Download Hi-Res ImageDownload to MS-PowerPointCite This:Environ. Sci. Technol. 2018, 52, 7, 3926-3934

Identifying Ammonia Hotspots in China Using a National Observation Network

Yuepeng Pan*
Yuepeng Pan
State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
*Phone: +86 01062022285. Fax: +86 01062362389. E-mail: [email protected]
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http://orcid.org/0000-0002-5547-0849

Shili Tian
Shili Tian
State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
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Yuanhong Zhao
Yuanhong Zhao
Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing, 100871, China
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Lin Zhang
Lin Zhang
Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing, 100871, China
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Xiaying Zhu
Xiaying Zhu
National Climate Center, China Meteorological Administration, Beijing 100081, China
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Jian Gao
Jian Gao
State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
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Wei Huang
Wei Huang
State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
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Yanbo Zhou
Yanbo Zhou
State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
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Yu Song
Yu Song
Department of Environmental Science, Peking University, Beijing 100871, China
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Qiang Zhang
Qiang Zhang
Ministry of Education Key Laboratory for Earth System Modeling, Center for Earth System Science, Tsinghua University, Beijing 100084, China
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Yuesi Wang
Yuesi Wang
State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
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Cite this: Environ. Sci. Technol. 2018, 52, 7, 3926–3934

Publication Date (Web):March 2, 2018

https://doi.org/10.1021/acs.est.7b05235

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Abstract

The limited availability of ammonia (NH₃) measurements is currently a barrier to understanding the vital role of NH₃ in secondary aerosol formation during haze pollution events and prevents a full assessment of the atmospheric deposition of reactive nitrogen. The observational gaps motivated us to design this study to investigate the spatial distributions and seasonal variations in atmospheric NH₃ on a national scale in China. On the basis of a 1-year observational campaign at 53 sites with uniform protocols, we confirm that abundant concentrations of NH₃ [1 to 23.9 μg m^–3] were identified in typical agricultural regions, especially over the North China Plain (NCP). The spatial pattern of the NH₃ surface concentration was generally similar to those of the satellite column concentrations as well as a bottom-up agriculture NH₃ emission inventory. However, the observed NH₃ concentrations at urban and desert sites were comparable with those from agricultural sites and 2–3 times those of mountainous/forest/grassland/waterbody sites. We also found that NH₃ deposition fluxes at urban sites account for only half of the emissions in the NCP, suggesting the transport of urban NH₃ emissions to downwind areas. This finding provides policy makers with insights into the potential mitigation of nonagricultural NH₃ sources in developed regions.

1. Introduction

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The intensive human activities of past decades have significantly affected the global nitrogen cycle by fixing N₂, both deliberately for fertilizer production and inadvertently during fossil fuel combustion.(1) Rapid increases in reactive nitrogen emissions to the atmosphere have resulted in serious reactive nitrogen pollution in the air and excessive nitrogen deposition in natural ecosystems worldwide.(2) To reduce these adverse impacts, previous efforts have been made to reduce oxidized nitrogen, such as NO_x emissions, whereas a reduction in reduced nitrogen (NH_x), especially in ammonia (NH₃) emissions, has not been fully implemented.(3,4) Between 2002 and 2013, NH₃ levels over agricultural regions experienced significant increasing trends across the U.S. (2.6% year^–1), the European Union (1.8% year^–1), and China (2.3% year^–1), as observed from satellite.(5) It is demonstrated that the deposition of reactive nitrogen in the U.S. has recently shifted from nitrate-dominated to ammonium-dominated conditions,(6) while NH_x plays a key role in atmospheric nitrogen deposition in China, contributing from 71% to 88% of the total depositions in hotspot regions, such as the North China Plain (NCP).(7)

In addition, there is increasing evidence indicating the critical role of NH₃ in the formation of secondary aerosols.(3,8) Extensive observations reveal that ammonium and related sulfate and nitrate contribute 10% and 35% of the particulate mass during haze events, respectively.(9) The profound role of NH₃ in haze pollution has also been highlighted by recent studies arguing its capability to neutralize aerosol pH, which can strongly enhance the formation of sulfate through the heterogeneous oxidation of SO₂ by NO₂.(10) All evidence leads to increasing concerns that future progress toward reducing the nitrogen-related impacts on aerosol pollution and nitrogen deposition will be increasingly difficult without a well-resolved spatiotemporal picture of NH₃.

Compared with the increasing number of rich data sets of satellite observations of atmospheric NH₃ concentration,(5,11,12) surface network data sets covering large geographical areas are still lacking,(13,14) especially in China.(15,16) To fill the observational data gaps, in this study, a year-round campaign was launched to measure monthly NH₃ by using uniform protocols with a diffusive technique and other supporting data across China. The objectives of the present study are to (1) identify the hotspots of NH₃ in China, (2) explore the variability of atmospheric NH₃, and (3) present the implications for mitigating NH₃ on a national scale. To our knowledge, this study represents the first national observations of NH₃ in China, especially in background regions, setting a baseline against which concentration changes resulting from future emission control strategies can be assessed. The data collected here are unique and will advance our understanding of atmospheric chemistry and related processes. The results will also be valuable for scientists and policy makers to estimate excess nitrogen inputs into ecosystems and validate atmospheric chemistry and transport models, including seasonal trends and regional variability.

2. Materials and Methods

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2.1. Ammonia Sampling Networks

Accurately measuring NH₃ concentrations in the air is not an easy task because of the interference of particle-borne ammonium.(17) However, this problem can be solved using the well-known fact that when ambient air passes through a tube, gas molecules diffuse much more quickly than particles onto the tube wall.(18) The main disadvantage of this manual sampling method (hereafter referred to as the diffusive sampling technique) is its low temporal resolution when high-frequency measurements (e.g., hourly) are needed. However, such a simple and cost-effective technique can increase the spatial resolution of the measurement and aid in screening studies to evaluate monitoring site locations(14) or in long-term measurements for trend analyses.(13)

For large-scale surveys of NH₃ variability across China, starting in September 2015, we implemented a passive NH₃ monitoring network based on the diffusive technique with monthly integrated measurements at 53 sites. The current Ammonia Monitoring Network in China (AMoN-China) was established mainly based on the Chinese Ecosystem Research Network (CERN, http://www.cern.ac.cn/0index/index.asp) and the Regional Atmospheric Deposition Observation Network on the NCP (READ-NCP).(7) AMoN-China includes 13 mountain and forest, 5 water body, 7 grassland, 4 desert, 11 farmland, and 13 urban/suburban/industrial sites (Figure 1). All of the sites are selected to be far away (>1 km) from a known source of NH₃ (e.g., feedlot areas) considering that the NH₃ concentrations decrease significantly away from the source (several hundred meters).(19) More details on the site selection and siting protocols can be found in Supporting Information (SI, text and Table S1).

Figure 1. Spatial distribution of ammonia concentrations observed from the surface network (site) versus satellite column data (grid) in China. The detailed surface observation site information can be found in Table 1 and SI. Satellite NH₃ total column distributions were derived from the infrared atmospheric sounding interferometer (IASI) aboard MetOp-A for the year 2015. We collected the observations from morning overpass time (9:30 LTC) and filtered the columns with relative error above 100% following procedures presented in Van Damme et al.(12) The filtered IASI satellite columns were then mapped to a 0.25° × 0.25° horizontal resolution by averaging available observations within each grid cell. The provincial boundary layer with a scale of 1:4,000,000 was obtained from the National Geomatics Center of China (http://ngcc.sbsm.gov.cn/). Maps were generated based upon a geospatial analysis using ESRI ArcGIS software (version 10.1, http://www.esri.com/software/arcgis/arcgis-for-desktop).

Sites were assigned to regions to assess whether the seasonal variations and spatial distributions of NH₃ concentrations show different patterns in different broad areas of China (Figure 2). The regions are defined as follows: the NCP (11 sites), northeast China (NE, 9 sites); northwest China (NW, 5 sites), southeast China (SE, 13 sites), southwest China (SW, 9 sites), and Central China (Central, 6 sites). The regions were chosen based on the spatially different geographical, climate, and available characteristics of the sites.

Figure 2. Seasonal variations of ammonia concentrations observed from the surface network (53 sites) in China.

2.2. Chemical Analysis and Validation of Ammonia Samplers

The year-round sampling campaign was carried out from September 2015 to August 2016. In total, 636 samples of NH₃ were collected using diffusive samplers (Analysts, CNR-Institute of Atmospheric Pollution, Roma, Italy). The passive sampler is made of polyethylene and employs a phosphorus-acid-impregnated glass microfiber filter as an adsorption layer. The sampler is a robust and reliable tool for measuring atmospheric NH₃; the development, theory, laboratory validation, and field application of the sampler have been fully described elsewhere.(20)

During sample collection, the passive samplers were exposed at a height of 2 m with their open ends oriented downward to exclude the dry deposition of particles. In addition, the sampler was protected from rain and direct sunlight by an inverted stainless-steel shield. After exposure, the passive samplers were returned to Beijing for analysis at the State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences. In the laboratory, 5 mL of deionized water was used to extract the exposed samples, and the ammonium ion concentration in the extraction was determined via ion chromatography with a cation separator and conductivity detector (Dionex Corp., Sunnyvale, CA, USA).

The ambient NH₃ concentrations (c_NH₃, μg m^–3) were calculated based on the amount of ammonium (m_NH₄⁺, μg) collected on the exposed filter and the sample collection time (t, hour), which can be expressed using the following equation:

where 9.06 × 10² is the conversion factor from the manufacturer’s description, which is a function of the parameters of the passive sampler. This formula assumes that the average temperature (T) during sampling is 20 °C. In the case that temperature is different, a correction coefficient of

is applied to c_NH₃. Such a temperature effect is negligible, with the corrected NH₃ concentrations being less than 5% at each 5 °C interval. Most of the sampling sites belong to the CERN, where the temperature was measured at each site using an automatic meteorological observation instrument (Milos520, Vaisala, Finland). In the case that the temperature was not measured at the site, the nearest meteorological observation station available on the China Meteorological Data Sharing Services System Web site (http://cdc.cma.gov.cn/) was used in this study.

Before and during the study period, comparisons with automatic reference methods were performed during two campaigns. During 2013, the Analysts passive sampler (monthly samples) were compared to the continuously active analyzers of MARGA (a model ADI 2080 online analyzer for the Monitoring of Aerosols and Gases, Applikon Analytical B.V. Corp., The Netherlands, aggregated to monthly data points), showing a linear regression slope of 1.10 ± 0.14 and R² of 0.94 (Figure 3a). This strong linear relationship indicates that the Analyst passive sampler is reliable for such a study, assuming that the NH₃ concentration values measured by the wet chemistry instruments are more accurate.(17) During this study, we also compared the Analysts passive samplers to DELTA (Denuder for Long-Term Atmospheric Sampling, Centre for Ecology and Hydrology, UK) at a monthly resolution. This comparison shows a linear regression slope close to unity (1.04 ± 0.17) and an intercept of 2.06 ± 2.23 μg m^–3 (Figure 3b); the bias appears to be systematic and thus does not impact the patterns of the spatial distributions or seasonal variations.

Figure 3. Comparisons of passive diffusion sampler to the continuously active analyzers of MARGA and DELTA. Ammonia concentrations are aggregated to monthly data points.

2.3. Dry Deposition Velocity Simulation

The inferential technique,(7) which combines the measured NH₃ concentration and a modeled dry deposition velocity (V_d) from the Goddard Earth Observing System-Chem (GEOS-Chem; http://geos-chem.org) chemical transport model, was used to estimate the dry deposition fluxes of NH₃. The GEOS-Chem simulation of nitrogen dry deposition has been described by Zhao et al.(21) The model is driven by the latest version of GEOS-FP assimilated meteorological fields from the NASA Global Modeling and Assimilation Office (GMAO), which has been applied to analyze particle pollution over the NCP.(22) Our simulation used the native GEOC-FP resolution of 0.25° latitude ×0.3125° longitude over East Asia (70°E–140°E, 15°N–55°N) and a coarse resolution of 2° latitude ×2.5° longitude over other places of the world.

Follow the standard big-leaf resistance-in-series model,(23)V_d in GEOS-Chem was calculated by considering the aerodynamic resistance, the boundary layer resistance, and the surface resistance. We did not consider air–surface bidirectional exchange of NH₃,(24) and we treated the NH₃ fluxes as uncoupled emission and deposition processes. The model was run from 2014 to 2016, and we applied the monthly V_d at a reference height of 2 m to the observed NH₃ concentrations to obtain monthly NH₃ dry deposition fluxes. The NH₃ monthly dry deposition fluxes calculated using the monthly mean concentration and V_d are approximately 7% higher than the hourly integrated values, reflecting some small covariance between the NH₃ concentrations and V_d in the model.

3. Results and Discussion

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3.1. Spatial Distribution of Ammonia in China

Large spatial differences in NH₃ concentrations were found at the 53 sites in the sampling network, with annual mean NH₃ concentrations during the 1-year period ranging from 1 to 23.9 μg m^–3, as illustrated in Table 1 and Figure 1. The upper range is higher than the concentrations observed in China around 2012 (0.3–13.1 μg m^–3)(16) and Asia around 2000 (<0.7–13.9 μg m^–3).(14) The overall mean NH₃ concentrations in this study reached 7.0 ± 5.4 μg m^–3, which is much higher than the values observed in the U.S. AMoN network using a similar diffusive sampling technique,(13) although the AMoN sites are mainly located outside the intensive source areas of the U.S. At the Colorado near-agricultural sites, the NH₃ concentrations reach 42.7 μg m^–3.(25)

Table 1. Seasonal and Annual Concentrations of Ammonia (μg m^–3) Observed at the 53 Sites in China during This Study Perioda

code	location	latitude	longitude	elvation (m)	land use types	region	SON	DJF	MAM	JJA	mean
FQA	Fengqiu	35.0	114.6	67	farmland	NCP	19.2	14.3	12.8	21.1	16.8
LCA	Luancheng	37.9	114.7	57	farmland	NCP	21.9	17.2	17.5	20.7	19.3
YCA	Yucheng	37.0	116.6	23	farmland	NCP	21.3	12.8	10.0	45.2	22.3
TSM	Tainshan	36.3	117.1	1506	mountain and shrubbery	NCP	3.3	2.8	5.6	3.8	3.9
XLM	Xinglong	40.4	117.6	872	mountain and shrubbery	NCP	3.6	0.9	6.1	5.1	3.9
YFS	Yangfang	40.2	116.1	73	suburban	NCP	6.0	4.1	6.0	11.9	7.0
CZS	Cangzhou	38.3	116.9	10	suburban	NCP	22.0	22.2	25.6	26.0	23.9
TJU	Tianjin	39.1	117.2	6	urban	NCP	12.3	7.2	11.0	14.5	11.3
BJU	Beijing	40.0	116.4	57	urban	NCP	16.6	7.2	14.9	16.3	13.7
BDI	Baoding	38.9	115.5	21	urban	NCP	12.7	10.5	12.4	25.7	15.3
TGI	Tanggu	39.0	117.7	0	urban and coastal	NCP	8.4	8.0	11.9	12.7	10.2
CLD	Cele	37.0	80.7	1319	desert	NW	7.3	3.1	5.1	9.1	6.1
FKD	Fukang	43.3	87.9	475	desert and suburban	NW	8.3	14.7	17.2	17.4	14.4
AKA	Akesu	40.6	80.8	1031	farmland	NW	3.8	3.2	10.9	17.6	8.9
HCA	Huocheng	44.0	80.7	590	farmland	NW	9.0	11.2	26.6	13.4	15.1
ALT	Altai Mountains	47.6	86.0	847	mountain and shrubbery	NW	2.4	/	9.3	6.2	5.5
SPT	Shapotou	37.5	105.0	1258	desert	central	4.2	2.3	5.1	9.0	5.1
ASA	Anshai	36.9	109.4	1207	farmland	central	1.6	3.8	5.4	6.7	4.3
LZA	Linze	39.4	100.1	1385	farmland	central	3.5	2.3	3.7	10.4	5.0
WNA	Weinan	34.7	109.3	411	farmland	central	8.3	7.7	13.1	20.3	12.4
WLG	Waliguan	36.3	100.9	3772	grassland	central	2.0	2.0	2.2	2.3	2.1
HBG	Haibei	37.6	101.3	3198	grassland	central	2.1	2.0	3.2	7.2	3.6
HTF	Huitong	26.9	109.6	524	forest	SE	2.1	1.9	0.8	1.8	1.7
QYF	Qianyanzhou	26.4	115.0	74	mountain and forest	SE	2.5	1.9	2.4	3.2	2.5
DHM	Dinghushan	23.2	112.6	44	mountain and forest	SE	3.8	2.6	3.2	1.7	2.8
HJK	Huanjiang	24.7	108.3	293	mountain and karst	SE	2.5	1.0	3.6	10.1	4.3
XMU	Xiamen	24.7	118.1	2	urban	SE	6.0	4.0	5.7	5.0	5.2
GZU	Guangzhou	23.1	113.3	14	urban	SE	4.9	4.4	6.9	6.9	5.8
THL	Taihu	31.6	120.3	7	urban	SE	3.4	5.7	6.0	10.3	6.3
MMU	Maoming	21.6	110.7	16	urban	SE	10.1	5.9	8.0	15.1	9.8
NJU	Nanjing	32.1	118.4	15	urban	SE	11.6	7.5	9.5	14.6	10.8
YXI	Yongxing island	16.8	112.3	10	waterbody and island	SE	3.2	1.9	2.0	3.7	2.7
PYL	Poyang lake	29.4	116.1	24	waterbody and lake	SE	1.6	2.5	2.0	4.4	2.6
DTL	Dongting lake	29.5	112.8	28	waterbody and lake	SE	3.7	4.1	6.0	9.0	5.7
DHL	Donghu lake	30.5	114.4	20	waterbody and lake	SE	3.8	3.8	7.3	10.4	6.3
NMD	Naiman	42.9	120.7	362	desert	NE	5.6	2.9	3.4	9.4	5.3
SYA	Shenyang	41.5	123.4	38	farmland	NE	5.1	2.3	6.7	12.6	6.7
MHF	Mohe	52.9	122.8	467	forest	NE	1.3	1.1	0.7	1.0	1.0
ERG	Ergun	50.2	119.4	525	grassland	NE	1.5	0.3	8.9	1.3	3.0
ING	Inner Mongolia	43.6	116.7	1187	grassland	NE	2.2	2.0	3.2	7.2	3.6
DAG	Daan	45.6	123.8	1299	grassland	NE	2.7	1.6	5.1	9.9	4.8
CCU	Changchun	44.0	125.4	195	grassland and suburban	NE	2.9	0.7	3.4	6.4	3.4
CBM	Changbaishan	42.4	128.1	736	mountain and forest	NE	0.7	0.7	8.3	23.4	8.3
SJW	Sanjiang	47.6	133.5	55	waterbody and wetland	NE	3.2	1.2	3.2	4.9	3.1
YTA	Yanting	31.3	105.5	437	farmland	SW	3.6	1.6	2.8	9.6	4.4
LSA	Lhasa	29.6	91.0	3640	farmland	SW	6.0	2.9	4.4	6.1	4.8
BNF	Xishuangbanna	22.0	100.8	648	forest	SW	4.9	5.5	6.4	4.2	5.3
ALD	Ali	33.4	79.7	4256	grassland	SW	1.3	0.9	0.7	6.3	1.7
ALM	Ailaoshan	24.3	101.0	2483	mountain and forest	SW	1.1	1.1	0.6	2.8	1.4
GGM	Gonggashan	29.6	102.0	2977	mountain and forest	SW	0.7	0.9	0.5	5.0	1.8
MXF	Maoxian	31.7	103.9	1826	mountain and shrubbery	SW	2.3	1.4	3.9	2.9	2.6
GZA	Guizhou	26.3	105.9	1468	urban	SW	3.4	2.3	4.7	5.3	3.9
CDU	Chengdu	30.6	104.0	490	urban	SW	7.9	5.5	9.6	10.5	8.4

^{^a}

SON = Sept–Oct–Nov, DJF = Dec–Jan–Feb, MAM = Mar–Apr–May, JJA = Jun–Jul–Aug.

The sites were assigned to six regions to assess the regional variations among them. The highest regional averaged ambient NH₃ concentrations were found over the NCP (13.4 μg m^–3), followed by those in the NW (10.0 μg m^–3), Central (5.4 μg m^–3), SE (5.1 μg m^–3), NE (4.4 μg m^–3), and SW (3.8 μg m^–3). The spatial distributions of the surface NH₃ concentrations were consistent with the top-down satellite NH₃ columns,(12) as shown in Figure 1, and similar to the bottom-up NH₃ emissions inventory from agriculture sources in China, as included in Figure 4. NCP is then confirmed to be the largest region with high surface concentrations and highest emissions. This region accounts for 43% of the NH₃ emitted from fertilization in China.(26)

Figure 4. Spatial distribution of the site-based dry deposition fluxes versus the gridded agriculture emission inventory of ammonia in China. The legend for gridded ammonia inventory was also shown in units of kg N ha^–1 year^–1 (numbers in the left corner), in addition to units of t year^–1 per 0.25° by 0.25°. The NH₃ inventory used in this study was obtained from the Multi-Resolution Emission Inventory of China (MEIC, http://meicmodel.org),(36) originally developed and described by Huang et al.(26) The MEIC inventory is provided with monthly gridded emissions of NH₃ at 0.25° × 0.25° for five sectors, that is, power generation, industry, residential, transportation, and agriculture. The agriculture sector is a dominant source of NH₃ emissions at the national scale, mainly contributed by fertilizer applications and manure managements. The year of 2012 was chosen to conduct the spatial comparison because emissions after 2012 are currently unavailable. The provincial boundary layer with a scale of 1:4 000 000 was obtained from the National Geomatics Center of China (http://ngcc.sbsm.gov.cn/). Maps were generated based upon a geospatial analysis using ESRI ArcGIS software (version 10.1, http://www.esri.com/software/arcgis/arcgis-for-desktop).

In addition, several smaller hotspots were observed in China, for example, in Dzungaria and surrounding the Tarim basin (NW), Chengdu Plain (SW), and Guanzhong Plain (Central). These hotspots coincided with intensive agricultural activities, suggesting the major contribution of volatilized fertilizer and livestock waste to atmospheric NH₃.(26) In vast regions surrounding these hotspots, for example, the Tibetan Plateau, South China, and Inner Mongolia, NH₃ levels were low and can be treated as the background values. In addition to the limited NH₃ sources in these background regions, cold weather, or acidic soil is unfavorable for NH₃ emissions. Heavy rainfall may also contribute to the scavenging of atmospheric NH₃,(21) resulting in the lower concentrations observed in South China.

3.2. Differences among Land Use Types

From the aspect of land use types, the highest values were observed at urban/suburban/industrial sites (10.8 μg m^–3), followed by those at farmland (10.2 μg m^–3), desert (7.8 μg m^–3), mountain and forest (3.6 μg m^–3), water body (3.6 μg m^–3), and grassland (3.4 μg m^–3) sites. Given the influences of volatilized fertilizer, the mean NH₃ concentrations at the WNA, HCA, FQA, LCA, and YCA agricultural sites reached 12.4, 15.1, 16.8, 19.3, and 22.3 μg m^–3, respectively (Table 1, where the abbreviations of the site names are defined, the same below). These values are much higher than the results from the other farmland sites, that is, AKA, SYA, LZA, LSA, YTA, and ASA, observed in this study. The difference is likely attributed to the different fertilizer inputs, climate zones, and soil pH values in these regions.

As shown in Table 1, the results also demonstrated relatively high NH₃ values at urban sites in the NCP, for example, TGI (10.2 μg m^–3), TJU (11.3 μg m^–3), BJU (13.7 μg m^–3), BDI (15.3 μg m^–3), and CZS (23.9 μg m^–3). Although agricultural activities are intensive in this region, nonagricultural emissions are an important contributor to atmospheric NH₃ in the region, as evidenced by the isotopic signatures.(27)

In addition, relatively high concentrations of NH₃ were also observed at urban sites in South China, for example, at NJU (10.8 μg m^–3), MMU (9.8 μg m^–3), CDU (8.4 μg m^–3), THL (6.3 μg m^–3), and GZU (5.8 μg m^–3). These values were higher than or comparable to those of nearby farmlands. For example, the average NH₃ concentration measured at the urban site CDU was twice that of the agricultural site YTA (4.4 μg m^–3). Such high values observed in urban areas are one of the distinct features in this study. Therefore, nonagricultural sources are suggested to be important contributors to atmospheric NH₃ in developed regions across China. An improved global NH₃ emission inventory for combustion and industrial sources provided distinct evidence that the emissions density of NH₃ in urban areas is an order of magnitude higher than in rural areas.(8)

Another important finding is the higher NH₃ concentrations observed at the desert sites of SPT, NMD, CLD, and FKD, which have values of 5.1, 5.3, 6.1, and 14.4 μg m^–3, respectively. These values are higher than those observed in background regions, including mountain and forest, water body and grassland sites, averaging 3.5 μg m^–3. This is the first observational evidence showing high NH₃ values over NW dry lands, in addition to over farmlands. This finding indicates an important regional source of NH₃ from dried saline soils nearby;(28) considering that a certain amount of non-sea-salt crustal sulfate has been observed from deserts and Gobi region in the north China.(29) The unexpected high values at the desert site of FKD (60 km to the NE of the Urumqi city) may be explained by the transport of nearby industrial and/or urban sources.

3.3. Seasonal Variations in Ammonia Concentration in China

When the data were aggregated at seasonal levels, the seasonal maximum NH₃ concentrations were observed in the summer, whereas the minimum values occurred in the winter at most sites (Figure 2). Note that pulse peaks were also observed during August at GGM, in May at ERG, in Dec at ASA and in July at HJK. At the mountainous/forest/grassland sites, the NH₃ concentrations exhibited weaker seasonal variations during the observational periods, with nearly constant values of less than 3.5 μg m^–3, reflecting the remoteness of the monitoring site and its ability to serve as the background value in China.

In contrast, the seasonal variations in NH₃ at agricultural sites were evident, with low values in the winter, elevated values in the late spring, peaks in the summer, and decreased values in the autumn. The relatively high values in the warmer seasons correspond with peak emissions from agricultural activities and high temperatures. A similar seasonal pattern can also be found at urban sites, for example, BDI and NJU, although the agricultural activities in urban regions were less evident.

Although the volatilization of NH₃ in agricultural regions was sufficient to justify the high NH₃ observed in developed regions during the warm season, the contribution of nonagricultural sources of NH₃ can not be neglected in urban areas.(30) In a case study, the NH₃ emissions from vehicles in urban Beijing may have contributed to the observed summer maximum.(31) However, such sources do not always have obvious seasonal changes. The recycling of predeposited NHx offers an alternative explanation for these seasonal changes, which was mentioned in a recent study.(32) This speculation was partially supported by a good correlation of NH₃ concentrations and ambient temperature at urban sites (e.g., BJU; Figure S1). Note that changes in emissions do not necessarily relate to changes in concentrations, and vice versa. Low NH₃ concentrations in winter may also be attributable to gas-to-particle conversion under cold weather conditions. Thus, nonagricultural emissions in urban areas may still be quite high in winter, for example. To fill the gap, concurrent measurements of NH₃ and NH₄⁺ concentrations and fluxes covering different seasons are needed.

3.4. Ammonia Dry Deposition versus Emissions in China

We estimated the dry deposition flux of NH₃ to assess the bulk input to ecosystems by combining the monthly observed concentrations with modeled V_d. The mean monthly V_d values of NH₃ modeled at most sites during the study period ranged from 0.20 to 0.55 cm s^–1, except for one coastal site (MMU, 1.02–1.42 cm s^–1) and an island site (YXI, 0.74–1.73 cm s^–1). These ranges agree well with the previous estimations in the target region.(7,16) The seasonal variations in V_d (data not shown) were weaker than the seasonal variations in the concentrations, implying that the ambient concentration plays a more important role in determining the dry deposition flux of NH₃. As a consequence, the spatial pattern of NH₃ dry deposition (Figure 4) was similar to that of the concentrations in China (Figure 1), as mentioned in section 3.1.

The annual dry deposition of NH₃ estimated in this study falls within the range of 0.8–30.3 kg N ha^–1 year^–1, with a national mean of 7.3 ± 6.1 kg N ha^–1 year^–1, which is slightly lower than the estimation (8.2 kg N ha^–1 year^–1) produced a few years ago.(16) Because of the relatively high ambient concentrations, the dry deposition of more than 10 kg N ha^–1 year^–1 of NH₃ was mostly estimated at those sites located in agricultural areas (e.g., YCA, LCA, FQA, HCA, and WNA) and in or near developed regions (e.g., CZS, BDI, BJU, NJU, TJU, and FKD). Note that the highest deposition was estimated for MMU because of both the high local concentrations and V_d.

Figure 5 compares the dry deposition fluxes estimated at the sites with the gridded agriculture emissions, showing that the NW sites exhibited deposition fluxes that were a factor of 2 (or more) greater than their emissions. Because dry deposition is the major sink of NH₃ in this region, the unexpected high deposition at the NW sites indicates missing sources in the current inventory. In contrast, the SE sites had higher emissions than deposition, highlighting the significant removal of NH₃ via precipitation (wet deposition) in South China.(21) At the NCP sites, estimated dry deposition fluxes accounted for 25%–75% of the emissions of NH₃. Considering the wet/dry deposition ratio,(7) the total NHx depositions at the YCA, LCA, YFS, and CZU sites would be much closer to those of the emissions, whereas the NHx deposition fluxes at the BDI, BJU, TJU, and FQA sites would be 50% of the emissions, suggesting the possible regional transport of NH₃ to the surrounding regions.

Figure 5. Comparison of the site-based dry deposition fluxes versus the gridded agriculture emission inventory of ammonia in China (1° by 1°). The sites are colored by region. The units of emission data were converted to kg N ha^–1 year^–1 for comparison with that of ammonia deposition. The 1:1 line represents equal ammonia dry deposition and emissions.

Uncertainties in both the emissions and deposition fluxes may also contribute to the discrepancies. For example, emission uncertainty is associated with activity data and emission factors (EFs).(26) The activity data were obtained via statistical information and were subject to systemic errors rather than regional inconsistencies. However, the EFs that are parametrized by the ambient temperature, soil properties, fertilizer types, and other factors may vary regionally;(33) thus, these speculations should be validated with future work. Uncertainties also exist in dry deposition estimations. In particular, NH₃ fluxes over vegetated land are bidirectional,(34) and the net direction of this flux is often uncertain. A so-called canopy compensation point was used in previous studies to determine the direction of the NH₃ flux.(24) Because the principle of bidirectional NH₃ exchange has been not employed in this study, the flux calculated here represents a rather nonconservative deposition estimate (upper boundary). In this study, NH₃ deposition may be overestimated at vegetated sites with relatively high canopy compensation points (e.g., up to 5 μgN m^–3) due to fertilized croplands(7) or vegetation.(35) We recommend future research to evaluate the effects of the stomatal compensation point on NH₃ deposition in agricultural sites due to the counterbalance between deposition and emission.

Supporting Information

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The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.est.7b05235.

Figure S1 illustrates the ammonia concentration and temperature correlation. Table S1 summarizes the site information. The text details the site selection and siting protocols with accompanying references (PDF)

es7b05235_si_001.pdf (361.38 kb)

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Corresponding Author
- Yuepeng Pan - State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China; http://orcid.org/0000-0002-5547-0849; Email: [email protected]
Authors
- Shili Tian - State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
- Yuanhong Zhao - Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing, 100871, China
- Lin Zhang - Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing, 100871, China
- Xiaying Zhu - National Climate Center, China Meteorological Administration, Beijing 100081, China
- Jian Gao - State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
- Wei Huang - State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
- Yanbo Zhou - State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
- Yu Song - Department of Environmental Science, Peking University, Beijing 100871, China
- Qiang Zhang - Ministry of Education Key Laboratory for Earth System Modeling, Center for Earth System Science, Tsinghua University, Beijing 100084, China
- Yuesi Wang - State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
Author Contributions
Y.P. and Y.W. conceived and designed the project, Y.P., Y. Z., and S.T. conducted the field work, Y.Z. and L.Z. performed the dry deposition modeling experiments, J.G. performed the MARGA measurements, Y.S. and Q.Z. prepared the ammonia emission inventory, Y.P., X.Z., and W.H. analyzed the data and drew figures, and Y.P. wrote the paper with comments from the coauthors.
Notes
The authors declare no competing financial interest.

Acknowledgments

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This work was supported by the National Key Research and Development Program of China (Grant 2017YFC0210100), the National Natural Science Foundation of China (Grant 41405144), and the State Key Special Project on “Agricultural emissions status and enhanced pollution control plan” (Grant DQGG0208). We are indebted to the staff who collected the samples at the sites (listed in Table 1) during the study period. We also thank three anonymous reviewers for insightful comments that helped to improve an earlier version of the manuscript.

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Persistent sulfate formation from London Fog to Chinese haze
Wang, Gehui; Zhang, Renyi; Gomez, Mario E.; Yang, Lingxiao; Zamora, Misti Levy; Hu, Min; Lin, Yun; Peng, Jianfei; Guo, Song; Meng, Jingjing; Li, Jianjun; Cheng, Chunlei; Hu, Tafeng; Ren, Yanqin; Wang, Yuesi; Gao, Jian; Cao, Junji; An, Zhisheng; Zhou, Weijian; Li, Guohui; Wang, Jiayuan; Tian, Pengfei; Marrero-Ortiz, Wilmarie; Secrest, Jeremiah; Du, Zhuofei; Zheng, Jing; Shang, Dongjie; Zeng, Limin; Shao, Min; Wang, Weigang; Huang, Yao; Wang, Yuan; Zhu, Yujiao; Li, Yixin; Hu, Jiaxi; Pan, Bowen; Cai, Li; Cheng, Yuting; Ji, Yuemeng; Zhang, Fang; Rosenfeld, Daniel; Liss, Peter S.; Duce, Robert A.; Kolb, Charles E.; Molina, Mario J.
Proceedings of the National Academy of Sciences of the United States of America (2016), 113 (48), 13630-13635CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)
Sulfate aerosols exert profound impacts on human and ecosystem health, weather, and climate, but their formation mechanism remains uncertain. Atm. models consistently underpredict sulfate levels under diverse environmental conditions. From atm. measurements in two Chinese megacities and complementary lab. expts., we show that the aq. oxidn. of SO2 by NO2 is key to efficient sulfate formation but is only feasible under two atm. conditions: on fine aerosols with high relative humidity and NH3 neutralization or under cloud conditions. Under polluted environments, this SO2 oxidn. process leads to large sulfate prodn. rates and promotes formation of nitrate and org. matter on aq. particles, exacerbating severe haze development. Effective haze mitigation is achievable by intervening in the sulfate formation process with enforced NH3 and NO2 control measures. In addn. to explaining the polluted episodes currently occurring in China and during the 1952 London Fog, this sulfate prodn. mechanism is widespread, and our results suggest a way to tackle this growing problem in China and much of the developing world.
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Beer, R.; Shephard, M. W.; Kulawik, S. S.; Clough, S. A.; Eldering, A.; Bowman, K. W.; Sander, S. P.; Fisher, B. M.; Payne, V. H.; Luo, M.; Osterman, G. B.; Worden, J. R. First satellite observations of lower tropospheric ammonia and methanol. Geophys. Res. Lett. 2008, 35 (9), L09801 DOI: 10.1029/2008GL033642
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11
First satellite observations of lower tropospheric ammonia and methanol
Beer, Reinhard; Shephard, Mark W.; Kulawik, Susan S.; Clough, Shepard A.; Eldering, Annmarie; Bowman, Kevin W.; Sander, Stanley P.; Fisher, Brendan M.; Payne, Vivienne H.; Luo, Mingzhao; Osterman, Gregory B.; Worden, John R.
Geophysical Research Letters (2008), 35 (9), L09801/1-L09801/5CODEN: GPRLAJ; ISSN:0094-8276. (American Geophysical Union)
The Tropospheric Emission Spectrometer (TES) on the EOS Aura satellite makes global measurements of IR radiances which are used to derive profiles of species such as O3, CO, H2O, HDO and CH4 as routine std. products. In addn., TES has a variety of special modes that provide denser spatial mapping over a limited geog. area. A continuous-coverage mode (called "transect", about 460 km long) has now been used to detect addnl. mols. indicative of regional air pollution. On 10 July 2007 at about 05:37 UTC (13:24 LMST) TES conducted such a transect observation over the Beijing area in northeast China. Examn. of the residual spectral radiances following the retrieval of the TES std. products revealed surprisingly strong features attributable to enhanced concns. of ammonia (NH3) and methanol (CH3OH), well above the normal background levels. This is the first time that these mols. have been detected in space-based nadir viewing measurements that penetrate into the lower atm.
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12
Van Damme, M.; Clarisse, L.; Heald, C. L.; Hurtmans, D.; Ngadi, Y.; Clerbaux, C.; Dolman, A. J.; Erisman, J. W.; Coheur, P. F. Global distributions, time series and error characterization of atmospheric ammonia (NH₃) from IASI satellite observations. Atmos. Chem. Phys. Discuss. 2014, 14 (6), 2905– 2922, DOI: 10.5194/acpd-13-24301-2013
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12
Global distributions, time series and error characterization of atmospheric ammonia (NH3) from IASI satellite observations
Van Damme, M.; Clarisse, L.; Heald, C. L.; Hurtmans, D.; Ngadi, Y.; Clerbaux, C.; Dolman, A. J.; Erisman, J. W.; Coheur, P. F.
Atmospheric Chemistry and Physics (2014), 14 (6), 2905-2922, 18 pp.CODEN: ACPTCE; ISSN:1680-7324. (Copernicus Publications)
Ammonia (NH3) emissions in the atm. have increased substantially over the past decades, largely because of intensive livestock prodn. and use of fertilizers. As a short-lived species, NH3 is highly variable in the atm. and its concn. is generally small, except near local sources. While ground-based measurements are possible, they are challenging and sparse. Advanced IR sounders in orbit have recently demonstrated their capability to measure NH3, offering a new tool to refine global and regional budgets. In this paper we describe an improved retrieval scheme of NH3 total columns from the measurements of the IR Atm. Sounding Interferometer (IASI). It exploits the hyperspectral character of this instrument by using an extended spectral range (800-1200 cm-1) where NH3 is optically active. This scheme consists of the calcn. of a dimensionless spectral index from the IASI level1C radiances, which is subsequently converted to a total NH3 column using look-up tables built from forward radiative transfer model simulations. We show how to retrieve the NH3 total columns from IASI quasi-globally and twice daily above both land and sea without large computational resources and with an improved detection limit. The retrieval also includes error characterization of the retrieved columns. Five years of IASI measurements (1 Nov. 2007 to 31 Oct. 2012) have been processed to acquire the first global and multiple-year data set of NH3 total columns, which are evaluated and compared to similar products from other retrieval methods. Spatial distributions from the five years data set are provided and analyzed at global and regional scales. In particular, we show the ability of this method to identify smaller emission sources than those previously reported, as well as transport patterns over the ocean. The five-year time series is further examd. in terms of seasonality and interannual variability (in particular as a function of fire activity) sep. for the Northern and Southern Hemispheres.
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Butler, T.; Vermeylen, F.; Lehmann, C. M.; Likens, G. E.; Puchalski, M. Increasing ammonia concentration trends in large regions of the USA derived from the NADP/AMoN network. Atmos. Environ. 2016, 146, 132– 140, DOI: 10.1016/j.atmosenv.2016.06.033
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13
Increasing ammonia concentration trends in large regions of the USA derived from the NADP/AMoN network
Butler, T.; Vermeylen, F.; Lehmann, C. M.; Likens, G. E.; Puchalski, M.
Atmospheric Environment (2016), 146 (), 132-140CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Ltd.)
Data from bi-weekly passive samplers from 18 of the longest operating National Atm. Deposition Program's (NADP) Ammonia Monitoring Network (AMoN) sites (most operating from 2008 to 2015) show that concns. of NH3 have been increasing (p-value < 0.0001) over large regions of the USA. This trend is occurring at a seasonal and annual level of aggregation. Using random coeff. models (RCM), the mean slope for the 18 sites combined shows an increase of NH3 concn. of +7% per yr, with a 95% confidence interval (C.I.) from +5% to +9% per yr. Travel blank cor. data using the same approach show increasing NH3 concns. of +9% (95% C.I. +5% to +13%) per yr. During a comparable period (2008-2014) NADP pptn. chem. sites in the same regions show significant increasing (p-value = 0.0001) pptn. NH+4 concns. trends for all sites combined of +5% (95% C.I. +3% to +7%) per yr. Emissions inventory data for the study period show nearly const. rates of NH3 emissions, but large redns. in NOx and SO2 emissions. Seasonal air quality data from the Clean Air Status and Trends Network (CASTNET) sites in these regions show significant declines in atm. particulate SO2-4 and NH+4, and particulate NO-3 plus HNO3 (total NO-3) during the same period. Less formation of acidic SO4 and NO3, due to reduced SO2 and NOx emissions, provide less substrate to interact with NH3 and form particulate ammonium species. Thus, concns. of NH3 can increase in the atm. even if emissions remain const. A likely result may be more localized deposition of NH3, as opposed to the more long-range transport and deposition of ammonium nitrate (NH4NO3) and sulfate (NH4)2SO4. Addnl., the spatial distribution of wet and dry acidic deposition will be impacted.
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Carmichael, G. R.; Ferm, M.; Thongboonchoo, N.; Woo, J.-H.; Chan, L. Y.; Murano, K.; Viet, P. H.; Mossberg, C.; Bala, R.; Boonjawat, J.; Upatum, P.; Mohan, M.; Adhikary, S. P.; Shrestha, A. B.; Pienaar, J. J.; Brunke, E. B.; Chen, T.; Jie, T.; Guoan, D.; Peng, L. C.; Dhiharto, S.; Harjanto, H.; Jose, A. M.; Kimani, W.; Kirouane, A.; Lacaux, J.-P.; Richard, S.; Barturen, O.; Cerda, J. C.; Athayde, A.; Tavares, T.; Cotrina, J. S.; Bilici, E. Measurements of sulfur dioxide, ozone and ammonia concentrations in Asia, Africa, and South America using passive samplers. Atmos. Environ. 2003, 37 (9), 1293– 1308, DOI: 10.1016/S1352-2310(02)01009-9
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14
Measurements of sulfur dioxide, ozone and ammonia concentrations in Asia, Africa, and South America using passive samplers
Carmichael, Gregory R.; Ferm, Martin; Thongboonchoo, Narisara; Woo, Jung-Hun; Chan, L. Y.; Murano, Kentaro; Viet, Pham Hung; Mossberg, Carl; Bala, Rajasekhlar; Boonjawat, Jariya; Upatum, Pramote; Mohan, Manju; Adhikary, Sharad P.; Shrestha, Arun B.; Pienaar, J. J.; Brunke, Ernst B.; Chen, Tai; Tang, Jie; Ding, Guoan; Peng, Leong Chow; Dhiharto, Sri; Harjanto, Hery; Jose, Aida M.; Kimani, Wilson; Kirouane, Abdelmalek; Lacaux, Jean-Pierre; Richard, Sandrine; Barturen, Osvaldo; Cerda, Jorge Carrasco; Athayde, Augusto; Tavares, Tania; Cotrina, Jose Silva; Bilici, Erdal
Atmospheric Environment (2003), 37 (9-10), 1293-1308CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Science Ltd.)
Measurements of gaseous SO2, NH3, and O3 using IVL passive sampler technol. were obtained during a pilot measurement program initiated as a key component of the newly established WMO/GAW Urban Research Meteorol. and Environment (GURME) project. Monthly measurements were obtained at 50 stations in Asia, Africa, South America, and Europe. The median SO2 concns. vary from a high of 13 ppb at Linan, China, to <0.03 ppb at four stations. At 30 of 50 regional stations, the obsd. median concns. are <1 ppb. Median NH3 concns. range from 20 ppb at Dhangadi, India, to <1 ppb at nine stations. At 27 of regional stations, the ambient NH3 levels exceed 1 ppb. The median ozone concns. vary from a max. of 45 ppb at Waliguan Mountain, China, to 8 ppb in Petit Saut, French Guiana. In general, the highest ozone values are found in the mid-latitudes, with the Northern hemisphere mid-latitude values exceeding the Southern hemisphere mid-latitude levels, and the lowest values are typically found in the tropical regions.
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15
Meng, Z.-Y.; Xu, X.-B.; Wang, T.; Zhang, X.-Y.; Yu, X.-L.; Wang, S.-F.; Lin, W.-L.; Chen, Y.-Z.; Jiang, Y.-A.; An, X.-Q. Ambient sulfur dioxide, nitrogen dioxide, and ammonia at ten background and rural sites in China during 2007–2008. Atmos. Environ. 2010, 44 (21), 2625– 2631, DOI: 10.1016/j.atmosenv.2010.04.008
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15
Ambient sulfur dioxide, nitrogen dioxide, and ammonia at ten background and rural sites in China during 2007-2008
Meng, Zhao-Yang; Xu, Xiao-Bin; Wang, Tao; Zhang, Xing-Ying; Yu, Xiao-Lan; Wang, Shu-Feng; Lin, Wei-Li; Chen, Yi-Zhen; Jiang, Yi-An; An, Xing-Qin
Atmospheric Environment (2010), 44 (21-22), 2625-2631CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Ltd.)
We present two years (Jan. 2007-Dec. 2008) of atm. SO2, NO2 and NH3 measurements from ten background or rural sites in nine provinces in China. The measurements were made on a monthly basis using passive samplers under careful quality control. The results show large geog. and seasonal variations in the concns. of these gases. The mean SO2 concn. varied from 0.7 ± 0.4 ppb at Waliguan on Qinghai Plateau to 67.3 ± 31.1 ppb at Kaili in Guizhou province. The mean NO2 concn. ranged from 0.6 ± 0.4 ppb at Waliguan to 23.9 ± 6.9 ppb at Houma in southern Shanxi. The mean NH3 concn. ranged from 2.8 ± 3.0 ppb at Shangdianzi in northeastern Beijing to 13.7 ± 8.4 ppb at Houma. At most sites, SO2 and NO2 peaked in winter and reached min. in summer, while NH3 showed max. values in summer and lower values in cold seasons. On the whole, the geog. distributions of the obsd. gas concns. are consistent with those of emissions. The ground measurements of SO2 and NO2 are contrasted to the SCIAMACHY SO2 and OMI NO2 tropospheric columns, resp. Although the satellite data can capture the main features of emissions and concns. of SO2, they do not reflect the variations of SO2 in the surface layer. The situation is better for the case of NO2. The OMI NO2 columns capture the geog. differences in the ground NO2 and correlate fairly well with the ground levels of NO2 at six of the ten sites.
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Xu, W.; Luo, X. S.; Pan, Y. P.; Zhang, L.; Tang, A. H.; Shen, J. L.; Zhang, Y.; Li, K. H.; Wu, Q. H.; Yang, D. W.; Zhang, Y. Y.; Xue, J.; Li, W. Q.; Li, Q. Q.; Tang, L.; Lu, S. H.; Liang, T.; Tong, Y. A.; Liu, P.; Zhang, Q.; Xiong, Z. Q.; Shi, X. J.; Wu, L. H.; Shi, W. Q.; Tian, K.; Zhong, X. H.; Shi, K.; Tang, Q. Y.; Zhang, L. J.; Huang, J. L.; He, C. E.; Kuang, F. H.; Zhu, B.; Liu, H.; Jin, X.; Xin, Y. J.; Shi, X. K.; Du, E. Z.; Dore, A. J.; Tang, S.; Collett, J. L.; Goulding, K.; Sun, Y. X.; Ren, J.; Zhang, F. S.; Liu, X. J. Quantifying atmospheric nitrogen deposition through a nationwide monitoring network across China. Atmos. Chem. Phys. 2015, 15 (21), 12345– 12360, DOI: 10.5194/acp-15-12345-2015
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Quantifying atmospheric nitrogen deposition through a nationwide monitoring network across China
Xu, W.; Luo, X. S.; Pan, Y. P.; Zhang, L.; Tang, A. H.; Shen, J. L.; Zhang, Y.; Li, K. H.; Wu, Q. H.; Yang, D. W.; Zhang, Y. Y.; Xue, J.; Li, W. Q.; Li, Q. Q.; Tang, L.; Lu, S. H.; Liang, T.; Tong, Y. A.; Liu, P.; Zhang, Q.; Xiong, Z. Q.; Shi, X. J.; Wu, L. H.; Shi, W. Q.; Tian, K.; Zhong, X. H.; Shi, K.; Tang, Q. Y.; Zhang, L. J.; Huang, J. L.; He, C. E.; Kuang, F. H.; Zhu, B.; Liu, H.; Jin, X.; Xin, Y. J.; Shi, X. K.; Du, E. Z.; Dore, A. J.; Tang, S.; Collett, J. L., Jr.; Goulding, K.; Sun, Y. X.; Ren, J.; Zhang, F. S.; Liu, X. J.; Collett, J. L.
Atmospheric Chemistry and Physics (2015), 15 (21), 12345-12360CODEN: ACPTCE; ISSN:1680-7324. (Copernicus Publications)
A Nationwide Nitrogen Deposition Monitoring Network (NNDMN) contg. 43 monitoring sites was established in China to measure gaseous NH3, NO2, and HNO3 and particulate NH+4 and NO-3 in air and/or pptn. from 2010 to 2014. Wet/bulk deposition fluxes of Nr species were collected by pptn. gauge method and measured by continuous-flow analyzer; dry deposition fluxes were estd. using airborne concn. measurements and inferential models. Our observations reveal large spatial variations of atm. Nr concns. and dry and wet/bulk Nr deposition. On a national basis, the annual av. concns. (1.3-47.0 μgNm-3) and dry plus wet/bulk deposition fluxes (2.9-83.3 kg N ha-1 yr-1) of inorg. Nr species are ranked by land use as urban >rural>background sites and by regions as north China>southeast China>southwest China>northeast China>northwest China>Tibetan Plateau, reflecting the impact of anthropogenic Nr emission. Av. dry and wet/bulk N deposition fluxes were 20.6 ±11.2 (mean ± std. deviation) and 19.3±9.2 kg N ha-1 yr-1 across China, with reduced N deposition dominating both dry and wet/bulk deposition. Our results suggest atm. dry N deposition is equally important to wet/bulk N deposition at the national scale. Therefore, both deposition forms should be included when considering the impacts of N deposition on environment and ecosystem health.
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von Bobrutzki, K.; Braban, C. F.; Famulari, D.; Jones, S. K.; Blackall, T.; Smith, T. E. L.; Blom, M.; Coe, H.; Gallagher, M.; Ghalaieny, M.; McGillen, M. R.; Percival, C. J.; Whitehead, J. D.; Ellis, R.; Murphy, J.; Mohacsi, A.; Pogany, A.; Junninen, H.; Rantanen, S.; Sutton, M. A.; Nemitz, E. Field inter-comparison of eleven atmospheric ammonia measurement techniques. Atmos. Meas. Tech. 2010, 3 (1), 91– 112, DOI: 10.5194/amt-3-91-2010
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17
Field inter-comparison of eleven atmospheric ammonia measurement techniques
von Bobrutzki, K.; Braban, C. F.; Famulari, D.; Jones, S. K.; Blackall, T.; Smith, T. E. L.; Blom, M.; Coe, H.; Gallagher, M.; Ghalaieny, M.; McGillen, M. R.; Percival, C. J.; Whitehead, J. D.; Ellis, R.; Murphy, J.; Mohacsi, A.; Pogany, A.; Junninen, H.; Rantanen, S.; Sutton, M. A.; Nemitz, E.
Atmospheric Measurement Techniques (2010), 3 (1), 91-113CODEN: AMTTC2; ISSN:1867-1381. (Copernicus Publications)
11 Instruments for the measurement of ambient concns. of atm. ammonia gas (NH3), based on eight different measurement methods were intercompared above an intensively managed agricultural field in late summer 2008 in Southern Scotland. To test the instruments over a wide range of concns., the field was fertilized with urea midway through the expt., leading to an increase in the av. concn. from 10 to 100 ppbv. The instruments deployed included three wet-chem. systems, one with offline anal. (annular rotating batch denuder, RBD) and two with online-anal. (Annular Denuder sampling with online Anal., AMANDA; AiRRmonia), two Quantum Cascade Laser Absorption Spectrometers (a large-cell dual system; DUAL-QCLAS, and a compact system; c-QCLAS), two photo-acoustic spectrometers (WaSul-Flux; Nitrolux-100), a Cavity Ring Down Spectrosmeter (CRDS), a Chem. Ionisation Mass Spectrometer (CIMS), an ion mobility spectrometer (IMS) and an Open-Path Fourier Transform Infra-Red (OP-FTIR) Spectrometer. The instruments were compared with each other and with the av. concn. of all instruments. An overall good agreement of hourly av. concns. between the instruments (R2>0.84), was obsd. for NH3 concns. at the field of up to 120 ppbv with the slopes against the av. ranging from 0.67 (DUAL-QCLAS) to 1.13 (AiR-Rmonia) with intercepts of -0.74 ppbv (RBD) to +2.69 ppbv (CIMS). More variability was found for performance for lower concns. (<10 ppbv). Here the main factors affecting measurements precision are (a) the inlet design, (b) the state of inlet filters (where applicable), and (c) the quality of gas-phase stds. (where applicable). By ref. to the fast (1 Hz) instruments deployed during the study, it was possible to characterize the response times of the slower instruments.
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Ferm, M. Method for determination of atmospheric ammonia. Atmos. Environ. 1979, 13 (10), 1385– 1393, DOI: 10.1016/0004-6981(79)90107-0
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18
Method for determination of atmospheric ammonia
Ferm, Martin
Atmospheric Environment (1967-1989) (1979), 13 (10), 1385-93CODEN: ATENBP; ISSN:0004-6981.
Detn. of NH3 in air with min. interference by particulate NH4+ was effected by drawing air through a vertical glass tube whose internal surface was coated with oxalic acid. Anal. was effected by dissolving the oxalic acid coating in NaOH and detg. the NH3 concn. with an ion selective electrode. The detection limit is 0.5 nmol NH3/m3 air sampled during 24 h with std. deviation 15%.
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Felix, J. D.; Elliott, E. M.; Gish, T.; Maghirang, R.; Cambal, L.; Clougherty, J. Examining the transport of ammonia emissions across landscapes using nitrogen isotope ratios. Atmos. Environ. 2014, 95, 563– 570, DOI: 10.1016/j.atmosenv.2014.06.061
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20
Perrino, C.; Catrambone, M. Development of a variable-path-length diffusive sampler for ammonia and evaluation of ammonia pollution in the urban area of Rome, Italy. Atmos. Environ. 2004, 38 (38), 6667– 6672, DOI: 10.1016/j.atmosenv.2004.08.032
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20
Development of a variable-path-length diffusive sampler for ammonia and evaluation of ammonia pollution in the urban area of Rome, Italy
Perrino, C.; Catrambone, M.
Atmospheric Environment (2004), 38 (38), 6667-6672CODEN: AENVEQ; ISSN:1352-2310. (Elsevier B.V.)
A variable-path-length diffusive sampler for the detn. of atm. ammonia was developed and tested. Polyethylene was found to be the best material for the construction of the sampler, while a glass body sampler of similar design yielded unreliable results; phosphorous acid was the best collecting medium. The low level of the field blanks and the high operative capacity make this device able to operate in a very wide loading range (0.3-100 μg); the possibility to vary the length of the diffusive pathway allows a further increase of the detectable concn. range (0.1-125 μg m-3 during a 1-mo exposure). Reproducibility is better than 5% and the comparison with ref. denuders demonstrated a good accuracy of the method (deviation lower than 5%). The deployment of these samplers in some field campaigns carried out in Rome allowed us to confirm the close link between ammonia concn. and traffic emission and to get an insight into the spatial variability of this pollutant.
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Zhao, Y.; Zhang, L.; Chen, Y.; Liu, X.; Xu, W.; Pan, Y.; Duan, L. Atmospheric nitrogen deposition to China: A model analysis on nitrogen budget and critical load exceedance. Atmos. Environ. 2017, 153, 32– 40, DOI: 10.1016/j.atmosenv.2017.01.018
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Atmospheric nitrogen deposition to China: A model analysis on nitrogen budget and critical load exceedance
Zhao, Yuanhong; Zhang, Lin; Chen, Youfan; Liu, Xuejun; Xu, Wen; Pan, Yuepeng; Duan, Lei
Atmospheric Environment (2017), 153 (), 32-40CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Ltd.)
We present a national-scale model anal. on the sources and processes of inorg. nitrogen deposition over China using the GEOS-Chem model at 1/2° × 1/3° horizontal resoln. Model results for 2008-2012 are evaluated with an ensemble of surface measurements of wet deposition flux and gaseous ammonia (NH3) concn., and satellite measurements of tropospheric NO2 columns. Annual total inorg. nitrogen deposition fluxes are simulated to be generally less than 10 kg N ha-1 a-1 in western China (less than 2 kg N ha-1 a-1 over Tibet), 15-50 kg N ha-1 a-1 in eastern China, and 16.4 kg N ha-1 a-1 averaged over China. Annual total deposition to China is 16.4 Tg N, with 10.2 Tg N (62%) from reduced nitrogen (NHx) and 6.2 Tg N from oxidized nitrogen (NOy). Domestic anthropogenic sources contribute 86% of the total deposition; foreign anthropogenic sources 7% and natural sources 7%. Annually 23% of domestically emitted NH3 and 36% for NOx are exported outside the terrestrial land of China. We find that atm. nitrogen deposition is about half of the nitrogen input from fertilizer application (29.6 Tg N a-1), and is much higher than that from natural biol. fixation (7.3 Tg N a-1) over China. A comparison of nitrogen deposition with crit. load ests. for eutrophication indicates that about 15% of the land over China experiences crit. load exceedances, demonstrating the necessity of nitrogen emission controls to avoid potential neg. ecol. effects.
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Zhang, L.; Shao, J.; Lu, X.; Zhao, Y.; Hu, Y.; Henze, D. K.; Liao, H.; Gong, S.; Zhang, Q. Sources and Processes Affecting Fine Particulate Matter Pollution over North China: An Adjoint Analysis of the Beijing APEC Period. Environ. Sci. Technol. 2016, 50 (16), 8731– 8740, DOI: 10.1021/acs.est.6b03010
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Sources and Processes Affecting Fine Particulate Matter Pollution over North China: An Adjoint Analysis of the Beijing APEC Period
Zhang, Lin; Shao, Jingyuan; Lu, Xiao; Zhao, Yuanhong; Hu, Yongyun; Henze, Daven K.; Liao, Hong; Gong, Sunling; Zhang, Qiang
Environmental Science & Technology (2016), 50 (16), 8731-8740CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
The stringent emission controls during APEC 2014 (Asia-Pacific Economic Cooperation Summit; Nov. 5-11, 2014) offered a unique opportunity to quantify factors affecting fine particulate matter (PM2.5) pollution over northern China. This work applied a 4-dimensional variational data assimilation system using the adjoint model, GEOS-Chem, to address this issue. Hourly surface PM2.5 and SO2 measurements for Oct. 15 to Nov. 14, 2014, were assimilated into the model to optimize daily aerosol primary and precursor emissions over northern China. Measured PM2.5 concns. in Beijing (50.3 μg/m3 av.) during APEC were 43% lower than the mean concn. (88.2 μg/m3) for the entire period, including APEC. Model results attributed about half of this redn. to meteorol., due to active cold surge occurrences during APEC. Surface measurement assimilations largely reduced model biases and estd. 6-30% lower aerosol emissions in the Beijing-Tianjin-Hebei region during APEC vs. late Oct. High PM2.5 events in Beijing during this period can occasionally be contributed by natural mineral dust; however, more events showed large sensitivity to inorg. aerosol sources, particularly NH3 and NOx emissions, reflecting strong aerosol NO3- formation in fall.
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Wesely, M. L. Parameterization of surface resistances to gaseous dry deposition in regional-scale numerical models. Atmos. Environ. 1989, 23 (6), 1293– 1304, DOI: 10.1016/0004-6981(89)90153-4
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Parameterization of surface resistances to gaseous dry deposition in regional-scale numerical models
Wesely, M. L.
Atmospheric Environment (1967-1989) (1989), 23 (6), 1293-304CODEN: ATENBP; ISSN:0004-6981.
Methods for estg. the dry deposition velocities of atm. gases in the US and surrounding areas are improved and incorporated into a revised computer code module for use in numerical models of atm. transport and deposition of pollutants over regional scales. The key improvement is the computation of bulk surface resistances along 3 distinct pathways of mass transfer to sites of deposition at the upper portions of vegetative canopies of structures, the lower portions, and the ground (or water surface). This approach replaces the previous technique of providing simple look-up tables of bulk surface resistances. With the surface resistances divided explicitly into distinct pathways, the bulk surface resistances for a large no. of gases in addn. to those usually addressed in acid deposition models (SO2, O3, NOx, and HNO3) can be computed, if ests. of the effective Henry's Law consts. and appropriate measures of the chem. reactivity of the various substances are known. This has been accomplished successfully for H2O2, HCHO, CH3CHO (to represent other aldehydes), CH3O2H (to represent org. peroxides), CH3C(O)O2H, HCOOH (to represent org. acids), NH3, CH3C(O)O2NO2, and HNO2. Other factors considered include surface temp., stomatal response to environmental parameters, the wetting of surfaces by dew and rain, and the covering of surfaces by snow. Surface emission of gases and variations of uptake characteristics by individual plant species within the land use types are not considered explicitly.
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Sutton, M. A.; Burkhardt, J. K.; Guerin, D.; Nemitz, E.; Fowler, D. Development of resistance models to describe measurements of bi-directional ammonia surface–atmosphere exchange. Atmos. Environ. 1998, 32 (3), 473– 480, DOI: 10.1016/S1352-2310(97)00164-7
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Development of resistance models to describe measurements of bi-directional ammonia surface-atmosphere exchange
Sutton, M. A.; Burkhardt, J. K.; Guerin, D.; Nemitz, E.; Fowler, D.
Atmospheric Environment (1998), 32 (3), 473-480CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Science Ltd.)
Ammonia fluxes over vegetated land are bi-directional, with differences between emission and deposition occurring in relation to environmental conditions (temp. and wetness), plants community (e.g. arable land, unfertilized ecosystems), as well as other factors such as plant phenol. Measurements of net NH3 fluxes over arable cropland are reported in the range -50 to 40 ng/m2-s. These are used as examples to highlight the factors affecting the exchange process. Net fluxes are expected to depend on the competition between deposition to leaf surfaces and bi-directional exchange with a stomatal compensation point for leaf tissues. Two resistance models are described. These est. a canopy compensation point, as the net potential for NH3 emission from the canopy. In the simpler of the 2 models, leaf surface uptake is parameterized using a resistance. This model is able to reproduce bi-directional fluxes, though there is also evidence that both cuticular NH3 absorption and desorption occur, dependent on previous fluxes. A more complex dynamic approach is therefore developed, treating cuticular uptake as a capacitance. The dynamic model is able to reproduce the pattern of desorption, but further development of both models is required to provide descriptions valid over longer periods and for a range of ecosystem types.
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Li, Y.; Thompson, T. M.; Van Damme, M.; Chen, X.; Benedict, K. B.; Shao, Y.; Day, D.; Boris, A.; Sullivan, A. P.; Ham, J.; Whitburn, S.; Clarisse, L.; Coheur, P. F.; Collett, J. L., Jr. Temporal and spatial variability of ammonia in urban and agricultural regions of northern Colorado, United States. Atmos. Chem. Phys. 2017, 17 (10), 6197– 6213, DOI: 10.5194/acp-17-6197-2017
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Temporal and spatial variability of ammonia in urban and agricultural regions of northern Colorado, United States
Li, Yi; Thompson, Tammy M.; Van Damme, Martin; Chen, Xi; Benedict, Katherine B.; Shao, Yixing; Day, Derek; Boris, Alexandra; Sullivan, Amy P.; Ham, Jay; Whitburn, Simon; Clarisse, Lieven; Coheur, Pierre-Francois; Collett, Jeffrey L., Jr.
Atmospheric Chemistry and Physics (2017), 17 (10), 6197-6213CODEN: ACPTCE; ISSN:1680-7324. (Copernicus Publications)
Concd. agricultural activities and animal feeding operations in the northeastern plains of Colorado represent an important source of atm. ammonia (NH3). The NH3 from these sources contributes to regional fine particle formation and to nitrogen deposition to sensitive ecosystems in Rocky Mountain National Park (RMNP), located ∼80 km to the west. In order to better understand temporal and spatial differences in NH3 concns. in this source region, weekly concns. of NH3 were measured at 14 locations during the summers of 2010 to 2015 using Radiello passive NH3 samplers. Weekly (biweekly in 2015) av. NH3 concns. ranged from 2.66 to 42.7 μg m-3, with the highest concns. near large concd. animal feeding operations (CAFOs). The annual summertime mean NH3 concns. were stable in this region from 2010 to 2015, providing a baseline against which concn. changes assocd. with future changes in regional NH3 emissions can be assessed. Vertical profiles of NH3 were also measured on the 300m Boulder Atm. Observatory (BAO) tower throughout 2012. The highest NH3 concn. along the vertical profile was always obsd. at the 10m height (annual av. concn. of 4.63 μg m-3), decreasing toward the surface (4.35 μg m-3) and toward higher altitudes (1.93 μg m-3). The NH3 spatial distributions measured using the passive samplers are compared with NH3 columns retrieved by the IR Atm. Sounding Interferometer (IASI) satellite and concns. simulated by the Comprehensive Air Quality Model with Extensions (CAMx). The satellite comparison adds to a growing body of evidence that IASI column retrievals of NH3 provide very useful insight into regional variability in atm. NH3, in this case even in a region with strong local sources and sharp spatial gradients. The CAMx comparison indicates that the model does a reasonable job simulating NH3 concns. near sources but tends to underpredict concns. at locations farther downwind. Excess NH3 deposition by the model is hypothesized as a possible explanation for this trend.
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Huang, X.; Song, Y.; Li, M.; Li, J.; Huo, Q.; Cai, X.; Zhu, T.; Hu, M.; Zhang, H. A high-resolution ammonia emission inventory in China. Global. Biogeochem. Cy 2012, 26 (1), GB1030 DOI: 10.1029/2011GB004161
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Pan, Y.; Tian, S.; Liu, D.; Fang, Y.; Zhu, X.; Zhang, Q.; Zheng, B.; Michalski, G.; Wang, Y. Fossil fuel combustion-related emissions dominate atmospheric ammonia sources during severe haze episodes: Evidence from ¹⁵N-stable isotope in size-resolved aerosol ammonium. Environ. Sci. Technol. 2016, 50 (15), 8049– 8056, DOI: 10.1021/acs.est.6b00634
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Fossil Fuel Combustion-Related Emissions Dominate Atmospheric Ammonia Sources during Severe Haze Episodes: Evidence from 15N-Stable Isotope in Size-Resolved Aerosol Ammonium
Pan, Yuepeng; Tian, Shili; Liu, Dongwei; Fang, Yunting; Zhu, Xiaying; Zhang, Qiang; Zheng, Bo; Michalski, Greg; Wang, Yuesi
Environmental Science & Technology (2016), 50 (15), 8049-8056CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
The redn. of NH3 emissions is urgently due to its role in aerosol nucleation and growth causing haze formation during its conversion to NH4+; however, the relative contributions of individual NH3 sources are unclear and debate remains over whether agricultural emissions dominate atm. NH3 in urban areas. Based on chem. and isotopic measurements of size-resolved aerosols in urban Beijing, China, the natural abundance of 15N (expressed using δ15N values) of NH4+ in fine particles varies with the development of haze episodes, from -37.1‰ to -21.7‰ during clean/dusty days (relative humidity, ∼40%), to -13.1‰ to +5.8‰ during hazy days (relative humidity, 70-90%). After accounting for isotope exchange between NH3 gas and aerosol NH4+, the δ15N value of initial NH3 during hazy days was -14.5‰ to -1.6‰, which indicates fossil fuel-based emissions. These emissions contributed 90% of total NH3 during hazy days in Beijing. Results demonstrated the anal. of δ15N values of aerosol NH4+ is a promising new tool for partitioning of atm. NH3 sources, providing policy-makers with insights into NH3 emissions and secondary aerosols for urban environment regulation.
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McCalley, C. K.; Sparks, J. P. Controls over nitric oxide and ammonia emissions from Mojave Desert soils. Oecologia 2008, 156 (4), 871– 881, DOI: 10.1007/s00442-008-1031-0
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Controls over nitric oxide and ammonia emissions from Mojave Desert soils
McCalley Carmody K; Sparks Jed P
Oecologia (2008), 156 (4), 871-81 ISSN:0029-8549.
Emissions of reactive N compounds produced during terrestrial N cycling can be an important N loss pathway from ecosystems. Most measurements of this process focus on NO and N(2)O efflux; however, in alkaline soils such as those in the Mojave Desert, NH(3) production can be an important component of N gas loss. We investigated patterns of NO and NH(3) emissions in the Mojave Desert and identified seasonal changes in temperature, precipitation and spatial heterogeneity in soil nutrients as primary controllers of soil efflux. Across all seasons, NH(3) dominated reactive N gas emissions with fluxes ranging from 0.9 to 10 ng N m(-2) s(-1) as compared to NO fluxes of 0.08-1.9 ng N m(-2) s(-1). Fluxes were higher in April and July than in October; however, a fall precipitation event yielded large increases in both NO and NH(3) efflux. To explore the mechanisms driving field observations, we combined NO and NH(3) soil flux measurements with laboratory manipulations of temperature, water and nutrient conditions. These experiments showed a large transient NH(3) pulse (~70-100 ng N m(-2) s(-1)) following water addition, presumably driven by an increase in soil NH(4) (+) concentrations. This was followed by an increase in NO production, with maximum NO flux rates of 34 ng N m(-2) s(-1). Our study suggests that immediately following water addition NH(3) volatilization proceeds at high rates due to the absence of microbial competition for NH(4) (+); during this period N gas loss is insensitive to changes in temperature and soil nutrients. Subsequently, NO emission increases and rates of both NO and NH(3) emission are sensitive to temperature and nutrient constraints on microbial activity. Addition of labile C reduces gaseous N losses, presumably by increasing microbial immobilization, whereas addition of NO(3) (-) stimulates NO and NH(3) efflux.
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Sun, Y.; Zhuang, G.; Huang, K.; Li, J.; Wang, Q.; Wang, Y.; Lin, Y.; Fu, J. S.; Zhang, W.; Tang, A.; Zhao, X. Asian dust over northern China and its impact on the downstream aerosol chemistry in 2004. J. Geophys. Res. 2010, 115 (D7), D00K09 DOI: 10.1029/2009JD012757
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There is no corresponding record for this reference.
30
Sun, K.; Tao, L.; Miller, D. J.; Pan, D.; Golston, L. M.; Zondlo, M. A.; Griffin, R. J.; Wallace, H. W.; Leong, Y. J.; Yang, M. M.; Zhang, Y.; Mauzerall, D. L.; Zhu, T. Vehicle Emissions as an Important Urban Ammonia Source in the United States and China. Environ. Sci. Technol. 2017, 51 (4), 2472– 2481, DOI: 10.1021/acs.est.6b02805
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Vehicle Emissions as an Important Urban Ammonia Source in the United States and China
Sun, Kang; Tao, Lei; Miller, David J.; Pan, Da; Golston, Levi M.; Zondlo, Mark A.; Griffin, Robert J.; Wallace, H. W.; Leong, Yu Jun; Yang, M. Melissa; Zhang, Yan; Mauzerall, Denise L.; Zhu, Tong
Environmental Science & Technology (2017), 51 (4), 2472-2481CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
Ammoniated aerosols are important for urban air quality, but emissions of the key precursor NH3 are not well quantified. Mobile lab. observations are used to characterize fleet-integrated NH3 emissions in six cities in the US and China. Vehicle NH3:CO2 emission ratios in the US are similar between cities (0.33-0.40 ppbv/ppmv, 15% uncertainty) despite differences in fleet compn., climate, and fuel compn. While Beijing, China has a comparable emission ratio (0.36 ppbv/ppmv) to the US cities, less developed Chinese cities show higher emission ratios (0.44 and 0.55 ppbv/ppmv). If the vehicle CO2 inventories are accurate, NH3 emissions from US vehicles (0.26±0.07 Tg/yr) are more than twice those of the National Emission Inventory (0.12 Tg/yr), while Chinese NH3 vehicle emissions (0.09±0.02 Tg/yr) are similar to a bottom-up inventory. Vehicle NH3 emissions outweigh agricultural sources for near half of the US population and require reconsideration in urban air quality models due to their significant emissions, co-location with other aerosol precursors, and the uncertainties regarding NH3 losses from upwind agricultural sources. Ammonia emissions in developing cities are esp. important because of their high emission ratios and rapid motorizations.
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Ianniello, A.; Spataro, F.; Esposito, G.; Allegrini, I.; Rantica, E.; Ancora, M.; Hu, M.; Zhu, T. Occurrence of gas phase ammonia in the area of Beijing (China). Atmos. Chem. Phys. 2010, 10, 9487– 9503, DOI: 10.5194/acp-10-9487-2010
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Occurrence of gas phase ammonia in the area of Beijing (China)
Ianniello, A.; Spataro, F.; Esposito, G.; Allegrini, I.; Rantica, E.; Ancora, M. P.; Hu, M.; Zhu, T.
Atmospheric Chemistry and Physics (2010), 10 (19), 9487-9503CODEN: ACPTCE; ISSN:1680-7316. (Copernicus Publications)
The atm. concns. of gaseous ammonia have been measured during two field campaigns in the winter and in the summer of 2007 at Beijing (China). These measurements were carried out by means of diffusion annular denuders coated with phosphorous acid. The results were discussed from the standpoint of temporal and diurnal variations and meteorol. effects. The daily av. NH3 concns. were in the range of 0.20-44.38 μg/m3 and showed regular temporal variations with higher concns. during summer and with lower during winter. The temporal trends seemed to be largely affected by air temp. because of agricultural sources. No diurnal variability was obsd. for gaseous NH3 levels in both winter and summer seasons. The highest ammonia value of 105.67 μg/m3 was measured in the early morning during the summer period when stable atm. conditions occurred. The diurnal winter and summer trends of ammonia showed a weak dependence on the air temp. and they were affected nearly by wind direction suggesting regional and local source influences. Ammonia was also correlated with the atm. mixing in the boundary layer, and, with NOx, CO and PM2.5 air concns. supporting the hypothesis that the traffic may be also an important source of ammonia in Beijing.
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Teng, X.; Hu, Q.; Zhang, L.; Qi, J.; Shi, J.; Xie, H.; Gao, H.; Yao, X. Identification of Major Sources of Atmospheric NH₃ in an Urban Environment in Northern China During Wintertime. Environ. Sci. Technol. 2017, 51 (12), 6839– 6848, DOI: 10.1021/acs.est.7b00328
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Identification of Major Sources of Atmospheric NH3 in an Urban Environment in Northern China During Wintertime
Teng, Xiaolin; Hu, Qingjing; Zhang, Leiming; Qi, Jiajia; Shi, Jinhui; Xie, Huan; Gao, Huiwang; Yao, Xiaohong
Environmental Science & Technology (2017), 51 (12), 6839-6848CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
To assess the relative contributions of traffic emissions and other potential sources to high atm. NH3 concns. in urban areas in winter, atm. NH3 and related pollutants were measured at an urban site ∼300 m from a major traffic road in northern China in Nov. and Dec. 2015. Hourly av. NH3 concn. were 0.3-10.8 ppb with an av. of 2.4 ppb during the campaign. Contrary to the common literature perspective, traffic emissions demonstrated to be a negligible contributor to atm. NH3. Atm. NH3 correlated well with ambient water vapor during many time periods lasting from tens of hours to several days, implying NH3 released from water evapn. is an important source. Emissions from local green space inside urban areas were identified to significantly contribute to obsd. atm. NH3 concns. for ∼60% of the sampling times. Evapn. of pre-deposited NHx by wet pptn. combined with local green space emissions likely caused spikes of atm. NH3 concn., mostly occurring 1-4 h after morning rush hours or after/during slight shower events. There were still ∼30% of samples with appreciable NH3 concns. for which major contributors have not yet been identified.
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Zhang, X.; Wu, Y.; Liu, X.; Reis, S.; Jin, J.; Dragosits, U.; Van Damme, M.; Clarisse, L.; Whitburn, S.; Coheur, P.-F.; Gu, B. Ammonia Emissions May Be Substantially Underestimated in China. Environ. Sci. Technol. 2017, 51 (21), 12089– 12096, DOI: 10.1021/acs.est.7b02171
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Ammonia Emissions Maybe Substantially Underestimated in China
Zhang, Xiuming; Wu, Yiyun; Liu, Xuejun; Reis, Stefan; Jin, Jiaxin; Dragosits, Ulrike; Van Damme, Martin; Clarisse, Lieven; Whitburn, Simon; Coheur, Pierre-Francois; Gu, Baojing
Environmental Science & Technology (2017), 51 (21), 12089-12096CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
China is a global hotspot of atm. NH3 emissions and, as a consequence, very high N deposition levels are documented. However, previous ests. of total NH3 emissions in China were much lower than inference from obsd. deposition values would suggest, highlighting the need for further study. We reevaluated NH3 emissions based on a mass balance approach, validated by N deposition monitoring and satellite observations, for China for 2000 to 2015. Total NH3 emissions in China increased from 12.1±0.8 Tg N/yr in 2000 to 15.6±0.9 Tg N/yr in 2015 at an annual rate of 1.9%, which is ∼40% higher than existing studies suggested. This difference is mainly due to more emission sources now having been included and NH3 emission rates from mineral fertilizer application and livestock having been underestimated previously. Our estd. NH3 emission levels are consistent with the measured deposition of NHx (including NH4+ and NH3) on land (11-14 Tg N/yr) and the substantial increases in NH3 concns. obsd. by satellite measurements over China. These findings substantially improve our understanding on NH3 emissions, implying that future air pollution control strategies have to consider the potentials of reducing NH3 emission in China.
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Fu, X.; Wang, S. X.; Ran, L. M.; Pleim, J. E.; Cooter, E.; Bash, J. O.; Benson, V.; Hao, J. M. Estimating NH₃ emissions from agricultural fertilizer application in China using the bi-directional CMAQ model coupled to an agro-ecosystem model. Atmos. Chem. Phys. 2015, 15 (12), 6637– 6649, DOI: 10.5194/acp-15-6637-2015
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Estimating NH3 emissions from agricultural fertilizer application in China using the bi-directional CMAQ model coupled to an agro-ecosystem model
Fu, X.; Wang, S. X.; Ran, L. M.; Pleim, J. E.; Cooter, E.; Bash, J. O.; Benson, V.; Hao, J. M.
Atmospheric Chemistry and Physics (2015), 15 (12), 6637-6649CODEN: ACPTCE; ISSN:1680-7324. (Copernicus Publications)
Atm. ammonia (NH3) plays an important role in atm. aerosol chem. China is one of the largest NH3 emitting countries with the majority of NH3 emissions coming from agricultural practices, such as fertilizer application and livestock prodn. The current NH3 emission ests. in China are mainly based on pre-defined emission factors that lack temporal or spatial details, which are needed to accurately predict NH3 emissions. This study provides the first online est. of NH3 emissions from agricultural fertilizer application in China, using an agricultural fertilizer modeling system which couples a regional air quality model (the Community Multi-scale Air Quality model, or CMAQ) and an agro-ecosystem model (the Environmental Policy Integrated Climate model, or EPIC). This method improves the spatial and temporal resoln. of NH3 emissions from this sector. We combined the cropland area data of 14 crops from 2710 counties with the Moderate Resoln. Imaging Spectroradiometer (MODIS) land use data to det. the crop distribution. The fertilizer application rates and methods for different crops were collected at provincial or agricultural region levels. The EPIC outputs of daily fertilizer application and soil characteristics were input into the CMAQ model and the hourly NH3 emissions were calcd. online with CMAQ running. The estd. agricultural fertilizer NH3 emissions in this study were approx. 3 Tg in 2011. The regions with the highest modeled emission rates are located in the North China Plain. Seasonally, peak ammonia emissions occur from Apr. to July. Compared with previous researches, this study considers an increased no. of influencing factors, such as meteorol. fields, soil and fertilizer application, and provides improved NH3 emissions with higher spatial and temporal resoln.
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Denmead, O. T.; Freney, J. R.; Dunin, F. X. Gas exchange between plant canopies and the atmosphere: Case-studies for ammonia. Atmos. Environ. 2008, 42 (14), 3394– 3406, DOI: 10.1016/j.atmosenv.2007.01.038
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Gas exchange between plant canopies and the atmosphere: Case-studies for ammonia
Denmead, O. T.; Freney, J. R.; Dunin, F. X.
Atmospheric Environment (2008), 42 (14), 3394-3406CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Ltd.)
We present the elements of an inverse Lagrangian model of gas transport in plant canopies. The model allows the effect of sites of gas exchange in the canopy and their source and sink strengths from measured profiles of mean gas concn. and statistics of the canopy turbulence. The practical application of the model is demonstrated through a case study of the fate of ammonia volatilized from fertilizer applied to the floor of a sugarcane crop. Some of the lost ammonia was absorbed by the foliage of the crop; the rest was lost to the atm. above. While there was excellent agreement between model predictions of the net flux from the canopy and independent micrometeorol. measurements of ammonia flux in the air-layer above it, verification of flux predictions within the canopy was much more difficult. Appeal was made to a process-based model of canopy gas exchange that describes gas transport to and from foliage surfaces in terms of diffusion across aerodynamic, boundary-layer and stomatal resistances in response to a difference in ammonia concn. between the air and leaf sub-stomatal cavities. There was acceptable agreement between the 2 models in their predictions of foliage ammonia uptake. We apply the process model to a study of the recapture of volatilized ammonia by sugarcane crops with different leaf area indexes (LAI). The study indicated recoveries increasing almost linearly with LAI and suggested probable recoveries in excess of 20% for canopies with LAIs of ≥2. These and other published studies of ammonia exchange between canopy and atm. that used both the inverse Lagrangian and process models suggest that their coupling provides a powerful tool for studying canopy gas exchange.
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Li, M.; Zhang, Q.; Kurokawa, J. I.; Woo, J. H.; He, K.; Lu, Z.; Ohara, T.; Song, Y.; Streets, D. G.; Carmichael, G. R.; Cheng, Y.; Hong, C.; Huo, H.; Jiang, X.; Kang, S.; Liu, F.; Su, H.; Zheng, B. MIX: a mosaic Asian anthropogenic emission inventory under the international collaboration framework of the MICS-Asia and HTAP. Atmos. Chem. Phys. 2017, 17 (2), 935– 963, DOI: 10.5194/acp-17-935-2017
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MIX: a mosaic Asian anthropogenic emission inventory under the international collaboration framework of the MICS-Asia and HTAP
Li, Meng; Zhang, Qiang; Kurokawa, Jun-ichi; Woo, Jung-Hun; He, Kebin; Lu, Zifeng; Ohara, Toshimasa; Song, Yu; Streets, David G.; Carmichael, Gregory R.; Cheng, Yafang; Hong, Chaopeng; Huo, Hong; Jiang, Xujia; Kang, Sicong; Liu, Fei; Su, Hang; Zheng, Bo
Atmospheric Chemistry and Physics (2017), 17 (2), 935-963CODEN: ACPTCE; ISSN:1680-7324. (Copernicus Publications)
The MIX inventory is developed for the years 2008 and 2010 to support the Model Inter-Comparison Study for Asia (MICS-Asia) and the Task Force on Hemispheric Transport of Air Pollution (TF HTAP) by a mosaic of up-to-date regional emission inventories. Emissions are estd. for all major anthropogenic sources in 29 countries and regions in Asia. We conducted detailed comparisons of different regional emission inventories and incorporated the best available ones for each region into the mosaic inventory at a uniform spatial and temporal resoln. Emissions are aggregated to five anthropogenic sectors: power, industry, residential, transportation, and agriculture. We est. the total Asian emissions of 10 species in 2010 as follows: 51.3 Tg SO2, 52.1 Tg NOx, 336.6 Tg CO, 67.0 Tg NMVOC (non-methane volatile org. compds.), 28.8 Tg NH3, 31.7 Tg PM10, 22.7 Tg PM2.5, 3.5 Tg BC, 8.3 Tg OC, and 17.3 Pg CO2. Emissions from China and India dominate the emissions of Asia for most of the species. We also estd. Asian emissions in 2006 using the same methodol. of MIX. The relative change rates of Asian emissions for the period of 2006-2010 are estd. as follows: -8.1% for SO2, C19.2% for NOx, C3.9% for CO, C15.5% for NMVOC, C1.7% for NH3, -3.4% for PM10, -1.6% for PM2.5, C5.5% for BC, C1.8% for OC, and C19.9% for CO2. Model-ready speciated NMVOC emissions for SAPRC-99 and CB05 mechanisms were developed following a profile-assignment approach. Monthly gridded emissions at a spatial resoln. of 0.25° ×0.25° are developed and can be accessed.
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Abstract
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Figure 1
Figure 1. Spatial distribution of ammonia concentrations observed from the surface network (site) versus satellite column data (grid) in China. The detailed surface observation site information can be found in Table 1 and SI. Satellite NH₃ total column distributions were derived from the infrared atmospheric sounding interferometer (IASI) aboard MetOp-A for the year 2015. We collected the observations from morning overpass time (9:30 LTC) and filtered the columns with relative error above 100% following procedures presented in Van Damme et al.(12) The filtered IASI satellite columns were then mapped to a 0.25° × 0.25° horizontal resolution by averaging available observations within each grid cell. The provincial boundary layer with a scale of 1:4,000,000 was obtained from the National Geomatics Center of China (http://ngcc.sbsm.gov.cn/). Maps were generated based upon a geospatial analysis using ESRI ArcGIS software (version 10.1, http://www.esri.com/software/arcgis/arcgis-for-desktop).
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Figure 2
Figure 2. Seasonal variations of ammonia concentrations observed from the surface network (53 sites) in China.
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Figure 3
Figure 3. Comparisons of passive diffusion sampler to the continuously active analyzers of MARGA and DELTA. Ammonia concentrations are aggregated to monthly data points.
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Figure 4
Figure 4. Spatial distribution of the site-based dry deposition fluxes versus the gridded agriculture emission inventory of ammonia in China. The legend for gridded ammonia inventory was also shown in units of kg N ha^–1 year^–1 (numbers in the left corner), in addition to units of t year^–1 per 0.25° by 0.25°. The NH₃ inventory used in this study was obtained from the Multi-Resolution Emission Inventory of China (MEIC, http://meicmodel.org),(36) originally developed and described by Huang et al.(26) The MEIC inventory is provided with monthly gridded emissions of NH₃ at 0.25° × 0.25° for five sectors, that is, power generation, industry, residential, transportation, and agriculture. The agriculture sector is a dominant source of NH₃ emissions at the national scale, mainly contributed by fertilizer applications and manure managements. The year of 2012 was chosen to conduct the spatial comparison because emissions after 2012 are currently unavailable. The provincial boundary layer with a scale of 1:4 000 000 was obtained from the National Geomatics Center of China (http://ngcc.sbsm.gov.cn/). Maps were generated based upon a geospatial analysis using ESRI ArcGIS software (version 10.1, http://www.esri.com/software/arcgis/arcgis-for-desktop).
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Figure 5
Figure 5. Comparison of the site-based dry deposition fluxes versus the gridded agriculture emission inventory of ammonia in China (1° by 1°). The sites are colored by region. The units of emission data were converted to kg N ha^–1 year^–1 for comparison with that of ammonia deposition. The 1:1 line represents equal ammonia dry deposition and emissions.
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  Human alteration of Earth is substantial and growing. Between one-third and one-half of the land surface has been transformed by human action; the carbon dioxide concn. in the atm. has increased by nearly 30 percent since the beginning of the Industrial Revolution; more atm. nitrogen is fixed by humanity than by all natural terrestrial sources combined; more than half of all accessible surface fresh water is put to use by humanity; and about one-quarter of the bird species on Earth have been driven to extinction. By these and other stds., it is clear that we live on a human-dominated planet.
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2. 2
  Galloway, J. N.; Townsend, A. R.; Erisman, J. W.; Bekunda, M.; Cai, Z.; Freney, J. R.; Martinelli, L. A.; Seitzinger, S. P.; Sutton, M. A. Transformation of the Nitrogen Cycle: Recent Trends, Questions, and Potential Solutions. Science 2008, 320 (5878), 889– 892, DOI: 10.1126/science.1136674
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  2
  Transformation of the Nitrogen Cycle: Recent Trends, Questions, and Potential Solutions
  Galloway, James N.; Townsend, Alan R.; Erisman, Jan Willem; Bekunda, Mateete; Cai, Zucong; Freney, John R.; Martinelli, Luiz A.; Seitzinger, Sybil P.; Sutton, Mark A.
  Science (Washington, DC, United States) (2008), 320 (5878), 889-892CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)
  A review is given on the transformation of the global nitrogen cycle, which reflects an increased combustion of fossil fuels, growing demand for nitrogen in agriculture and industry, and pervasive inefficiencies in its use. Much anthropogenic nitrogen is lost to air, water, and land to cause a cascade of environmental and human health problems. Simultaneously, food prodn. in some parts of the world is nitrogen-deficient, highlighting inequities in the distribution of nitrogen-contg. fertilizers. Optimizing the need for a key human resource while minimizing its neg. consequences requires an integrated interdisciplinary approach and the development of strategies to decrease nitrogen-contg. waste.
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3. 3
  Fu, X.; Wang, S.; Xing, J.; Zhang, X.; Wang, T.; Hao, J. Increasing Ammonia Concentrations Reduce the Effectiveness of Particle Pollution Control Achieved via SO2 and NOX Emissions Reduction in East China. Environ. Sci. Technol. Lett. 2017, 4 (6), 221– 227, DOI: 10.1021/acs.estlett.7b00143
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  3
  Increasing Ammonia Concentrations Reduce the Effectiveness of Particle Pollution Control Achieved via SO2 and NOX Emissions Reduction in East China
  Fu, Xiao; Wang, Shuxiao; Xing, Jia; Zhang, Xiaoye; Wang, Tao; Hao, Jiming
  Environmental Science & Technology Letters (2017), 4 (6), 221-227CODEN: ESTLCU; ISSN:2328-8930. (American Chemical Society)
  Atm. ammonia (NH3) plays a crucial role in the formation of secondary inorg. aerosols (SIAs). Although China produces a large amt. of NH3 emissions, it has not yet taken any measures to control NH3 emissions. Satellite retrievals show that NH3 vertical column densities (VCDs) have obviously increased in recent years, by approx. 20% from 2011 to 2014, in contrast to the decreases seen for SO2 and NOX VCDs. Evidence of the ground-based observations and satellite retrievals indicates that the increases in NH3 concns. have weakened the benefits of the redn. in SIA concns. (esp. for nitrate) from SO2 and NOX emissions control. Results from model simulations suggest that the simultaneous control of NH3 emissions in conjunction with SO2 and NOX emissions is more effective in reducing particulate matter (PM) pollution than the process without NH3 emissions control is. Our findings indicate that the continual increases in free NH3 concns. can result in a lower sensitivity of PM redn. to NH3 emissions control in the future, and reducing NH3 emissions is urgently required for the effective control of PM pollution in China.
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4. 4
  Liu, X.; Zhang, Y.; Han, W.; Tang, A.; Shen, J.; Cui, Z.; Vitousek, P.; Erisman, J. W.; Goulding, K.; Christie, P.; Fangmeier, A.; Zhang, F. Enhanced nitrogen deposition over China. Nature 2013, 494 (7438), 459– 462, DOI: 10.1038/nature11917
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  4
  Enhanced nitrogen deposition over China
  Liu, Xuejun; Zhang, Ying; Han, Wenxuan; Tang, Aohan; Shen, Jianlin; Cui, Zhenling; Vitousek, Peter; Erisman, Jan Willem; Goulding, Keith; Christie, Peter; Fangmeier, Andreas; Zhang, Fusuo
  Nature (London, United Kingdom) (2013), 494 (7438), 459-462CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)
  China is experiencing intense air pollution caused, in large part, by anthropogenic reactive N emissions. These emissions result in deposition of atm. N to terrestrial and aquatic ecosystems, with implications for human and ecosystem health, greenhouse gas balance, and biodiversity; however, information on the magnitude and environmental impact of N deposition in China is limited. This work used nation-wide datasets on bulk N deposition, plant foliar N, and crop N uptake (from long-term unfertilized soil) to evaluate N deposition dynamics and their effect on ecosystems across China from 1980 to 2010. The av. annual bulk N deposition increased by ∼8 kg N/ha (P <0.001) from the 1980s (13.2 kg N/ha) and the 2000s (21.1 kg M/ha). N deposition rates in the industrialized and agriculturally intense regions were are as high as the peak deposition levels in northwestern Europe in the 1980s, before the introduction of mitigation measures. N from NH4+ was the dominant form of N in bulk deposition, but the rate of increase was largest for N deposition from NO3-, in agreement with decreased NH3:NOx emission ratios since 1980. The impact of N deposition on Chinese ecosystems included significantly increased plant foliar N concns. in natural and semi-natural (non-agricultural) ecosystems, and increased crop N uptake from long-term unfertilized cropland. China and other economies are facing a continuing challenge to reduce reactive N emissions, N deposition, and their neg. effects on human health and the environment.
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5. 5
  Warner, J. X.; Dickerson, R. R.; Wei, Z.; Strow, L. L.; Wang, Y.; Liang, Q. Increased atmospheric ammonia over the world’s major agricultural areas detected from space. Geophys. Res. Lett. 2017, 44 (6), 2875– 2884, DOI: 10.1002/2016GL072305
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  5
  Increased atmospheric ammonia over the world's major agricultural areas detected from space
  Warner, J. X.; Dickerson, R. R.; Wei, Z.; Strow, L. L.; Wang, Y.; Liang, Q.
  Geophysical Research Letters (2017), 44 (6), 2875-2884CODEN: GPRLAJ; ISSN:1944-8007. (Wiley-Blackwell)
  This study provides evidence of substantial increases in atm. ammonia (NH3) concns. (14 yr) over several of the worlds major agricultural regions, using recently available retrievals from the Atm. IR Sounder (AIRS) aboard NASA's Aqua satellite. The main sources of atm. NH3 are farming and animal husbandry involving reactive nitrogen ultimately derived from fertilizer use; rates of emission are also sensitive to climate change. Significant increasing trends are seen over the U.S. (2.61% yr-1), the European Union (EU) (1.83% yr-1), and China (2.27% yr-1). Over the EU, the trend results from decreased scavenging by acid aerosols. Over the U.S., the increase results from a combination of decreased chem. loss and increased soil temps. Over China, decreased chem. loss, increasing temps., and increased fertilizer use all play a role. Over South Asia, increased NH3 emissions are masked by increased SO2 and NOx emissions, leading to increased aerosol loading and adverse health effects.
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6. 6
  Li, Y.; Schichtel, B. A.; Walker, J. T.; Schwede, D. B.; Chen, X.; Lehmann, C. M.; Puchalski, M. A.; Gay, D. A.; Collett, J., Jr Increasing importance of deposition of reduced nitrogen in the United States. Proc. Natl. Acad. Sci. U. S. A. 2016, 113 (21), 5874– 5879, DOI: 10.1073/pnas.1525736113
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  6
  Increasing importance of deposition of reduced nitrogen in the United States
  Li, Yi; Schichtel, Bret A.; Walker, John T.; Schwede, Donna B.; Chen, Xi; Lehmann, Christopher M. B.; Puchalski, Melissa A.; Gay, David A.; Collett, Jeffrey L., Jr.
  Proceedings of the National Academy of Sciences of the United States of America (2016), 113 (21), 5874-5879CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)
  Rapid development of agriculture and fossil fuel combustion greatly increased US reactive nitrogen emissions to the atm. in the second half of the 20th century, resulting in excess nitrogen deposition to natural ecosystems. Recent efforts to lower nitrogen oxides emissions have substantially decreased nitrate wet deposition. Levels of wet ammonium deposition, by contrast, have increased in many regions. Together these changes have altered the balance between oxidized and reduced nitrogen deposition. Across most of the United States, wet deposition has transitioned from being nitrate-dominated in the 1980s to ammonium-dominated in recent years. Ammonia has historically not been routinely measured because there are no specific regulatory requirements for its measurement. Recent expansion in ammonia observations, however, along with ongoing measurements of nitric acid and fine particle ammonium and nitrate, permit new insight into the balance of oxidized and reduced nitrogen in the total (wet + dry) US nitrogen deposition budget. Observations from 37 sites reveal that reduced nitrogen contributes, on av., ∼65% of the total inorg. nitrogen deposition budget. Dry deposition of ammonia plays an esp. key role in nitrogen deposition, contributing from 19% to 65% in different regions. Future progress toward reducing US nitrogen deposition will be increasingly difficult without a redn. in ammonia emissions.
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7. 7
  Pan, Y.; Wang, Y.; Tang, G.; Wu, D. Wet and dry deposition of atmospheric nitrogen at ten sites in Northern China. Atmos. Chem. Phys. 2012, 12 (14), 6515– 6535, DOI: 10.5194/acp-12-6515-2012
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  7
  Wet and dry deposition of atmospheric nitrogen at ten sites in Northern China
  Pan, Y. P.; Wang, Y. S.; Tang, G. Q.; Wu, D.
  Atmospheric Chemistry and Physics (2012), 12 (14), 6515-6535CODEN: ACPTCE; ISSN:1680-7316. (Copernicus Publications)
  Emissions of reactive nitrogen (N) species can affect surrounding ecosystems via atm. deposition. However, few long-term and multi-site measurements have focused on both the wet and the dry deposition of individual N species in large areas of Northern China. Thus, the magnitude of atm. deposition of various N species in Northern China remains uncertain. In this study, the wet and dry atm. deposition of different N species was investigated during a three-year observation campaign at ten selected sites in Northern China. The results indicate that N deposition levels in Northern China were high with a ten-site, three-year av. of 60.6 kg N ha-1 yr-1. The deposition levels showed spatial and temporal variation in the range of 28.5-100.4 kg N ha-1 yr-1. Of the annual total deposition, 40% was deposited via pptn., and the remaining 60% was comprised of dry-deposited forms. Compared with gaseous N species, particulate N species were not the major contributor of dry-deposited N; they contributed approx. 10% to the total flux. On an annual basis, oxidized species accounted for 21% of total N deposition, thereby implying that other forms of gaseous N, such as NH3, comprised a dominant portion of the total flux. The contribution of NO3- to N deposition was enhanced in certain urban and industrial areas, possibly due to the fossil fuse combustion. As expected, the total N deposition in Northern China was significantly larger than the values reported by national scale monitoring networks in Europe, North America and East Asia because of high rates of wet deposition and gaseous NH3 dry deposition. Taken together, these findings show that NH3 emissions should be abated to mitigate high N deposition and assocd. potential impacts on ecosystems in Northern China. The present results improve our understanding of spatio-temporal variations of magnitudes, pathways and species of deposited N in the target areas, and are important not only to inform conservation and regulatory bodies but also to initiate further detailed studies. Uncertainties among current observations underscore the need to quantify the impact of vegetation on dry deposition and to refine the simulation of dry deposition velocity.
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8. 8
  Meng, W.; Zhong, Q.; Yun, X.; Zhu, X.; Huang, T.; Shen, H.; Chen, Y.; Chen, H.; Zhou, F.; Liu, J.; Wang, X.; Zeng, E. Y.; Tao, S. Improvement of a Global High-Resolution Ammonia Emission Inventory for Combustion and Industrial Sources with New Data from the Residential and Transportation Sectors. Environ. Sci. Technol. 2017, 51 (5), 2821– 2829, DOI: 10.1021/acs.est.6b03694
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  8
  Improvement of a Global High-Resolution Ammonia Emission Inventory for Combustion and Industrial Sources with New Data from the Residential and Transportation Sectors
  Meng, Wenjun; Zhong, Qirui; Yun, Xiao; Zhu, Xi; Huang, Tianbo; Shen, Huizhong; Chen, Yilin; Chen, Han; Zhou, Feng; Liu, Junfeng; Wang, Xinming; Zeng, Eddy Y.; Tao, Shu
  Environmental Science & Technology (2017), 51 (5), 2821-2829CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
  There is increasing evidence indicating the crit. role of ammonia (NH3) in the formation of secondary aerosols. Therefore, high quality NH3 emission inventory is important for modeling particulate matter in the atm. Unfortunately, without directly measured emission factors (EFs) in developing countries, using data from developed countries could result in an underestimation of these emissions. A series of newly reported EFs for China provide an opportunity to update the NH3 emission inventory. In addn., a recently released fuel consumption data product has allowed for a multisource, high-resoln. inventory to be assembled. In this study, an improved global NH3 emission inventory for combustion and industrial sources with high sectorial (70 sources), spatial (0.1° × 0.1°), and temporal (monthly) resolns. was compiled for the years 1960 to 2013. The estd. emissions from transportation (1.59 Tg) sectors in 2010 was 2.2 times higher than those of previous reports. The spatial variation of the emissions was assocd. with population, gross domestic prodn., and temp. Unlike other major air pollutants, NH3 emissions continue to increase, even in developed countries, which is likely caused by an increased use of biomass fuel in the residential sector. The emissions d. of NH3 in urban areas is an order of magnitude higher than in rural areas.
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9. 9
  Tian, S.; Pan, Y.; Liu, Z.; Wen, T.; Wang, Y. Size-resolved aerosol chemical analysis of extreme haze pollution events during early 2013 in urban Beijing, China. J. Hazard. Mater. 2014, 279, 452– 460, DOI: 10.1016/j.jhazmat.2014.07.023
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  9
  Size-resolved aerosol chemical analysis of extreme haze pollution events during early 2013 in urban Beijing, China
  Tian, Shili; Pan, Yuepeng; Liu, Zirui; Wen, Tianxue; Wang, Yuesi
  Journal of Hazardous Materials (2014), 279 (), 452-460CODEN: JHMAD9; ISSN:0304-3894. (Elsevier B.V.)
  Using size-resolved filter sampling and chem. characterization, high concns. of water-sol. ions, carbonaceous species and heavy metals were found in both fine (PM2.1) and coarse (PM2.1-9) particles in Beijing during haze events in early 2013. Even on clear days, av. mass concn. of submicron particles (PM1.1) was several times higher than that previously measured in most of abroad urban areas. A high concn. of particulate matter on haze days weakens the incident solar radiation, which reduces the generation rate of secondary org. carbon in PM1.1. We show that the peak mass concn. of particles shifted from 0.43-0.65 μm on clear days to 0.65-1.1 μm on lightly polluted days and to 1.1-2.1 μm on heavily polluted days. The peak shifts were also found for the following species: org. carbon, elemental carbon, NH+4, SO2-4, NO-3, K, Cu, Zn, Cd and Pb. Our findings demonstrate that secondary inorg. aerosols (36%) and org. matter (26%) dominated the fine particle mass on heavily polluted days, while their contribution reduced to 29% and 18%, resp., on clear days. Besides fine particles, anthropogenic chem. species also substantially accumulated in the coarse mode, which suggests that particles with aerodynamic diam. larger than 2.1 μm cannot be neglected during severe haze events.
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10. 10
  Wang, G.; Zhang, R.; Gomez, M. E.; Yang, L.; Levy Zamora, M.; Hu, M.; Lin, Y.; Peng, J.; Guo, S.; Meng, J.; Li, J.; Cheng, C.; Hu, T.; Ren, Y.; Wang, Y.; Gao, J.; Cao, J.; An, Z.; Zhou, W.; Li, G.; Wang, J.; Tian, P.; Marrero-Ortiz, W.; Secrest, J.; Du, Z.; Zheng, J.; Shang, D.; Zeng, L.; Shao, M.; Wang, W.; Huang, Y.; Wang, Y.; Zhu, Y.; Li, Y.; Hu, J.; Pan, B.; Cai, L.; Cheng, Y.; Ji, Y.; Zhang, F.; Rosenfeld, D.; Liss, P. S.; Duce, R. A.; Kolb, C. E.; Molina, M. J. Persistent sulfate formation from London Fog to Chinese haze. Proc. Natl. Acad. Sci. U. S. A. 2016, 113 (48), 13630– 13635, DOI: 10.1073/pnas.1616540113
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  10
  Persistent sulfate formation from London Fog to Chinese haze
  Wang, Gehui; Zhang, Renyi; Gomez, Mario E.; Yang, Lingxiao; Zamora, Misti Levy; Hu, Min; Lin, Yun; Peng, Jianfei; Guo, Song; Meng, Jingjing; Li, Jianjun; Cheng, Chunlei; Hu, Tafeng; Ren, Yanqin; Wang, Yuesi; Gao, Jian; Cao, Junji; An, Zhisheng; Zhou, Weijian; Li, Guohui; Wang, Jiayuan; Tian, Pengfei; Marrero-Ortiz, Wilmarie; Secrest, Jeremiah; Du, Zhuofei; Zheng, Jing; Shang, Dongjie; Zeng, Limin; Shao, Min; Wang, Weigang; Huang, Yao; Wang, Yuan; Zhu, Yujiao; Li, Yixin; Hu, Jiaxi; Pan, Bowen; Cai, Li; Cheng, Yuting; Ji, Yuemeng; Zhang, Fang; Rosenfeld, Daniel; Liss, Peter S.; Duce, Robert A.; Kolb, Charles E.; Molina, Mario J.
  Proceedings of the National Academy of Sciences of the United States of America (2016), 113 (48), 13630-13635CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)
  Sulfate aerosols exert profound impacts on human and ecosystem health, weather, and climate, but their formation mechanism remains uncertain. Atm. models consistently underpredict sulfate levels under diverse environmental conditions. From atm. measurements in two Chinese megacities and complementary lab. expts., we show that the aq. oxidn. of SO2 by NO2 is key to efficient sulfate formation but is only feasible under two atm. conditions: on fine aerosols with high relative humidity and NH3 neutralization or under cloud conditions. Under polluted environments, this SO2 oxidn. process leads to large sulfate prodn. rates and promotes formation of nitrate and org. matter on aq. particles, exacerbating severe haze development. Effective haze mitigation is achievable by intervening in the sulfate formation process with enforced NH3 and NO2 control measures. In addn. to explaining the polluted episodes currently occurring in China and during the 1952 London Fog, this sulfate prodn. mechanism is widespread, and our results suggest a way to tackle this growing problem in China and much of the developing world.
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11. 11
  Beer, R.; Shephard, M. W.; Kulawik, S. S.; Clough, S. A.; Eldering, A.; Bowman, K. W.; Sander, S. P.; Fisher, B. M.; Payne, V. H.; Luo, M.; Osterman, G. B.; Worden, J. R. First satellite observations of lower tropospheric ammonia and methanol. Geophys. Res. Lett. 2008, 35 (9), L09801 DOI: 10.1029/2008GL033642
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  11
  First satellite observations of lower tropospheric ammonia and methanol
  Beer, Reinhard; Shephard, Mark W.; Kulawik, Susan S.; Clough, Shepard A.; Eldering, Annmarie; Bowman, Kevin W.; Sander, Stanley P.; Fisher, Brendan M.; Payne, Vivienne H.; Luo, Mingzhao; Osterman, Gregory B.; Worden, John R.
  Geophysical Research Letters (2008), 35 (9), L09801/1-L09801/5CODEN: GPRLAJ; ISSN:0094-8276. (American Geophysical Union)
  The Tropospheric Emission Spectrometer (TES) on the EOS Aura satellite makes global measurements of IR radiances which are used to derive profiles of species such as O3, CO, H2O, HDO and CH4 as routine std. products. In addn., TES has a variety of special modes that provide denser spatial mapping over a limited geog. area. A continuous-coverage mode (called "transect", about 460 km long) has now been used to detect addnl. mols. indicative of regional air pollution. On 10 July 2007 at about 05:37 UTC (13:24 LMST) TES conducted such a transect observation over the Beijing area in northeast China. Examn. of the residual spectral radiances following the retrieval of the TES std. products revealed surprisingly strong features attributable to enhanced concns. of ammonia (NH3) and methanol (CH3OH), well above the normal background levels. This is the first time that these mols. have been detected in space-based nadir viewing measurements that penetrate into the lower atm.
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12. 12
  Van Damme, M.; Clarisse, L.; Heald, C. L.; Hurtmans, D.; Ngadi, Y.; Clerbaux, C.; Dolman, A. J.; Erisman, J. W.; Coheur, P. F. Global distributions, time series and error characterization of atmospheric ammonia (NH₃) from IASI satellite observations. Atmos. Chem. Phys. Discuss. 2014, 14 (6), 2905– 2922, DOI: 10.5194/acpd-13-24301-2013
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  12
  Global distributions, time series and error characterization of atmospheric ammonia (NH3) from IASI satellite observations
  Van Damme, M.; Clarisse, L.; Heald, C. L.; Hurtmans, D.; Ngadi, Y.; Clerbaux, C.; Dolman, A. J.; Erisman, J. W.; Coheur, P. F.
  Atmospheric Chemistry and Physics (2014), 14 (6), 2905-2922, 18 pp.CODEN: ACPTCE; ISSN:1680-7324. (Copernicus Publications)
  Ammonia (NH3) emissions in the atm. have increased substantially over the past decades, largely because of intensive livestock prodn. and use of fertilizers. As a short-lived species, NH3 is highly variable in the atm. and its concn. is generally small, except near local sources. While ground-based measurements are possible, they are challenging and sparse. Advanced IR sounders in orbit have recently demonstrated their capability to measure NH3, offering a new tool to refine global and regional budgets. In this paper we describe an improved retrieval scheme of NH3 total columns from the measurements of the IR Atm. Sounding Interferometer (IASI). It exploits the hyperspectral character of this instrument by using an extended spectral range (800-1200 cm-1) where NH3 is optically active. This scheme consists of the calcn. of a dimensionless spectral index from the IASI level1C radiances, which is subsequently converted to a total NH3 column using look-up tables built from forward radiative transfer model simulations. We show how to retrieve the NH3 total columns from IASI quasi-globally and twice daily above both land and sea without large computational resources and with an improved detection limit. The retrieval also includes error characterization of the retrieved columns. Five years of IASI measurements (1 Nov. 2007 to 31 Oct. 2012) have been processed to acquire the first global and multiple-year data set of NH3 total columns, which are evaluated and compared to similar products from other retrieval methods. Spatial distributions from the five years data set are provided and analyzed at global and regional scales. In particular, we show the ability of this method to identify smaller emission sources than those previously reported, as well as transport patterns over the ocean. The five-year time series is further examd. in terms of seasonality and interannual variability (in particular as a function of fire activity) sep. for the Northern and Southern Hemispheres.
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13. 13
  Butler, T.; Vermeylen, F.; Lehmann, C. M.; Likens, G. E.; Puchalski, M. Increasing ammonia concentration trends in large regions of the USA derived from the NADP/AMoN network. Atmos. Environ. 2016, 146, 132– 140, DOI: 10.1016/j.atmosenv.2016.06.033
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  13
  Increasing ammonia concentration trends in large regions of the USA derived from the NADP/AMoN network
  Butler, T.; Vermeylen, F.; Lehmann, C. M.; Likens, G. E.; Puchalski, M.
  Atmospheric Environment (2016), 146 (), 132-140CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Ltd.)
  Data from bi-weekly passive samplers from 18 of the longest operating National Atm. Deposition Program's (NADP) Ammonia Monitoring Network (AMoN) sites (most operating from 2008 to 2015) show that concns. of NH3 have been increasing (p-value < 0.0001) over large regions of the USA. This trend is occurring at a seasonal and annual level of aggregation. Using random coeff. models (RCM), the mean slope for the 18 sites combined shows an increase of NH3 concn. of +7% per yr, with a 95% confidence interval (C.I.) from +5% to +9% per yr. Travel blank cor. data using the same approach show increasing NH3 concns. of +9% (95% C.I. +5% to +13%) per yr. During a comparable period (2008-2014) NADP pptn. chem. sites in the same regions show significant increasing (p-value = 0.0001) pptn. NH+4 concns. trends for all sites combined of +5% (95% C.I. +3% to +7%) per yr. Emissions inventory data for the study period show nearly const. rates of NH3 emissions, but large redns. in NOx and SO2 emissions. Seasonal air quality data from the Clean Air Status and Trends Network (CASTNET) sites in these regions show significant declines in atm. particulate SO2-4 and NH+4, and particulate NO-3 plus HNO3 (total NO-3) during the same period. Less formation of acidic SO4 and NO3, due to reduced SO2 and NOx emissions, provide less substrate to interact with NH3 and form particulate ammonium species. Thus, concns. of NH3 can increase in the atm. even if emissions remain const. A likely result may be more localized deposition of NH3, as opposed to the more long-range transport and deposition of ammonium nitrate (NH4NO3) and sulfate (NH4)2SO4. Addnl., the spatial distribution of wet and dry acidic deposition will be impacted.
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14. 14
  Carmichael, G. R.; Ferm, M.; Thongboonchoo, N.; Woo, J.-H.; Chan, L. Y.; Murano, K.; Viet, P. H.; Mossberg, C.; Bala, R.; Boonjawat, J.; Upatum, P.; Mohan, M.; Adhikary, S. P.; Shrestha, A. B.; Pienaar, J. J.; Brunke, E. B.; Chen, T.; Jie, T.; Guoan, D.; Peng, L. C.; Dhiharto, S.; Harjanto, H.; Jose, A. M.; Kimani, W.; Kirouane, A.; Lacaux, J.-P.; Richard, S.; Barturen, O.; Cerda, J. C.; Athayde, A.; Tavares, T.; Cotrina, J. S.; Bilici, E. Measurements of sulfur dioxide, ozone and ammonia concentrations in Asia, Africa, and South America using passive samplers. Atmos. Environ. 2003, 37 (9), 1293– 1308, DOI: 10.1016/S1352-2310(02)01009-9
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  14
  Measurements of sulfur dioxide, ozone and ammonia concentrations in Asia, Africa, and South America using passive samplers
  Carmichael, Gregory R.; Ferm, Martin; Thongboonchoo, Narisara; Woo, Jung-Hun; Chan, L. Y.; Murano, Kentaro; Viet, Pham Hung; Mossberg, Carl; Bala, Rajasekhlar; Boonjawat, Jariya; Upatum, Pramote; Mohan, Manju; Adhikary, Sharad P.; Shrestha, Arun B.; Pienaar, J. J.; Brunke, Ernst B.; Chen, Tai; Tang, Jie; Ding, Guoan; Peng, Leong Chow; Dhiharto, Sri; Harjanto, Hery; Jose, Aida M.; Kimani, Wilson; Kirouane, Abdelmalek; Lacaux, Jean-Pierre; Richard, Sandrine; Barturen, Osvaldo; Cerda, Jorge Carrasco; Athayde, Augusto; Tavares, Tania; Cotrina, Jose Silva; Bilici, Erdal
  Atmospheric Environment (2003), 37 (9-10), 1293-1308CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Science Ltd.)
  Measurements of gaseous SO2, NH3, and O3 using IVL passive sampler technol. were obtained during a pilot measurement program initiated as a key component of the newly established WMO/GAW Urban Research Meteorol. and Environment (GURME) project. Monthly measurements were obtained at 50 stations in Asia, Africa, South America, and Europe. The median SO2 concns. vary from a high of 13 ppb at Linan, China, to <0.03 ppb at four stations. At 30 of 50 regional stations, the obsd. median concns. are <1 ppb. Median NH3 concns. range from 20 ppb at Dhangadi, India, to <1 ppb at nine stations. At 27 of regional stations, the ambient NH3 levels exceed 1 ppb. The median ozone concns. vary from a max. of 45 ppb at Waliguan Mountain, China, to 8 ppb in Petit Saut, French Guiana. In general, the highest ozone values are found in the mid-latitudes, with the Northern hemisphere mid-latitude values exceeding the Southern hemisphere mid-latitude levels, and the lowest values are typically found in the tropical regions.
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15. 15
  Meng, Z.-Y.; Xu, X.-B.; Wang, T.; Zhang, X.-Y.; Yu, X.-L.; Wang, S.-F.; Lin, W.-L.; Chen, Y.-Z.; Jiang, Y.-A.; An, X.-Q. Ambient sulfur dioxide, nitrogen dioxide, and ammonia at ten background and rural sites in China during 2007–2008. Atmos. Environ. 2010, 44 (21), 2625– 2631, DOI: 10.1016/j.atmosenv.2010.04.008
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  15
  Ambient sulfur dioxide, nitrogen dioxide, and ammonia at ten background and rural sites in China during 2007-2008
  Meng, Zhao-Yang; Xu, Xiao-Bin; Wang, Tao; Zhang, Xing-Ying; Yu, Xiao-Lan; Wang, Shu-Feng; Lin, Wei-Li; Chen, Yi-Zhen; Jiang, Yi-An; An, Xing-Qin
  Atmospheric Environment (2010), 44 (21-22), 2625-2631CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Ltd.)
  We present two years (Jan. 2007-Dec. 2008) of atm. SO2, NO2 and NH3 measurements from ten background or rural sites in nine provinces in China. The measurements were made on a monthly basis using passive samplers under careful quality control. The results show large geog. and seasonal variations in the concns. of these gases. The mean SO2 concn. varied from 0.7 ± 0.4 ppb at Waliguan on Qinghai Plateau to 67.3 ± 31.1 ppb at Kaili in Guizhou province. The mean NO2 concn. ranged from 0.6 ± 0.4 ppb at Waliguan to 23.9 ± 6.9 ppb at Houma in southern Shanxi. The mean NH3 concn. ranged from 2.8 ± 3.0 ppb at Shangdianzi in northeastern Beijing to 13.7 ± 8.4 ppb at Houma. At most sites, SO2 and NO2 peaked in winter and reached min. in summer, while NH3 showed max. values in summer and lower values in cold seasons. On the whole, the geog. distributions of the obsd. gas concns. are consistent with those of emissions. The ground measurements of SO2 and NO2 are contrasted to the SCIAMACHY SO2 and OMI NO2 tropospheric columns, resp. Although the satellite data can capture the main features of emissions and concns. of SO2, they do not reflect the variations of SO2 in the surface layer. The situation is better for the case of NO2. The OMI NO2 columns capture the geog. differences in the ground NO2 and correlate fairly well with the ground levels of NO2 at six of the ten sites.
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16. 16
  Xu, W.; Luo, X. S.; Pan, Y. P.; Zhang, L.; Tang, A. H.; Shen, J. L.; Zhang, Y.; Li, K. H.; Wu, Q. H.; Yang, D. W.; Zhang, Y. Y.; Xue, J.; Li, W. Q.; Li, Q. Q.; Tang, L.; Lu, S. H.; Liang, T.; Tong, Y. A.; Liu, P.; Zhang, Q.; Xiong, Z. Q.; Shi, X. J.; Wu, L. H.; Shi, W. Q.; Tian, K.; Zhong, X. H.; Shi, K.; Tang, Q. Y.; Zhang, L. J.; Huang, J. L.; He, C. E.; Kuang, F. H.; Zhu, B.; Liu, H.; Jin, X.; Xin, Y. J.; Shi, X. K.; Du, E. Z.; Dore, A. J.; Tang, S.; Collett, J. L.; Goulding, K.; Sun, Y. X.; Ren, J.; Zhang, F. S.; Liu, X. J. Quantifying atmospheric nitrogen deposition through a nationwide monitoring network across China. Atmos. Chem. Phys. 2015, 15 (21), 12345– 12360, DOI: 10.5194/acp-15-12345-2015
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  16
  Quantifying atmospheric nitrogen deposition through a nationwide monitoring network across China
  Xu, W.; Luo, X. S.; Pan, Y. P.; Zhang, L.; Tang, A. H.; Shen, J. L.; Zhang, Y.; Li, K. H.; Wu, Q. H.; Yang, D. W.; Zhang, Y. Y.; Xue, J.; Li, W. Q.; Li, Q. Q.; Tang, L.; Lu, S. H.; Liang, T.; Tong, Y. A.; Liu, P.; Zhang, Q.; Xiong, Z. Q.; Shi, X. J.; Wu, L. H.; Shi, W. Q.; Tian, K.; Zhong, X. H.; Shi, K.; Tang, Q. Y.; Zhang, L. J.; Huang, J. L.; He, C. E.; Kuang, F. H.; Zhu, B.; Liu, H.; Jin, X.; Xin, Y. J.; Shi, X. K.; Du, E. Z.; Dore, A. J.; Tang, S.; Collett, J. L., Jr.; Goulding, K.; Sun, Y. X.; Ren, J.; Zhang, F. S.; Liu, X. J.; Collett, J. L.
  Atmospheric Chemistry and Physics (2015), 15 (21), 12345-12360CODEN: ACPTCE; ISSN:1680-7324. (Copernicus Publications)
  A Nationwide Nitrogen Deposition Monitoring Network (NNDMN) contg. 43 monitoring sites was established in China to measure gaseous NH3, NO2, and HNO3 and particulate NH+4 and NO-3 in air and/or pptn. from 2010 to 2014. Wet/bulk deposition fluxes of Nr species were collected by pptn. gauge method and measured by continuous-flow analyzer; dry deposition fluxes were estd. using airborne concn. measurements and inferential models. Our observations reveal large spatial variations of atm. Nr concns. and dry and wet/bulk Nr deposition. On a national basis, the annual av. concns. (1.3-47.0 μgNm-3) and dry plus wet/bulk deposition fluxes (2.9-83.3 kg N ha-1 yr-1) of inorg. Nr species are ranked by land use as urban >rural>background sites and by regions as north China>southeast China>southwest China>northeast China>northwest China>Tibetan Plateau, reflecting the impact of anthropogenic Nr emission. Av. dry and wet/bulk N deposition fluxes were 20.6 ±11.2 (mean ± std. deviation) and 19.3±9.2 kg N ha-1 yr-1 across China, with reduced N deposition dominating both dry and wet/bulk deposition. Our results suggest atm. dry N deposition is equally important to wet/bulk N deposition at the national scale. Therefore, both deposition forms should be included when considering the impacts of N deposition on environment and ecosystem health.
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17. 17
  von Bobrutzki, K.; Braban, C. F.; Famulari, D.; Jones, S. K.; Blackall, T.; Smith, T. E. L.; Blom, M.; Coe, H.; Gallagher, M.; Ghalaieny, M.; McGillen, M. R.; Percival, C. J.; Whitehead, J. D.; Ellis, R.; Murphy, J.; Mohacsi, A.; Pogany, A.; Junninen, H.; Rantanen, S.; Sutton, M. A.; Nemitz, E. Field inter-comparison of eleven atmospheric ammonia measurement techniques. Atmos. Meas. Tech. 2010, 3 (1), 91– 112, DOI: 10.5194/amt-3-91-2010
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  17
  Field inter-comparison of eleven atmospheric ammonia measurement techniques
  von Bobrutzki, K.; Braban, C. F.; Famulari, D.; Jones, S. K.; Blackall, T.; Smith, T. E. L.; Blom, M.; Coe, H.; Gallagher, M.; Ghalaieny, M.; McGillen, M. R.; Percival, C. J.; Whitehead, J. D.; Ellis, R.; Murphy, J.; Mohacsi, A.; Pogany, A.; Junninen, H.; Rantanen, S.; Sutton, M. A.; Nemitz, E.
  Atmospheric Measurement Techniques (2010), 3 (1), 91-113CODEN: AMTTC2; ISSN:1867-1381. (Copernicus Publications)
  11 Instruments for the measurement of ambient concns. of atm. ammonia gas (NH3), based on eight different measurement methods were intercompared above an intensively managed agricultural field in late summer 2008 in Southern Scotland. To test the instruments over a wide range of concns., the field was fertilized with urea midway through the expt., leading to an increase in the av. concn. from 10 to 100 ppbv. The instruments deployed included three wet-chem. systems, one with offline anal. (annular rotating batch denuder, RBD) and two with online-anal. (Annular Denuder sampling with online Anal., AMANDA; AiRRmonia), two Quantum Cascade Laser Absorption Spectrometers (a large-cell dual system; DUAL-QCLAS, and a compact system; c-QCLAS), two photo-acoustic spectrometers (WaSul-Flux; Nitrolux-100), a Cavity Ring Down Spectrosmeter (CRDS), a Chem. Ionisation Mass Spectrometer (CIMS), an ion mobility spectrometer (IMS) and an Open-Path Fourier Transform Infra-Red (OP-FTIR) Spectrometer. The instruments were compared with each other and with the av. concn. of all instruments. An overall good agreement of hourly av. concns. between the instruments (R2>0.84), was obsd. for NH3 concns. at the field of up to 120 ppbv with the slopes against the av. ranging from 0.67 (DUAL-QCLAS) to 1.13 (AiR-Rmonia) with intercepts of -0.74 ppbv (RBD) to +2.69 ppbv (CIMS). More variability was found for performance for lower concns. (<10 ppbv). Here the main factors affecting measurements precision are (a) the inlet design, (b) the state of inlet filters (where applicable), and (c) the quality of gas-phase stds. (where applicable). By ref. to the fast (1 Hz) instruments deployed during the study, it was possible to characterize the response times of the slower instruments.
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18. 18
  Ferm, M. Method for determination of atmospheric ammonia. Atmos. Environ. 1979, 13 (10), 1385– 1393, DOI: 10.1016/0004-6981(79)90107-0
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  18
  Method for determination of atmospheric ammonia
  Ferm, Martin
  Atmospheric Environment (1967-1989) (1979), 13 (10), 1385-93CODEN: ATENBP; ISSN:0004-6981.
  Detn. of NH3 in air with min. interference by particulate NH4+ was effected by drawing air through a vertical glass tube whose internal surface was coated with oxalic acid. Anal. was effected by dissolving the oxalic acid coating in NaOH and detg. the NH3 concn. with an ion selective electrode. The detection limit is 0.5 nmol NH3/m3 air sampled during 24 h with std. deviation 15%.
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19. 19
  Felix, J. D.; Elliott, E. M.; Gish, T.; Maghirang, R.; Cambal, L.; Clougherty, J. Examining the transport of ammonia emissions across landscapes using nitrogen isotope ratios. Atmos. Environ. 2014, 95, 563– 570, DOI: 10.1016/j.atmosenv.2014.06.061
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20. 20
  Perrino, C.; Catrambone, M. Development of a variable-path-length diffusive sampler for ammonia and evaluation of ammonia pollution in the urban area of Rome, Italy. Atmos. Environ. 2004, 38 (38), 6667– 6672, DOI: 10.1016/j.atmosenv.2004.08.032
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  20
  Development of a variable-path-length diffusive sampler for ammonia and evaluation of ammonia pollution in the urban area of Rome, Italy
  Perrino, C.; Catrambone, M.
  Atmospheric Environment (2004), 38 (38), 6667-6672CODEN: AENVEQ; ISSN:1352-2310. (Elsevier B.V.)
  A variable-path-length diffusive sampler for the detn. of atm. ammonia was developed and tested. Polyethylene was found to be the best material for the construction of the sampler, while a glass body sampler of similar design yielded unreliable results; phosphorous acid was the best collecting medium. The low level of the field blanks and the high operative capacity make this device able to operate in a very wide loading range (0.3-100 μg); the possibility to vary the length of the diffusive pathway allows a further increase of the detectable concn. range (0.1-125 μg m-3 during a 1-mo exposure). Reproducibility is better than 5% and the comparison with ref. denuders demonstrated a good accuracy of the method (deviation lower than 5%). The deployment of these samplers in some field campaigns carried out in Rome allowed us to confirm the close link between ammonia concn. and traffic emission and to get an insight into the spatial variability of this pollutant.
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21. 21
  Zhao, Y.; Zhang, L.; Chen, Y.; Liu, X.; Xu, W.; Pan, Y.; Duan, L. Atmospheric nitrogen deposition to China: A model analysis on nitrogen budget and critical load exceedance. Atmos. Environ. 2017, 153, 32– 40, DOI: 10.1016/j.atmosenv.2017.01.018
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  21
  Atmospheric nitrogen deposition to China: A model analysis on nitrogen budget and critical load exceedance
  Zhao, Yuanhong; Zhang, Lin; Chen, Youfan; Liu, Xuejun; Xu, Wen; Pan, Yuepeng; Duan, Lei
  Atmospheric Environment (2017), 153 (), 32-40CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Ltd.)
  We present a national-scale model anal. on the sources and processes of inorg. nitrogen deposition over China using the GEOS-Chem model at 1/2° × 1/3° horizontal resoln. Model results for 2008-2012 are evaluated with an ensemble of surface measurements of wet deposition flux and gaseous ammonia (NH3) concn., and satellite measurements of tropospheric NO2 columns. Annual total inorg. nitrogen deposition fluxes are simulated to be generally less than 10 kg N ha-1 a-1 in western China (less than 2 kg N ha-1 a-1 over Tibet), 15-50 kg N ha-1 a-1 in eastern China, and 16.4 kg N ha-1 a-1 averaged over China. Annual total deposition to China is 16.4 Tg N, with 10.2 Tg N (62%) from reduced nitrogen (NHx) and 6.2 Tg N from oxidized nitrogen (NOy). Domestic anthropogenic sources contribute 86% of the total deposition; foreign anthropogenic sources 7% and natural sources 7%. Annually 23% of domestically emitted NH3 and 36% for NOx are exported outside the terrestrial land of China. We find that atm. nitrogen deposition is about half of the nitrogen input from fertilizer application (29.6 Tg N a-1), and is much higher than that from natural biol. fixation (7.3 Tg N a-1) over China. A comparison of nitrogen deposition with crit. load ests. for eutrophication indicates that about 15% of the land over China experiences crit. load exceedances, demonstrating the necessity of nitrogen emission controls to avoid potential neg. ecol. effects.
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22. 22
  Zhang, L.; Shao, J.; Lu, X.; Zhao, Y.; Hu, Y.; Henze, D. K.; Liao, H.; Gong, S.; Zhang, Q. Sources and Processes Affecting Fine Particulate Matter Pollution over North China: An Adjoint Analysis of the Beijing APEC Period. Environ. Sci. Technol. 2016, 50 (16), 8731– 8740, DOI: 10.1021/acs.est.6b03010
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  22
  Sources and Processes Affecting Fine Particulate Matter Pollution over North China: An Adjoint Analysis of the Beijing APEC Period
  Zhang, Lin; Shao, Jingyuan; Lu, Xiao; Zhao, Yuanhong; Hu, Yongyun; Henze, Daven K.; Liao, Hong; Gong, Sunling; Zhang, Qiang
  Environmental Science & Technology (2016), 50 (16), 8731-8740CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
  The stringent emission controls during APEC 2014 (Asia-Pacific Economic Cooperation Summit; Nov. 5-11, 2014) offered a unique opportunity to quantify factors affecting fine particulate matter (PM2.5) pollution over northern China. This work applied a 4-dimensional variational data assimilation system using the adjoint model, GEOS-Chem, to address this issue. Hourly surface PM2.5 and SO2 measurements for Oct. 15 to Nov. 14, 2014, were assimilated into the model to optimize daily aerosol primary and precursor emissions over northern China. Measured PM2.5 concns. in Beijing (50.3 μg/m3 av.) during APEC were 43% lower than the mean concn. (88.2 μg/m3) for the entire period, including APEC. Model results attributed about half of this redn. to meteorol., due to active cold surge occurrences during APEC. Surface measurement assimilations largely reduced model biases and estd. 6-30% lower aerosol emissions in the Beijing-Tianjin-Hebei region during APEC vs. late Oct. High PM2.5 events in Beijing during this period can occasionally be contributed by natural mineral dust; however, more events showed large sensitivity to inorg. aerosol sources, particularly NH3 and NOx emissions, reflecting strong aerosol NO3- formation in fall.
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23. 23
  Wesely, M. L. Parameterization of surface resistances to gaseous dry deposition in regional-scale numerical models. Atmos. Environ. 1989, 23 (6), 1293– 1304, DOI: 10.1016/0004-6981(89)90153-4
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  23
  Parameterization of surface resistances to gaseous dry deposition in regional-scale numerical models
  Wesely, M. L.
  Atmospheric Environment (1967-1989) (1989), 23 (6), 1293-304CODEN: ATENBP; ISSN:0004-6981.
  Methods for estg. the dry deposition velocities of atm. gases in the US and surrounding areas are improved and incorporated into a revised computer code module for use in numerical models of atm. transport and deposition of pollutants over regional scales. The key improvement is the computation of bulk surface resistances along 3 distinct pathways of mass transfer to sites of deposition at the upper portions of vegetative canopies of structures, the lower portions, and the ground (or water surface). This approach replaces the previous technique of providing simple look-up tables of bulk surface resistances. With the surface resistances divided explicitly into distinct pathways, the bulk surface resistances for a large no. of gases in addn. to those usually addressed in acid deposition models (SO2, O3, NOx, and HNO3) can be computed, if ests. of the effective Henry's Law consts. and appropriate measures of the chem. reactivity of the various substances are known. This has been accomplished successfully for H2O2, HCHO, CH3CHO (to represent other aldehydes), CH3O2H (to represent org. peroxides), CH3C(O)O2H, HCOOH (to represent org. acids), NH3, CH3C(O)O2NO2, and HNO2. Other factors considered include surface temp., stomatal response to environmental parameters, the wetting of surfaces by dew and rain, and the covering of surfaces by snow. Surface emission of gases and variations of uptake characteristics by individual plant species within the land use types are not considered explicitly.
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24. 24
  Sutton, M. A.; Burkhardt, J. K.; Guerin, D.; Nemitz, E.; Fowler, D. Development of resistance models to describe measurements of bi-directional ammonia surface–atmosphere exchange. Atmos. Environ. 1998, 32 (3), 473– 480, DOI: 10.1016/S1352-2310(97)00164-7
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  24
  Development of resistance models to describe measurements of bi-directional ammonia surface-atmosphere exchange
  Sutton, M. A.; Burkhardt, J. K.; Guerin, D.; Nemitz, E.; Fowler, D.
  Atmospheric Environment (1998), 32 (3), 473-480CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Science Ltd.)
  Ammonia fluxes over vegetated land are bi-directional, with differences between emission and deposition occurring in relation to environmental conditions (temp. and wetness), plants community (e.g. arable land, unfertilized ecosystems), as well as other factors such as plant phenol. Measurements of net NH3 fluxes over arable cropland are reported in the range -50 to 40 ng/m2-s. These are used as examples to highlight the factors affecting the exchange process. Net fluxes are expected to depend on the competition between deposition to leaf surfaces and bi-directional exchange with a stomatal compensation point for leaf tissues. Two resistance models are described. These est. a canopy compensation point, as the net potential for NH3 emission from the canopy. In the simpler of the 2 models, leaf surface uptake is parameterized using a resistance. This model is able to reproduce bi-directional fluxes, though there is also evidence that both cuticular NH3 absorption and desorption occur, dependent on previous fluxes. A more complex dynamic approach is therefore developed, treating cuticular uptake as a capacitance. The dynamic model is able to reproduce the pattern of desorption, but further development of both models is required to provide descriptions valid over longer periods and for a range of ecosystem types.
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25. 25
  Li, Y.; Thompson, T. M.; Van Damme, M.; Chen, X.; Benedict, K. B.; Shao, Y.; Day, D.; Boris, A.; Sullivan, A. P.; Ham, J.; Whitburn, S.; Clarisse, L.; Coheur, P. F.; Collett, J. L., Jr. Temporal and spatial variability of ammonia in urban and agricultural regions of northern Colorado, United States. Atmos. Chem. Phys. 2017, 17 (10), 6197– 6213, DOI: 10.5194/acp-17-6197-2017
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  25
  Temporal and spatial variability of ammonia in urban and agricultural regions of northern Colorado, United States
  Li, Yi; Thompson, Tammy M.; Van Damme, Martin; Chen, Xi; Benedict, Katherine B.; Shao, Yixing; Day, Derek; Boris, Alexandra; Sullivan, Amy P.; Ham, Jay; Whitburn, Simon; Clarisse, Lieven; Coheur, Pierre-Francois; Collett, Jeffrey L., Jr.
  Atmospheric Chemistry and Physics (2017), 17 (10), 6197-6213CODEN: ACPTCE; ISSN:1680-7324. (Copernicus Publications)
  Concd. agricultural activities and animal feeding operations in the northeastern plains of Colorado represent an important source of atm. ammonia (NH3). The NH3 from these sources contributes to regional fine particle formation and to nitrogen deposition to sensitive ecosystems in Rocky Mountain National Park (RMNP), located ∼80 km to the west. In order to better understand temporal and spatial differences in NH3 concns. in this source region, weekly concns. of NH3 were measured at 14 locations during the summers of 2010 to 2015 using Radiello passive NH3 samplers. Weekly (biweekly in 2015) av. NH3 concns. ranged from 2.66 to 42.7 μg m-3, with the highest concns. near large concd. animal feeding operations (CAFOs). The annual summertime mean NH3 concns. were stable in this region from 2010 to 2015, providing a baseline against which concn. changes assocd. with future changes in regional NH3 emissions can be assessed. Vertical profiles of NH3 were also measured on the 300m Boulder Atm. Observatory (BAO) tower throughout 2012. The highest NH3 concn. along the vertical profile was always obsd. at the 10m height (annual av. concn. of 4.63 μg m-3), decreasing toward the surface (4.35 μg m-3) and toward higher altitudes (1.93 μg m-3). The NH3 spatial distributions measured using the passive samplers are compared with NH3 columns retrieved by the IR Atm. Sounding Interferometer (IASI) satellite and concns. simulated by the Comprehensive Air Quality Model with Extensions (CAMx). The satellite comparison adds to a growing body of evidence that IASI column retrievals of NH3 provide very useful insight into regional variability in atm. NH3, in this case even in a region with strong local sources and sharp spatial gradients. The CAMx comparison indicates that the model does a reasonable job simulating NH3 concns. near sources but tends to underpredict concns. at locations farther downwind. Excess NH3 deposition by the model is hypothesized as a possible explanation for this trend.
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  Huang, X.; Song, Y.; Li, M.; Li, J.; Huo, Q.; Cai, X.; Zhu, T.; Hu, M.; Zhang, H. A high-resolution ammonia emission inventory in China. Global. Biogeochem. Cy 2012, 26 (1), GB1030 DOI: 10.1029/2011GB004161
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  Pan, Y.; Tian, S.; Liu, D.; Fang, Y.; Zhu, X.; Zhang, Q.; Zheng, B.; Michalski, G.; Wang, Y. Fossil fuel combustion-related emissions dominate atmospheric ammonia sources during severe haze episodes: Evidence from ¹⁵N-stable isotope in size-resolved aerosol ammonium. Environ. Sci. Technol. 2016, 50 (15), 8049– 8056, DOI: 10.1021/acs.est.6b00634
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  Fossil Fuel Combustion-Related Emissions Dominate Atmospheric Ammonia Sources during Severe Haze Episodes: Evidence from 15N-Stable Isotope in Size-Resolved Aerosol Ammonium
  Pan, Yuepeng; Tian, Shili; Liu, Dongwei; Fang, Yunting; Zhu, Xiaying; Zhang, Qiang; Zheng, Bo; Michalski, Greg; Wang, Yuesi
  Environmental Science & Technology (2016), 50 (15), 8049-8056CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
  The redn. of NH3 emissions is urgently due to its role in aerosol nucleation and growth causing haze formation during its conversion to NH4+; however, the relative contributions of individual NH3 sources are unclear and debate remains over whether agricultural emissions dominate atm. NH3 in urban areas. Based on chem. and isotopic measurements of size-resolved aerosols in urban Beijing, China, the natural abundance of 15N (expressed using δ15N values) of NH4+ in fine particles varies with the development of haze episodes, from -37.1‰ to -21.7‰ during clean/dusty days (relative humidity, ∼40%), to -13.1‰ to +5.8‰ during hazy days (relative humidity, 70-90%). After accounting for isotope exchange between NH3 gas and aerosol NH4+, the δ15N value of initial NH3 during hazy days was -14.5‰ to -1.6‰, which indicates fossil fuel-based emissions. These emissions contributed 90% of total NH3 during hazy days in Beijing. Results demonstrated the anal. of δ15N values of aerosol NH4+ is a promising new tool for partitioning of atm. NH3 sources, providing policy-makers with insights into NH3 emissions and secondary aerosols for urban environment regulation.
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28. 28
  McCalley, C. K.; Sparks, J. P. Controls over nitric oxide and ammonia emissions from Mojave Desert soils. Oecologia 2008, 156 (4), 871– 881, DOI: 10.1007/s00442-008-1031-0
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  Controls over nitric oxide and ammonia emissions from Mojave Desert soils
  McCalley Carmody K; Sparks Jed P
  Oecologia (2008), 156 (4), 871-81 ISSN:0029-8549.
  Emissions of reactive N compounds produced during terrestrial N cycling can be an important N loss pathway from ecosystems. Most measurements of this process focus on NO and N(2)O efflux; however, in alkaline soils such as those in the Mojave Desert, NH(3) production can be an important component of N gas loss. We investigated patterns of NO and NH(3) emissions in the Mojave Desert and identified seasonal changes in temperature, precipitation and spatial heterogeneity in soil nutrients as primary controllers of soil efflux. Across all seasons, NH(3) dominated reactive N gas emissions with fluxes ranging from 0.9 to 10 ng N m(-2) s(-1) as compared to NO fluxes of 0.08-1.9 ng N m(-2) s(-1). Fluxes were higher in April and July than in October; however, a fall precipitation event yielded large increases in both NO and NH(3) efflux. To explore the mechanisms driving field observations, we combined NO and NH(3) soil flux measurements with laboratory manipulations of temperature, water and nutrient conditions. These experiments showed a large transient NH(3) pulse (~70-100 ng N m(-2) s(-1)) following water addition, presumably driven by an increase in soil NH(4) (+) concentrations. This was followed by an increase in NO production, with maximum NO flux rates of 34 ng N m(-2) s(-1). Our study suggests that immediately following water addition NH(3) volatilization proceeds at high rates due to the absence of microbial competition for NH(4) (+); during this period N gas loss is insensitive to changes in temperature and soil nutrients. Subsequently, NO emission increases and rates of both NO and NH(3) emission are sensitive to temperature and nutrient constraints on microbial activity. Addition of labile C reduces gaseous N losses, presumably by increasing microbial immobilization, whereas addition of NO(3) (-) stimulates NO and NH(3) efflux.
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29. 29
  Sun, Y.; Zhuang, G.; Huang, K.; Li, J.; Wang, Q.; Wang, Y.; Lin, Y.; Fu, J. S.; Zhang, W.; Tang, A.; Zhao, X. Asian dust over northern China and its impact on the downstream aerosol chemistry in 2004. J. Geophys. Res. 2010, 115 (D7), D00K09 DOI: 10.1029/2009JD012757
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30. 30
  Sun, K.; Tao, L.; Miller, D. J.; Pan, D.; Golston, L. M.; Zondlo, M. A.; Griffin, R. J.; Wallace, H. W.; Leong, Y. J.; Yang, M. M.; Zhang, Y.; Mauzerall, D. L.; Zhu, T. Vehicle Emissions as an Important Urban Ammonia Source in the United States and China. Environ. Sci. Technol. 2017, 51 (4), 2472– 2481, DOI: 10.1021/acs.est.6b02805
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  Vehicle Emissions as an Important Urban Ammonia Source in the United States and China
  Sun, Kang; Tao, Lei; Miller, David J.; Pan, Da; Golston, Levi M.; Zondlo, Mark A.; Griffin, Robert J.; Wallace, H. W.; Leong, Yu Jun; Yang, M. Melissa; Zhang, Yan; Mauzerall, Denise L.; Zhu, Tong
  Environmental Science & Technology (2017), 51 (4), 2472-2481CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
  Ammoniated aerosols are important for urban air quality, but emissions of the key precursor NH3 are not well quantified. Mobile lab. observations are used to characterize fleet-integrated NH3 emissions in six cities in the US and China. Vehicle NH3:CO2 emission ratios in the US are similar between cities (0.33-0.40 ppbv/ppmv, 15% uncertainty) despite differences in fleet compn., climate, and fuel compn. While Beijing, China has a comparable emission ratio (0.36 ppbv/ppmv) to the US cities, less developed Chinese cities show higher emission ratios (0.44 and 0.55 ppbv/ppmv). If the vehicle CO2 inventories are accurate, NH3 emissions from US vehicles (0.26±0.07 Tg/yr) are more than twice those of the National Emission Inventory (0.12 Tg/yr), while Chinese NH3 vehicle emissions (0.09±0.02 Tg/yr) are similar to a bottom-up inventory. Vehicle NH3 emissions outweigh agricultural sources for near half of the US population and require reconsideration in urban air quality models due to their significant emissions, co-location with other aerosol precursors, and the uncertainties regarding NH3 losses from upwind agricultural sources. Ammonia emissions in developing cities are esp. important because of their high emission ratios and rapid motorizations.
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31. 31
  Ianniello, A.; Spataro, F.; Esposito, G.; Allegrini, I.; Rantica, E.; Ancora, M.; Hu, M.; Zhu, T. Occurrence of gas phase ammonia in the area of Beijing (China). Atmos. Chem. Phys. 2010, 10, 9487– 9503, DOI: 10.5194/acp-10-9487-2010
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  Occurrence of gas phase ammonia in the area of Beijing (China)
  Ianniello, A.; Spataro, F.; Esposito, G.; Allegrini, I.; Rantica, E.; Ancora, M. P.; Hu, M.; Zhu, T.
  Atmospheric Chemistry and Physics (2010), 10 (19), 9487-9503CODEN: ACPTCE; ISSN:1680-7316. (Copernicus Publications)
  The atm. concns. of gaseous ammonia have been measured during two field campaigns in the winter and in the summer of 2007 at Beijing (China). These measurements were carried out by means of diffusion annular denuders coated with phosphorous acid. The results were discussed from the standpoint of temporal and diurnal variations and meteorol. effects. The daily av. NH3 concns. were in the range of 0.20-44.38 μg/m3 and showed regular temporal variations with higher concns. during summer and with lower during winter. The temporal trends seemed to be largely affected by air temp. because of agricultural sources. No diurnal variability was obsd. for gaseous NH3 levels in both winter and summer seasons. The highest ammonia value of 105.67 μg/m3 was measured in the early morning during the summer period when stable atm. conditions occurred. The diurnal winter and summer trends of ammonia showed a weak dependence on the air temp. and they were affected nearly by wind direction suggesting regional and local source influences. Ammonia was also correlated with the atm. mixing in the boundary layer, and, with NOx, CO and PM2.5 air concns. supporting the hypothesis that the traffic may be also an important source of ammonia in Beijing.
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32. 32
  Teng, X.; Hu, Q.; Zhang, L.; Qi, J.; Shi, J.; Xie, H.; Gao, H.; Yao, X. Identification of Major Sources of Atmospheric NH₃ in an Urban Environment in Northern China During Wintertime. Environ. Sci. Technol. 2017, 51 (12), 6839– 6848, DOI: 10.1021/acs.est.7b00328
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  Identification of Major Sources of Atmospheric NH3 in an Urban Environment in Northern China During Wintertime
  Teng, Xiaolin; Hu, Qingjing; Zhang, Leiming; Qi, Jiajia; Shi, Jinhui; Xie, Huan; Gao, Huiwang; Yao, Xiaohong
  Environmental Science & Technology (2017), 51 (12), 6839-6848CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
  To assess the relative contributions of traffic emissions and other potential sources to high atm. NH3 concns. in urban areas in winter, atm. NH3 and related pollutants were measured at an urban site ∼300 m from a major traffic road in northern China in Nov. and Dec. 2015. Hourly av. NH3 concn. were 0.3-10.8 ppb with an av. of 2.4 ppb during the campaign. Contrary to the common literature perspective, traffic emissions demonstrated to be a negligible contributor to atm. NH3. Atm. NH3 correlated well with ambient water vapor during many time periods lasting from tens of hours to several days, implying NH3 released from water evapn. is an important source. Emissions from local green space inside urban areas were identified to significantly contribute to obsd. atm. NH3 concns. for ∼60% of the sampling times. Evapn. of pre-deposited NHx by wet pptn. combined with local green space emissions likely caused spikes of atm. NH3 concn., mostly occurring 1-4 h after morning rush hours or after/during slight shower events. There were still ∼30% of samples with appreciable NH3 concns. for which major contributors have not yet been identified.
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33. 33
  Zhang, X.; Wu, Y.; Liu, X.; Reis, S.; Jin, J.; Dragosits, U.; Van Damme, M.; Clarisse, L.; Whitburn, S.; Coheur, P.-F.; Gu, B. Ammonia Emissions May Be Substantially Underestimated in China. Environ. Sci. Technol. 2017, 51 (21), 12089– 12096, DOI: 10.1021/acs.est.7b02171
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  Ammonia Emissions Maybe Substantially Underestimated in China
  Zhang, Xiuming; Wu, Yiyun; Liu, Xuejun; Reis, Stefan; Jin, Jiaxin; Dragosits, Ulrike; Van Damme, Martin; Clarisse, Lieven; Whitburn, Simon; Coheur, Pierre-Francois; Gu, Baojing
  Environmental Science & Technology (2017), 51 (21), 12089-12096CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
  China is a global hotspot of atm. NH3 emissions and, as a consequence, very high N deposition levels are documented. However, previous ests. of total NH3 emissions in China were much lower than inference from obsd. deposition values would suggest, highlighting the need for further study. We reevaluated NH3 emissions based on a mass balance approach, validated by N deposition monitoring and satellite observations, for China for 2000 to 2015. Total NH3 emissions in China increased from 12.1±0.8 Tg N/yr in 2000 to 15.6±0.9 Tg N/yr in 2015 at an annual rate of 1.9%, which is ∼40% higher than existing studies suggested. This difference is mainly due to more emission sources now having been included and NH3 emission rates from mineral fertilizer application and livestock having been underestimated previously. Our estd. NH3 emission levels are consistent with the measured deposition of NHx (including NH4+ and NH3) on land (11-14 Tg N/yr) and the substantial increases in NH3 concns. obsd. by satellite measurements over China. These findings substantially improve our understanding on NH3 emissions, implying that future air pollution control strategies have to consider the potentials of reducing NH3 emission in China.
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34. 34
  Fu, X.; Wang, S. X.; Ran, L. M.; Pleim, J. E.; Cooter, E.; Bash, J. O.; Benson, V.; Hao, J. M. Estimating NH₃ emissions from agricultural fertilizer application in China using the bi-directional CMAQ model coupled to an agro-ecosystem model. Atmos. Chem. Phys. 2015, 15 (12), 6637– 6649, DOI: 10.5194/acp-15-6637-2015
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  Estimating NH3 emissions from agricultural fertilizer application in China using the bi-directional CMAQ model coupled to an agro-ecosystem model
  Fu, X.; Wang, S. X.; Ran, L. M.; Pleim, J. E.; Cooter, E.; Bash, J. O.; Benson, V.; Hao, J. M.
  Atmospheric Chemistry and Physics (2015), 15 (12), 6637-6649CODEN: ACPTCE; ISSN:1680-7324. (Copernicus Publications)
  Atm. ammonia (NH3) plays an important role in atm. aerosol chem. China is one of the largest NH3 emitting countries with the majority of NH3 emissions coming from agricultural practices, such as fertilizer application and livestock prodn. The current NH3 emission ests. in China are mainly based on pre-defined emission factors that lack temporal or spatial details, which are needed to accurately predict NH3 emissions. This study provides the first online est. of NH3 emissions from agricultural fertilizer application in China, using an agricultural fertilizer modeling system which couples a regional air quality model (the Community Multi-scale Air Quality model, or CMAQ) and an agro-ecosystem model (the Environmental Policy Integrated Climate model, or EPIC). This method improves the spatial and temporal resoln. of NH3 emissions from this sector. We combined the cropland area data of 14 crops from 2710 counties with the Moderate Resoln. Imaging Spectroradiometer (MODIS) land use data to det. the crop distribution. The fertilizer application rates and methods for different crops were collected at provincial or agricultural region levels. The EPIC outputs of daily fertilizer application and soil characteristics were input into the CMAQ model and the hourly NH3 emissions were calcd. online with CMAQ running. The estd. agricultural fertilizer NH3 emissions in this study were approx. 3 Tg in 2011. The regions with the highest modeled emission rates are located in the North China Plain. Seasonally, peak ammonia emissions occur from Apr. to July. Compared with previous researches, this study considers an increased no. of influencing factors, such as meteorol. fields, soil and fertilizer application, and provides improved NH3 emissions with higher spatial and temporal resoln.
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35. 35
  Denmead, O. T.; Freney, J. R.; Dunin, F. X. Gas exchange between plant canopies and the atmosphere: Case-studies for ammonia. Atmos. Environ. 2008, 42 (14), 3394– 3406, DOI: 10.1016/j.atmosenv.2007.01.038
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  Gas exchange between plant canopies and the atmosphere: Case-studies for ammonia
  Denmead, O. T.; Freney, J. R.; Dunin, F. X.
  Atmospheric Environment (2008), 42 (14), 3394-3406CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Ltd.)
  We present the elements of an inverse Lagrangian model of gas transport in plant canopies. The model allows the effect of sites of gas exchange in the canopy and their source and sink strengths from measured profiles of mean gas concn. and statistics of the canopy turbulence. The practical application of the model is demonstrated through a case study of the fate of ammonia volatilized from fertilizer applied to the floor of a sugarcane crop. Some of the lost ammonia was absorbed by the foliage of the crop; the rest was lost to the atm. above. While there was excellent agreement between model predictions of the net flux from the canopy and independent micrometeorol. measurements of ammonia flux in the air-layer above it, verification of flux predictions within the canopy was much more difficult. Appeal was made to a process-based model of canopy gas exchange that describes gas transport to and from foliage surfaces in terms of diffusion across aerodynamic, boundary-layer and stomatal resistances in response to a difference in ammonia concn. between the air and leaf sub-stomatal cavities. There was acceptable agreement between the 2 models in their predictions of foliage ammonia uptake. We apply the process model to a study of the recapture of volatilized ammonia by sugarcane crops with different leaf area indexes (LAI). The study indicated recoveries increasing almost linearly with LAI and suggested probable recoveries in excess of 20% for canopies with LAIs of ≥2. These and other published studies of ammonia exchange between canopy and atm. that used both the inverse Lagrangian and process models suggest that their coupling provides a powerful tool for studying canopy gas exchange.
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36. 36
  Li, M.; Zhang, Q.; Kurokawa, J. I.; Woo, J. H.; He, K.; Lu, Z.; Ohara, T.; Song, Y.; Streets, D. G.; Carmichael, G. R.; Cheng, Y.; Hong, C.; Huo, H.; Jiang, X.; Kang, S.; Liu, F.; Su, H.; Zheng, B. MIX: a mosaic Asian anthropogenic emission inventory under the international collaboration framework of the MICS-Asia and HTAP. Atmos. Chem. Phys. 2017, 17 (2), 935– 963, DOI: 10.5194/acp-17-935-2017
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  36
  MIX: a mosaic Asian anthropogenic emission inventory under the international collaboration framework of the MICS-Asia and HTAP
  Li, Meng; Zhang, Qiang; Kurokawa, Jun-ichi; Woo, Jung-Hun; He, Kebin; Lu, Zifeng; Ohara, Toshimasa; Song, Yu; Streets, David G.; Carmichael, Gregory R.; Cheng, Yafang; Hong, Chaopeng; Huo, Hong; Jiang, Xujia; Kang, Sicong; Liu, Fei; Su, Hang; Zheng, Bo
  Atmospheric Chemistry and Physics (2017), 17 (2), 935-963CODEN: ACPTCE; ISSN:1680-7324. (Copernicus Publications)
  The MIX inventory is developed for the years 2008 and 2010 to support the Model Inter-Comparison Study for Asia (MICS-Asia) and the Task Force on Hemispheric Transport of Air Pollution (TF HTAP) by a mosaic of up-to-date regional emission inventories. Emissions are estd. for all major anthropogenic sources in 29 countries and regions in Asia. We conducted detailed comparisons of different regional emission inventories and incorporated the best available ones for each region into the mosaic inventory at a uniform spatial and temporal resoln. Emissions are aggregated to five anthropogenic sectors: power, industry, residential, transportation, and agriculture. We est. the total Asian emissions of 10 species in 2010 as follows: 51.3 Tg SO2, 52.1 Tg NOx, 336.6 Tg CO, 67.0 Tg NMVOC (non-methane volatile org. compds.), 28.8 Tg NH3, 31.7 Tg PM10, 22.7 Tg PM2.5, 3.5 Tg BC, 8.3 Tg OC, and 17.3 Pg CO2. Emissions from China and India dominate the emissions of Asia for most of the species. We also estd. Asian emissions in 2006 using the same methodol. of MIX. The relative change rates of Asian emissions for the period of 2006-2010 are estd. as follows: -8.1% for SO2, C19.2% for NOx, C3.9% for CO, C15.5% for NMVOC, C1.7% for NH3, -3.4% for PM10, -1.6% for PM2.5, C5.5% for BC, C1.8% for OC, and C19.9% for CO2. Model-ready speciated NMVOC emissions for SAPRC-99 and CB05 mechanisms were developed following a profile-assignment approach. Monthly gridded emissions at a spatial resoln. of 0.25° ×0.25° are developed and can be accessed.
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- Figure S1 illustrates the ammonia concentration and temperature correlation. Table S1 summarizes the site information. The text details the site selection and siting protocols with accompanying references (PDF)
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Identifying Ammonia Hotspots in China Using a National Observation Network

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Abstract

1. Introduction

2. Materials and Methods

2.1. Ammonia Sampling Networks

Figure 1

Figure 2

2.2. Chemical Analysis and Validation of Ammonia Samplers

Figure 3

2.3. Dry Deposition Velocity Simulation

3. Results and Discussion

3.1. Spatial Distribution of Ammonia in China

Figure 4

3.2. Differences among Land Use Types

3.3. Seasonal Variations in Ammonia Concentration in China

3.4. Ammonia Dry Deposition versus Emissions in China

Figure 5

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Acknowledgments

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Abstract

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

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