ACS Publications. Most Trusted. Most Cited. Most Read
Reactivity of Cyanobacteria Metabolites with Ozone: Multicompound Competition Kinetics
More

OR SEARCH CITATIONS

My Activity
Publications

Figure 1Loading Img
Download Hi-Res ImageDownload to MS-PowerPointCite This:Environ. Sci. Technol. 2024, 58, 26, 11802-11811
  • Open Access
Physico-Chemical Treatment and Resource Recovery

Reactivity of Cyanobacteria Metabolites with Ozone: Multicompound Competition Kinetics
Click to copy article linkArticle link copied!

  • Valentin Rougé
    Valentin Rougé
    Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
    More by Valentin Rougé
  • Urs von Gunten*
    Urs von Gunten
    Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
    School of Architecture, Civil and Environmental Engineering (ENAC), École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
    *Phone: +41 58 765 5270. Email: [email protected]
    More by Urs von Gunten
  • Elisabeth M.L. Janssen*
    Elisabeth M.L. Janssen
    Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
    *Phone: +41 58 765 5428. Email: [email protected]
    More by Elisabeth M.L. Janssen
    Orcidhttps://orcid.org/0000-0002-5475-6730
Open PDFSupporting Information (2)

Environmental Science & Technology

Cite this: Environ. Sci. Technol. 2024, 58, 26, 11802–11811
Click to copy citationCitation copied!
https://doi.org/10.1021/acs.est.4c02242
Published June 17, 2024

Copyright © 2024 The Authors. Published by American Chemical Society. This publication is licensed under

CC-BY 4.0 .

Abstract

Click to copy section linkSection link copied!
High Resolution Image
Download MS PowerPoint Slide

Cyanobacterial blooms occur at increasing frequency and intensity, notably in freshwater. This leads to the introduction of complex mixtures of their products, i.e., cyano-metabolites, to drinking water treatment plants. To assess the fate of cyano-metabolite mixtures during ozonation, a novel multicompound ozone (O3) competition kinetics method was developed. Sixteen competitors with known second-order rate constants for their reaction with O3 ranging between 1 and 108 M–1 s–1 were applied to cover a wide range of the O3 reactivity. The apparent second-order rate constants (kapp,O3) at pH 7 were simultaneously determined for 31 cyano-metabolites. kapp,O3 for olefin- and phenol-containing cyano-metabolites were consistent with their expected reactivity (0.4–1.7 × 106 M–1 s–1) while kapp,O3 for tryptophan- and thioether-containing cyano-metabolites were significantly higher than expected (3.4–7.3 × 107 M–1 s–1). Cyano-metabolites containing these moieties are predicted to be well abated during ozonation. For cyano-metabolites containing heterocycles, kapp,O3 varied from <102 to 5.0 × 103 M–1 s–1, giving first insights into the O3 reactivity of this class of compounds. Due to lower O3 reactivities, heterocycle- and aliphatic amine-containing cyano-metabolites may be only partially degraded by a direct O3 reaction near circumneutral pH. Hydroxyl radicals, which are formed during ozonation, may be more important for their abatement. This novel multicompound kinetic method allows a high-throughput screening of ozonation kinetics.

This publication is licensed under

CC-BY 4.0 .
  • cc licence
  • by licence
Copyright © 2024 The Authors. Published by American Chemical Society

Subjects

what are subjects

Keywords

what are keywords

Synopsis

Cyanobacteria metabolites are becoming an increasing concern for water supply. This study reports second-order rate constants for the reactions of 31 cyanobacteria metabolites with ozone determined simultaneously by a novel multicompound competition kinetic method.

Introduction

Click to copy section linkSection link copied!
Cyanobacteria are among the most ubiquitous organisms on the globe, comprising almost 2000 identified species living in freshwater, terrestrial, or marine environments. (1,2) Some cyanobacteria can form dense blooms that can cause significant deterioration of the water quality, notably by increasing turbidity, depleting oxygen by decomposition of biomass after blooms subside, and releasing toxins. (3) These blooms can occur in freshwater reservoirs that are resources for drinking water treatment plants and have been increasing in intensity and frequency worldwide in the last decades. (3,4) Toxins can be part of a complex mixture of metabolites produced by cyanobacteria (i.e., cyano-metabolites) and can enter water treatment plants. (5) If no appropriate treatment is in place, toxins may even end up in the finished drinking water, requiring temporary safety warnings to the population. (6,7) Recognizing the human health concerns, the World Health Organization proposes chronic, lifetime, and acute short-term drinking water guideline values for cyanobacterial toxins. (8) Therefore, water suppliers need to account for the presence of cyano-metabolites in raw water, anticipate the probable intensification of blooming events, and develop mitigation strategies at the source and/or appropriate treatment.
Ozone (O3) is a well-established and widely applied oxidant for disinfection, micropollutant degradation, and mitigation of disinfection byproducts, which has many advantages over other chemical oxidants. (9,10,15) It can be used to efficiently degrade known potent toxins such as microcystins. (11,12) However, a large number and diversity of other cyano-metabolites exist, with 2425 currently known compounds listed in a shared database for cyano-metabolites (CyanoMetDB, version 02, 2023), for which ozonation kinetics have not been studied to date. (13,14) Therefore, further investigations of the reactivity of O3 with cyano-metabolites are needed to better assess its efficiency as a barrier against potential bloom-related toxins. Many cyano-metabolites contain functional groups such as olefins or phenols that have known reactivity with O3, (9,15) which can help predicting their abatement during ozonation. However, a given moiety can have significant variability in reactivity depending on the pH and substituents. (9) One case in point is moieties such as phenols or amines, for which the O3 reactivity is pH-dependent because of their acid–base speciation, controlled by the pKa values. The pKa can shift depending on the neighboring functional groups and is often challenging to accurately predict. (16) In addition, little to no information is available for some functional groups such as heterocycles present in cyano-metabolites. Apparent second-order rate constants (kapp,O3) of the reactions between a target compound and O3 can be obtained in pure water by various direct and indirect methods, including competition kinetics, in the presence of an appropriate reference compound (competitor) and a hydroxyl radical (•OH) scavenger (e.g., tert-butanol). (9,17) However, the vast majority of cyano-metabolites are not commercially available and would have to be isolated from laboratory-grown cyanobacteria cultures, which is a major obstacle to studying the ozonation of individual cyano-metabolites.
To overcome this shortcoming, the aim of this study was to develop a novel multicompound competition kinetic approach to determine kapp,O3 in mixtures of cyano-metabolites. Sixteen competitor compounds, mostly micropollutants with various functional groups, were selected to cover a wide range of partially overlapping second-order rate constants (1 to 108 M–1 s–1). Regardless of the complexity of the matrix, the abatements of two given compounds (here between a cyano-metabolite and a competitor) are correlated because they are subjected to the same O3 exposure. (9) Ozonation experiments in the presence of the competitors and cyano-metabolite mixtures from two strains, Microcystis aeruginosa PCC7806 and Planktothrix rubescens K-0576, were performed at pH 7 and 8 in the presence of an •OH scavenger to determine kapp,O3 for 31 metabolites. This was possible by measuring simultaneously the relative abatement of cyano-metabolites and competitors by a previously developed LC-HRMS/MS method. (18,19) Several kapp,O3 per cyano-metabolites could be measured using several competitors, providing a more robust determination and preventing biased values.

Materials and Methods

Click to copy section linkSection link copied!

Standards and Reagents

The purity and suppliers of all chemicals and solvents are provided in Table S1 (Supporting Information SI1). Aerucyclamide A was previously isolated from Microcystis aeruginosa PCC7806, purified, and kept in DMSO. (20) Stock solutions of the competitors (10 mM) were prepared in acetone or ultrapure water (Arium Pro, Sartorius, 18.7 MΩ cm). O3 stock solutions were prepared by sparging O3/O2 gas mixtures produced by an O3 generator (BMT 803 BT, BMT Messtechnik, Berlin, Germany) in ultrapure water cooled in an ice bath. The concentration of the O3 stock solution (0.9–1.3 mM) was measured spectrophotometrically at 260 nm in a 1 cm quartz cuvette (ε260 = 3200 M–1 cm–1). (9)

Cyanobacterial Cultures and Extraction

Microcystis aeruginosa PCC7806 and Planktothrix rubescens K-0576 were obtained from the Pasteur Culture Collection (PCC) and the Norwegian Culture Collection of Algae (NORCCA), respectively. Cyanobacteria were cultivated, and their biomass extracted and purified as previously described. (21) Details are provided in Text S1. Cyano-metabolites were stored in MeOH/H2O (85/15 v/v) at −20 °C for up to a month without significant degradation (Figure S1a). An aliquot of the extract was mixed with an equal volume of pure water, evaporated to dryness under vacuum (Syncore Analyst R-12, BÜCHI Labortechnik AG, 55 °C, 60 rpm, 80 min at 150 mbar, 20 min at 90 mbar, and 80 min at 20 mbar) and redissolved in ultrapure water. No loss of identified cyano-metabolites was observed during the evaporation to dryness (Figure S1b). This approach guaranteed the absence of MeOH during ozonation, which is a promotor for •OH formation during ozonation. (9)

Cyano-metabolite Analysis and Identification

Cyano-metabolites were analyzed by HPLC (Dionex Ultimate 3000 RS pump, Thermo Fischer Scientific) with a Kinetex C18 column (2.6 μm, 2.1 × 100 mm, with SecurityGuard ULTRA precolumn, Phenomenex), coupled to a high-resolution tandem mass spectrometer (HRMS/MS, Exploris, ThermoFisher Scientific). (18,19) Details for the HPLC and HRMS/MS methods are provided in Text S2. Elution was carried out using a gradient with MeOH and ultrapure water both acidified with 0.1% formic acid. HRMS/MS used electrospray ionization (ESI) with both positive and negative ionization modes at 3.5 and 2.5 kV, respectively.
Data evaluation and peak area extraction was performed with Skyline 22.2 (MacCoss Lab). The ion chromatograms were screened with a suspect list obtained from CyanoMetDB (Version 02, 2023), (14) searching for the [M – 2H]2–, [M – H]−, [M + H]+, and [M + 2H]2+ ions. (13,14) Suspects were considered only if they fulfilled the following criteria: (i) exact mass < 4 ppm, (ii) isotope dot product > 0.9, and (iii) peak area ≥ 107. Then, suspects were further considered if their retention times matched their expected polarities and if good MS2 spectra were obtained. The final list of cyano-metabolites is provided in Table S4. Since no spectral libraries exist for most cyano-metabolites, in-silico fragmentation predictions were used to facilitate manual compound annotation of MS2 spectra (MetFrag Web and Sirius 4.4). (22,23) Suspected structures were manually evaluated, prioritizing fragmentation around the peptide bonds (details are given in Text S3). Only compounds identified with a confidence level of at least 3 were used (see Table S4). (24) The MS2 annotations and, when possible, head-to-tail MS2 comparisons with standards or bioreagents are available in a separate data spreadsheet (SI2).

Ozonation Experiments

Kinetic studies were performed at room temperature (22 ± 1 °C), using cyano-metabolite mixtures extracted from 0.8 to 1.2 gbiomass L–1 of Planktothrix or Microcystis, in the presence of competitors (at 0.4 μM each), phosphate buffer (4 mM, pH 7 or 8), and tert-butanol (80 mM). The dissolved organic carbon concentrations of the samples (excluding tert-butanol) were about 12–16 mgC L–1. The cyano-metabolite and competitor mixture was split in 1 mL aliquots to which 1 mL of prediluted O3 was added under vigorous stirring. O3 was prediluted in pure water from the O3 stock to prevent the spiking of samples with small volumes of highly concentrated O3, leading to strong concentration gradients and potentially undesired side reactions. The O3 doses were in the range of 0.1–90 μM after dilution (0.01–7.9 mgO3/gbiomass). Experiments were performed in triplicate on three separate days.

Determination of Second-Order Rate Constants

Competition kinetics were applied to determine the kapp,O3 of cyano-metabolites (kapp,O3,cyanomet): (9)
ln([Cyanomet][Cyanomet]0)=ln([Comp][Comp]0)×kapp,O3,cyanometkapp,O3,comp
(1)
Instead of concentrations, peak areas can directly be used (as long as the response is linear) because only the relative abatement needs to be known. kapp,O3,cyanomet can be derived from the linear regression slope of the ln of the cyano-metabolite relative residual peak area as a function of the ln of the competitor relative residual peak areas. kapp,O3,comp values are provided in Table 1 for pH 7. For competitors undergoing acid–base speciation, kapp,O3,comp is pH-dependent and was calculated at a given pH by eq 2:
kapp,O3,comp=∑1xkx×αx
(2)
with x being the number of species, kx the second-order rate constant for the reaction of a given species with O3 (Table S3), and αx the molar fraction of the given species at a given pH.
Table 1. List of 16 Selected Competitors with Their kapp,O3 Values at pH 7a
Competitor (abbreviation)kapp,O3 at pH 7 (M–1 s–1)Competitor (abbreviation)kapp,O3 at pH 7 (M–1 s–1)
Acetylsulfamethoxazole (ASMX)(2.5 ± 0.1) × 102 (ref  (17))Penicillin G (PG)(4.8 ± 0.1) × 103 (ref  (17))
Alachlor (ALA)3.8 ± 0.4 (ref  (25))Picloram (PCL)(1.4 ± 0.2) × 102 (ref  (25))
Bezafibrate (BZF)(5.9 ± 0.5) × 102 (ref  (26))Roxithromycin (ROX)(6.3 ± 1.4) × 104 (ref  (17))
Carbamazepine (CBZ)(6.1 ± 0.1) × 105 (ref  (27))Sulfamethoxazole (SMX)(1.1 ± 0.2) × 106e (ref  (17))
Carbofuran (CBF)6.2 × 102 (ref  (25))Tramadol (TRA)(4.0 ± 0.9) × 103 (ref  (28))
2.1 × 102c
Ciprofloxacin (CIP)(1.9 ± 0.7) × 104 (ref  (17))Triclosan (TRI)(3.8 ± 0.8) × 107 (ref  (29))
Diazepam (DZP)(7.5 ± 0.15) × 10–1 (ref (26))Trimethoprim (TMP)(5.4 ± 1.1) × 105e (ref  (17))
Dibromomethylparabenb (DMP)8.4 × 107 (ref  (30))Tylosin (TYL)(1.0 ± 0.2) × 105e (ref  (17))
(4.3 ± 0.3) × 106d
a

The structures and species-specific second-order rate constants for the reactions with O3 are shown in Table S3.

b

IUPAC name: methyl 3,5-dibromo-4-hydroxybenzoate.

c

Second-order rate constant corrected for stoichiometry. See explanations in section Validation of Competitors.

d

Second-order rate constants redetermined using cinnamic acid and phenol as competitors. See details in section Validation of Competitors and Text S4.

e

Second-order rate constants recalculated based on the re-evaluated second-order rate constant for cinnamic acid by Kim et al. (31)

Examples of correlation plots between relative abatements of cyano-metabolites and competitors are shown in Figure S4. Only data points with a relative abatement of cyano-metabolites and competitors between 10% and 90% were considered. There were two main reasons for this approach: (i) a wide range of O3 doses was applied and each compound only reacted at a specific range of O3 doses. For compounds with intermediate or low reactivity, many data points at negligible abatement would overly impact the linear regression, which was avoided by setting a minimum of 10% abatement. (ii) The 90% maximum abatement limit was set to avoid loss of linearity, prevent high leverage data points and eventual interference due to carryover between sample injections on the HPLC-HRMS/MS.
kapp,O3 for a given cyano-metabolite/competitor pair was only calculated if (i) there were 10 or more data points, (ii) the coefficient of determination (R2) was higher than 0.9, (iii) the intercept was negligible (intercept < 10 × slope), and (iv) the slope was between 0.1 and 10 (i.e., if the kapp,O3 for the cyano-metabolite and the kapp,O3 for the competitor were within 1 order of magnitude). The statistical parameters of each successful linear regression are provided in Tables S5–S10. For a given cyano-metabolite/competitor pair, the standard error (SE) of the cyano-metabolite kapp (SEcyanomet/comp) was the result of the propagation of the standard error on the slope (SEslope) and on the kapp,O3 of the competitor (SEcomp):
SEcyanomet/comp=(SEcompkapp,O3,comp)2+(SEslopeslope)2
(3)
The uncertainty in kapp,O3,comp given in the literature was used for SEcomp. If no error was provided in the literature for the kapp,O3 of the competitor, a 20% relative error was set (most kapp,O3,comp values have relative errors of 20% or less). For competitors with acid–base speciation, the error of kapp,O3 in the literature was replaced by the error induced from ±0.05 pH variation, if the latter was greater. This was the case for roxithromycin, tramadol, and triclosan at pH 7.
For a given cyano-metabolite, several kapp,O3 could be obtained from several competitors (e.g., anabaenopeptin A correlated with trimethoprim, carbamazepine, tylosin, sulfamethoxazole and dibromomethylparaben, each giving a kapp,O3). In addition, the same cyano-metabolite could be monitored at different ionizations (given in Table S4) in HRMS/MS (e.g., the [M + H]+ and [M – H]− ions of anabaenopeptin A were simultaneously monitored). Different ionizations did not significantly impact the kapp,O3 (<20% difference, kapp,O3 for individual ionizations are not shown). All the kapp,O3 determined for a given cyano-metabolite were averaged and the standard error was either the standard deviation of all the kapp,O3 or the highest competitor-specific kapp,O3 standard error, whichever was the highest.

Results and Discussion

Click to copy section linkSection link copied!

Identification of Cyano-metabolites in Microcystis and Planktothrix Extracts

A total of 31 cyano-metabolites with sufficient signal intensity for kinetic studies were identified from the selected strains: 1 aeruginosin, 5 anabaenopeptins, 7 cyanopeptolins, 6 cyclamides, 10 microcystins, and 2 unclassified cyano-metabolites. (32) Figure 1 shows the structures of representative cyano-metabolites for each class. Highlighted moieties represent the parts of the molecule that can change for other identified variants of the same class. The full cyano-metabolite list with their structures is provided in the SI (Table S4, Tables S11–S14, and Figure S5).

Figure 1

Figure 1. Representative cyano-metabolites detected in Microcystis aeruginosa and Planktothrix rubescens cultures. Highlighted moieties represent the parts of the molecules that can vary in the other cyano-metabolites of the same class identified in this study. Circles indicate the main attack sites of the O3. The full lists of cyano-metabolites and their structures are provided in Table S4, Tables S11–S14, and Figure S5.

High Resolution Image
Download MS PowerPoint Slide
Aeruginosin-group-608 is the only noncyclic cyano-metabolite identified in this study. It refers to one of the three known stereoisomers of the shown structure (Figure 1). Aeruginosins are tetrapeptides notably characterized by a lactic acid derivative that contains a phenol, which is expected to be a major reactive site for O3. (33)
Cyclamides, represented by aerucyclamide C in Figure 1, are cyclic hexapeptides characterized by heterocyclic groups such as thiazole, oxazole, thiazoline, and oxazoline that have unknown reactivities toward O3. In our study, oxazole was determined to be the main reactive site in aerucyclamide C (see explanation in “Determination of Second-Order Rate Constants for the Reactions of Cyano-metabolites with Ozone”). One cyclamide, aerucyclamide D, contains a methionine, which is expected to be a major reactive site (Table S13). (34)
Anabaenopeptins are characterized by a cyclic pentapeptide containing a lysine. The lysine’s α-amine branches out to form a urea bond with the N-terminal of a sixth amino acid outside of the cycle (an arginine in the case of anabaenopeptin B, Figure 1). All the anabaenopeptins identified in this study contain a homotyrosine and eventually a tyrosine, which are expected to be the major reactive sites for O3. (34)
Cyanopeptolins are characterized by a cyclic hexadepsipeptide containing a 3-amino-6-methoxy-2-piperidone and a threonine that forms an ester bond (Figure 1). In addition, the N-terminus of the threonine branches out to two supplementary amino acids. The main O3 attack site in cyanopeptolin D is expected to be the tertiary amine on the side chain of the lysine derivative. In other cyanopeptolins, the lysine derivative is replaced by other amino acids such as a normal lysine or a tyrosine, which are also expected to be major reactive sites (Table S12). (34,35)
Microcystins (abbreviated as MC) are cyclic heptapeptides with a characteristic Adda moiety (3-amino-9-methoxy-2,6,8-trimethyl-10-phenyl-deca-4,6-dienoic acid) (Figure 1). Adda contains conjugated olefins that are a major reactive site for O3. (12,31) One microcystin, [Mdha-GSH7]MC-LR, contains an additional thioether that is expected to be more reactive than the conjugated olefins (Figure S5). (34)
Two additional cyclic cyano-metabolites, identified in Planktothrix, are planktocyclin and piricyclamide ILGEGEGWNYNP+prenyl (Figure S5). They contain a methionine and tryptophan, respectively, which are expected to be the main reactive sites. (34)

Validation of Competitors

First, the abatement of competitors and their previously published kapp,O3 values were evaluated in the presence of cyano-metabolite mixtures extracted from the two selected cyanobacteria strains. The abatement of the selected competitors as a function of the O3 dose in the presence of the cyano-metabolite mixture from Microcystis at pH 7 is shown in Figure 2a. The abatement of the competitors was generally consistent with their reactivity: a higher kapp,O3 led to a higher abatement for a specific ozone dose. However, a few exceptions were observed: dibromomethylparaben (DMP, kapp,O3 = 8.4 × 107 M–1 s–1) should be more reactive than triclosan (TRI) and vancomycin (VM, not shown in Table 1) (3.8 × 107 and 1.2 × 106 M–1 s–1, respectively). (17,29,30) However, Figure 2a shows that DMP (open diamonds) required higher or similar O3 doses than TRI (reverse blue triangles) or VM (reverse red triangles) for an equivalent abatement. Likewise, carbofuran (CBF, blue circles) required higher O3 doses than benzafibrate (BZF, red circles) to reach an equivalent abatement, while their reported kapp,O3 values are comparable (6.2 × 102 and 5.9 × 102 M–1 s–1, respectively). (25,26)

Figure 2

Figure 2. Simultaneous abatement of (a) the selected competitors and (b) representative cyano-metabolites from 0.6 gbiomass L–1 of Microcystis as a function of the specific O3 dose at pH 7 (2 mM phosphate) and 22 °C and in the presence of tert-butanol (40 mM). For the abbreviations of the competitors, see Table 1 (except VM which stands for vancomycin).

High Resolution Image
Download MS PowerPoint Slide
To evaluate whether the observed discrepancies were significant, competitors were systematically compared to each other, using eq 1. The abatement of a given competitor was correlated with the other competitors with similar reactivities, i.e., leading to regression slopes between 0.1 and 10, from which apparent second-order rate constants were calculated (kmeasured). Figure 3a shows for each competitor the ratios between kmeasured in the Microcystis extract at pH 7 and the previously published apparent second-order rate constant (kliterature, shown in Table 1). For example, for penicillin G (PG), three symbols are shown, which represent three kmeasured/kliterature ratios using tramadol (TRA, open circle), BZF (filled red circle), and ciprofloxacin (CIP, filled blue diamond) as competitors. The kmeasured/kliterature ratios for PG were between 0.7 and 1.4, which is in the range of variations for second-order rate constants from different studies. Overall, the majority of kmeasured/kliterature ratios were between 0.5 and 2, which is an acceptable variation range for competition kinetics (Figure 3a). However, using carbofuran (CBF), VM, or DMP as competitors consistently led to ratios beyond a 2-fold difference, suggesting that their kliterature could be inaccurate, as discussed in more detail in the following. For diazepam (DZP), alachlor (ALA), and picloram (PCL) no kmeasured/kliterature values were determined as they were not significantly degraded at the applied O3 doses (Figure 2a).

Figure 3

Figure 3. Competitor evaluation during the ozonation of a Microcystis extract (0.6 gbiomass L–1) at pH 7 (2 mM phosphate) and 22 °C and in the presence of tert-butanol (40 mM). The evaluation was done by calculating the ratios between the kapp,O3 determined by pairs of competitors (kmeasured) and the kapp,O3 from the literature (kliterature, see Table 1). Panels (a) and (b) show the kmeasured/kliterature ratios using unmodified and adjusted kliterature, respectively (only kliterature of CBF and DMP were adjusted; see explanation in the text). The vertical lines correspond to the limits for the acceptable kmeasured/kliterature range, set between 0.5 and 2. For the abbreviations of the competitors see Table 1 (except VM which stands for vancomycin).

High Resolution Image
Download MS PowerPoint Slide

Carbofuran (CBF)

The kmeasured values of CBF with acetylsulfamethoxazole (ASMX) or BZF as competitors were 2 to 3-fold lower than its kliterature (black and red filled circles on the CBF line, Figure 3a). Conversely, the kmeasured values of ASMX and BZF with CBF as competitor were 2 to 3-fold higher than their kliterature (blue filled circles, Figure 3a). This discrepancy was attributed to the determination method of kO3,CBF. kO3,CBF (6.2 × 102 M–1 s–1) was previously measured by monitoring the O3 decrease in excess of CBF. (25) However, the O3:CBF reaction stoichiometry was determined in our study to be 3:1 (see Figure S6), implying that kO3,CBF related to CBF abatement has to be divided by a stoichiometric factor of 3, resulting in a corrected kO3,CBF of 2.1 × 102 M–1 s–1. Using the corrected kO3,CBF, the kmeasured/kliterature ratios involving CBF improved from 0.3–2.9 to 0.8–1.4 (Figure 3b).

Vancomycin (VM)

The kmeasured values of VM determined with trimethoprim (TMP), tylosin (TYL), sulfamethoxazole (SMX), and TRI as competitors were 3 to 7-fold higher than its kliterature (symbols on the VM line, Figure 3a). Conversely, the kmeasured values of TMP, TYL, SMX, and TRI determined with VM as competitor were 2 to 8-fold lower than their kliterature (red filled triangles, Figure 3a). VM contains a resorcinol, a phenol, and amine groups that serve as secondary reaction sites. Due to the complexity of VM (six pKa values and three activated aromatic rings) no species-specific second-order rate constants could previously be determined and only kapp,O3 values were available, which may have caused such a discrepancy. (17) Because of this complexity, kO3,VM was not reassessed, omitted from Figure 3b, and not considered further in this study.

Dibromomethylparaben (DMP)

The kmeasured values of DMP determined with TMP, CBZ, TYL SMX, and TRI as competitors were more than 10-fold lower than the reported literature value (symbols on the DMP line, Figure 3a). Conversely, the kmeasured values of TMP, CBZ, TYL, SMX, and TRI determined with DMP as competitor were 10 to 25-fold higher than the reported values (open diamonds, Figure 3a). kO3,DMP of the deprotonated DMP (8.4 × 107 M–1 s–1) has previously been determined by competition kinetics with indigotrisulfonate as competitor at pH ≥ 7. (30) The kO3 of indigotrisulfonate has been determined with 1,3,5-trimethoxybenzene as competitor and the kO3 of the latter with buten-3-ol as competitor. (36) This cascade for determinations of second-order rate constants might have led to accumulated errors. In the present study, kO3,DMP was redetermined using cinnamic acid and phenol as competitors, for which directly measured kO3 are available. (31,33) A corrected kO3,DMP = (4.3 ± 0.3) × 106 M–1 s–1 was measured for the deprotonated DMP, 19-fold lower than the previous literature value (details are provided in Text S4). The kO3 for protonated DMP was not re-evaluated as it is expected to be negligible in the studied pH range (pKa = 4.7). Using the corrected kO3,DMP, the kmeasured/kliterature ratios involving DMP improved from 0.04–27 to 0.7–1.8 (Figure 3b).

Validation in Planktothrix Mixture and at pH 8

After correcting the apparent kO3,CBF and kO3,DMP values and excluding VM, all the kmeasured were within a factor of 2 of the kliterature at pH 7 and therefore the selected competitors were suitable for this study. A similar exercise was done in the presence of the cyano-metabolite mixture from Planktothrix at pH 7 and 8, but only for competitors with a kapp,O3 > 104 M–1 s–1 (see Figure S7). Again, all the kmeasured values were within a factor of 2 of the kliterature values, excluding VM, further validating the competitor kapp,O3, especially for the pH-dependent competitors ROX, TMP, and TYL. For these three competitors, due to pKa values between 7.1 and 9.2 and kO3,neutral > kO3,protonated (see Table S3), their kapp,O3 values increase 1.7 to 9.5-fold when increasing the pH from 7 to 8. This pH effect can be a supplementary source of error when determining kapp,O3 due to added uncertainties on pH control, pKa, and model fitting. The kapp,O3 of TRI is also pH-dependent, but it was too reactive to be correlated with any of the other competitors at pH 8.

Determination of Second-Order Rate Constants for the Reactions of Cyano-metabolites with Ozone

The abatement of representative cyano-metabolites as a function of the specific O3 dose is shown in Figure 2b. The abatement of each cyano-metabolite was correlated to the abatement of the competitors with similar reactivity. Examples of abatement correlation plots used for the determination of kapp,O3 of cyano-metabolites are given in Figure S4. A summary of the averaged kapp,O3 of cyano-metabolites at pH 7 determined with multiple competitors is provided in Table 2, classified by their main reactive moieties. Competitor-specific kapp,O3 values are provided for all cyano-metabolites in Table S16. Overall, of the 31 metabolites, three did not react with O3 at a measurable rate (kapp,O3 < 102 M–1 s–1), six metabolites reacted slowly/moderately with kapp,O3 ≤ 5.0 × 103 M–1 s–1, 19 metabolites reacted readily with kapp,O3 ranging between 3.6 × 105 and 1.9 × 106 M–1 s–1, and three metabolites reacted rapidly with kapp,O3 ranging between 3.4 and 7.3 × 107 M–1 s–1. The structure–reactivity dependency for the reaction of these metabolites with O3 is discussed in the following.
Table 2. Apparent Second-Order Rate Constants (kapp,O3) at pH 7 for the Reactions of O3 with Cyano-metabolites from Microcystis aeruginosa (PCC7806) and Planktothrix rubescens (K-0576)a
Cyano-metabolitesCyanobacterial strainkapp,O3 at pH 7 (M–1 s–1)dCompetitors
Tryptophan
Piricyclamide ILGEGEGWNYNP + prenylPlanktothrix(7.3 ± 1.7) × 107TRI
Thioethers
[Mdha-GSH7]MC-LRMicrocystis(1.9 ± 0.4) × 106TMP, TYL, SMX, DMP
Aerucyclamide DMicrocystis(5.2 ± 1.5) × 107DMP, TRI
PlanktocyclinPlanktothrix(3.4 ± 0.9) × 107DMP, TRI
Olefins
[d-Asp3,(E)-Dhb7]MC-RRPlanktothrix(1.7 ± 0.3) × 106TMP, CBZ, TYL, SMX, DMP
[d-Asp3,Dha7]MC-RRPlanktothrix(1.3 ± 0.3) × 106TMP, CBZ, TYL, SMX, DMP
[d-Asp3,DMAdda5]MC-RRPlanktothrix(1.7 ± 0.3) × 106TMP, CBZ, TYL, SMX, DMP
[d-Asp3]MC-LAPlanktothrix(9.7 ± 2.1) × 105TMP, CBZ, TYL, SMX
[d-Asp3]MC-LRMicrocystis, Planktothrix(1.1 ± 0.2) × 106, (1.1 ± 0.2) × 106TMP, CBZ, TYL, SMX, DMP
MC-HilRMicrocystis(1.1 ± 0.2) × 106TMP, CBZ, TYL, SMX, DMP
MC-LAbaPlanktothrix(1.1 ± 0.2) × 106TMP, CBZ, TYL, SMX
MC-LRMicrocystis, Planktothrix(1.1 ± 0.2) × 106, (1.1 ± 0.2) × 106TMP, CBZ, TYL, SMX, DMP
Microcystin-group-967Microcystis(1.1 ± 0.2) × 106TMP, CBZ, TYL, SMX
Phenols
Aeruginosin-group-608Planktothrix(1.6 ± 0.3) × 106TMP, CBZ, TYL, SMX, DMP
Anabaenopeptin APlanktothrix(1.2 ± 0.2) × 106TMP, CBZ, TYL, SMX, DMP
Anabaenopeptin BPlanktothrix(9.7 ± 1.9) × 105TMP, CBZ, TYL, SMX
Anabaenopeptin FPlanktothrix(1.0 ± 0.2) × 106TMP, CBZ, TYL, SMX
Anabaenopeptin SA13Planktothrix(1.2 ± 0.2) × 106TMP, CBZ, TYL, SMX
Cyanopeptolin 1020Planktothrix(5.7 ± 1.2) × 105TMP, CBZ, TYL, SMX
Cyanopeptolin 963AbMicrocystis(3.6 ± 0.8) × 105TMP, CBZ, TYL, SMX
Oscillamide YPlanktothrix(1.2 ± 0.3) × 106TMP, CBZ, TYL, SMX
Oscillapeptin JPlanktothrix(1.6 ± 0.4) × 106TMP, CBZ, TYL, SMX, DMP
Amines
Cyanopeptolin Bb,cMicrocystis<102 
Cyanopeptolin Cb,cMicrocystis(1.0 ± 0.3) × 102ASMX, BZF, CBF, TRA, PG
Cyanopeptolin DbMicrocystis(2.0 ± 0.5) × 103ASMX, BZF, CBF, TRA, PG
Heterocycles
Aerucyclamide AMicrocystis(8.8 ± 1.6) × 101ASMX, BZF, CBF
Aerucyclamide BMicrocystis<102 
Aerucyclamide CMicrocystis(4.2 ± 1.1) × 103TRA, PG
Microcyclamide 7806AMicrocystis(4.7 ± 1.2) × 103BZF, TRA, PG
Microcyclamide 7806BMicrocystis(5.0 ± 1.1) × 103BZF, TRA, PG
Benzene
Cyanopeptolin AbMicrocystis<102 
a

The kapp,O3 values were determined by competition kinetics with the indicated competitors. For abbreviations of competitors, see Table 1.

b

Cyano-metabolites for which an isomer with the same MS2 fragmentation was found within 1 min of retention time. kapp,O3 for the two isomers were within ±20%.

c

The kapp,O3 of these cyano-metabolites is to be taken with caution. Cyanopeptolin C is a potential product, yet minor, of cyanopeptolin D ozonation and cyanopeptolin B a potential product, yet minor, of cyanopeptolin C ozonation (see explanation in text and in Text S5).

d

Whenever a cyano-metabolite was present in the two strains, two kapp,O3 are reported.

Tryptophan and Thioether

Tryptophan- and thioether-containing cyano-metabolites were the most reactive toward O3 with kapp,O3 at pH 7 in the range 3.4–7.3 × 107 M–1 s–1, excluding [Mdha-GSH7]MC-LR (Table 2). These kapp,O3 were an order of magnitude higher than reported kapp,O3 values for free tryptophan (7.0 × 106 M–1 s–1) and methionine (4.0 × 106 M–1 s–1). (34) In the previous study, kapp,O3 values for free tryptophan and methionine were measured with histidine or 3-hexenoic acid as competitors for which kapp,O3 are significantly lower (1.9 × 105 and 2.4 × 105 M–1 s–1, respectively, at pH 7). (34) This large difference in kapp,O3 is not ideal for competition kinetics and may lead to high errors. Therefore, the kO3 values of these two amino acids need to be redetermined in future studies. The kapp,O3 obtained for [Mdha-GSH7]MC-LR (1.9 × 106 M–1 s–1) was much lower than those obtained for aerucyclamide D and planktocyclin (Table 2). In [Mdha-GSH7]MC-LR, the thioether is attached to the microcystin ring on one side and to the rest of the glutathione on the other side (Figure S5). This position may cause a decrease in O3 reactivity of the thioether in [Mdha-GSH7]MC-LR. Large variations in the reactivity of thioethers have previously been observed for pharmaceuticals. (17) The measured kapp,O3 for [Mdha-GSH7]MC-LR was similar to that of other microcystins (Table 2). It is therefore uncertain whether the main attack site for O3 is the thioether or the olefins. Further investigation of the effect of complex substituents on the thioether reactivity is required.

Olefins and Phenols

The kapp,O3 of olefin-containing cyano-metabolites ranged between 1.0 and 1.7 × 106 M–1 s–1, somewhat higher than the kO3 value of the protonated form of sorbic acid (3.7 ± 0.3 × 105 M–1 s–1, adjusted with the re-evaluated kcinnamic acid). (12,31) In addition, the same kapp,O3 for MC-LR was calculated in Microcystis and Planktothrix ((1.1 ± 0.2) × 106 M–1 s–1), consistent with a previous study ((8.5 ± 0.2) × 105 M–1 s–1). (31) It is worth noting that MC-LR is one of the main cyano-metabolites in Microcystis while it is a minor cyano-metabolite in Planktothrix (about 50 times less concentrated), further demonstrating that the matrix does not interfere with the determination of kapp,O3. Phenol-containing cyano-metabolites had kapp,O3 ranging between 0.4 and 1.6 × 106 M–1 s–1, consistent with the reactivity of phenol (1.8 ± 0.5 × 106 M–1 s–1). (33) In addition, cyano-metabolites containing two phenols (e.g., anabaenopeptins A and SA13) were not significantly more reactive than those with one phenol (e.g., anabaenopeptins B and F).

Amines

Three cyano-metabolites contain amines: cyanopeptolin B, cyanopeptolin C, and cyanopeptolin D. These three cyanopeptolins have the same structure, apart from the amine-containing moieties, which are expected to be the main reactive sites (Table S12). Cyanopeptolin B contains a primary amine on the side chain of a lysine. Cyanopeptolins C and D contain lysine derivatives, in which the side chain amine is substituted by one and two methyls, respectively. The reactivity order of these three cyanopeptolins at pH 7 was cyanopeptolin D (tertiary amine) > cyanopeptolin C (secondary amine) > cyanopeptolin B (primary amine), consistent with the ozonation literature on amines (Table 2). (35) However, the kapp,O3 of the tertiary amine-containing cyanopeptolin D ((2.0 ± 0.5) × 103 M–1 s–1) was an order of magnitude higher than the kapp,O3 of triethylamine reported in the literature ((2.2 ± 0.1) × 102 M–1 s–1). (35) This difference may be, in part, due to a lower pKa for cyanopeptolin D compared with that of triethylamine. The predicted pKa of cyanopeptolin D was 0.5 pH-unit lower than the predicted pKa of triethylamine (pKa predicted by ChemAxon software, shown in Table S17). As the neutral amine is the reactive form with O3, a lower pKa leads to a higher reactivity at pH 7. Another difference between cyanopeptolins and small model compounds was the extent of the decrease in reactivity between the tertiary and secondary amine. The kapp,O3 of cyanopeptolin D (tertiary amine) was 20-fold higher than the kapp,O3 of cyanopeptolin C (secondary amine) (Table 2). By comparison, the literature value of the kapp,O3 of triethylamine (tertiary amine) is only 1.7 times higher than the kapp,O3 of diethylamine (secondary amine). (35) Again, pKa may play a role. The predicted pKa for cyanopeptolin C (secondary amine) was 1.2 pH-units higher than that for cyanopeptolin D (tertiary amine), while the predicted pKa for diethylamine was only 0.4 pH-units higher than that for triethylamine (Table S17). An increased pKa for secondary amines compared to tertiary amines can explain, in part, their lower reactivity at pH 7. However, the kapp,O3 values of cyanopeptolin C and B need to be taken with caution. A possible yet minor product of tertiary amine ozonation is the corresponding secondary amine (5% from trimethylamine). (35) Similarly, the ozonation of a secondary amine can lead to minor yields of the corresponding primary amine (8% from diethylamine). (35) Cyanopeptolin C can therefore be formed from cyanopeptolin D ozonation, and cyanopeptolin B can be formed from cyanopeptolin C ozonation. Although no increase was observed for cyanopeptolin C and B (Figure S8), it could have been masked by their degradation during ozonation, leading to underestimated kapp,O3 and to the large kapp,O3 difference between cyanopeptolins D and C. However, it was estimated that no more than 10% of the initial cyanopeptolin C should be formed from cyanopeptolin D, suggesting that its kapp,O3 was not significantly underestimated (see details in Text S5).

Heterocycles

Four cyano-metabolites contained heterocycles that likely served as primary O3 reaction sites. At pH 7, kapp,O3 values for aerucyclamide A and B were much lower (<102 M–1 s–1) compared to aerucyclamide C and microcyclamides 7806A and 7806B (4.2–5.0 × 103 M–1 s–1) (Table 2). Comparing the structures of these four cyano-metabolites can help identify the reactive moieties. Oxazole was only present in the more reactive aerucyclamide C and microcyclamide 7806A and 7806B while thiazole, oxazoline, and thiazoline were present in at least one of the less reactive aerucyclamide A and B (Table S13). Altogether, this suggests that the moieties responsible for the reactivity of aerucyclamide C and microcyclamide 7806A and 7806B are oxazole. The kapp,O3 of the other heterocycles are likely <102 M–1 s–1 and need to be further studied.

pH Effect on Reaction Kinetics

The kapp,O3 of cyano-metabolites present in the Planktothrix extract were also measured at pH 8 (Table S18). For the kapp,O3 of olefin-containing cyano-metabolites, a <20% difference was observed between pH 7 and 8, consistent with their pH-independent reactivities (Tables 2 and S18). Conversely, the kapp,O3 for phenol-containing cyano-metabolites increased by a factor ranging between 7 ± 2 and 9 ± 2 when increasing the pH from 7 to 8 (using kapp,O3 determined with TYL, which is the only competitor that correlated at both pH values), due to the shift from protonated to deprotonated phenol moieties (Tables S16 and S18). This increase is close to the 10-fold increase of kapp,O3 expected for phenolic compounds when increasing the pH from 7 to 8. (33)
For tryptophan- and thioether-containing cyano-metabolites, large discrepancies between the two competitors used at pH 8, DMP and TRI, were observed. The kapp,O3 values determined with TRI were 6-fold higher than those determined with DMP (Table S18). When validating competitors, TRI was too reactive to be correlated to any other competitor at pH 8 while DMP was validated by four other competitors (see the section Validation of Competitors and Figure S7b). Hence, the kapp,O3 determined with TRI at pH 8 may be overestimated. The kapp,O3 of the thioether-containing planktocyclin was comparable at pH 7 and 8 when measured with DMP ((2.8 ± 0.4) × 107 and (1.8 ± 0.2) × 107 M–1 s–1, respectively), consistent with the expected pH-independence of thioether reactivity. For the tryptophan-containing piricyclamide ILGEGEGWNYNP+prenyl, only TRI could be correlated at pH 7 and 8; therefore the pH effect on its kapp,O3 cannot be discussed.

Practical Implications

This study demonstrates the applicability of the multicompound approach for the screening of kapp,O3 for many cyano-metabolites and with a minimal set of experiments. As toxins and bioactive metabolites from cyanobacteria are usually not commercially available and can only be extracted from the producing bacteria as mixtures, multicompound competition kinetics are the most efficient way to gain knowledge on the efficiency of their abatement during ozonation. Multicompound competition kinetics are a rapid screening tool to determine the kinetics of O3 for a wide range of compounds at once. It is important to note that possible interferences associated with the complexity of the matrix and the measurement method exist: (1) the formation of a target compound from the oxidation of another (un)known compound, (2) the variation of the signal inherent to mass spectrometry, and (3) the effect of the matrix on the ionization of analytes. Strict regression criteria can help prevent such problems (high R2, negligible intercept, and restricted abatement ranges). In addition, the use of multiple competitors per target compound provides more resilience, preventing a strong bias when determining the kapp,O3. To this end, it was shown that a number of competitor compounds had incorrect kapp,O3, which could be problematic if they would have been used as single competitors. Therefore, a cross check of second-order rate constants is recommended for competition kinetics experiments. A limitation for the determination of second-order rate constants was the lack of competitors with kapp,O3 > ∼107 M–1 s–1, which was evident for the determination of kapp,O3 of thioether- and tryptophan-containing cyano-metabolites. Therefore, further studies are needed to determine second-order rate constants at the higher end of the O3 reactivity, even though for compounds with such high reactivities, a complete abatement is already expected at low specific O3 doses. Overall the proposed novel approach has many advantages as a screening tool; however, if kapp,O3 needs to be determined with high precision, conventional methods focusing on individual compounds should be favored, and if possible, direct methods and not competition kinetics should be applied.
The majority of the 31 cyano-metabolites identified in Microcystis and Planktothrix had kapp,O3 ≥ 105 M–1 s–1, indicating they should be degraded by specific O3 doses typically applied in drinking water treatment. (12) Without reactive moieties such as tryptophan, thioether, phenol, and olefin, other cyano-metabolites showed significantly lower reactivity (kapp,O3 ≤ 103 M–1 s–1), indicating they might only be partially degraded by O3. In this case, the oxidation by the secondarily formed •OH may enhance their abatement significantly. (37) Because of the high molecular weights of the detected cyano-metabolites and a low selectivity of •OH, it can be assumed that the second-order rate constants for the reaction of cyano-metabolites with •OH are close to diffusion control (1010 M–1 s–1). (38,39) For example, MC-LR and aerucyclamide A have kapp,OH values of 1.1 × 1010 and 6.4 × 109 M–1 s–1, respectively, at pH 7. (12,40) Furthermore, the multicompound competition kinetics allowed us to gain insight into structural moieties that have been underrepresented in the ozonation literature thus far. This is notably exemplified in this study by the high reactivity of tryptophan- and thioether-containing cyano-metabolites compared to the literature, revealing a lack of knowledge on the O3 reactivity of these moieties. In addition, preliminary insights were obtained on the reactivity of O3 with the heterocycles oxazole, thiazole, oxazoline, and thiazoline.

Supporting Information

Click to copy section linkSection link copied!

The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.est.4c02242.

  • Additional experimental details, information on competitors, structures of all identified cyano-metabolites, details on kO3,DMP redetermination, supplementary cyano-metabolite rate constants, and linear regression statistical parameters (PDF)

  • Spreadsheet containing the confirmation of cyano-metabolite structures by MS2 spectra annotation (XLSX)

Terms & Conditions

Most electronic Supporting Information files are available without a subscription to ACS Web Editions. Such files may be downloaded by article for research use (if there is a public use license linked to the relevant article, that license may permit other uses). Permission may be obtained from ACS for other uses through requests via the RightsLink permission system: http://pubs.acs.org/page/copyright/permissions.html.

Author Information

Click to copy section linkSection link copied!
  • Corresponding Authors
    • Urs von Gunten - Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland;  School of Architecture, Civil and Environmental Engineering (ENAC), École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland;  Email: [email protected]
    • Elisabeth M.L. Janssen - Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland;  Orcidhttps://orcid.org/0000-0002-5475-6730;  Email: [email protected]
  • Author
    • Valentin Rougé - Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
  • Notes
    The authors declare no competing financial interest.

Acknowledgments

Click to copy section linkSection link copied!

This study was supported by the Eawag discretionary fund and the waterworks Zürich (Stadt Zürich, Wasserversorgung WVZ). We thank Karl Gademann (University Zürich, Switzerland) for providing aerucyclamide A. BioRender was used for the TOC art.

References

Click to copy section linkSection link copied!

This article references 40 other publications.

  1. 1
    Whitton, B. A.; Potts, M. Introduction to the Cyanobacteria. In Ecology of Cyanobacteria II: Their Diversity in Space and Time; Whitton, B. A., Ed.; Springer Netherlands: Dordrecht, 2012; pp 1– 13.
    Google Scholar
    There is no corresponding record for this reference.
  2. 2
    Hauer, T.; Komárek, J. CyanoDB 2.0- On-line database of cyanobacterial genera; University of South Bohemia and Institute of Botany, Academy of Sciences of the Czech Republic: 2022.
    Google Scholar
    There is no corresponding record for this reference.
  3. 3
    Huisman, J.; Codd, G. A.; Paerl, H. W.; Ibelings, B. W.; Verspagen, J. M. H.; Visser, P. M. Cyanobacterial blooms. Nat. Rev. Microbiol 2018, 16 (8), 471– 483,  DOI: 10.1038/s41579-018-0040-1
    Google Scholar
    3
    Cyanobacterial blooms
    Huisman, Jef; Codd, Geoffrey A.; Paerl, Hans W.; Ibelings, Bas W.; Verspagen, Jolanda M. H.; Visser, Petra M.
    Nature Reviews Microbiology (2018), 16 (8), 471-483CODEN: NRMACK; ISSN:1740-1526. (Nature Research)
    A review. Cyanobacteria can form dense and sometimes toxic blooms in freshwater and marine environments, which threaten ecosystem functioning and degrade water quality for recreation, drinking water, fisheries and human health. Here, we review evidence indicating that cyanobacterial blooms are increasing in frequency, magnitude and duration globally. We highlight species traits and environmental conditions that enable cyanobacteria to thrive and explain why eutrophication and climate change catalyze the global expansion of cyanobacterial blooms. Finally, we discuss management strategies, including nutrient load redns., changes in hydrodynamics and chem. and biol. controls, that can help to prevent or mitigate the proliferation of cyanobacterial blooms.
  4. 4
    He, X.; Liu, Y.-L.; Conklin, A.; Westrick, J.; Weavers, L. K.; Dionysiou, D. D.; Lenhart, J. J.; Mouser, P. J.; Szlag, D.; Walker, H. W. Toxic cyanobacteria and drinking water: Impacts, detection, and treatment. Harmful Algae 2016, 54, 174– 193,  DOI: 10.1016/j.hal.2016.01.001
    Google Scholar
    4
    Toxic cyanobacteria and drinking water: Impacts, detection, and treatment
    He, Xuexiang; Liu, Yen-Ling; Conklin, Amanda; Westrick, Judy; Weavers, Linda K.; Dionysiou, Dionysios D.; Lenhart, John J.; Mouser, Paula J.; Szlag, David; Walker, Harold W.
    Harmful Algae (2016), 54 (), 174-193CODEN: HAALDD; ISSN:1568-9883. (Elsevier B.V.)
    Blooms of toxic cyanobacteria in water supply systems are a global issue affecting water supplies on every major continent except Antarctica. The occurrence of toxic cyanobacteria in freshwater is increasing in both frequency and distribution. The protection of water supplies has therefore become increasingly more challenging. To reduce the risk from toxic cyanobacterial blooms in drinking water, a multi-barrier approach is needed, consisting of prevention, source control, treatment optimization, and monitoring. In this paper, current research on some of the crit. elements of this multi-barrier approach are reviewed and synthesized, with an emphasis on the effectiveness of water treatment technologies for removing cyanobacteria and related toxic compds. This paper synthesizes and updates a no. of previous review articles on various aspects of this multi-barrier approach in order to provide a holistic resource for researchers, water managers and engineers, as well as water treatment plant operators.
  5. 5
    Beversdorf, L. J.; Rude, K.; Weirich, C. A.; Bartlett, S. L.; Seaman, M.; Kozik, C.; Biese, P.; Gosz, T.; Suha, M.; Stempa, C.; Shaw, C.; Hedman, C.; Piatt, J. J.; Miller, T. R. Analysis of cyanobacterial metabolites in surface and raw drinking waters reveals more than microcystin. Water Res. 2018, 140, 280– 290,  DOI: 10.1016/j.watres.2018.04.032
    Google Scholar
    5
    Analysis of cyanobacterial metabolites in surface and raw drinking waters reveals more than microcystin
    Beversdorf, Lucas J.; Rude, Kayla; Weirich, Chelsea A.; Bartlett, Sarah L.; Seaman, Mary; Kozik, Christine; Biese, Peter; Gosz, Timothy; Suha, Michael; Stempa, Christopher; Shaw, Christopher; Hedman, Curtis; Piatt, Joseph J.; Miller, Todd R.
    Water Research (2018), 140 (), 280-290CODEN: WATRAG; ISSN:0043-1354. (Elsevier Ltd.)
    Freshwater cyanobacterial blooms are becoming increasingly problematic in regions that rely on surface waters for drinking water prodn. Microcystins (MCs) are toxic peptides produced by multiple cyanobacterial genera with a global occurrence. Cyanobacteria also produce a variety of other toxic and/or otherwise bioactive peptides (TBPs) that have gained less attention including cyanopeptolins (Cpts), anabaenopeptins (Apts), and microginins (Mgn). In this study, we compared temporal and spatial trends of four MCs (MCLR, MCRR, MCYR, MCLA), three Cpts (Cpt1020, Cpt1041, Cpt1007), two Apts (AptF, AptB), and Mgn690 in raw drinking water and at six surface water locations above these drinking water intakes in a eutrophic lake. All four MC congeners and five of six TBPs were detected in lake and raw drinking water. Across all samples, MCLR was the most frequently detected metabolite (100% of samples) followed by MCRR (97%) > Cpt1007 (74%) > MCYR (69%) > AptF (67%) > MCLA (61%) > AptB (54%) > Mgn690 (29%) and Cpt1041 (15%). Mean concns. of MCs, Apts, and Cpts into two drinking water intakes were 3.9± 4.7, 0.14± 0.21, and 0.38± 0.92, resp. Mean concns. in surface water were significantly higher (p<0.05) than in drinking water intakes for MCs but not for Cpts and Apts. Temporal trends in MCs, Cpts, and Apts in the two raw drinking water intakes were significantly correlated (p < 0.05) with measures of cell abundance (chlorophyll-a, Microcystis cell d.), UV absorbance, and turbidity in surface water. This study expands current information about cyanobacterial TBPs that occur in lakes and that enter drinking water treatment plants and underscores the need to det. the fate of less studied cyanobacterial metabolites during drinking water treatment that may exacerbate toxicity of more well-known cyanobacterial toxins.
  6. 6
    Bullerjahn, G. S.; McKay, R. M.; Davis, T. W.; Baker, D. B.; Boyer, G. L.; D’Anglada, L. V.; Doucette, G. J.; Ho, J. C.; Irwin, E. G.; Kling, C. L.; Kudela, R. M.; Kurmayer, R.; Michalak, A. M.; Ortiz, J. D.; Otten, T. G.; Paerl, H. W.; Qin, B.; Sohngen, B. L.; Stumpf, R. P.; Visser, P. M.; Wilhelm, S. W. Global solutions to regional problems: Collecting global expertise to address the problem of harmful cyanobacterial blooms. A Lake Erie case study. Harmful Algae 2016, 54, 223– 238,  DOI: 10.1016/j.hal.2016.01.003
    Google Scholar
    6
    Global solutions to regional problems: Collecting global expertise to address the problem of harmful cyanobacterial blooms. A Lake Erie case study
    Bullerjahn George S; McKay Robert M; Davis Timothy W; Baker David B; Boyer Gregory L; D'Anglada Lesley V; Doucette Gregory J; Ho Jeff C; Irwin Elena G; Sohngen Brent L; Kling Catherine L; Kudela Raphael M; Kurmayer Rainer; Michalak Anna M; Ortiz Joseph D; Otten Timothy G; Paerl Hans W; Qin Boqiang; Stumpf Richard P; Visser Petra M; Wilhelm Steven W
    Harmful algae (2016), 54 (), 223-238 ISSN:.
    In early August 2014, the municipality of Toledo, OH (USA) issued a 'do not drink' advisory on their water supply directly affecting over 400,000 residential customers and hundreds of businesses (Wilson, 2014). This order was attributable to levels of microcystin, a potent liver toxin, which rose to 2.5μgL(-1) in finished drinking water. The Toledo crisis afforded an opportunity to bring together scientists from around the world to share ideas regarding factors that contribute to bloom formation and toxigenicity, bloom and toxin detection as well as prevention and remediation of bloom events. These discussions took place at an NSF- and NOAA-sponsored workshop at Bowling Green State University on April 13 and 14, 2015. In all, more than 100 attendees from six countries and 15 US states gathered together to share their perspectives. The purpose of this review is to present the consensus summary of these issues that emerged from discussions at the Workshop. As additional reports in this special issue provide detailed reviews on many major CHAB species, this paper focuses on the general themes common to all blooms, such as bloom detection, modeling, nutrient loading, and strategies to reduce nutrients.
  7. 7
    Tanber, G. Toxin leaves 500,000 in northwest Ohio without drinking water. Reuters , 2014.
    Google Scholar
    There is no corresponding record for this reference.
  8. 8
    WHO. Guidelines for Drinking-Water Quality, 4th ed.; WHO: Geneva, 2017.
    Google Scholar
    There is no corresponding record for this reference.
  9. 9
    von Sonntag, C.; von Gunten, U. Chemistry of Ozone in Water and Wastewater Treatment: From Basic Principles to Applications; International Water Association: 2012.
    Google Scholar
    There is no corresponding record for this reference.
  10. 10
    Rougé, V.; von Gunten, U.; Lafont de Sentenac, M.; Massi, M.; Wright, P. J.; Croué, J.-P.; Allard, S. Comparison of the impact of ozone, chlorine dioxide, ferrate and permanganate pre-oxidation on organic disinfection byproduct formation during post-chlorination. Environ. Sci. Water Res. Technol. 2020, 6 (9), 2382– 2395,  DOI: 10.1039/D0EW00411A
    Google Scholar
    10
    Comparison of the impact of ozone, chlorine dioxide, ferrate and permanganate pre-oxidation on organic disinfection byproduct formation during post-chlorination
    Rouge, Valentin; von Gunten, Urs; Lafont de Sentenac, Mariette; Massi, Massimiliano; Wright, Phillip J.; Croue, Jean-Philippe; Allard, Sebastien
    Environmental Science: Water Research & Technology (2020), 6 (9), 2382-2395CODEN: ESWRAR; ISSN:2053-1419. (Royal Society of Chemistry)
    A comparative study of the impact of four pre-oxidants, ozone (O3), chlorine dioxide (ClO2), permanganate (Mn(VII)) and ferrate (Fe(VI)), on the formation of trihalomethanes (THMs), haloacetonitriles (HANs) and adsorbable org. halogens (AOX) in chlorinated synthetic and real waters was conducted. The influence of pH (6.5-8.1) and bromide (0-500μg L-1) was evaluated in terms of disinfection byproduct (DBP) formation and theor. toxicity assessment (based on THM and HAN formation). All oxidants were efficient in mitigating chlorinated DBPs, except Mn(VII) which had little impact on THM formation. The pH depression improved AOX mitigation by O3 and Fe(VI) but diminished Mn(VII) efficiency for all DBPs. Pre-oxidn. was less efficient in mitigating brominated DBPs and generally enhanced the bromine substitution factor. Although HANs were formed at low concns. compared to THMs, they dominated the calcd. toxicity, particularly the brominated HANs. The increased dibromoacetonitrile formation after pre-oxidn. was a major factor counteracting the benefits of the overall DBP mitigation. In the presence of bromide, the pre-oxidant dose should be optimized to decrease the reactivity of the matrix while controlling the toxicity induced by formation of brominated DBPs, notably brominated HANs.
  11. 11
    Rodríguez, E.; Onstad, G. D.; Kull, T. P. J.; Metcalf, J. S.; Acero, J. L.; von Gunten, U. Oxidative elimination of cyanotoxins: Comparison of ozone, chlorine, chlorine dioxide and permanganate. Water Res. 2007, 41 (15), 3381– 3393,  DOI: 10.1016/j.watres.2007.03.033
    Google Scholar
    11
    Oxidative elimination of cyanotoxins: Comparison of ozone, chlorine, chlorine dioxide and permanganate
    Rodriguez, Eva; Onstad, Gretchen D.; Kull, Tomas P. J.; Metcalf, James S.; Acero, Juan L.; von Gunten, Urs
    Water Research (2007), 41 (15), 3381-3393CODEN: WATRAG; ISSN:0043-1354. (Elsevier Ltd.)
    As the World Health Organization (WHO) progresses with provisional Drinking Water Guidelines of 1 μg/L for microcystin-LR and a proposed Guideline of 1 μg/L for cylindrospermopsin, efficient treatment strategies are needed to prevent cyanotoxins such as these from reaching consumers. A kinetic database has been compiled for the oxidative treatment of three cyanotoxins: microcystin-LR (MC-LR), cylindrospermopsin (CYN), and anatoxin-a (ANTX) with ozone, chlorine, chlorine dioxide and permanganate. This kinetic database contains rate consts. not previously reported and detd. in the present work (e.g. for permanganate oxidn. of ANTX and chlorine dioxide oxidn. of CYN and ANTX), together with previously published rate consts. for the remaining oxidn. processes. Second-order rate consts. measured in pure aq. solns. of these toxins could be used in a kinetic model to predict the toxin oxidn. efficiency of ozone, chlorine, chlorine dioxide and permanganate when applied to natural waters. Oxidants were applied to water from a eutrophic Swiss lake (Lake Greifensee) in static-dose testing and dynamic time-resolved expts. to confirm predictions from the kinetic database, and to investigate the effects of a natural matrix on toxin oxidn. and byproduct formation. Overall, permanganate can effectively oxidize ANTX and MC-LR, while chlorine will oxidize CYN and MC-LR and ozone is capable of oxidizing all three toxins with the highest rate. The formation of trihalomethanes (THMs) in the treated water may be a restriction to the application of sufficiently high-chlorine doses.
  12. 12
    Onstad, G. D.; Strauch, S.; Meriluoto, J.; Codd, G. A.; von Gunten, U. Selective Oxidation of Key Functional Groups in Cyanotoxins during Drinking Water Ozonation. Environ. Sci. Technol. 2007, 41 (12), 4397– 4404,  DOI: 10.1021/es0625327
    Google Scholar
    12
    Selective Oxidation of Key Functional Groups in Cyanotoxins during Drinking Water Ozonation
    Onstad, Gretchen D.; Strauch, Sabine; Meriluoto, Jussi; Codd, Geoffrey A.; von Gunten, Urs
    Environmental Science & Technology (2007), 41 (12), 4397-4404CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    Chem. kinetics were detd. for the reactions of ozone and hydroxyl radicals with the three cyanotoxins microcystin-LR (MC-LR), cylindrospermopsin (CYN) and anatoxin-a (ANTX). The second-order rate consts. (kO3) at pH 8 were 4.1 ± 0.1 × 105 M-1 s-1 for MC-LR, ∼3.4 × 105 M-1 s-1 for CYN, and ∼6.4 × 104 M-1 s-1 for ANTX. The reaction of ozone with MC-LR exhibits a kO3 similar to that of the conjugated diene in sorbic acid (9.6 ± 0.3 × 105 M-1 s-1) at pH 8. The pH dependence and value of kO3 for CYN at pH > 8 (∼2.5 ± 0.1 × 106 M-1 s-1) are similar to deprotonated amines of 6-methyluracil. The kO3 of ANTX at pH > 9 (∼8.7 ± 2.2 × 105 M-1 s-1) agrees with that of neutral diethylamine, and the value at pH < 8 (2.8 ± 0.2 × 104 M-1 s-1) corresponds to an olefin. Second-order rate consts. for reaction with OH radicals (•OH), kOH for cyanotoxins were measured at pH 7 to be 1.1 ± 0.01 × 1010 M-1 s-1 for MC-LR, 5.5 ± 0.01 × 109 M-1 s-1 for CYN, and 3.0 ± 0.02 × 109 M-1 s-1 for ANTX. Natural waters from Switzerland and Finland were examd. for the influence of variations of dissolved org. matter, SUVA254, and alky. on cyanotoxin oxidn. For a Swiss water (1.6 mg/L DOC), 0.2, 0.4, and 0.8 mg/L ozone doses were required for 95% oxidn. of MC-LR, CYN, and ANTX, resp. For the Finnish water (13.1 mg/L DOC), >2 mg/L ozone dose was required for each toxin. The contribution of hydroxyl radicals to toxin oxidn. during ozonation of natural water was greatest for ANTX > CYN > MC-LR. Overall, the order of reactivity of cyanotoxins during ozonation of natural waters corresponds to the relative magnitudes of the second-order rate consts. for their reaction with ozone and •OH. Ozone primarily attacks the structural moieties responsible for the toxic effects of MC-LR, CYN, and ANTX, suggesting that ozone selectively detoxifies these cyanotoxins.
  13. 13
    Jones, M. R.; Pinto, E.; Torres, M. A.; Dörr, F.; Mazur-Marzec, H.; Szubert, K.; Tartaglione, L.; Dell’Aversano, C.; Miles, C. O.; Beach, D. G.; McCarron, P.; Sivonen, K.; Fewer, D. P.; Jokela, J.; Janssen, E. M. L. CyanoMetDB, a comprehensive public database of secondary metabolites from cyanobacteria. Water Res. 2021, 196, 117017,  DOI: 10.1016/j.watres.2021.117017
    Google Scholar
    13
    CyanoMetDB, a comprehensive public database of secondary metabolites from cyanobacteria
    Jones, Martin R.; Pinto, Ernani; Torres, Mariana A.; Dorr, Fabiane; Mazur-Marzec, Hanna; Szubert, Karolina; Tartaglione, Luciana; Dell'Aversano, Carmela; Miles, Christopher O.; Beach, Daniel G.; McCarron, Pearse; Sivonen, Kaarina; Fewer, David P.; Jokela, Jouni; Janssen, Elisabeth M.-L.
    Water Research (2021), 196 (), 117017CODEN: WATRAG; ISSN:0043-1354. (Elsevier Ltd.)
    A review. Harmful cyanobacterial blooms, which frequently contain toxic secondary metabolites, are reported in aquatic environments around the world. More than two thousand cyanobacterial secondary metabolites have been reported from diverse sources over the past fifty years. A comprehensive, publically-accessible database detailing these secondary metabolites would facilitate research into their occurrence, functions and toxicol. risks. To address this need we created CyanoMetDB, a highly curated, flat-file, openly-accessible database of cyanobacterial secondary metabolites collated from 850 peer-reviewed articles published between 1967 and 2020. CyanoMetDB contains 2010 cyanobacterial metabolites and 99 structurally related compds. This has nearly doubled the no. of entries with complete literature metadata and structural compn. information compared to previously available open access databases. The dataset includes microcytsins, cyanopeptolins, other depsipeptides, anabaenopeptins, microginins, aeruginosins, cyclamides, cryptophycins, saxitoxins, spumigins, microviridins, and anatoxins among other metabolite classes. A comprehensive database dedicated to cyanobacterial secondary metabolites facilitates: (1) the detection and dereplication of known cyanobacterial toxins and secondary metabolites; (2) the identification of novel natural products from cyanobacteria; (3) research on biosynthesis of cyanobacterial secondary metabolites, including substructure searches; and (4) the investigation of their abundance, persistence, and toxicity in natural environments.
  14. 14
    Janssen, E. M.-L. J.; Martin, R.; Pinto, E.; Dörr, F.; Torres, M. A.; Rios Jacinavicius, F.; Mazur-Marzec, H.; Szubert, K.; Konkel, R.; Tartaglione, L.; Dell’Aversano, C.; Miglione, A.; McCarron, P.; Beach, D. G.; Miles, C. O.; Fewer, D. P.; Sivonen, K.; Jokela, J.; Wahlsten, M.; Niedermeyer, T. H. J.; Schanbacher, F.; Leão, P.; Preto, M.; D’Agostino, P. M.-L.; Baunach, M.; Dittmann, E.; Reher, R. S75 | CyanoMetDB | Comprehensive database of secondary metabolites from cyanobacteria (NORMAN-SLE-S75.0.2.0) [Data set]. In Zenodo , 2023.
    Google Scholar
    There is no corresponding record for this reference.
  15. 15
    Lim, S.; Shi, J. L.; von Gunten, U.; McCurry, D. L. Ozonation of organic compounds in water and wastewater: A critical review. Water Res. 2022, 213, 118053,  DOI: 10.1016/j.watres.2022.118053
    Google Scholar
    15
    Ozonation of organic compounds in water and wastewater: A critical review
    Lim, Sungeun; Shi, Jiaming Lily; von Gunten, Urs; McCurry, Daniel L.
    Water Research (2022), 213 (), 118053CODEN: WATRAG; ISSN:0043-1354. (Elsevier Ltd.)
    A review. Ozonation has been applied in water treatment for more than a century, first for disinfection, later for oxidn. of inorg. and org. pollutants. In recent years, ozone has been increasingly applied for enhanced municipal wastewater treatment for ecosystem protection and for potable water reuse. These applications triggered significant research efforts on the abatement efficiency of org. contaminants and the ensuing formation of transformation products. This endeavor was accompanied by developments in anal. and computational chem., which allowed to improve the mechanistic understanding of ozone reactions. This crit. review assesses the challenges of ozonation of impaired water qualities such as wastewaters and provides an up-to-date compilation of the recent kinetic and mechanistic findings of ozone reactions with dissolved org. matter, various functional groups (olefins, arom. compds., heterocyclic compds., aliph. nitrogen-contg. compds., sulfur-contg. compds., hydrocarbons, carbanions, β-diketones) and antibiotic resistance genes.
  16. 16
    Schwarzenbach, R. P.; Gschwend, P. M.; Imboden, D. M. Environmental Organic Chemistry, 2nd ed.; John Wiley & Sons: Hoboken, NJ, 2002; pp 245– 274.
    Google Scholar
    There is no corresponding record for this reference.
  17. 17
    Dodd, M. C.; Buffle, M.-O.; von Gunten, U. Oxidation of Antibacterial Molecules by Aqueous Ozone: Moiety-Specific Reaction Kinetics and Application to Ozone-Based Wastewater Treatment. Environ. Sci. Technol. 2006, 40 (6), 1969– 1977,  DOI: 10.1021/es051369x
    Google Scholar
    17
    Oxidation of Antibacterial Molecules by Aqueous Ozone: Moiety-Specific Reaction Kinetics and Application to Ozone-Based Wastewater Treatment
    Dodd, Michael C.; Buffle, Marc-Olivier; von Gunten, Urs
    Environmental Science & Technology (2006), 40 (6), 1969-1977CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    Ozone and hydroxyl radical (•OH) reaction kinetics were measured for 14 antibacterial compds. from nine structural families, to det. whether municipal wastewater ozonation is likely to result in selective oxidn. of these compds.' biochem. essential moieties. Each substrate is oxidized by ozone with an apparent 2nd-order rate const., k''O3,app > 1 × 103/M-s, at pH 7, with the exception of N(4)-acetylsulfamethoxazole (k''O3,app is 2.5 × 102/M-s). K''O3,app values (pH 7) for macrolides, sulfamethoxazole, trimethoprim, tetracycline, vancomycin, and amikacin appear to correspond directly to oxidn. of biochem. essential moieties. Initial reactions of ozone with N(4)-acetylsulfamethoxazole, fluoroquinolones, lincomycin, and β-lactams do not lead to appreciable oxidn. of biochem. essential moieties. However, ozone oxidizes these moieties within fluoroquinolones and lincomycin via slower reactions. Measured k''O3,app values and 2nd-order •OH rate consts., k''•OH,app, were utilized to characterize pollutant losses during ozonization of secondary municipal wastewater effluent. These losses depended on k''O3,app, but independent of k''•OH,app. Ozone doses ≥3 mg/L yielded ≥99% depletion of fast-reacting substrates (k''O3,app >5 × 104/M-s) at pH 7.7. Ten substrates reacted predominantly with ozone; only 4 were oxidized predominantly by •OH. These results indicate that many antibacterial compds. will be oxidized in wastewater via moiety-specific reactions with ozone.
  18. 18
    Natumi, R.; Dieziger, C.; Janssen, E. M. L. Cyanobacterial Toxins and Cyanopeptide Transformation Kinetics by Singlet Oxygen and pH-Dependence in Sunlit Surface Waters. Environ. Sci. Technol. 2021, 55 (22), 15196– 15205,  DOI: 10.1021/acs.est.1c04194
    Google Scholar
    There is no corresponding record for this reference.
  19. 19
    Jones, M.; Janssen, E. M. L. Quantification of Multi-class Cyanopeptides in Swiss Lakes with Automated Extraction, Enrichment and Analysis by Online-SPE HPLC-HRMS/MS. CHIMIA 2022, 76 (1–2), 133– 144,  DOI: 10.2533/chimia.2022.133
    Google Scholar
    There is no corresponding record for this reference.
  20. 20
    Portmann, C.; Blom, J. F.; Gademann, K.; Jüttner, F. Aerucyclamides A and B: Isolation and Synthesis of Toxic Ribosomal Heterocyclic Peptides from the Cyanobacterium Microcystis aeruginosa PCC 7806. J. Nat. Prod. 2008, 71 (7), 1193– 1196,  DOI: 10.1021/np800118g
    Google Scholar
    20
    Aerucyclamides A and B: isolation and synthesis of toxic ribosomal heterocyclic peptides from the cyanobacterium Microcystis aeruginosa PCC 7806
    Portmann, Cyril; Blom, Judith F.; Gademann, Karl; Juttner, Friedrich
    Journal of Natural Products (2008), 71 (7), 1193-1196CODEN: JNPRDF; ISSN:0163-3864. (American Chemical Society-American Society of Pharmacognosy)
    Two new modified hexacyclopeptides, aerucyclamides A and B, were isolated from the toxic freshwater cyanobacterium M. aeruginosa PCC 7806. The constitution was assigned by spectroscopic methods, and the configuration detd. by chem. degrdn. and anal. by Marfey's method combined with chem. synthesis. Synthetic aerucyclamide B was obtained through oxidn. of aerucyclamide A (MnO2, benzene). The aerucyclamides were toxic to the freshwater crustacean Thamnocephalus platyurus, exhibiting LC50 values for congeners A and B of 30.5 and 33.8 μM, resp.
  21. 21
    Natumi, R.; Marcotullio, S.; Janssen, E. M. L. Phototransformation kinetics of cyanobacterial toxins and secondary metabolites in surface waters. Environ. Sci. Eur. 2021, 33 (1), 26,  DOI: 10.1186/s12302-021-00465-3
    Google Scholar
    There is no corresponding record for this reference.
  22. 22
    Ruttkies, C.; Schymanski, E. L.; Wolf, S.; Hollender, J.; Neumann, S. MetFrag relaunched: incorporating strategies beyond in silico fragmentation. J. Cheminformatics 2016, 8 (1), 3,  DOI: 10.1186/s13321-016-0115-9
    Google Scholar
    22
    MetFrag relaunched: incorporating strategies beyond in silico fragmentation
    Ruttkies, Christoph; Schymanski, Emma L.; Wolf, Sebastian; Hollender, Juliane; Neumann, Steffen
    Journal of Cheminformatics (2016), 8 (), 3/1-3/16CODEN: JCOHB3; ISSN:1758-2946. (Chemistry Central Ltd.)
    Background: The in silico fragmenter MetFrag, launched in 2010, was one of the first approaches combining compd. database searching and fragmentation prediction for small mol. identification from tandem mass spectrometry data. Since then many new approaches have evolved, as has MetFrag itself. This article details the latest developments to MetFrag and its use in small mol. identification since the original publication. Results: MetFrag has gone through algorithmic and scoring refinements. New features include the retrieval of ref., data source and patent information via ChemSpider and PubChem web services, as well as InChIKey filtering to reduce candidate redundancy due to stereoisomerism. Candidates can be filtered or scored differently based on criteria like occurrence of certain elements and/or substructures prior to fragmentation, or presence in so-called "suspect lists". Retention time information can now be calcd. either within MetFrag with a sufficient amt. of user-provided retention times, or incorporated sep. as "user-defined scores" to be included in candidate ranking. The changes to MetFrag were evaluated on the original dataset as well as a dataset of 473 merged high resoln. tandem mass spectra (HR-MS/MS) and compared with another open source in silico fragmenter, CFM-ID. Using HR-MS/MS information only, MetFrag2.2 and CFM-ID had 30 and 43 Top 1 ranks, resp., using PubChem as a database. Including ref. and retention information in MetFrag2.2 improved this to 420 and 336 Top 1 ranks with ChemSpider and PubChem (89 and 71 %), resp., and even up to 343 Top 1 ranks (PubChem) when combining with CFM-ID. The optimal parameters and wts. were verified using three addnl. datasets of 824 merged HR-MS/MS spectra in total. Further examples are given to demonstrate flexibility of the enhanced features. Conclusions: In many cases addnl. information is available from the exptl. context to add to small mol. identification, which is esp. useful where the mass spectrum alone is not sufficient for candidate selection from a large no. of candidates. The results achieved with MetFrag2.2 clearly show the benefit of considering this addnl. information. The new functions greatly enhance the chance of identification success and have been incorporated into a command line interface in a flexible way designed to be integrated into high throughput workflows.
  23. 23
    Dührkop, K.; Fleischauer, M.; Ludwig, M.; Aksenov, A. A.; Melnik, A. V.; Meusel, M.; Dorrestein, P. C.; Rousu, J.; Böcker, S. SIRIUS 4: a rapid tool for turning tandem mass spectra into metabolite structure information. Nat. Methods 2019, 16 (4), 299– 302,  DOI: 10.1038/s41592-019-0344-8
    Google Scholar
    23
    SIRIUS 4: a rapid tool for turning tandem mass spectra into metabolite structure information
    Duehrkop, Kai; Fleischauer, Markus; Ludwig, Marcus; Aksenov, Alexander A.; Melnik, Alexey V.; Meusel, Marvin; Dorrestein, Pieter C.; Rousu, Juho; Boecker, Sebastian
    Nature Methods (2019), 16 (4), 299-302CODEN: NMAEA3; ISSN:1548-7091. (Nature Research)
    Mass spectrometry is a predominant exptl. technique in metabolomics and related fields, but metabolite structural elucidation remains highly challenging. We report SIRIUS 4 (https://bio.informatik.uni-jena.de/sirius/), which provides a fast computational approach for mol. structure identification. SIRIUS 4 integrates CSI:FingerID for searching in mol. structure databases. Using SIRIUS 4, we achieved identification rates of more than 70% on challenging metabolomics datasets.
  24. 24
    Schymanski, E. L.; Jeon, J.; Gulde, R.; Fenner, K.; Ruff, M.; Singer, H. P.; Hollender, J. Identifying Small Molecules via High Resolution Mass Spectrometry: Communicating Confidence. Environ. Sci. Technol. 2014, 48 (4), 2097– 2098,  DOI: 10.1021/es5002105
    Google Scholar
    24
    Identifying Small Molecules via High Resolution Mass Spectrometry: Communicating Confidence
    Schymanski, Emma L.; Jeon, Junho; Gulde, Rebekka; Fenner, Kathrin; Ruff, Matthias; Singer, Heinz P.; Hollender, Juliane
    Environmental Science & Technology (2014), 48 (4), 2097-2098CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    A method and framework for describing the identification of small mols. by high resoln. mass spectrometry (HRMS) is presented. A 5 level classification scheme was developed to indicate the proposed identification confidence levels in HRMS. The levels are confirmed structure, probable structure, substance class, unequivocal mol. formula, and exact mass of interest.
  25. 25
    David Yao, C. C.; Haag, W. R. Rate constants for direct reactions of ozone with several drinking water contaminants. Water Res. 1991, 25 (7), 761– 773,  DOI: 10.1016/0043-1354(91)90155-J
    Google Scholar
    There is no corresponding record for this reference.
  26. 26
    Huber, M. M.; Canonica, S.; Park, G.-Y.; von Gunten, U. Oxidation of Pharmaceuticals during Ozonation and Advanced Oxidation Processes. Environ. Sci. Technol. 2003, 37 (5), 1016– 1024,  DOI: 10.1021/es025896h
    Google Scholar
    26
    Oxidation of Pharmaceuticals during Ozonation and Advanced Oxidation Processes
    Huber, Marc M.; Canonica, Silvio; Park, Gun-Young; von Gunten, Urs
    Environmental Science and Technology (2003), 37 (5), 1016-1024CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    Oxidn. of pharmaceuticals during conventional ozonation and advanced oxidn. processes (AOP) in drinking water purifn. was studied. In a first step, second-order rate consts. for reactions of selected pharmaceuticals with O3 (kO3) and OH- (kOH) were detd. in bench-scale expts. (apparent kO3 at pH 7 and 20°): bezafibrate (590 ± 50/M-s), carbamazepine (∼3 × 105/M-s), diazepam (0.75 ± 0.15/M-s), diclofenac (∼1 × 106/M-s), 17α-ethinylestradiol (∼3 × 106/M-s), ibuprofen (9.6 ± 1.0/M-s), iopromide (<0.8/M-s), sulfamethoxazole (∼2.5 × 106/M-s), and roxithromycin (∼7 × 104/M-s). For 5 of the pharmaceuticals, apparent kO3 at pH 7 was >5 × 104/M-s, indicating these compds. are completely transformed during ozonation. KOH values were from 3.3 to 9.8 × 109/M-s. Compared to other important micro-pollutants, e.g., Me tert-Bu ether (MTBE) and atrazine, the selected pharmaceuticals reacted about 2-3 times faster with OH-. In the second part of the study, oxidn. kinetics of selected pharmaceuticals were examd. in ozonation expts. performed in different natural water. Second-order rate consts. detd. in pure aq. soln. could be applied to predict behavior of pharmaceuticals dissolved in natural water. Overall it was concluded that ozonation and AOP are promising processes to efficiently remove pharmaceuticals in drinking water.
  27. 27
    Wolf, C.; von Gunten, U.; Kohn, T. Kinetics of Inactivation of Waterborne Enteric Viruses by Ozone. Environ. Sci. Technol. 2018, 52 (4), 2170– 2177,  DOI: 10.1021/acs.est.7b05111
    Google Scholar
    27
    Kinetics of Inactivation of Waterborne Enteric Viruses by Ozone
    Wolf, Camille; von Gunten, Urs; Kohn, Tamar
    Environmental Science & Technology (2018), 52 (4), 2170-2177CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    Ozone is an effective disinfectant against all types of waterborne pathogens. However, accurate and quant. kinetic data regarding virus inactivation by ozone are scarce, because of the exptl. challenges assocd. with the high reactivity of ozone toward viruses. Here, we established an exptl. batch system that allows tailoring and quantifying of very low ozone exposures and simultaneously measuring virus inactivation. Second-order ozone inactivation rate consts. (kO3-virus) of five enteric viruses [lab. and two environmental strains of coxsackievirus B5 (CVF, CVEnv1, and CVEnv2), human adenovirus (HAdV), and echovirus 11 (EV)] and four bacteriophages (MS2, Qβ, T4, and Φ174) were measured in buffered solns. The kO3-virus values of all tested viruses ranged from 4.5 × 105 to 3.3 × 106 M-1s-1. For MS2, kO3-MS2 depended only weakly on temp. (2-22 °C; Ea = 22.2 kJ mol-1) and pH (6.5-8.5), with an increase in kO3-MS2 with increasing pH. The susceptibility of the selected viruses toward ozone decreases in the following order: Qβ > CVEnv2 > EV ≈ MS2 > Φ174 ≈ T4 > HAdV > CVF ≈ CVEnv1. On the basis of the measured kO3-Virus and typical ozone exposures applied in water and wastewater treatment, we conclude that ozone is a highly effective disinfectant for virus control.
  28. 28
    Zimmermann, S. G.; Schmukat, A.; Schulz, M.; Benner, J.; von Gunten, U.; Ternes, T. A. Kinetic and Mechanistic Investigations of the Oxidation of Tramadol by Ferrate and Ozone. Environ. Sci. Technol. 2012, 46 (2), 876– 884,  DOI: 10.1021/es203348q
    Google Scholar
    28
    Kinetic and Mechanistic Investigations of the Oxidation of Tramadol by Ferrate and Ozone
    Zimmermann, Saskia G.; Schmukat, Annekatrin; Schulz, Manoj; Benner, Jessica; Gunten, Urs von; Ternes, Thomas A.
    Environmental Science & Technology (2012), 46 (2), 876-884CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    The kinetics and oxidn. products (OPs) of tramadol (TRA), an opioid, were investigated for its oxidn. with ferrate (Fe(VI)) and ozone (O3). The kinetics could be explained by the speciation of the tertiary amine moiety of TRA, with apparent second-order rate consts. of 7.4 (±0.4) M-1 s-1 (Fe(VI)) and 4.2 (±0.3) × 104 M-1 s-1 (O3) at pH 8.0, resp. In total, six OPs of TRA were identified for both oxidants using Qq-LIT-MS, LTQ-FT-MS, GC-MS, and moiety-specific chem. reactions. In excess of oxidants, these OPs can be further transformed to unidentified OPs. Kinetics and OP identification confirmed that the lone electron pair of the amine-N is the predominant site of oxidant attack. An oxygen transfer mechanism can explain the formation of N-oxide-TRA, while a one-electron transfer may result in the formation of N-centered radical cation intermediates, which could lead to the obsd. N-dealkylation, and to the identified formamide and aldehyde derivs. via several intermediate steps. The proposed radical intermediate mechanism is favored for Fe(VI) leading predominantly to N-desmethyl-TRA (ca. 40%), whereas the proposed oxygen transfer prevails for O3 attack resulting in N-oxide-TRA as the main OP (ca. 90%).
  29. 29
    Suarez, S.; Dodd, M. C.; Omil, F.; von Gunten, U. Kinetics of triclosan oxidation by aqueous ozone and consequent loss of antibacterial activity: Relevance to municipal wastewater ozonation. Water Res. 2007, 41 (12), 2481– 2490,  DOI: 10.1016/j.watres.2007.02.049
    Google Scholar
    There is no corresponding record for this reference.
  30. 30
    Lee, W.; Marcotullio, S.; Yeom, H.; Son, H.; Kim, T.-H.; Lee, Y. Reaction kinetics and degradation efficiency of halogenated methylparabens during ozonation and UV/H2O2 treatment of drinking water and wastewater effluent. J. Hazard. Mater. 2022, 427, 127878,  DOI: 10.1016/j.jhazmat.2021.127878
    Google Scholar
    There is no corresponding record for this reference.
  31. 31
    Kim, M. S.; Lee, C. Ozonation of Microcystins: Kinetics and Toxicity Decrease. Environ. Sci. Technol. 2019, 53 (11), 6427– 6435,  DOI: 10.1021/acs.est.8b06645
    Google Scholar
    There is no corresponding record for this reference.
  32. 32
    Janssen, E. M. L. Cyanobacterial peptides beyond microcystins - A review on co-occurrence, toxicity, and challenges for risk assessment. Water Res. 2019, 151, 488– 499,  DOI: 10.1016/j.watres.2018.12.048
    Google Scholar
    32
    Cyanobacterial peptides beyond microcystins - A review on co-occurrence, toxicity, and challenges for risk assessment
    Janssen, Elisabeth M.-L.
    Water Research (2019), 151 (), 488-499CODEN: WATRAG; ISSN:0043-1354. (Elsevier Ltd.)
    Cyanobacterial bloom events that produce natural toxins occur in freshwaters across the globe, yet the potential risk of many cyanobacterial metabolites remains mostly unknown. Only microcystins, one class of cyanopeptides, have been studied intensively and the wealth of evidence regarding exposure concns. and toxicity led to their inclusion in risk management frameworks for water quality. However, cyanobacteria produce an incredible diversity of hundreds of cyanopeptides beyond the class of microcystins. The question arises, whether the other cyanopeptides are in fact of no human and ecol. concern or whether these compds. merely received (too) little attention thus far. Current observations suggest that an assessment of their (eco)toxicol. risk is indeed relevant: First, other cyanopeptides, including cyanopeptolins and anabaenopeptins, can occur just as frequently and at similar nanomolar concns. as microcystins in surface waters. Second, cyanopeptolins, anabaenopeptins, aeruginosins and microginins inhibit proteases in the nanomolar range, in contrast to protein phosphatase inhibition by microcystins. Cyanopeptolins, aeruginosins, and aerucyclamide also show toxicity against grazers in the micromolar range comparable to microcystins. The key challenge for a comprehensive risk assessment of cyanopeptides remains their large structural diversity, lack of ref. stds., and high anal. requirements for identification and quantification. One way forward would be a prevalence study to identify the priority candidates of tentatively abundant, persistent, and toxic cyanopeptides to make comprehensive risk assessments more manageable.
  33. 33
    Hoigné, J.; Bader, H. Rate constants of reactions of ozone with organic and inorganic compounds in water─II. Water Res. 1983, 17 (2), 185– 194,  DOI: 10.1016/0043-1354(83)90099-4
    Google Scholar
    33
    Rate constants of reactions of ozone with organic and inorganic compounds in water. II. Dissociating organic compounds
    Hoigne, J.; Bader, H.
    Water Research (1983), 17 (2), 185-94CODEN: WATRAG; ISSN:0043-1354.
    Comprehensive lists of rate consts. of reactions of O3 with acidic and basic org. chem. dissolved in water, such as amines, amino acids, carboxylic acids, and phenols are reported. The second-order rate consts. increase with pH as does the degree of deprotonation of the dissolved substances, e.g. HCOOH [64-18-6] 1-100, glyoxalic acid [298-12-4] 0.2-2, and phenols 103-109/M s. The electrophilic reactions of O3 with non-dissocg. compds. are important for the understanding of the pH dependence of the rate and selectivity of ozonation reactions and for explaining the chem. effects of O3 on impurities in drinking water and wastewaters.
  34. 34
    Pryor, W. A.; Giamalva, D. H.; Church, D. F. Kinetics of ozonation. 2. Amino acids and model compounds in water and comparisons to rates in nonpolar solvents. J. Am. Chem. Soc. 1984, 106 (23), 7094– 7100,  DOI: 10.1021/ja00335a038
    Google Scholar
    34
    Kinetics of ozonation. 2. Amino acids and model compounds in water and comparisons to rates in nonpolar solvents
    Pryor, William A.; Giamalva, David H.; Church, Daniel F.
    Journal of the American Chemical Society (1984), 106 (23), 7094-100CODEN: JACSAT; ISSN:0002-7863.
    Abs. rates of reaction of amino acids and model compds. with ozone were measured in aq. buffer solns. For the less reactive amino acids and for amines, the rates of reaction are proportional to the amt. of free (i.e., unprotonated) amine present and therefore are relatively slow below pH 7. The rates of reaction of the amides are also slow. Rates of reaction of the more reactive amino acids at pH 7.0 are in the order of cysteine > tryptophan > methionine > tyrosine > histidine. 3-Hexenoic acid, a model of a polyunsatd. fatty acid (PUFA), is similar in reactivity to methionine or tyrosine. The more reactive amino acids, whether free or in polypeptides, must be considered as possible targets for the reaction of ozone in vivo, along with the more usually considered PUFA. Which of these types of target mols. might receive the most damage in vivo probably depends on accessibility, cellular architecture.
  35. 35
    Lim, S.; McArdell, C. S.; von Gunten, U. Reactions of aliphatic amines with ozone: Kinetics and mechanisms. Water Res. 2019, 157, 514– 528,  DOI: 10.1016/j.watres.2019.03.089
    Google Scholar
    37
    Reactions of aliphatic amines with ozone: Kinetics and mechanisms
    Lim, Sungeun; McArdell, Christa S.; von Gunten, Urs
    Water Research (2019), 157 (), 514-528CODEN: WATRAG; ISSN:0043-1354. (Elsevier Ltd.)
    Aliph. amines are common constituents in micropollutants and dissolved org. matter and present in elevated concns. in wastewater-impacted source waters. Due to high reactivity, reactions of aliph. amines with ozone are likely to occur during ozonation in water and wastewater treatment. We investigated the kinetics and mechanisms of the reactions of ozone with ethylamine, diethylamine, and triethylamine as model nitrogenous compds. Species-specific second-order rate consts. for the neutral parent amines ranged from 9.3 × 104 to 2.2 × 106 M-1s-1 and the apparent second-order rate consts. at pH 7 for potential or identified transformation products were 6.8 × 105 M-1s-1 for N,N-diethylhydroxylamine, ∼105 M-1s-1 for N-ethylhydroxylamine, 1.9 × 103 M-1s-1 for N-ethylethanimine oxide, and 3.4 M-1s-1 for nitroethane. Product analyses revealed that all amines were transformed to products contg. a nitrogen-oxygen bond (e.g., triethylamine N-oxide and nitroethane) with high yields, i.e., 64-100% with regard to the abated target amines. These findings could be confirmed by measurements of singlet oxygen and hydroxyl radical which are formed during the amine-ozone reactions. Based on the high yields of nitroethane from ethylamine and diethylamine, a significant formation of nitroalkanes can be expected during ozonation of waters contg. high levels of dissolved org. nitrogen, as expected in wastewaters or wastewater-impaired source waters. This may pose adverse effects on the aquatic environment and human health.
  36. 36
    Muñoz, F.; von Sonntag, C. Determination of fast ozone reactions in aqueous solution by competition kinetics. J. Chem. Soc. Perkin Trans. 2 2000, (4), 661– 664,  DOI: 10.1039/a909668j
    Google Scholar
    There is no corresponding record for this reference.
  37. 37
    Kim, M. S.; Cha, D.; Lee, K.-M.; Lee, H.-J.; Kim, T.; Lee, C. Modeling of ozone decomposition, oxidant exposures, and the abatement of micropollutants during ozonation processes. Water Res. 2020, 169, 115230,  DOI: 10.1016/j.watres.2019.115230
    Google Scholar
    39
    Modeling of ozone decomposition, oxidant exposures, and the abatement of micropollutants during ozonation processes
    Kim, Min Sik; Cha, Dongwon; Lee, Ki-Myeong; Lee, Hye-Jin; Kim, Taewan; Lee, Changha
    Water Research (2020), 169 (), 115230CODEN: WATRAG; ISSN:0043-1354. (Elsevier Ltd.)
    This study demonstrates new empirical models to predict the decompn. of ozone (O3) and the exposures of oxidants (i.e., O3 and hydroxyl radical, ·OH) during the ozonation of natural waters. Four models were developed for the instantaneous O3 demand, first-order rate const. for the secondary O3 decay, O3 exposure (∫[O3]dt), and ·OH exposure ((∫[·OH]dt)), as functions of five independent variables, namely the O3 dose, concn. of dissolved org. carbon (DOC), pH, alky., and temp. The models were derived by polynomial regression anal. of exptl. data obtained by controlling variables in natural water samples from a single source water (Maegok water in Korea), and they exhibited high accuracies for regression (R2 = 0.99 for the three O3 models, and R2 = 0.96 for the ·OH exposure model). The three O3 models exhibited excellent internal validity for Maegok water samples of different conditions (that were not used for the model development). They also showed acceptable external validity for seven natural water samples collected from different sources (not Maegok water); the IOD model showed somewhat poor external validity. The models for oxidant exposures were successfully used to predict the abatement of micropollutants by ozonation; the model predictions showed high accuracy for Maegok water, but not for the other natural waters.
  38. 38
    Anbar, M.; Neta, P. A compilation of specific bimolecular rate constants for the reactions of hydrated electrons, hydrogen atoms and hydroxyl radicals with inorganic and organic compounds in aqueous solution. International Journal of Applied Radiation and Isotopes 1967, 18 (7), 493– 523,  DOI: 10.1016/0020-708X(67)90115-9
    Google Scholar
    40
    A compilation of specific bimolecular rate constants for the reactions of hydrated electrons, hydrogen atoms, and hydroxyl radicals with inorganic and organic compounds in aqueous solution
    Anbar, Michael; Neta, Pedatsur
    International Journal of Applied Radiation and Isotopes (1967), 18 (7), 493-523CODEN: IJARAY; ISSN:0020-708X.
    A compilation of rate consts. for over 600 compds. from 164 references.
  39. 39
    Appiani, E.; Page, S. E.; McNeill, K. On the Use of Hydroxyl Radical Kinetics to Assess the Number-Average Molecular Weight of Dissolved Organic Matter. Environ. Sci. Technol. 2014, 48 (20), 11794– 11802,  DOI: 10.1021/es5021873
    Google Scholar
    41
    On the Use of Hydroxyl Radical Kinetics to Assess the Number-Average Molecular Weight of Dissolved Organic Matter
    Appiani, Elena; Page, Sarah E.; McNeill, Kristopher
    Environmental Science & Technology (2014), 48 (20), 11794-11802CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    An indirect method to assess the av. size of dissolved org. matter (DOM) is described, which is based on the reaction of hydroxyl radical (HO•) quenching by DOM. HO• is often assumed to be relatively unselective, reacting with nearly all org. mols. with similar rate consts. Literature values for HO• reaction with org. mols. were surveyed to assess the unselectivity of DOM and to det. a representative quenching rate const. (krep =5.6 × 109/M-s). This value was used to assess the av. mol. wt. of various humic and fulvic acid isolates as model DOM, using literature HO• quenching consts., kC,DOM. The results obtained by this method were compared with previous ests. of av. mol. wt. The av. mol. wt. (Mn) values obtained with this approach are lower than the Mn measured by other techniques such as size exclusion chromatog. (SEC), vapor pressure osmometry (VPO), and flow field fractionation (FFF). This suggests that DOM is an esp. good quencher for HO•, reacting at rates close to the diffusion-control limit. It was further obsd. that humic acids generally react faster than fulvic acids. The high reactivity of humic acids toward HO• is in line with the antioxidant properties of DOM. The benefit of this method is that it provides a firm upper bound on the av. mol. wt. of DOM, based on the kinetic limits of the HO• reaction. The results indicate low av. mol. wt. values, which is most consistent with the recent understanding of DOM. A possible DOM size distribution is discussed to reconcile the small nature of DOM with the large-mol. behavior obsd. in other studies.
  40. 40
    Sha, H.; Nie, J.; Lian, L.; Yan, S.; Song, W. Phototransformation of an emerging cyanotoxin (Aerucyclamide A) in simulated natural waters. Water Res. 2021, 201, 117339,  DOI: 10.1016/j.watres.2021.117339
    Google Scholar
    There is no corresponding record for this reference.

Cited By

Click to copy section linkSection link copied!

This article has not yet been cited by other publications.

Download PDF
Go to Environmental Science & Technology
Get e-Alerts
Get e-Alerts

Environmental Science & Technology

Cite this: Environ. Sci. Technol. 2024, 58, 26, 11802–11811
Click to copy citationCitation copied!
https://doi.org/10.1021/acs.est.4c02242
Published June 17, 2024

Copyright © 2024 The Authors. Published by American Chemical Society. This publication is licensed under

CC-BY 4.0 .

Article Views

1663

Altmetric

-

Citations

-
Learn about these metrics

Article Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.

Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.

The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated.

  • Abstract

    High Resolution Image
    Download MS PowerPoint Slide

    Figure 1

    Figure 1. Representative cyano-metabolites detected in Microcystis aeruginosa and Planktothrix rubescens cultures. Highlighted moieties represent the parts of the molecules that can vary in the other cyano-metabolites of the same class identified in this study. Circles indicate the main attack sites of the O3. The full lists of cyano-metabolites and their structures are provided in Table S4, Tables S11–S14, and Figure S5.

    High Resolution Image
    Download MS PowerPoint Slide

    Figure 2

    Figure 2. Simultaneous abatement of (a) the selected competitors and (b) representative cyano-metabolites from 0.6 gbiomass L–1 of Microcystis as a function of the specific O3 dose at pH 7 (2 mM phosphate) and 22 °C and in the presence of tert-butanol (40 mM). For the abbreviations of the competitors, see Table 1 (except VM which stands for vancomycin).

    High Resolution Image
    Download MS PowerPoint Slide

    Figure 3

    Figure 3. Competitor evaluation during the ozonation of a Microcystis extract (0.6 gbiomass L–1) at pH 7 (2 mM phosphate) and 22 °C and in the presence of tert-butanol (40 mM). The evaluation was done by calculating the ratios between the kapp,O3 determined by pairs of competitors (kmeasured) and the kapp,O3 from the literature (kliterature, see Table 1). Panels (a) and (b) show the kmeasured/kliterature ratios using unmodified and adjusted kliterature, respectively (only kliterature of CBF and DMP were adjusted; see explanation in the text). The vertical lines correspond to the limits for the acceptable kmeasured/kliterature range, set between 0.5 and 2. For the abbreviations of the competitors see Table 1 (except VM which stands for vancomycin).

    High Resolution Image
    Download MS PowerPoint Slide

  • References

    This article references 40 other publications.

    1. 1
      Whitton, B. A.; Potts, M. Introduction to the Cyanobacteria. In Ecology of Cyanobacteria II: Their Diversity in Space and Time; Whitton, B. A., Ed.; Springer Netherlands: Dordrecht, 2012; pp 1– 13.
      There is no corresponding record for this reference.
    2. 2
      Hauer, T.; Komárek, J. CyanoDB 2.0- On-line database of cyanobacterial genera; University of South Bohemia and Institute of Botany, Academy of Sciences of the Czech Republic: 2022.
      There is no corresponding record for this reference.
    3. 3
      Huisman, J.; Codd, G. A.; Paerl, H. W.; Ibelings, B. W.; Verspagen, J. M. H.; Visser, P. M. Cyanobacterial blooms. Nat. Rev. Microbiol 2018, 16 (8), 471– 483,  DOI: 10.1038/s41579-018-0040-1
      3
      Cyanobacterial blooms
      Huisman, Jef; Codd, Geoffrey A.; Paerl, Hans W.; Ibelings, Bas W.; Verspagen, Jolanda M. H.; Visser, Petra M.
      Nature Reviews Microbiology (2018), 16 (8), 471-483CODEN: NRMACK; ISSN:1740-1526. (Nature Research)
      A review. Cyanobacteria can form dense and sometimes toxic blooms in freshwater and marine environments, which threaten ecosystem functioning and degrade water quality for recreation, drinking water, fisheries and human health. Here, we review evidence indicating that cyanobacterial blooms are increasing in frequency, magnitude and duration globally. We highlight species traits and environmental conditions that enable cyanobacteria to thrive and explain why eutrophication and climate change catalyze the global expansion of cyanobacterial blooms. Finally, we discuss management strategies, including nutrient load redns., changes in hydrodynamics and chem. and biol. controls, that can help to prevent or mitigate the proliferation of cyanobacterial blooms.
    4. 4
      He, X.; Liu, Y.-L.; Conklin, A.; Westrick, J.; Weavers, L. K.; Dionysiou, D. D.; Lenhart, J. J.; Mouser, P. J.; Szlag, D.; Walker, H. W. Toxic cyanobacteria and drinking water: Impacts, detection, and treatment. Harmful Algae 2016, 54, 174– 193,  DOI: 10.1016/j.hal.2016.01.001
      4
      Toxic cyanobacteria and drinking water: Impacts, detection, and treatment
      He, Xuexiang; Liu, Yen-Ling; Conklin, Amanda; Westrick, Judy; Weavers, Linda K.; Dionysiou, Dionysios D.; Lenhart, John J.; Mouser, Paula J.; Szlag, David; Walker, Harold W.
      Harmful Algae (2016), 54 (), 174-193CODEN: HAALDD; ISSN:1568-9883. (Elsevier B.V.)
      Blooms of toxic cyanobacteria in water supply systems are a global issue affecting water supplies on every major continent except Antarctica. The occurrence of toxic cyanobacteria in freshwater is increasing in both frequency and distribution. The protection of water supplies has therefore become increasingly more challenging. To reduce the risk from toxic cyanobacterial blooms in drinking water, a multi-barrier approach is needed, consisting of prevention, source control, treatment optimization, and monitoring. In this paper, current research on some of the crit. elements of this multi-barrier approach are reviewed and synthesized, with an emphasis on the effectiveness of water treatment technologies for removing cyanobacteria and related toxic compds. This paper synthesizes and updates a no. of previous review articles on various aspects of this multi-barrier approach in order to provide a holistic resource for researchers, water managers and engineers, as well as water treatment plant operators.
    5. 5
      Beversdorf, L. J.; Rude, K.; Weirich, C. A.; Bartlett, S. L.; Seaman, M.; Kozik, C.; Biese, P.; Gosz, T.; Suha, M.; Stempa, C.; Shaw, C.; Hedman, C.; Piatt, J. J.; Miller, T. R. Analysis of cyanobacterial metabolites in surface and raw drinking waters reveals more than microcystin. Water Res. 2018, 140, 280– 290,  DOI: 10.1016/j.watres.2018.04.032
      5
      Analysis of cyanobacterial metabolites in surface and raw drinking waters reveals more than microcystin
      Beversdorf, Lucas J.; Rude, Kayla; Weirich, Chelsea A.; Bartlett, Sarah L.; Seaman, Mary; Kozik, Christine; Biese, Peter; Gosz, Timothy; Suha, Michael; Stempa, Christopher; Shaw, Christopher; Hedman, Curtis; Piatt, Joseph J.; Miller, Todd R.
      Water Research (2018), 140 (), 280-290CODEN: WATRAG; ISSN:0043-1354. (Elsevier Ltd.)
      Freshwater cyanobacterial blooms are becoming increasingly problematic in regions that rely on surface waters for drinking water prodn. Microcystins (MCs) are toxic peptides produced by multiple cyanobacterial genera with a global occurrence. Cyanobacteria also produce a variety of other toxic and/or otherwise bioactive peptides (TBPs) that have gained less attention including cyanopeptolins (Cpts), anabaenopeptins (Apts), and microginins (Mgn). In this study, we compared temporal and spatial trends of four MCs (MCLR, MCRR, MCYR, MCLA), three Cpts (Cpt1020, Cpt1041, Cpt1007), two Apts (AptF, AptB), and Mgn690 in raw drinking water and at six surface water locations above these drinking water intakes in a eutrophic lake. All four MC congeners and five of six TBPs were detected in lake and raw drinking water. Across all samples, MCLR was the most frequently detected metabolite (100% of samples) followed by MCRR (97%) > Cpt1007 (74%) > MCYR (69%) > AptF (67%) > MCLA (61%) > AptB (54%) > Mgn690 (29%) and Cpt1041 (15%). Mean concns. of MCs, Apts, and Cpts into two drinking water intakes were 3.9± 4.7, 0.14± 0.21, and 0.38± 0.92, resp. Mean concns. in surface water were significantly higher (p<0.05) than in drinking water intakes for MCs but not for Cpts and Apts. Temporal trends in MCs, Cpts, and Apts in the two raw drinking water intakes were significantly correlated (p < 0.05) with measures of cell abundance (chlorophyll-a, Microcystis cell d.), UV absorbance, and turbidity in surface water. This study expands current information about cyanobacterial TBPs that occur in lakes and that enter drinking water treatment plants and underscores the need to det. the fate of less studied cyanobacterial metabolites during drinking water treatment that may exacerbate toxicity of more well-known cyanobacterial toxins.
    6. 6
      Bullerjahn, G. S.; McKay, R. M.; Davis, T. W.; Baker, D. B.; Boyer, G. L.; D’Anglada, L. V.; Doucette, G. J.; Ho, J. C.; Irwin, E. G.; Kling, C. L.; Kudela, R. M.; Kurmayer, R.; Michalak, A. M.; Ortiz, J. D.; Otten, T. G.; Paerl, H. W.; Qin, B.; Sohngen, B. L.; Stumpf, R. P.; Visser, P. M.; Wilhelm, S. W. Global solutions to regional problems: Collecting global expertise to address the problem of harmful cyanobacterial blooms. A Lake Erie case study. Harmful Algae 2016, 54, 223– 238,  DOI: 10.1016/j.hal.2016.01.003
      6
      Global solutions to regional problems: Collecting global expertise to address the problem of harmful cyanobacterial blooms. A Lake Erie case study
      Bullerjahn George S; McKay Robert M; Davis Timothy W; Baker David B; Boyer Gregory L; D'Anglada Lesley V; Doucette Gregory J; Ho Jeff C; Irwin Elena G; Sohngen Brent L; Kling Catherine L; Kudela Raphael M; Kurmayer Rainer; Michalak Anna M; Ortiz Joseph D; Otten Timothy G; Paerl Hans W; Qin Boqiang; Stumpf Richard P; Visser Petra M; Wilhelm Steven W
      Harmful algae (2016), 54 (), 223-238 ISSN:.
      In early August 2014, the municipality of Toledo, OH (USA) issued a 'do not drink' advisory on their water supply directly affecting over 400,000 residential customers and hundreds of businesses (Wilson, 2014). This order was attributable to levels of microcystin, a potent liver toxin, which rose to 2.5μgL(-1) in finished drinking water. The Toledo crisis afforded an opportunity to bring together scientists from around the world to share ideas regarding factors that contribute to bloom formation and toxigenicity, bloom and toxin detection as well as prevention and remediation of bloom events. These discussions took place at an NSF- and NOAA-sponsored workshop at Bowling Green State University on April 13 and 14, 2015. In all, more than 100 attendees from six countries and 15 US states gathered together to share their perspectives. The purpose of this review is to present the consensus summary of these issues that emerged from discussions at the Workshop. As additional reports in this special issue provide detailed reviews on many major CHAB species, this paper focuses on the general themes common to all blooms, such as bloom detection, modeling, nutrient loading, and strategies to reduce nutrients.
    7. 7
      Tanber, G. Toxin leaves 500,000 in northwest Ohio without drinking water. Reuters , 2014.
      There is no corresponding record for this reference.
    8. 8
      WHO. Guidelines for Drinking-Water Quality, 4th ed.; WHO: Geneva, 2017.
      There is no corresponding record for this reference.
    9. 9
      von Sonntag, C.; von Gunten, U. Chemistry of Ozone in Water and Wastewater Treatment: From Basic Principles to Applications; International Water Association: 2012.
      There is no corresponding record for this reference.
    10. 10
      Rougé, V.; von Gunten, U.; Lafont de Sentenac, M.; Massi, M.; Wright, P. J.; Croué, J.-P.; Allard, S. Comparison of the impact of ozone, chlorine dioxide, ferrate and permanganate pre-oxidation on organic disinfection byproduct formation during post-chlorination. Environ. Sci. Water Res. Technol. 2020, 6 (9), 2382– 2395,  DOI: 10.1039/D0EW00411A
      10
      Comparison of the impact of ozone, chlorine dioxide, ferrate and permanganate pre-oxidation on organic disinfection byproduct formation during post-chlorination
      Rouge, Valentin; von Gunten, Urs; Lafont de Sentenac, Mariette; Massi, Massimiliano; Wright, Phillip J.; Croue, Jean-Philippe; Allard, Sebastien
      Environmental Science: Water Research & Technology (2020), 6 (9), 2382-2395CODEN: ESWRAR; ISSN:2053-1419. (Royal Society of Chemistry)
      A comparative study of the impact of four pre-oxidants, ozone (O3), chlorine dioxide (ClO2), permanganate (Mn(VII)) and ferrate (Fe(VI)), on the formation of trihalomethanes (THMs), haloacetonitriles (HANs) and adsorbable org. halogens (AOX) in chlorinated synthetic and real waters was conducted. The influence of pH (6.5-8.1) and bromide (0-500μg L-1) was evaluated in terms of disinfection byproduct (DBP) formation and theor. toxicity assessment (based on THM and HAN formation). All oxidants were efficient in mitigating chlorinated DBPs, except Mn(VII) which had little impact on THM formation. The pH depression improved AOX mitigation by O3 and Fe(VI) but diminished Mn(VII) efficiency for all DBPs. Pre-oxidn. was less efficient in mitigating brominated DBPs and generally enhanced the bromine substitution factor. Although HANs were formed at low concns. compared to THMs, they dominated the calcd. toxicity, particularly the brominated HANs. The increased dibromoacetonitrile formation after pre-oxidn. was a major factor counteracting the benefits of the overall DBP mitigation. In the presence of bromide, the pre-oxidant dose should be optimized to decrease the reactivity of the matrix while controlling the toxicity induced by formation of brominated DBPs, notably brominated HANs.
    11. 11
      Rodríguez, E.; Onstad, G. D.; Kull, T. P. J.; Metcalf, J. S.; Acero, J. L.; von Gunten, U. Oxidative elimination of cyanotoxins: Comparison of ozone, chlorine, chlorine dioxide and permanganate. Water Res. 2007, 41 (15), 3381– 3393,  DOI: 10.1016/j.watres.2007.03.033
      11
      Oxidative elimination of cyanotoxins: Comparison of ozone, chlorine, chlorine dioxide and permanganate
      Rodriguez, Eva; Onstad, Gretchen D.; Kull, Tomas P. J.; Metcalf, James S.; Acero, Juan L.; von Gunten, Urs
      Water Research (2007), 41 (15), 3381-3393CODEN: WATRAG; ISSN:0043-1354. (Elsevier Ltd.)
      As the World Health Organization (WHO) progresses with provisional Drinking Water Guidelines of 1 μg/L for microcystin-LR and a proposed Guideline of 1 μg/L for cylindrospermopsin, efficient treatment strategies are needed to prevent cyanotoxins such as these from reaching consumers. A kinetic database has been compiled for the oxidative treatment of three cyanotoxins: microcystin-LR (MC-LR), cylindrospermopsin (CYN), and anatoxin-a (ANTX) with ozone, chlorine, chlorine dioxide and permanganate. This kinetic database contains rate consts. not previously reported and detd. in the present work (e.g. for permanganate oxidn. of ANTX and chlorine dioxide oxidn. of CYN and ANTX), together with previously published rate consts. for the remaining oxidn. processes. Second-order rate consts. measured in pure aq. solns. of these toxins could be used in a kinetic model to predict the toxin oxidn. efficiency of ozone, chlorine, chlorine dioxide and permanganate when applied to natural waters. Oxidants were applied to water from a eutrophic Swiss lake (Lake Greifensee) in static-dose testing and dynamic time-resolved expts. to confirm predictions from the kinetic database, and to investigate the effects of a natural matrix on toxin oxidn. and byproduct formation. Overall, permanganate can effectively oxidize ANTX and MC-LR, while chlorine will oxidize CYN and MC-LR and ozone is capable of oxidizing all three toxins with the highest rate. The formation of trihalomethanes (THMs) in the treated water may be a restriction to the application of sufficiently high-chlorine doses.
    12. 12
      Onstad, G. D.; Strauch, S.; Meriluoto, J.; Codd, G. A.; von Gunten, U. Selective Oxidation of Key Functional Groups in Cyanotoxins during Drinking Water Ozonation. Environ. Sci. Technol. 2007, 41 (12), 4397– 4404,  DOI: 10.1021/es0625327
      12
      Selective Oxidation of Key Functional Groups in Cyanotoxins during Drinking Water Ozonation
      Onstad, Gretchen D.; Strauch, Sabine; Meriluoto, Jussi; Codd, Geoffrey A.; von Gunten, Urs
      Environmental Science & Technology (2007), 41 (12), 4397-4404CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      Chem. kinetics were detd. for the reactions of ozone and hydroxyl radicals with the three cyanotoxins microcystin-LR (MC-LR), cylindrospermopsin (CYN) and anatoxin-a (ANTX). The second-order rate consts. (kO3) at pH 8 were 4.1 ± 0.1 × 105 M-1 s-1 for MC-LR, ∼3.4 × 105 M-1 s-1 for CYN, and ∼6.4 × 104 M-1 s-1 for ANTX. The reaction of ozone with MC-LR exhibits a kO3 similar to that of the conjugated diene in sorbic acid (9.6 ± 0.3 × 105 M-1 s-1) at pH 8. The pH dependence and value of kO3 for CYN at pH > 8 (∼2.5 ± 0.1 × 106 M-1 s-1) are similar to deprotonated amines of 6-methyluracil. The kO3 of ANTX at pH > 9 (∼8.7 ± 2.2 × 105 M-1 s-1) agrees with that of neutral diethylamine, and the value at pH < 8 (2.8 ± 0.2 × 104 M-1 s-1) corresponds to an olefin. Second-order rate consts. for reaction with OH radicals (•OH), kOH for cyanotoxins were measured at pH 7 to be 1.1 ± 0.01 × 1010 M-1 s-1 for MC-LR, 5.5 ± 0.01 × 109 M-1 s-1 for CYN, and 3.0 ± 0.02 × 109 M-1 s-1 for ANTX. Natural waters from Switzerland and Finland were examd. for the influence of variations of dissolved org. matter, SUVA254, and alky. on cyanotoxin oxidn. For a Swiss water (1.6 mg/L DOC), 0.2, 0.4, and 0.8 mg/L ozone doses were required for 95% oxidn. of MC-LR, CYN, and ANTX, resp. For the Finnish water (13.1 mg/L DOC), >2 mg/L ozone dose was required for each toxin. The contribution of hydroxyl radicals to toxin oxidn. during ozonation of natural water was greatest for ANTX > CYN > MC-LR. Overall, the order of reactivity of cyanotoxins during ozonation of natural waters corresponds to the relative magnitudes of the second-order rate consts. for their reaction with ozone and •OH. Ozone primarily attacks the structural moieties responsible for the toxic effects of MC-LR, CYN, and ANTX, suggesting that ozone selectively detoxifies these cyanotoxins.
    13. 13
      Jones, M. R.; Pinto, E.; Torres, M. A.; Dörr, F.; Mazur-Marzec, H.; Szubert, K.; Tartaglione, L.; Dell’Aversano, C.; Miles, C. O.; Beach, D. G.; McCarron, P.; Sivonen, K.; Fewer, D. P.; Jokela, J.; Janssen, E. M. L. CyanoMetDB, a comprehensive public database of secondary metabolites from cyanobacteria. Water Res. 2021, 196, 117017,  DOI: 10.1016/j.watres.2021.117017
      13
      CyanoMetDB, a comprehensive public database of secondary metabolites from cyanobacteria
      Jones, Martin R.; Pinto, Ernani; Torres, Mariana A.; Dorr, Fabiane; Mazur-Marzec, Hanna; Szubert, Karolina; Tartaglione, Luciana; Dell'Aversano, Carmela; Miles, Christopher O.; Beach, Daniel G.; McCarron, Pearse; Sivonen, Kaarina; Fewer, David P.; Jokela, Jouni; Janssen, Elisabeth M.-L.
      Water Research (2021), 196 (), 117017CODEN: WATRAG; ISSN:0043-1354. (Elsevier Ltd.)
      A review. Harmful cyanobacterial blooms, which frequently contain toxic secondary metabolites, are reported in aquatic environments around the world. More than two thousand cyanobacterial secondary metabolites have been reported from diverse sources over the past fifty years. A comprehensive, publically-accessible database detailing these secondary metabolites would facilitate research into their occurrence, functions and toxicol. risks. To address this need we created CyanoMetDB, a highly curated, flat-file, openly-accessible database of cyanobacterial secondary metabolites collated from 850 peer-reviewed articles published between 1967 and 2020. CyanoMetDB contains 2010 cyanobacterial metabolites and 99 structurally related compds. This has nearly doubled the no. of entries with complete literature metadata and structural compn. information compared to previously available open access databases. The dataset includes microcytsins, cyanopeptolins, other depsipeptides, anabaenopeptins, microginins, aeruginosins, cyclamides, cryptophycins, saxitoxins, spumigins, microviridins, and anatoxins among other metabolite classes. A comprehensive database dedicated to cyanobacterial secondary metabolites facilitates: (1) the detection and dereplication of known cyanobacterial toxins and secondary metabolites; (2) the identification of novel natural products from cyanobacteria; (3) research on biosynthesis of cyanobacterial secondary metabolites, including substructure searches; and (4) the investigation of their abundance, persistence, and toxicity in natural environments.
    14. 14
      Janssen, E. M.-L. J.; Martin, R.; Pinto, E.; Dörr, F.; Torres, M. A.; Rios Jacinavicius, F.; Mazur-Marzec, H.; Szubert, K.; Konkel, R.; Tartaglione, L.; Dell’Aversano, C.; Miglione, A.; McCarron, P.; Beach, D. G.; Miles, C. O.; Fewer, D. P.; Sivonen, K.; Jokela, J.; Wahlsten, M.; Niedermeyer, T. H. J.; Schanbacher, F.; Leão, P.; Preto, M.; D’Agostino, P. M.-L.; Baunach, M.; Dittmann, E.; Reher, R. S75 | CyanoMetDB | Comprehensive database of secondary metabolites from cyanobacteria (NORMAN-SLE-S75.0.2.0) [Data set]. In Zenodo , 2023.
      There is no corresponding record for this reference.
    15. 15
      Lim, S.; Shi, J. L.; von Gunten, U.; McCurry, D. L. Ozonation of organic compounds in water and wastewater: A critical review. Water Res. 2022, 213, 118053,  DOI: 10.1016/j.watres.2022.118053
      15
      Ozonation of organic compounds in water and wastewater: A critical review
      Lim, Sungeun; Shi, Jiaming Lily; von Gunten, Urs; McCurry, Daniel L.
      Water Research (2022), 213 (), 118053CODEN: WATRAG; ISSN:0043-1354. (Elsevier Ltd.)
      A review. Ozonation has been applied in water treatment for more than a century, first for disinfection, later for oxidn. of inorg. and org. pollutants. In recent years, ozone has been increasingly applied for enhanced municipal wastewater treatment for ecosystem protection and for potable water reuse. These applications triggered significant research efforts on the abatement efficiency of org. contaminants and the ensuing formation of transformation products. This endeavor was accompanied by developments in anal. and computational chem., which allowed to improve the mechanistic understanding of ozone reactions. This crit. review assesses the challenges of ozonation of impaired water qualities such as wastewaters and provides an up-to-date compilation of the recent kinetic and mechanistic findings of ozone reactions with dissolved org. matter, various functional groups (olefins, arom. compds., heterocyclic compds., aliph. nitrogen-contg. compds., sulfur-contg. compds., hydrocarbons, carbanions, β-diketones) and antibiotic resistance genes.
    16. 16
      Schwarzenbach, R. P.; Gschwend, P. M.; Imboden, D. M. Environmental Organic Chemistry, 2nd ed.; John Wiley & Sons: Hoboken, NJ, 2002; pp 245– 274.
      There is no corresponding record for this reference.
    17. 17
      Dodd, M. C.; Buffle, M.-O.; von Gunten, U. Oxidation of Antibacterial Molecules by Aqueous Ozone: Moiety-Specific Reaction Kinetics and Application to Ozone-Based Wastewater Treatment. Environ. Sci. Technol. 2006, 40 (6), 1969– 1977,  DOI: 10.1021/es051369x
      17
      Oxidation of Antibacterial Molecules by Aqueous Ozone: Moiety-Specific Reaction Kinetics and Application to Ozone-Based Wastewater Treatment
      Dodd, Michael C.; Buffle, Marc-Olivier; von Gunten, Urs
      Environmental Science & Technology (2006), 40 (6), 1969-1977CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      Ozone and hydroxyl radical (•OH) reaction kinetics were measured for 14 antibacterial compds. from nine structural families, to det. whether municipal wastewater ozonation is likely to result in selective oxidn. of these compds.' biochem. essential moieties. Each substrate is oxidized by ozone with an apparent 2nd-order rate const., k''O3,app > 1 × 103/M-s, at pH 7, with the exception of N(4)-acetylsulfamethoxazole (k''O3,app is 2.5 × 102/M-s). K''O3,app values (pH 7) for macrolides, sulfamethoxazole, trimethoprim, tetracycline, vancomycin, and amikacin appear to correspond directly to oxidn. of biochem. essential moieties. Initial reactions of ozone with N(4)-acetylsulfamethoxazole, fluoroquinolones, lincomycin, and β-lactams do not lead to appreciable oxidn. of biochem. essential moieties. However, ozone oxidizes these moieties within fluoroquinolones and lincomycin via slower reactions. Measured k''O3,app values and 2nd-order •OH rate consts., k''•OH,app, were utilized to characterize pollutant losses during ozonization of secondary municipal wastewater effluent. These losses depended on k''O3,app, but independent of k''•OH,app. Ozone doses ≥3 mg/L yielded ≥99% depletion of fast-reacting substrates (k''O3,app >5 × 104/M-s) at pH 7.7. Ten substrates reacted predominantly with ozone; only 4 were oxidized predominantly by •OH. These results indicate that many antibacterial compds. will be oxidized in wastewater via moiety-specific reactions with ozone.
    18. 18
      Natumi, R.; Dieziger, C.; Janssen, E. M. L. Cyanobacterial Toxins and Cyanopeptide Transformation Kinetics by Singlet Oxygen and pH-Dependence in Sunlit Surface Waters. Environ. Sci. Technol. 2021, 55 (22), 15196– 15205,  DOI: 10.1021/acs.est.1c04194
      There is no corresponding record for this reference.
    19. 19
      Jones, M.; Janssen, E. M. L. Quantification of Multi-class Cyanopeptides in Swiss Lakes with Automated Extraction, Enrichment and Analysis by Online-SPE HPLC-HRMS/MS. CHIMIA 2022, 76 (1–2), 133– 144,  DOI: 10.2533/chimia.2022.133
      There is no corresponding record for this reference.
    20. 20
      Portmann, C.; Blom, J. F.; Gademann, K.; Jüttner, F. Aerucyclamides A and B: Isolation and Synthesis of Toxic Ribosomal Heterocyclic Peptides from the Cyanobacterium Microcystis aeruginosa PCC 7806. J. Nat. Prod. 2008, 71 (7), 1193– 1196,  DOI: 10.1021/np800118g
      20
      Aerucyclamides A and B: isolation and synthesis of toxic ribosomal heterocyclic peptides from the cyanobacterium Microcystis aeruginosa PCC 7806
      Portmann, Cyril; Blom, Judith F.; Gademann, Karl; Juttner, Friedrich
      Journal of Natural Products (2008), 71 (7), 1193-1196CODEN: JNPRDF; ISSN:0163-3864. (American Chemical Society-American Society of Pharmacognosy)
      Two new modified hexacyclopeptides, aerucyclamides A and B, were isolated from the toxic freshwater cyanobacterium M. aeruginosa PCC 7806. The constitution was assigned by spectroscopic methods, and the configuration detd. by chem. degrdn. and anal. by Marfey's method combined with chem. synthesis. Synthetic aerucyclamide B was obtained through oxidn. of aerucyclamide A (MnO2, benzene). The aerucyclamides were toxic to the freshwater crustacean Thamnocephalus platyurus, exhibiting LC50 values for congeners A and B of 30.5 and 33.8 μM, resp.
    21. 21
      Natumi, R.; Marcotullio, S.; Janssen, E. M. L. Phototransformation kinetics of cyanobacterial toxins and secondary metabolites in surface waters. Environ. Sci. Eur. 2021, 33 (1), 26,  DOI: 10.1186/s12302-021-00465-3
      There is no corresponding record for this reference.
    22. 22
      Ruttkies, C.; Schymanski, E. L.; Wolf, S.; Hollender, J.; Neumann, S. MetFrag relaunched: incorporating strategies beyond in silico fragmentation. J. Cheminformatics 2016, 8 (1), 3,  DOI: 10.1186/s13321-016-0115-9
      22
      MetFrag relaunched: incorporating strategies beyond in silico fragmentation
      Ruttkies, Christoph; Schymanski, Emma L.; Wolf, Sebastian; Hollender, Juliane; Neumann, Steffen
      Journal of Cheminformatics (2016), 8 (), 3/1-3/16CODEN: JCOHB3; ISSN:1758-2946. (Chemistry Central Ltd.)
      Background: The in silico fragmenter MetFrag, launched in 2010, was one of the first approaches combining compd. database searching and fragmentation prediction for small mol. identification from tandem mass spectrometry data. Since then many new approaches have evolved, as has MetFrag itself. This article details the latest developments to MetFrag and its use in small mol. identification since the original publication. Results: MetFrag has gone through algorithmic and scoring refinements. New features include the retrieval of ref., data source and patent information via ChemSpider and PubChem web services, as well as InChIKey filtering to reduce candidate redundancy due to stereoisomerism. Candidates can be filtered or scored differently based on criteria like occurrence of certain elements and/or substructures prior to fragmentation, or presence in so-called "suspect lists". Retention time information can now be calcd. either within MetFrag with a sufficient amt. of user-provided retention times, or incorporated sep. as "user-defined scores" to be included in candidate ranking. The changes to MetFrag were evaluated on the original dataset as well as a dataset of 473 merged high resoln. tandem mass spectra (HR-MS/MS) and compared with another open source in silico fragmenter, CFM-ID. Using HR-MS/MS information only, MetFrag2.2 and CFM-ID had 30 and 43 Top 1 ranks, resp., using PubChem as a database. Including ref. and retention information in MetFrag2.2 improved this to 420 and 336 Top 1 ranks with ChemSpider and PubChem (89 and 71 %), resp., and even up to 343 Top 1 ranks (PubChem) when combining with CFM-ID. The optimal parameters and wts. were verified using three addnl. datasets of 824 merged HR-MS/MS spectra in total. Further examples are given to demonstrate flexibility of the enhanced features. Conclusions: In many cases addnl. information is available from the exptl. context to add to small mol. identification, which is esp. useful where the mass spectrum alone is not sufficient for candidate selection from a large no. of candidates. The results achieved with MetFrag2.2 clearly show the benefit of considering this addnl. information. The new functions greatly enhance the chance of identification success and have been incorporated into a command line interface in a flexible way designed to be integrated into high throughput workflows.
    23. 23
      Dührkop, K.; Fleischauer, M.; Ludwig, M.; Aksenov, A. A.; Melnik, A. V.; Meusel, M.; Dorrestein, P. C.; Rousu, J.; Böcker, S. SIRIUS 4: a rapid tool for turning tandem mass spectra into metabolite structure information. Nat. Methods 2019, 16 (4), 299– 302,  DOI: 10.1038/s41592-019-0344-8
      23
      SIRIUS 4: a rapid tool for turning tandem mass spectra into metabolite structure information
      Duehrkop, Kai; Fleischauer, Markus; Ludwig, Marcus; Aksenov, Alexander A.; Melnik, Alexey V.; Meusel, Marvin; Dorrestein, Pieter C.; Rousu, Juho; Boecker, Sebastian
      Nature Methods (2019), 16 (4), 299-302CODEN: NMAEA3; ISSN:1548-7091. (Nature Research)
      Mass spectrometry is a predominant exptl. technique in metabolomics and related fields, but metabolite structural elucidation remains highly challenging. We report SIRIUS 4 (https://bio.informatik.uni-jena.de/sirius/), which provides a fast computational approach for mol. structure identification. SIRIUS 4 integrates CSI:FingerID for searching in mol. structure databases. Using SIRIUS 4, we achieved identification rates of more than 70% on challenging metabolomics datasets.
    24. 24
      Schymanski, E. L.; Jeon, J.; Gulde, R.; Fenner, K.; Ruff, M.; Singer, H. P.; Hollender, J. Identifying Small Molecules via High Resolution Mass Spectrometry: Communicating Confidence. Environ. Sci. Technol. 2014, 48 (4), 2097– 2098,  DOI: 10.1021/es5002105
      24
      Identifying Small Molecules via High Resolution Mass Spectrometry: Communicating Confidence
      Schymanski, Emma L.; Jeon, Junho; Gulde, Rebekka; Fenner, Kathrin; Ruff, Matthias; Singer, Heinz P.; Hollender, Juliane
      Environmental Science & Technology (2014), 48 (4), 2097-2098CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      A method and framework for describing the identification of small mols. by high resoln. mass spectrometry (HRMS) is presented. A 5 level classification scheme was developed to indicate the proposed identification confidence levels in HRMS. The levels are confirmed structure, probable structure, substance class, unequivocal mol. formula, and exact mass of interest.
    25. 25
      David Yao, C. C.; Haag, W. R. Rate constants for direct reactions of ozone with several drinking water contaminants. Water Res. 1991, 25 (7), 761– 773,  DOI: 10.1016/0043-1354(91)90155-J
      There is no corresponding record for this reference.
    26. 26
      Huber, M. M.; Canonica, S.; Park, G.-Y.; von Gunten, U. Oxidation of Pharmaceuticals during Ozonation and Advanced Oxidation Processes. Environ. Sci. Technol. 2003, 37 (5), 1016– 1024,  DOI: 10.1021/es025896h
      26
      Oxidation of Pharmaceuticals during Ozonation and Advanced Oxidation Processes
      Huber, Marc M.; Canonica, Silvio; Park, Gun-Young; von Gunten, Urs
      Environmental Science and Technology (2003), 37 (5), 1016-1024CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      Oxidn. of pharmaceuticals during conventional ozonation and advanced oxidn. processes (AOP) in drinking water purifn. was studied. In a first step, second-order rate consts. for reactions of selected pharmaceuticals with O3 (kO3) and OH- (kOH) were detd. in bench-scale expts. (apparent kO3 at pH 7 and 20°): bezafibrate (590 ± 50/M-s), carbamazepine (∼3 × 105/M-s), diazepam (0.75 ± 0.15/M-s), diclofenac (∼1 × 106/M-s), 17α-ethinylestradiol (∼3 × 106/M-s), ibuprofen (9.6 ± 1.0/M-s), iopromide (<0.8/M-s), sulfamethoxazole (∼2.5 × 106/M-s), and roxithromycin (∼7 × 104/M-s). For 5 of the pharmaceuticals, apparent kO3 at pH 7 was >5 × 104/M-s, indicating these compds. are completely transformed during ozonation. KOH values were from 3.3 to 9.8 × 109/M-s. Compared to other important micro-pollutants, e.g., Me tert-Bu ether (MTBE) and atrazine, the selected pharmaceuticals reacted about 2-3 times faster with OH-. In the second part of the study, oxidn. kinetics of selected pharmaceuticals were examd. in ozonation expts. performed in different natural water. Second-order rate consts. detd. in pure aq. soln. could be applied to predict behavior of pharmaceuticals dissolved in natural water. Overall it was concluded that ozonation and AOP are promising processes to efficiently remove pharmaceuticals in drinking water.
    27. 27
      Wolf, C.; von Gunten, U.; Kohn, T. Kinetics of Inactivation of Waterborne Enteric Viruses by Ozone. Environ. Sci. Technol. 2018, 52 (4), 2170– 2177,  DOI: 10.1021/acs.est.7b05111
      27
      Kinetics of Inactivation of Waterborne Enteric Viruses by Ozone
      Wolf, Camille; von Gunten, Urs; Kohn, Tamar
      Environmental Science & Technology (2018), 52 (4), 2170-2177CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      Ozone is an effective disinfectant against all types of waterborne pathogens. However, accurate and quant. kinetic data regarding virus inactivation by ozone are scarce, because of the exptl. challenges assocd. with the high reactivity of ozone toward viruses. Here, we established an exptl. batch system that allows tailoring and quantifying of very low ozone exposures and simultaneously measuring virus inactivation. Second-order ozone inactivation rate consts. (kO3-virus) of five enteric viruses [lab. and two environmental strains of coxsackievirus B5 (CVF, CVEnv1, and CVEnv2), human adenovirus (HAdV), and echovirus 11 (EV)] and four bacteriophages (MS2, Qβ, T4, and Φ174) were measured in buffered solns. The kO3-virus values of all tested viruses ranged from 4.5 × 105 to 3.3 × 106 M-1s-1. For MS2, kO3-MS2 depended only weakly on temp. (2-22 °C; Ea = 22.2 kJ mol-1) and pH (6.5-8.5), with an increase in kO3-MS2 with increasing pH. The susceptibility of the selected viruses toward ozone decreases in the following order: Qβ > CVEnv2 > EV ≈ MS2 > Φ174 ≈ T4 > HAdV > CVF ≈ CVEnv1. On the basis of the measured kO3-Virus and typical ozone exposures applied in water and wastewater treatment, we conclude that ozone is a highly effective disinfectant for virus control.
    28. 28
      Zimmermann, S. G.; Schmukat, A.; Schulz, M.; Benner, J.; von Gunten, U.; Ternes, T. A. Kinetic and Mechanistic Investigations of the Oxidation of Tramadol by Ferrate and Ozone. Environ. Sci. Technol. 2012, 46 (2), 876– 884,  DOI: 10.1021/es203348q
      28
      Kinetic and Mechanistic Investigations of the Oxidation of Tramadol by Ferrate and Ozone
      Zimmermann, Saskia G.; Schmukat, Annekatrin; Schulz, Manoj; Benner, Jessica; Gunten, Urs von; Ternes, Thomas A.
      Environmental Science & Technology (2012), 46 (2), 876-884CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      The kinetics and oxidn. products (OPs) of tramadol (TRA), an opioid, were investigated for its oxidn. with ferrate (Fe(VI)) and ozone (O3). The kinetics could be explained by the speciation of the tertiary amine moiety of TRA, with apparent second-order rate consts. of 7.4 (±0.4) M-1 s-1 (Fe(VI)) and 4.2 (±0.3) × 104 M-1 s-1 (O3) at pH 8.0, resp. In total, six OPs of TRA were identified for both oxidants using Qq-LIT-MS, LTQ-FT-MS, GC-MS, and moiety-specific chem. reactions. In excess of oxidants, these OPs can be further transformed to unidentified OPs. Kinetics and OP identification confirmed that the lone electron pair of the amine-N is the predominant site of oxidant attack. An oxygen transfer mechanism can explain the formation of N-oxide-TRA, while a one-electron transfer may result in the formation of N-centered radical cation intermediates, which could lead to the obsd. N-dealkylation, and to the identified formamide and aldehyde derivs. via several intermediate steps. The proposed radical intermediate mechanism is favored for Fe(VI) leading predominantly to N-desmethyl-TRA (ca. 40%), whereas the proposed oxygen transfer prevails for O3 attack resulting in N-oxide-TRA as the main OP (ca. 90%).
    29. 29
      Suarez, S.; Dodd, M. C.; Omil, F.; von Gunten, U. Kinetics of triclosan oxidation by aqueous ozone and consequent loss of antibacterial activity: Relevance to municipal wastewater ozonation. Water Res. 2007, 41 (12), 2481– 2490,  DOI: 10.1016/j.watres.2007.02.049
      There is no corresponding record for this reference.
    30. 30
      Lee, W.; Marcotullio, S.; Yeom, H.; Son, H.; Kim, T.-H.; Lee, Y. Reaction kinetics and degradation efficiency of halogenated methylparabens during ozonation and UV/H2O2 treatment of drinking water and wastewater effluent. J. Hazard. Mater. 2022, 427, 127878,  DOI: 10.1016/j.jhazmat.2021.127878
      There is no corresponding record for this reference.
    31. 31
      Kim, M. S.; Lee, C. Ozonation of Microcystins: Kinetics and Toxicity Decrease. Environ. Sci. Technol. 2019, 53 (11), 6427– 6435,  DOI: 10.1021/acs.est.8b06645
      There is no corresponding record for this reference.
    32. 32
      Janssen, E. M. L. Cyanobacterial peptides beyond microcystins - A review on co-occurrence, toxicity, and challenges for risk assessment. Water Res. 2019, 151, 488– 499,  DOI: 10.1016/j.watres.2018.12.048
      32
      Cyanobacterial peptides beyond microcystins - A review on co-occurrence, toxicity, and challenges for risk assessment
      Janssen, Elisabeth M.-L.
      Water Research (2019), 151 (), 488-499CODEN: WATRAG; ISSN:0043-1354. (Elsevier Ltd.)
      Cyanobacterial bloom events that produce natural toxins occur in freshwaters across the globe, yet the potential risk of many cyanobacterial metabolites remains mostly unknown. Only microcystins, one class of cyanopeptides, have been studied intensively and the wealth of evidence regarding exposure concns. and toxicity led to their inclusion in risk management frameworks for water quality. However, cyanobacteria produce an incredible diversity of hundreds of cyanopeptides beyond the class of microcystins. The question arises, whether the other cyanopeptides are in fact of no human and ecol. concern or whether these compds. merely received (too) little attention thus far. Current observations suggest that an assessment of their (eco)toxicol. risk is indeed relevant: First, other cyanopeptides, including cyanopeptolins and anabaenopeptins, can occur just as frequently and at similar nanomolar concns. as microcystins in surface waters. Second, cyanopeptolins, anabaenopeptins, aeruginosins and microginins inhibit proteases in the nanomolar range, in contrast to protein phosphatase inhibition by microcystins. Cyanopeptolins, aeruginosins, and aerucyclamide also show toxicity against grazers in the micromolar range comparable to microcystins. The key challenge for a comprehensive risk assessment of cyanopeptides remains their large structural diversity, lack of ref. stds., and high anal. requirements for identification and quantification. One way forward would be a prevalence study to identify the priority candidates of tentatively abundant, persistent, and toxic cyanopeptides to make comprehensive risk assessments more manageable.
    33. 33
      Hoigné, J.; Bader, H. Rate constants of reactions of ozone with organic and inorganic compounds in water─II. Water Res. 1983, 17 (2), 185– 194,  DOI: 10.1016/0043-1354(83)90099-4
      33
      Rate constants of reactions of ozone with organic and inorganic compounds in water. II. Dissociating organic compounds
      Hoigne, J.; Bader, H.
      Water Research (1983), 17 (2), 185-94CODEN: WATRAG; ISSN:0043-1354.
      Comprehensive lists of rate consts. of reactions of O3 with acidic and basic org. chem. dissolved in water, such as amines, amino acids, carboxylic acids, and phenols are reported. The second-order rate consts. increase with pH as does the degree of deprotonation of the dissolved substances, e.g. HCOOH [64-18-6] 1-100, glyoxalic acid [298-12-4] 0.2-2, and phenols 103-109/M s. The electrophilic reactions of O3 with non-dissocg. compds. are important for the understanding of the pH dependence of the rate and selectivity of ozonation reactions and for explaining the chem. effects of O3 on impurities in drinking water and wastewaters.
    34. 34
      Pryor, W. A.; Giamalva, D. H.; Church, D. F. Kinetics of ozonation. 2. Amino acids and model compounds in water and comparisons to rates in nonpolar solvents. J. Am. Chem. Soc. 1984, 106 (23), 7094– 7100,  DOI: 10.1021/ja00335a038
      34
      Kinetics of ozonation. 2. Amino acids and model compounds in water and comparisons to rates in nonpolar solvents
      Pryor, William A.; Giamalva, David H.; Church, Daniel F.
      Journal of the American Chemical Society (1984), 106 (23), 7094-100CODEN: JACSAT; ISSN:0002-7863.
      Abs. rates of reaction of amino acids and model compds. with ozone were measured in aq. buffer solns. For the less reactive amino acids and for amines, the rates of reaction are proportional to the amt. of free (i.e., unprotonated) amine present and therefore are relatively slow below pH 7. The rates of reaction of the amides are also slow. Rates of reaction of the more reactive amino acids at pH 7.0 are in the order of cysteine > tryptophan > methionine > tyrosine > histidine. 3-Hexenoic acid, a model of a polyunsatd. fatty acid (PUFA), is similar in reactivity to methionine or tyrosine. The more reactive amino acids, whether free or in polypeptides, must be considered as possible targets for the reaction of ozone in vivo, along with the more usually considered PUFA. Which of these types of target mols. might receive the most damage in vivo probably depends on accessibility, cellular architecture.
    35. 35
      Lim, S.; McArdell, C. S.; von Gunten, U. Reactions of aliphatic amines with ozone: Kinetics and mechanisms. Water Res. 2019, 157, 514– 528,  DOI: 10.1016/j.watres.2019.03.089
      37
      Reactions of aliphatic amines with ozone: Kinetics and mechanisms
      Lim, Sungeun; McArdell, Christa S.; von Gunten, Urs
      Water Research (2019), 157 (), 514-528CODEN: WATRAG; ISSN:0043-1354. (Elsevier Ltd.)
      Aliph. amines are common constituents in micropollutants and dissolved org. matter and present in elevated concns. in wastewater-impacted source waters. Due to high reactivity, reactions of aliph. amines with ozone are likely to occur during ozonation in water and wastewater treatment. We investigated the kinetics and mechanisms of the reactions of ozone with ethylamine, diethylamine, and triethylamine as model nitrogenous compds. Species-specific second-order rate consts. for the neutral parent amines ranged from 9.3 × 104 to 2.2 × 106 M-1s-1 and the apparent second-order rate consts. at pH 7 for potential or identified transformation products were 6.8 × 105 M-1s-1 for N,N-diethylhydroxylamine, ∼105 M-1s-1 for N-ethylhydroxylamine, 1.9 × 103 M-1s-1 for N-ethylethanimine oxide, and 3.4 M-1s-1 for nitroethane. Product analyses revealed that all amines were transformed to products contg. a nitrogen-oxygen bond (e.g., triethylamine N-oxide and nitroethane) with high yields, i.e., 64-100% with regard to the abated target amines. These findings could be confirmed by measurements of singlet oxygen and hydroxyl radical which are formed during the amine-ozone reactions. Based on the high yields of nitroethane from ethylamine and diethylamine, a significant formation of nitroalkanes can be expected during ozonation of waters contg. high levels of dissolved org. nitrogen, as expected in wastewaters or wastewater-impaired source waters. This may pose adverse effects on the aquatic environment and human health.
    36. 36
      Muñoz, F.; von Sonntag, C. Determination of fast ozone reactions in aqueous solution by competition kinetics. J. Chem. Soc. Perkin Trans. 2 2000, (4), 661– 664,  DOI: 10.1039/a909668j
      There is no corresponding record for this reference.
    37. 37
      Kim, M. S.; Cha, D.; Lee, K.-M.; Lee, H.-J.; Kim, T.; Lee, C. Modeling of ozone decomposition, oxidant exposures, and the abatement of micropollutants during ozonation processes. Water Res. 2020, 169, 115230,  DOI: 10.1016/j.watres.2019.115230
      39
      Modeling of ozone decomposition, oxidant exposures, and the abatement of micropollutants during ozonation processes
      Kim, Min Sik; Cha, Dongwon; Lee, Ki-Myeong; Lee, Hye-Jin; Kim, Taewan; Lee, Changha
      Water Research (2020), 169 (), 115230CODEN: WATRAG; ISSN:0043-1354. (Elsevier Ltd.)
      This study demonstrates new empirical models to predict the decompn. of ozone (O3) and the exposures of oxidants (i.e., O3 and hydroxyl radical, ·OH) during the ozonation of natural waters. Four models were developed for the instantaneous O3 demand, first-order rate const. for the secondary O3 decay, O3 exposure (∫[O3]dt), and ·OH exposure ((∫[·OH]dt)), as functions of five independent variables, namely the O3 dose, concn. of dissolved org. carbon (DOC), pH, alky., and temp. The models were derived by polynomial regression anal. of exptl. data obtained by controlling variables in natural water samples from a single source water (Maegok water in Korea), and they exhibited high accuracies for regression (R2 = 0.99 for the three O3 models, and R2 = 0.96 for the ·OH exposure model). The three O3 models exhibited excellent internal validity for Maegok water samples of different conditions (that were not used for the model development). They also showed acceptable external validity for seven natural water samples collected from different sources (not Maegok water); the IOD model showed somewhat poor external validity. The models for oxidant exposures were successfully used to predict the abatement of micropollutants by ozonation; the model predictions showed high accuracy for Maegok water, but not for the other natural waters.
    38. 38
      Anbar, M.; Neta, P. A compilation of specific bimolecular rate constants for the reactions of hydrated electrons, hydrogen atoms and hydroxyl radicals with inorganic and organic compounds in aqueous solution. International Journal of Applied Radiation and Isotopes 1967, 18 (7), 493– 523,  DOI: 10.1016/0020-708X(67)90115-9
      40
      A compilation of specific bimolecular rate constants for the reactions of hydrated electrons, hydrogen atoms, and hydroxyl radicals with inorganic and organic compounds in aqueous solution
      Anbar, Michael; Neta, Pedatsur
      International Journal of Applied Radiation and Isotopes (1967), 18 (7), 493-523CODEN: IJARAY; ISSN:0020-708X.
      A compilation of rate consts. for over 600 compds. from 164 references.
    39. 39
      Appiani, E.; Page, S. E.; McNeill, K. On the Use of Hydroxyl Radical Kinetics to Assess the Number-Average Molecular Weight of Dissolved Organic Matter. Environ. Sci. Technol. 2014, 48 (20), 11794– 11802,  DOI: 10.1021/es5021873
      41
      On the Use of Hydroxyl Radical Kinetics to Assess the Number-Average Molecular Weight of Dissolved Organic Matter
      Appiani, Elena; Page, Sarah E.; McNeill, Kristopher
      Environmental Science & Technology (2014), 48 (20), 11794-11802CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      An indirect method to assess the av. size of dissolved org. matter (DOM) is described, which is based on the reaction of hydroxyl radical (HO•) quenching by DOM. HO• is often assumed to be relatively unselective, reacting with nearly all org. mols. with similar rate consts. Literature values for HO• reaction with org. mols. were surveyed to assess the unselectivity of DOM and to det. a representative quenching rate const. (krep =5.6 × 109/M-s). This value was used to assess the av. mol. wt. of various humic and fulvic acid isolates as model DOM, using literature HO• quenching consts., kC,DOM. The results obtained by this method were compared with previous ests. of av. mol. wt. The av. mol. wt. (Mn) values obtained with this approach are lower than the Mn measured by other techniques such as size exclusion chromatog. (SEC), vapor pressure osmometry (VPO), and flow field fractionation (FFF). This suggests that DOM is an esp. good quencher for HO•, reacting at rates close to the diffusion-control limit. It was further obsd. that humic acids generally react faster than fulvic acids. The high reactivity of humic acids toward HO• is in line with the antioxidant properties of DOM. The benefit of this method is that it provides a firm upper bound on the av. mol. wt. of DOM, based on the kinetic limits of the HO• reaction. The results indicate low av. mol. wt. values, which is most consistent with the recent understanding of DOM. A possible DOM size distribution is discussed to reconcile the small nature of DOM with the large-mol. behavior obsd. in other studies.
    40. 40
      Sha, H.; Nie, J.; Lian, L.; Yan, S.; Song, W. Phototransformation of an emerging cyanotoxin (Aerucyclamide A) in simulated natural waters. Water Res. 2021, 201, 117339,  DOI: 10.1016/j.watres.2021.117339
      There is no corresponding record for this reference.

  • Supporting Information

    Supporting Information

    The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.est.4c02242.

    • Additional experimental details, information on competitors, structures of all identified cyano-metabolites, details on kO3,DMP redetermination, supplementary cyano-metabolite rate constants, and linear regression statistical parameters (PDF)

    • Spreadsheet containing the confirmation of cyano-metabolite structures by MS2 spectra annotation (XLSX)


    Terms & Conditions

    Most electronic Supporting Information files are available without a subscription to ACS Web Editions. Such files may be downloaded by article for research use (if there is a public use license linked to the relevant article, that license may permit other uses). Permission may be obtained from ACS for other uses through requests via the RightsLink permission system: http://pubs.acs.org/page/copyright/permissions.html.