surfaces, direct emission, photolysis of ortho-substituted nitrophenols, the postulated formation from the reaction of HO2 × H2O with NO2, photolysis of adsorbed HNO3 on ground and aerosols, and HONO produced by photosensitized conversion of NO2 on the surface increases the daytime modelled HONO to 0.1 ppbV, still leaving a significant missing daytime source. The missing HONO is plotted against a series of parameters including NO2 and OH reactivity (used as a proxy for org. material), with little correlation seen. Much better correlation is obsd. with the product of these species with j(NO2), in particular NO2 and the product of NO2 with OH reactivity. This suggests the missing HONO source is in some way related to NO2 and also requires sunlight. Increasing the photo-sensitized surface conversion rate of NO2 by a factor of 10 to a mean daytime first-order loss of ∼6 × 10-5 s-1 (but which varies as a function of j(NO2)) closes the daytime HONO budget at all times (apart from the late afternoon), suggesting that urban surfaces may enhance this photosensitized source. The effect of the missing HONO to OH radical prodn. is also investigated and it is shown that the model needs to be constrained to measured HONO in order to accurately reproduce the OH radical measurements.
    88. 88
      Zha, Q.; Xue, L.; Wang, T.; Xu, Z.; Yeung, C.; Louie, P. K. K.; Luk, C. W. Y. Large conversion rates of NO2 to HNO2 observed in air masses from the South China Sea: Evidence of strong production at sea surface?. Geophys. Res. Lett. 2014, 41 (21), 7710– 7715,  DOI: 10.1002/2014GL061429
      88
      Large conversion rates of NO2 to HNO2 observed in air masses from the South China Sea: Evidence of strong production at sea surface?
      Zha, Qiaozhi; Xue, Likun; Wang, Tao; Xu, Zheng; Yeung, Chungpong; Louie, Peter K. K.; Luk, Connie W. Y.
      Geophysical Research Letters (2014), 41 (21), 7710-7715CODEN: GPRLAJ; ISSN:1944-8007. (Wiley-Blackwell)
      Nitrous acid (HONO) plays important roles in tropospheric chem., but its source(s) are not completely understood. Here, we analyze measurements of HONO, nitrogen dioxide (NO2), and related parameters at a coastal site in Hong Kong during Sept.-Dec. 2012. The nocturnal NO2-to-HONO conversion rates were estd. in air masses passing over land and sea surfaces. The conversion rates in the "sea cases" (3.17-3.36 × 10-2 h-1) were significantly higher than those in the "land cases" in our study (1.20-1.30 × 10-2 h-1) and in previous studies by others. These results suggest that air-sea interactions may be a significant source of atm. HONO and need to be considered in chem. transport models.
    89. 89
      Liu, X.; Ran, L.; Lin, W.; Xu, X.; Ma, Z.; Dong, F.; He, D.; Zhou, L.; Shi, Q.; Wang, Y. Measurement report: Variations in surface SO2 and NOx mixing ratios from 2004 to 2016 at a background site in the North China Plain. Atmos. Chem. Phys. 2022, 22 (10), 7071– 7085,  DOI: 10.5194/acp-22-7071-2022
      There is no corresponding record for this reference.
    90. 90
      Chen, J.; Li, C.; Ristovski, Z.; Milic, A.; Gu, Y.; Islam, M. S.; Wang, S.; Hao, J.; Zhang, H.; He, C.; Guo, H.; Fu, H.; Miljevic, B.; Morawska, L.; Thai, P.; Lam, Y. F.; Pereira, G.; Ding, A.; Huang, X.; Dumka, U. C. A review of biomass burning: Emissions and impacts on air quality, health and climate in China. Sci. Total Environ. 2017, 579, 1000– 1034,  DOI: 10.1016/j.scitotenv.2016.11.025
      90
      A review of biomass burning: Emissions and impacts on air quality, health and climate in China
      Chen, Jianmin; Li, Chunlin; Ristovski, Zoran; Milic, Andelija; Gu, Yuantong; Islam, Mohammad S.; Wang, Shuxiao; Hao, Jiming; Zhang, Hefeng; He, Congrong; Guo, Hai; Fu, Hongbo; Miljevic, Branka; Morawska, Lidia; Thai, Phong; Lam, Yun Fat; Pereira, Gavin; Ding, Aijun; Huang, Xin; Dumka, Umesh C.
      Science of the Total Environment (2017), 579 (), 1000-1034CODEN: STENDL; ISSN:0048-9697. (Elsevier B.V.)
      A comprehensive review of biomass burning (BB) emissions and their impacts on air quality, human health, and climate in China is given. including literature concerning field measurements, lab. studies and the impacts of BB indoors and outdoors in China. It attempted to provide a basis for policy-makers to formulate policies and regulations. Topics discussed include: introduction; BB monitoring (field observations, satellite remote sensing, lab. studies, BB campaigns); BB types (forest fire, agricultural straw open burning, wood and straw combustion as fuel, misc.); BB pollutants (particulate matter [carbonaceous, other important components], smoke particle phys. properties [size distribution, hygroscopicity, d., volatility, optical properties], morphol. and mixing state, gaseous pollutants, polycyclic arom. hydrocarbons, emission trends and control); BB plumes (transport, atm. aging [transmission electron microscopy plus energy-dispersive x-ray spectroscopy, and aerosol mass spectrometry approaches, O3 formation from BB emissions]); BB impacts (severe haze episodes, air quality impacts [annual and seasonal properties, BB episode impact assessment], health, climate and weather); research priorities and insights (field campaigns, aging, health and climate).
    91. 91
      Yuan, B.; Liu, Y.; Shao, M.; Lu, S.; Streets, D. G. Biomass Burning Contributions to Ambient VOCs Species at a Receptor Site in the Pearl River Delta (PRD), China. Environ. Sci. Technol. 2010, 44 (12), 4577– 4582,  DOI: 10.1021/es1003389
      91
      Biomass burning contributions to ambient VOCs species at a receptor site in the Pearl River Delta (PRD), China
      Yuan, Bin; Liu, Ying; Shao, Min; Lu, Sihua; Streets, David G.
      Environmental Science & Technology (2010), 44 (12), 4577-4582CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      Ambient VOCs were measured by a proton transfer reaction-mass spectrometer (PTR-MS) at a receptor site in the Pearl River Delta (PRD), China during Oct. 19-Nov. 18, 2008. Biomass burning plumes are identified by using acetonitrile as tracer, and enhancement ratios of 9 VOCs species relative to acetonitrile are obtained from linear regression anal. and the source-tracer-ratio method. Enhancement ratios detd. by the 2 different methods show good agreement for most VOCs species. Biomass burning contributions are investigated by using the source-tracer-ratio method. Biomass burning contributed 9.5%-17.7% to mixing ratios of the 9 VOCs. The estd. biomass burning contributions are compared with local emission inventories. Large discrepancies are obsd. between our results and the ests. in 2 emission inventories. Though biomass burning emissions in TRACE-P inventory agree well with our results, the VOCs speciation for arom. compds. may be not appropriate for Guangdong.
    92. 92
      Juncosa Calahorrano, J. F.; Lindaas, J.; O’Dell, K.; Palm, B. B.; Peng, Q.; Flocke, F.; Pollack, I. B.; Garofalo, L. A.; Farmer, D. K.; Pierce, J. R.; Collett, J. L.; Weinheimer, A.; Campos, T.; Hornbrook, R. S.; Hall, S. R.; Ullmann, K.; Pothier, M. A.; Apel, E. C.; Permar, W.; Hu, L.; Hills, A. J.; Montzka, D.; Tyndall, G.; Thornton, J. A.; Fischer, E. V. Daytime Oxidized Reactive Nitrogen Partitioning in Western U.S. Wildfire Smoke Plumes. Journal of Geophysical Research: Atmospheres 2021, 126 (4), e2020JD033484,  DOI: 10.1029/2020JD033484
      There is no corresponding record for this reference.
    93. 93
      Hughes, D. D.; Christiansen, M. B.; Milani, A.; Vermeuel, M. P.; Novak, G. A.; Alwe, H. D.; Dickens, A. F.; Pierce, R. B.; Millet, D. B.; Bertram, T. H.; Stanier, C. O.; Stone, E. A. PM2.5 chemistry, organosulfates, and secondary organic aerosol during the 2017 Lake Michigan Ozone Study. Atmos. Environ. 2021, 244, 117939,  DOI: 10.1016/j.atmosenv.2020.117939
      93
      PM2.5 chemistry, organosulfates, and secondary organic aerosol during the 2017 Lake Michigan Ozone Study
      Hughes, Dagen D.; Christiansen, Megan B.; Milani, Alissa; Vermeuel, Michael P.; Novak, Gordon A.; Alwe, Hariprasad D.; Dickens, Angela F.; Pierce, R. Bradley; Millet, Dylan B.; Bertram, Timothy H.; Stanier, Charles O.; Stone, Elizabeth A.
      Atmospheric Environment (2021), 244 (), 117939CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Ltd.)
      The Lake Michigan Ozone Study from 21 May to 23 June 2017 (LMOS 2017) aimed to better understand the anthropogenic and biogenic sources that contribute to ozone and fine particles (PM2.5) along the coast of Lake Michigan. Here, we focus on the chem. compn. of daytime and nighttime PM2.5-esp. org. carbon, inorg. ions and organosulfates-at a ground-based supersite in Zion, Illinois. PM2.5 mass concns. ranged from 1.5 to 12.9 μg m-3 with an av. (±std. error) of 5.2 ± 0.4 μg m-3. The most significant contributor to PM2.5 mass was org. matter (OM; calcd. as 1.7 x org. carbon [OC]; contributing an av. of 59 ± 2%), followed by sulfate (17± 1%), ammonium (6.3 ± 0.3%), nitrate (3.5 ± 0.4%), and elemental carbon (EC; 3.4± 0.2%). During each of the three periods of high ozone, PM2.5 had different regional characteristics. Period A (2-3 June) was impacted by lake breeze and south-easterly air masses that travelled over major urban areas. Period A had the highest daily PM2.5 mass concns. (11.4 ± 1.5 μg m-3) and EC with a relatively low OC:EC ratio of 7.0, indicating the influence of sources with low OC:EC ratios, which includes the anthropogenic combustion of fossil fuels and biomass. Period B (10-13 June) was impacted by air masses traveling from the southern US. It had a relatively high OC:EC ratio of 18, the highest PM2.5 sulfate concns. and aerosol acidity, and elevated mixing ratios of isoprene along with its oxidn. products Me vinyl ketone (MVK) and methacrolein (MACR). Peak concns. of organosulfates, including methyltetrol sulfate (m/z 215; C5H11SO-7), were also obsd. throughout period B. Period C (13-17 June) followed a change to northerly winds. PM2.5 concns. decreased along with decreases in sulfate, acidity, and most organosulfates. Throughout the study, organosulfates accounted for an av. of 4% of OM and up to 15% of OM in Period B. Organosulfates were largely isoprene-derived, with lessor contributions from monoterpenes (0.3%) and anthropogenic sources (0.5%). Through these measurements of organosulfates in the Great Lakes region, we demonstrate the importance of anthropogenic sulfate emissions and aerosol acidity on SOA formation, and establish that isoprene-derived organosulfates, in particular, contribute significantly to PM2.5. With other LMOS observations, the chem. signatures of PM2.5, and back trajectories show that ozone episodes cooccur with localized lake-breeze meteorol. within air masses that vary from episode to episode in chem. history and source region.
    94. 94
      Lindaas, J.; Pollack, I. B.; Garofalo, L. A.; Pothier, M. A.; Farmer, D. K.; Kreidenweis, S. M.; Campos, T. L.; Flocke, F.; Weinheimer, A. J.; Montzka, D. D.; Tyndall, G. S.; Palm, B. B.; Peng, Q.; Thornton, J. A.; Permar, W.; Wielgasz, C.; Hu, L.; Ottmar, R. D.; Restaino, J. C.; Hudak, A. T.; Ku, I. T.; Zhou, Y.; Sive, B. C.; Sullivan, A.; Collett, J. L.; Fischer, E. V. Emissions of Reactive Nitrogen From Western U.S. Wildfires During Summer 2018. Journal of Geophysical Research: Atmospheres 2021, 126 (2), e2020JD032657,  DOI: 10.1029/2020JD032657
      There is no corresponding record for this reference.
    95. 95
      Peng, Q.; Palm, B. B.; Melander, K. E.; Lee, B. H.; Hall, S. R.; Ullmann, K.; Campos, T.; Weinheimer, A. J.; Apel, E. C.; Hornbrook, R. S.; Hills, A. J.; Montzka, D. D.; Flocke, F.; Hu, L.; Permar, W.; Wielgasz, C.; Lindaas, J.; Pollack, I. B.; Fischer, E. V.; Bertram, T. H.; Thornton, J. A. HONO Emissions from Western U.S. Wildfires Provide Dominant Radical Source in Fresh Wildfire Smoke. Environ. Sci. Technol. 2020, 54, 5954,  DOI: 10.1021/acs.est.0c00126
      95
      HONO Emissions from Western U.S. Wildfires Provide Dominant Radical Source in Fresh Wildfire Smoke
      Peng, Qiaoyun; Palm, Brett B.; Melander, Kira E.; Lee, Ben H.; Hall, Samuel R.; Ullmann, Kirk; Campos, Teresa; Weinheimer, Andrew J.; Apel, Eric C.; Hornbrook, Rebecca S.; Hills, Alan J.; Montzka, Denise D.; Flocke, Frank; Hu, Lu; Permar, Wade; Wielgasz, Catherine; Lindaas, Jakob; Pollack, Ilana B.; Fischer, Emily V.; Bertram, Timothy H.; Thornton, Joel A.
      Environmental Science & Technology (2020), 54 (10), 5954-5963CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      Wildfires are an important source of HONO, a photo-labile radical precursor, yet in-situ measurements and quantification of primary HONO emissions from open wildfires are scarce. Airborne observations of HONO within wildfire plumes sampled during the Western Wildfire Expt. for Cloud Chem., Aerosol Absorption and Nitrogen (WE-CAN) campaign were obsd. ΔHONO:ΔCO ratios close to fire locations were 0.7-17 pptv/ppbv, using a max. enhancement method, with a median similar to previous observations of temperate forest fire plumes. Measured HONO:NOx enhancement ratios were generally factors of 2 or higher at early plume ages vs. previous studies. Enhancement ratios scaled with modified combustion efficiency and certain nitrogenous trace gases, which may be useful to est. HONO release when HONO observations are lacking or plumes have photochem. exposures >1 h, since emitted HONO is rapidly photolyzed. HONO photolysis was the dominant contributor to hydrogen oxide radicals (HOx = OH- + HO2) in the early stage (<3 h) wildfire plume evolution. Results highlighted the HONO role as a major component of reactive N emissions from wildfires and the main driver of initial photochem. oxidn.
    96. 96
      Xu, R.; Li, X.; Dong, H.; Wu, Z.; Chen, S.; Xin, F.; Gao, J.; Guo, S.; Hu, M.; Li, D.; Liu, Y.; Liu, Y.; Lou, S.; Lu, K.; Meng, X.; Wang, H.; Zeng, L.; Zong, T.; Hu, J.; Zhang, Y. Measurement of gaseous and particulate formaldehyde in the Yangtze River Delta, China. Atmos. Environ. 2020, 224, 117114  DOI: 10.1016/j.atmosenv.2019.117114
      There is no corresponding record for this reference.
    97. 97
      Brock, C. A.; Cozic, J.; Bahreini, R.; Froyd, K. D.; Middlebrook, A. M.; McComiskey, A.; Brioude, J.; Cooper, O. R.; Stohl, A.; Aikin, K. C.; de Gouw, J. A.; Fahey, D. W.; Ferrare, R. A.; Gao, R. S.; Gore, W.; Holloway, J. S.; Hübler, G.; Jefferson, A.; Lack, D. A.; Lance, S.; Moore, R. H.; Murphy, D. M.; Nenes, A.; Novelli, P. C.; Nowak, J. B.; Ogren, J. A.; Peischl, J.; Pierce, R. B.; Pilewskie, P.; Quinn, P. K.; Ryerson, T. B.; Schmidt, K. S.; Schwarz, J. P.; Sodemann, H.; Spackman, J. R.; Stark, H.; Thomson, D. S.; Thornberry, T.; Veres, P.; Watts, L. A.; Warneke, C.; Wollny, A. G. Characteristics, sources, and transport of aerosols measured in spring 2008 during the aerosol, radiation, and cloud processes affecting Arctic Climate (ARCPAC) Project. Atmospheric Chemistry and Physics 2011, 11 (6), 2423– 2453,  DOI: 10.5194/acp-11-2423-2011
      There is no corresponding record for this reference.
    98. 98
      Hecobian, A.; Liu, Z.; Hennigan, C. J.; Huey, L. G.; Jimenez, J. L.; Cubison, M. J.; Vay, S.; Diskin, G. S.; Sachse, G. W.; Wisthaler, A.; Mikoviny, T.; Weinheimer, A. J.; Liao, J.; Knapp, D. J.; Wennberg, P. O.; Kürten, A.; Crounse, J. D.; Clair, J. S.; Wang, Y.; Weber, R. J. Comparison of chemical characteristics of 495 biomass burning plumes intercepted by the NASA DC-8 aircraft during the ARCTAS/CARB-2008 field campaign. Atmos. Chem. Phys. 2011, 11 (24), 13325– 13337,  DOI: 10.5194/acp-11-13325-2011
      98
      Comparison of chemical characteristics of 495 biomass burning plumes intercepted by the NASA DC-8 aircraft during the ARCTAS/CARB-2008 field campaign
      Hecobian, A.; Liu, Z.; Hennigan, C. J.; Huey, L. G.; Jimenez, J. L.; Cubison, M. J.; Vay, S.; Diskin, G. S.; Sachse, G. W.; Wisthaler, A.; Mikoviny, T.; Weinheimer, A. J.; Liao, J.; Knapp, D. J.; Wennberg, P. O.; Kurten, A.; Crounse, J. D.; St. Clair, J.; Wang, Y.; Weber, R. J.
      Atmospheric Chemistry and Physics (2011), 11 (24, Pt. 2), 13325-13337CODEN: ACPTCE; ISSN:1680-7316. (Copernicus Publications)
      This paper compares measurements of gaseous and particulate emissions from a wide range of biomass-burning plumes intercepted by the NASA DC-8 research aircraft during the three phases of the ARCTAS-2008 expt.: ARCTAS-A, based out of Fairbanks, Alaska, USA (3 Apr. to 19 Apr. 2008); ARCTAS-B based out of Cold Lake, Alberta, Canada (29 June to 13 July 2008); and ARCTAS-CARB, based out of Palmdale, California, USA (18 June to 24 June 2008). Approx. 500 smoke plumes from biomass burning emissions that varied in age from minutes to days were segregated by fire source region and urban emission influences. The normalized excess mixing ratios (NEMR) of gaseous (carbon dioxide, acetonitrile, hydrogen cyanide, toluene, benzene, methane, oxides of nitrogen and ozone) and fine aerosol particulate components (nitrate, sulfate, ammonium, chloride, org. aerosols and water sol. org. carbon) of these plumes were compared. A detailed statistical anal. of the different plume categories for different gaseous and aerosol species is presented in this paper. The comparison of NEMR values showed that CH4 concns. were higher in air-masses that were influenced by urban emissions. Fresh biomass burning plumes mixed with urban emissions showed a higher degree of oxidative processing in comparison with fresh biomass burning only plumes. This was evident in higher concns. of inorg. aerosol components such as sulfate, nitrate and ammonium, but not reflected in the org. components. Lower NOx NEMRs combined with high sulfate, nitrate and ammonium NEMRs in aerosols of plumes subject to long-range transport, when comparing all plume categories, provided evidence of advanced processing of these plumes.
    99. 99
      Pandit, S.; Grassian, V. H. Gas-Phase Nitrous Acid (HONO) Is Controlled by Surface Interactions of Adsorbed Nitrite (NO2−) on Common Indoor Material Surfaces. Environ. Sci. Technol. 2022, 56 (17), 12045– 12054,  DOI: 10.1021/acs.est.2c02042
      There is no corresponding record for this reference.
    100. 100
      Zhang, Q.; Wang, Y.; Liu, M.; Zheng, M.; Yuan, L.; Liu, J.; Tao, S.; Wang, X. Wintertime Formation of Large Sulfate Particles in China and Implications for Human Health. Environ. Sci. Technol. 2023, 57, 20010,  DOI: 10.1021/acs.est.3c05645
      There is no corresponding record for this reference.
    101. 101
      Zheng, M.; Wang, Y.; Bao, J.; Yuan, L.; Zheng, H.; Yan, Y.; Liu, D.; Xie, M.; Kong, S. Initial Cost Barrier of Ammonia Control in Central China. Geophys. Res. Lett. 2019, 46 (23), 14175– 14184,  DOI: 10.1029/2019GL084351
      There is no corresponding record for this reference.
    102. 102
      Zhang, W.; Tong, S.; Jia, C.; Wang, L.; Liu, B.; Tang, G.; Ji, D.; Hu, B.; Liu, Z.; Li, W.; Wang, Z.; Liu, Y.; Wang, Y.; Ge, M. Different HONO Sources for Three Layers at the Urban Area of Beijing. Environ. Sci. Technol. 2020, 54 (20), 12870– 12880,  DOI: 10.1021/acs.est.0c02146
      102
      Different HONO sources for three layers at the urban area of Beijing
      Zhang, Wenqian; Tong, Shengrui; Jia, Chenhui; Wang, Lili; Liu, Baoxian; Tang, Guiqian; Ji, Dongsheng; Hu, Bo; Liu, Zirui; Li, Weiran; Wang, Zhen; Liu, Yang; Wang, Yuesi; Ge, Maofa
      Environmental Science & Technology (2020), 54 (20), 12870-12880CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      Gaseous nitrous acid (HONO) is a crucial precursor of the hydroxyl (OH) radical, which is a "detergent" in the atm. Nowadays, HONO formation mechanisms at polluted urban areas are controversial, which restricts the understanding of atm. oxidative capacity and radical cycling. Herein, multiday vertical observation of HONO and NOx was simultaneously performed at three heights at the urban area of Beijing for the first time. The vertical distribution of HONO was often unexpected, and it had the highest HONO concn. at 120 m, followed by those at 8 and 240 m. 0D box model simulations suggest that ground and aerosol surfaces might play similar roles in NO2 conversion at 8 m during the whole measurement. NO2 conversion on aerosol surfaces was the most important HONO source aloft during haze days. At daytime, a strong missing HONO source unexpectedly existed in the urban aloft, and it was relevant to solar radiation and consumed OH.
    103. 103
      Jiang, Y.; Xue, L.; Shen, H.; Dong, C.; Xiao, Z.; Wang, W. Dominant Processes of HONO Derived from Multiple Field Observations in Contrasting Environments. Environmental Science & Technology Letters 2022, 9 (4), 258– 264,  DOI: 10.1021/acs.estlett.2c00004
      There is no corresponding record for this reference.
    104. 104
      Ye, C.; Zhou, X.; Pu, D.; Stutz, J.; Festa, J.; Spolaor, M.; Tsai, C.; Cantrell, C.; Mauldin, R. L., 3rd; Campos, T.; Weinheimer, A.; Hornbrook, R. S.; Apel, E. C.; Guenther, A.; Kaser, L.; Yuan, B.; Karl, T.; Haggerty, J.; Hall, S.; Ullmann, K.; Smith, J. N.; Ortega, J.; Knote, C. Rapid cycling of reactive nitrogen in the marine boundary layer. Nature 2016, 532 (7600), 489– 491,  DOI: 10.1038/nature17195
      104
      Rapid cycling of reactive nitrogen in the marine boundary layer
      Ye, Chunxiang; Zhou, Xianliang; Pu, Dennis; Stutz, Jochen; Festa, James; Spolaor, Max; Tsai, Catalina; Cantrell, Christopher; Mauldin, Roy L.; Campos, Teresa; Weinheimer, Andrew; Hornbrook, Rebecca S.; Apel, Eric C.; Guenther, Alex; Kaser, Lisa; Yuan, Bin; Karl, Thomas; Haggerty, Julie; Hall, Samuel; Ullmann, Kirk; Smith, James N.; Ortega, John; Knote, Christoph
      Nature (London, United Kingdom) (2016), 532 (7600), 489-491CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)
      NOx are essential for the formation of secondary atm. aerosols and of atm. oxidants such as ozone and the hydroxyl radical, which controls the self-cleansing capacity of the atm. Nitric acid, a major oxidn. product of NOx, has traditionally been considered to be a permanent sink of NOx. However, model studies predict higher ratios of nitric acid to NOx in the troposphere than are obsd. A renoxification process that recycles nitric acid into NOx has been proposed to reconcile observations with model studies, but the mechanisms responsible for this process remain uncertain. We present data from an aircraft measurement campaign over the North Atlantic Ocean and find evidence for rapid recycling of nitric acid to nitrous acid and NOx in the clean marine boundary layer via particulate nitrate photolysis. Lab. expts. further demonstrate the photolysis of particulate nitrate collected on filters at a rate >2 orders of magnitude greater than that of gaseous nitric acid, with nitrous acid as the main product. Box model calcns. based on the Master Chem. Mechanism suggest that particulate nitrate photolysis mainly sustains the obsd. levels of nitrous acid and NOx at midday under typical marine boundary layer conditions. Given that oceans account for >70% of Earth's surface, we propose that particulate nitrate photolysis could be a substantial tropospheric NOx source. Recycling of NOx in remote oceanic regions with minimal direct NOx emissions could increase the formation of tropospheric oxidants and secondary atm. aerosols on a global scale.
    105. 105
      Ramazan, K. A.; Wingen, L. M.; Miller, Y.; Chaban, G. M.; Gerber, R. B.; Xantheas, S. S.; Finlayson-Pitts, B. J. New Experimental and Theoretical Approach to the Heterogeneous Hydrolysis of NO2: Key Role of Molecular Nitric Acid and Its Complexes. J. Phys. Chem. A 2006, 110 (21), 6886– 6897,  DOI: 10.1021/jp056426n
      105
      New Experimental and Theoretical Approach to the Heterogeneous Hydrolysis of NO2: Key Role of Molecular Nitric Acid and Its Complexes
      Ramazan, K. A.; Wingen, L. M.; Miller, Y.; Chaban, G. M.; Gerber, R. B.; Xantheas, S. S.; Finlayson-Pitts, B. J.
      Journal of Physical Chemistry A (2006), 110 (21), 6886-6897CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
      Although heterogeneous chem. on surfaces in the troposphere is known to be important, there are currently only a few techniques available to study the nature of surface-adsorbed species and their chem. and photochem. under atm. conditions of 1 atm pressure and in the presence of water vapor. A lab. approach using a combination of long path Fourier transform IR spectroscopy (FTIR) and attenuated total reflectance (ATR) FTIR which allows simultaneous observation and measurement of gases and surface species is reported. Theory identified surface-adsorbed intermediates and products and estd. their relative concns. At intermediate relative humidity typical of the tropospheric boundary layer, HNO3 formed during NO2 heterogeneous hydrolysis was shown to exist as NO3- from dissocn. of HNO3 formed on the surface and as mol. HNO3. In both cases, ions and HNO3 are complexed to water mols. Upon pumping, water is selectively removed, shifting the NO3--HNO3(water)y equil. toward more dehydrated forms of HNO3 and ultimately to HNO3 dimers. Irradiating the HNO3-water film using 300-400 nm radiation generated gaseous NO; irradn. at 254 nm generated NO and HNO2, resulting in conversion of surface-adsorbed NOx into photochem.-active NOx. Results which suggest the assumption that HNO3 deposition or formation provides a permanent removal mechanism from the atm. may not be correct. A potential role of surface-adsorbed HNO3 and other species formed during heterogeneous hydrolysis of NO2 during oxidn. of orgs. on surfaces, and in the generation of gas-phase HNO2 on local to global scales, should be considered.
    106. 106
      Zhou, X.; Gao, H.; He, Y.; Huang, G.; Bertman, S. B.; Civerolo, K.; Schwab, J. Nitric acid photolysis on surfaces in low-NOx environments: Significant atmospheric implications. Geophys. Res. Lett. 2003, 30 (23), 2217,  DOI: 10.1029/2003GL018620
      There is no corresponding record for this reference.
    107. 107
      Hauglustaine, D. A.; Ridley, B. A.; Solomon, S.; Hess, P. G.; Madronich, S. HNO3/NOx ratio in the remote troposphere During MLOPEX 2: Evidence for nitric acid reduction on carbonaceous aerosols?. Geophys. Res. Lett. 1996, 23 (19), 2609– 2612,  DOI: 10.1029/96GL02474
      107
      HNO3/NOx Ratio in the remote troposphere during MLOPEX 2: Evidence for nitric acid reduction on carbonaceous aerosols?
      Hauglustaine, D. A.; Ridley, B. A.; Solomon, S.; Hess, P. G.; Madronich, S.
      Geophysical Research Letters (1996), 23 (19), 2609-2612CODEN: GPRLAJ; ISSN:0094-8276. (American Geophysical Union)
      The [HNO3]/[NOx] ratio is generally over-estd. by a factor of 5-10 in photochem. models in comparison to tropospheric measurements. In this study, the heterogeneous redn. of HNO3 into NO on carbonaceous aerosols [Lary et al., 1996] has been introduced in a photochem. box-model on the basis of black carbon mass densities measured during MLOPEX 2. This recycling to NOx decreases the [HNO3]/[NOx] ratio close to obsd. values. The concomitant increase in modeled NOx concn. is also in better agreement with the observations, and has substantial implications for the ozone budget in the remote atm. Large uncertainties in the est. of black carbon surface area and of accommodation coeffs. preclude definitive conclusions until more detailed measurements are carried out.
    108. 108
      Liu, Z.; Wang, Y.; Gu, D.; Zhao, C.; Huey, L. G.; Stickel, R.; Liao, J.; Shao, M.; Zhu, T.; Zeng, L.; Amoroso, A.; Costabile, F.; Chang, C. C.; Liu, S. C. Summertime photochemistry during CAREBeijing-2007: ROx budgets and O3 formation. Atmospheric Chemistry and Physics 2012, 12 (16), 7737– 7752,  DOI: 10.5194/acp-12-7737-2012
      There is no corresponding record for this reference.
    109. 109
      Dyson, J. E.; Boustead, G. A.; Fleming, L. T.; Blitz, M.; Stone, D.; Arnold, S. R.; Whalley, L. K.; Heard, D. E. Production of HONO from NO2 uptake on illuminated TiO2 aerosol particles and following the illumination of mixed TiO2/ammonium nitrate particles. Atmos. Chem. Phys. 2021, 21 (7), 5755– 5775,  DOI: 10.5194/acp-21-5755-2021
      There is no corresponding record for this reference.
    110. 110
      Reed, C.; Evans, M. J.; Crilley, L. R.; Bloss, W. J.; Sherwen, T.; Read, K. A.; Lee, J. D.; Carpenter, L. J. Evidence for renoxification in the tropical marine boundary layer. Atmos. Chem. Phys. 2017, 17 (6), 4081– 4092,  DOI: 10.5194/acp-17-4081-2017
      110
      Evidence for renoxification in the tropical marine boundary layer
      Reed, Chris; Evans, Mathew J.; Crilley, Leigh R.; Bloss, William J.; Sherwen, Tomas; Read, Katie A.; Lee, James D.; Carpenter, Lucy J.
      Atmospheric Chemistry and Physics (2017), 17 (6), 4081-4092CODEN: ACPTCE; ISSN:1680-7324. (Copernicus Publications)
      We present 2 years of NOx observations from the Cape Verde Atm. Observatory located in the tropical Atlantic boundary layer. We find that NOx mixing ratios peak around solar noon (at 20-30 pptV depending on season), which is counter to box model simulations that show a midday min. due to OH conversion of NO2 to HNO3. Prodn. of NOx via decompn. of org. nitrogen species and the photolysis of HNO3 appear insufficient to provide the obsd. noontime max. A rapid photolysis of nitrate aerosol to produce HONO and NO2, however, is able to simulate the obsd. diurnal cycle. This would make it the dominant source of NOx at this remote marine boundary layer site, overturning the previous paradigm according to which the transport of org. nitrogen species, such as PAN, is the dominant source. We show that obsd. mixing ratios (Nov.-Dec. 2015) of HONO at Cape Verde (∼3.5 pptV peak at solar noon) are consistent with this route for NOx prodn. Reactions between the nitrate radical and halogen hydroxides which have been postulated in the literature appear to improve the box model simulation of NOx. This rapid conversion of aerosol phase nitrate to NOx changes our perspective of the NOx cycling chem. in the tropical marine boundary layer, suggesting a more chem. complex environment than previously thought.
    111. 111
      Kasibhatla, P.; Sherwen, T.; Evans, M. J.; Carpenter, L. J.; Reed, C.; Alexander, B.; Chen, Q.; Sulprizio, M. P.; Lee, J. D.; Read, K. A.; Bloss, W.; Crilley, L. R.; Keene, W. C.; Pszenny, A. A. P.; Hodzic, A. Global impact of nitrate photolysis in sea-salt aerosol on NOx, OH, and O3 in the marine boundary layer. Atmospheric Chemistry and Physics 2018, 18 (15), 11185– 11203,  DOI: 10.5194/acp-18-11185-2018
      There is no corresponding record for this reference.
    112. 112
      Ha, P. T. M.; Kanaya, Y.; Taketani, F.; Andrés Hernández, M. D.; Schreiner, B.; Pfeilsticker, K.; Sudo, K. Implementation of HONO into the chemistry–climate model CHASER (V4.0): roles in tropospheric chemistry. Geosci. Model Dev. 2023, 16 (3), 927– 960,  DOI: 10.5194/gmd-16-927-2023
      There is no corresponding record for this reference.
    113. 113
      Crilley, L. R.; Kramer, L. J.; Pope, F. D.; Reed, C.; Lee, J. D.; Carpenter, L. J.; Hollis, L. D. J.; Ball, S. M.; Bloss, W. J. Is the ocean surface a source of nitrous acid (HONO) in the marine boundary layer?. Atmos. Chem. Phys. 2021, 21 (24), 18213– 18225,  DOI: 10.5194/acp-21-18213-2021
      113
      Is the ocean surface a source of nitrous acid (HONO) in the marine boundary layer?
      Crilley, Leigh R.; Kramer, Louisa J.; Pope, Francis D.; Reed, Chris; Lee, James D.; Carpenter, Lucy J.; Hollis, Lloyd D. J.; Ball, Stephen M.; Bloss, William J.
      Atmospheric Chemistry and Physics (2021), 21 (24), 18213-18225CODEN: ACPTCE; ISSN:1680-7324. (Copernicus Publications)
      Nitrous acid, HONO, is a key net photolytic precursor to OH radicals in the atm. boundary layer. As OH is the dominant atm. oxidant, driving the removal of many primary pollutants and the formation of secondary species, a quant. understanding of HONO sources is important to predict atm. oxidising capacity. While a no. of HONO formation mechanisms have been identified, recent work has ascribed significant importance to the dark, ocean-surface-mediated conversion of NO2 to HONO in the coastal marine boundary layer. In order to evaluate the role of this mechanism, here we analyze measurements of HONO and related species obtained at two contrasting coastal locations - Cabo Verde (Atlantic Ocean, denoted Cape Verde herein), representative of the clean remote tropical marine boundary layer, and Weybourne (United Kingdom), representative of semi-polluted northern European coastal waters. As expected, higher av. concns. of HONO (70 ppt) were obsd. in marine air for the more anthropogenically influenced Weybourne location compared to Cape Verde (HONO < 5 ppt). At both sites, the approx. const. HONO/NO2 ratio at night pointed to a low importance for the dark, ocean-surface-mediated conversion of NO2 into HONO, whereas the midday max. in the HONO/NO2 ratios indicated significant contributions from photo-enhanced HONO formation mechanisms (or other sources). We obtained an upper limit to the rate coeff. of dark, ocean-surface HONO-to-NO2 conversion of CHONO = 0.0011 ppb h-1 from the Cape Verde observations; this is a factor of 5 lower than the slowest rate reported previously. These results point to significant geog. variation in the predominant HONO formation mechanisms in marine environments and indicate that caution is required when extrapolating the importance of such mechanisms from individual study locations to assess regional and/or global impacts on oxidising capacity. As a significant fraction of atm. processing occurs in the marine boundary layer, particularly in the tropics, better constraint of the possible ocean surface source of HONO is important for a quant. understanding of chem. processing of primary trace gases in the global atm. boundary layer and assocd. impacts upon air pollution and climate.
    114. 114
      Wang, P.; Chen, Y.; Hu, J.; Zhang, H.; Ying, Q. Attribution of Tropospheric Ozone to NOx and VOC Emissions: Considering Ozone Formation in the Transition Regime. Environ. Sci. Technol. 2019, 53 (3), 1404– 1412,  DOI: 10.1021/acs.est.8b05981
      114
      Attribution of Tropospheric Ozone to NOx and VOC Emissions: Considering Ozone Formation in the Transition Regime
      Wang, Peng; Chen, Yuan; Hu, Jianlin; Zhang, Hongliang; Ying, Qi
      Environmental Science & Technology (2019), 53 (3), 1404-1412CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      An improved, three-regime (3R) O3 attribution technique for O3 source apportionment in regional chem. transport models was developed to divide the entire range of VOC-NOx-O3 formation sensitivity to VOC-limited, transition, and NOx-limited regimes, based on the value of a regime indicator, R. Threshold R values to mark the start (Rts) and end (Rte) of the transition regime are defined at the point where O3-NOx sensitivity turns from neg. to pos., and where O3-NOx sensitivity is 10 times higher than O3-VOC sensitivity. Rts and Rte are detd. using NOx and VOC sensitivity simulations in a box model with a modified SAPRC-11 mechanism. For the widely used indicator ration R = (PH2O2 + PROOH)/PHNO3, based on H2O2, HNO3 and org. hydroperoxides (ROOH) prodn. rates, recommended Rts and Rte values are 0.047 and 5.142, resp. Parameterized attribution functions, depending only on R values, were developed to apportion modeled in-situ O3 formation in the transition regime to NOx and VOC. New 3R and the traditional two-regime (2R) schemes are incorporated into the Community Multiscale Air Quality model to quantify NOx and VOC contributions to regional O3 concns. in China in Aug. 2013. The 3R approach predicted ∼5-10 ppb and up to 15 ppb higher NOx contributions to 8-h O3 over the North China Plain, Yangtze River Delta, and the Pearl River Delta vs. the 2R approach. Large differences in O3 attribution between 2R and 3R can have significant policy implications for air pollution emission controls.
    115. 115
      Ye, C.; Zhou, X.; Zhang, Y.; Wang, Y.; Wang, J.; Zhang, C.; Woodward-Massey, R.; Cantrell, C.; Mauldin, R. L.; Campos, T.; Hornbrook, R. S.; Ortega, J.; Apel, E. C.; Haggerty, J.; Hall, S.; Ullmann, K.; Weinheimer, A.; Stutz, J.; Karl, T.; Smith, J. N.; Guenther, A.; Song, S. Synthesizing evidence for the external cycling of NOx in high- to low-NOx atmospheres. Nat. Commun. 2023, 14 (1), 7995,  DOI: 10.1038/s41467-023-43866-z
      There is no corresponding record for this reference.
    116. 116
      Tang, Y.; An, J.; Wang, F.; Li, Y.; Qu, Y.; Chen, Y.; Lin, J. Impacts of an unknown daytime HONO source on the mixing ratio and budget of HONO, and hydroxyl, hydroperoxyl, and organic peroxy radicals, in the coastal regions of China. Atmos. Chem. Phys. 2015, 15 (16), 9381– 9398,  DOI: 10.5194/acp-15-9381-2015
      116
      Impacts of an unknown daytime HONO source on the mixing ratio and budget of HONO, and hydroxyl, hydroperoxyl, and organic peroxy radicals, in the coastal regions of China
      Tang, Y.; An, J.; Wang, F.; Li, Y.; Qu, Y.; Chen, Y.; Lin, J.
      Atmospheric Chemistry and Physics (2015), 15 (16), 9381-9398CODEN: ACPTCE; ISSN:1680-7324. (Copernicus Publications)
      Many field expts. have found high nitrous acid (HONO) mixing ratios in both urban and rural areas during daytime, but these high daytime HONO mixing ratios cannot be explained well by gas-phase prodn., HONO emissions, and nighttime hydrolysis conversion of nitrogen dioxide (NO2) on aerosols, suggesting that an unknown daytime HONO source (Punknown) could exist. The formula Punknown ≈ 19.60[NO2] · J(NO2) was obtained using obsd. data from 13 field expts. across the globe. The three addnl. HONO sources (i.e., the Punknown, nighttime hydrolysis conversion of NO2 on aerosols, and HONO emissions) were coupled into the WRF-Chem model (Weather Research and Forecasting model coupled with Chem.) to assess the Punknown impacts on the concns. and budgets of HONO and peroxy (hydroxyl, hydroperoxyl, and org. peroxy) radicals (ROx) (= OH + HO2 + RO2) in the coastal regions of China. Results indicated that the addnl. HONO sources produced a significant improvement in HONO and OH simulations, particularly in the daytime. High daytime av. Punknown values were found in the coastal regions of China, with a max. of 2.5 ppb h-1 in the Beijing-Tianjin-Hebei region. The Punknown produced a 60-250% increase of OH, HO2, and RO2 near the ground in the major cities of the coastal regions of China, and a 5-48% increase of OH, HO2, and RO2 in the daytime meridionalmean mixing ratios within 1000m above the ground. When the three addnl. HONO sources were included, the photolysis of HONO was the second most important source in the OH prodn. rate in Beijing, Shanghai, and Guangzhou before 10:00 LST with a max. of 3.72 ppb h-1 and a corresponding Punknown contribution of 3.06 ppb h-1 in Beijing, whereas the reaction of HO2 + NO (nitric oxide) was dominant after 10:00 LST with a max. of 9.38 ppb h-1 and a corresponding Punknown contribution of 7.23 ppb h-1 in Beijing. The whole ROx cycle was accelerated by the three addnl. HONO sources, esp. the Punknown. The daytime av. OH prodn. rate was enhanced by 0.67 due to the three addnl. HONO sources; [0.64], due to the Punknown, to 4.32 [3.86] ppb h-1, via the reaction of HO2 + NO, and by 0.49 [0.47] to 1.86 [1.86] ppb h-1, via the photolysis of HONO. The OH daytime av. loss rate was enhanced by 0.58 [0.55] to 2.03 [1.92] ppb h-1, via the reaction of OH + NO2, and by 0.31 [0.28] to 1.78 [1.64] ppb h-1, via the reaction of OH + CO (carbon monoxide) in Beijing, Shanghai, and Guangzhou. Similarly, the three addnl. HONO sources produced an increase of 0.31 [0.28] (with a corresponding Punknown contribution) to 1.78 [1.64] ppb h-1, via the reaction of OH + CO, and 0.10 [0.09] to 0.63 [0.59] ppb h-1, via the reaction of CH3O2 (methylperoxy radical) + NO in the daytime av. HO2 prodn. rate, and 0.67 [0.61] to 4.32 [4.27] ppb h-1, via the reaction of HO2 + NO in the daytime av. HO2 loss rate in Beijing, Shanghai, and Guangzhou. The above results suggest that the Punknown considerably enhanced the ROx concns. and accelerated ROx cycles in the coastal regions of China, and could produce significant increases in concns. of in-org. aerosols and secondary org. aerosols and further aggrava haze events in these regions.
    117. 117
      Wang, W.; Parrish, D. D.; Wang, S.; Bao, F.; Ni, R.; Li, X.; Yang, S.; Wang, H.; Cheng, Y.; Su, H. Long-term trend of ozone pollution in China during 2014–2020: distinct seasonal and spatial characteristics and ozone sensitivity. Atmos. Chem. Phys. 2022, 22 (13), 8935– 8949,  DOI: 10.5194/acp-22-8935-2022
      117
      Long-term trend of ozone pollution in China during 2014-2020: distinct seasonal and spatial characteristics and ozone sensitivity
      Wang, Wenjie; Parrish, David D.; Wang, Siwen; Bao, Fengxia; Ni, Ruijing; Li, Xin; Yang, Suding; Wang, Hongli; Cheng, Yafang; Su, Hang
      Atmospheric Chemistry and Physics (2022), 22 (13), 8935-8949CODEN: ACPTCE; ISSN:1680-7324. (Copernicus Publications)
      In the past decade, ozone (O3) pollution has become a severe environmental problem in China's major cities. Here, based on available observational records, we investigated the long-term trend of O3 pollution in China during 2014-2020. The O3 concns. were slightly higher in urban areas than in non-urban areas. During these 7 years, the highest O3 concns. primarily occurred during summer in northern China, and during autumn or spring in southern China. Although O3 precursors, including nitrogen oxides (NOx) and carbon monoxide (CO), continuously decreased, O3 concns. generally increased throughout the 7 years with a slower increasing rate after 2017. The long-term trend of O3 concns. differed across seasons, esp. from 2019 to 2020, when O3 concns. decreased in summer and increased in winter. To analyze the causes of this obsd. trend, a photochem. box model was used to investigate the change in the O3 sensitivity regime in two representative cities - Beijing and Shanghai. Our model simulations suggest that the summertime O3 sensitivity regime in urban areas of China has changed from a VOC-limited regime to a transition regime during 2014-2020. By 2020, the urban photochem. was in a transition regime in summer but in a VOC-limited regime in winter. This study helps to understand the distinct trends of O3 in China and provides insights into efficient future O3 control strategies in different regions and seasons.
    118. 118
      Yin, H.; Lu, X.; Sun, Y.; Li, K.; Gao, M.; Zheng, B.; Liu, C. Unprecedented decline in summertime surface ozone over eastern China in 2020 comparably attributable to anthropogenic emission reductions and meteorology. Environmental Research Letters 2021, 16 (12), 124069  DOI: 10.1088/1748-9326/ac3e22
      118
      Unprecedented decline in summertime surface ozone over eastern China in 2020 comparably attributable to anthropogenic emission reductions and meteorology
      Yin, Hao; Lu, Xiao; Sun, Youwen; Li, Ke; Gao, Meng; Zheng, Bo; Liu, Cheng
      Environmental Research Letters (2021), 16 (12), 124069CODEN: ERLNAL; ISSN:1748-9326. (IOP Publishing Ltd.)
      China's nationwide monitoring network initiated in 2013 has witnessed continuous increases of urban summertime surface ozone to 2019 by about 5% year-1, among the fastest ozone trends in the recent decade reported in the Tropospheric ozone assessment report. Here we report that surface ozone levels averaged over cities in eastern China cities decrease by 5.5 ppbv in May-August 2020 compared to the 2019 levels, representing an unprecedented ozone redn. since 2013. We combine the high-resoln. GEOS-Chem chem. model and the eXtreme Gradient Boosting (XGBoost) machine learning model to quantify the drivers of this redn. We est. that changes in anthropogenic emissions alone decrease ozone by 3.2 (2.9-3.6) ppbv (57% of the total 5.5 ppbv redn.) averaged over cities in eastern China and by 2.5 ∼ 3.2 ppbv in the three key city clusters for ozone mitigation. These redns. appear to be driven by decreases in anthropogenic emissions of both nitrogen oxides (NOx) and volatile org. compds., likely reflecting the stringent emission control measures implemented by The Chinese Ministry of Environmental and Ecol. in summer 2020, as supported by obsd. decline in tropospheric formaldehyde (HCHO) and nitrogen dioxides (NO2) from satellite and by bottom-up emission ests. Comparable to the emission-driven ozone redn., the wetter and cooler weather conditions in 2020 decrease ozone by 2.3 (1.9-2.6) ppbv (43%). Our analyses indicate that the current emission control strategies can be effective for ozone mitigation in China yet tracking future ozone changes is essential for further evaluation. Our study also reveals important potential to combine the mechanism-based, state-of-art atm. chem. models with machine learning model to improve the attribution of ozone drivers.
    119. 119
      Xu, J.; Huang, X.; Wang, N.; Li, Y.; Ding, A. Understanding ozone pollution in the Yangtze River Delta of eastern China from the perspective of diurnal cycles. Science of The Total Environment 2021, 752, 141928  DOI: 10.1016/j.scitotenv.2020.141928
      There is no corresponding record for this reference.
    120. 120
      Li, K.; Jacob, D. J.; Shen, L.; Lu, X.; De Smedt, I.; Liao, H. Increases in surface ozone pollution in China from 2013 to 2019: anthropogenic and meteorological influences. Atmos. Chem. Phys. 2020, 20 (19), 11423– 11433,  DOI: 10.5194/acp-20-11423-2020
      120
      Increases in surface ozone pollution in China from 2013 to 2019: anthropogenic and meteorological influences
      Li, Ke; Jacob, Daniel J.; Shen, Lu; Lu, Xiao; De Smedt, Isabelle; Liao, Hong
      Atmospheric Chemistry and Physics (2020), 20 (19), 11423-11433CODEN: ACPTCE; ISSN:1680-7324. (Copernicus Publications)
      Surface ozone data from the Chinese Ministry of Ecol. and Environment (MEE) network show sustained increases across the country over the 2013-2019 period. Despite Phase 2 of the Clean Air Action Plan targeting ozone pollution, ozone was higher in 2018-2019 than in previous years. The mean summer 2013-2019 trend in max. 8 h av. (MDA8) ozone was 1.9 ppb a-1 (p < 0.01) across China and 3.3 ppb a-1 (p < 0.01) over the North China Plain (NCP). Fitting ozone to meteorol. variables with a multiple linear regression model shows that meteorol. played a significant but not dominant role in the 2013-2019 ozone trend, contributing 0.70 ppb a-1 (p < 0.01) across China and 1.4 ppb a-1 (p = 0.02) over the NCP. Rising June-July temps. over the NCP were the main meteorol. driver, particularly in recent years (2017-2019), and were assocd. with increased foehn winds. NCP data for 2017-2019 show a 15% decrease in fine particulate matter (PM2.5) that may be driving the continued anthropogenic increase in ozone, as well as unmitigated emissions of volatile org. compds. (VOCs). VOC emission redns., as targeted by Phase 2 of the Chinese Clean Air Action Plan, are needed to reverse the increase in ozone.

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    • Details on the instrument used, preparation of observational data, and parametrizations of HONO sources; summary of the observed pollutant concentrations; detailed statistical test results for analyses on biomass burning impact, aerosol acidity impact, and HONO source evaluations; comparisons with previous studies on key kinetic parameters, and HONO/NO2/pNO3 measurements; O3 production efficiency with changing NO2 concentration; observed O3 and NO2 levels in eastern China from 2014 to 2022 (PDF)


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