Carbon and nitrogen stable isotope fractionation during abiotic hydrolysis of pesticides

Masbou, Jérémy; Drouin, Guillaume; Payraudeau, Sylvain; Imfeld, Gwenaël

doi:10.1016/j.chemosphere.2018.09.056

Cited by 47 publications

(66 citation statements)

References 39 publications

(63 reference statements)

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“…In addition, the isotope fractionation of SM in our experiments with sterile soil was not significant (Δδ 13 C ˂ 2‰ within the range of analytical uncertainty, data not shown) while it is known that abiotic hydrolysis can certainly result in pronounced isotopic fractionation. For example, alkaline hydrolysis of SM has been observed previously (ε C = -2.8‰ ± 0.6‰) (Masbou et al, 2018a), compared to ε C = -1.5‰ ± 0.5‰ for SM degradation under biotic conditions (Alvarez-Zaldívar et al, 2018). In sterile experiments, ESA and OXA levels remained one order of magnitude lower than in biotic experiments (Appendix A Fig.…”

Section: Sm Degradation and But Sorption Are Major Dissipation Processes In Agricultural Soilsmentioning

confidence: 63%

Dissipation of S-metolachlor and butachlor in agricultural soils and responses of bacterial communities: Insights from compound-specific isotope and biomolecular analyses

Torabi

Wiegert

Guyot

et al. 2020

Journal of Environmental Sciences

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The soil dissipation of the widely used herbicides S-metolachlor (SM) and butachlor (BUT) was evaluated in laboratory microcosms at two environmentally relevant doses (15 and 150 µg/g) and for two agricultural soils (crop and paddy). Over 80% of SM and BUT were dissipated within 60 and 30 days, respectively, except in experiments with crop soil at 150 µg/g. Based on compound-specific isotope analysis (CSIA) and observed dissipation, biodegradation was the main process responsible for the observed decrease of SM and BUT in the paddy soil. For SM, biodegradation dominated over other dissipation processes, with changes of carbon isotope ratios (Δδ 13 C) of up to 6.5‰ after 60 days, and concomitant production of ethane sulfonic acid (ESA) and oxanilic acid (OXA) transformation products.In crop soil experiments, biodegradation of SM occurred to a lesser extent than in paddy soil, and sorption was the main driver of apparent BUT dissipation. Sequencing of the 16S rRNA gene showed that soil type and duration of herbicide exposure were the main determinants of bacterial community variation. In contrast, herbicide identity and spiking dose had no significant effect. In paddy soil experiments, a high (4:1, V/V) ESA to OXA ratio for SM was observed, and phylotypes assigned to anaerobic Clostridiales and sulfur reducers such as Desulfuromonadales and Syntrophobacterales were dominant for both herbicides. Crop soil 2 microcosms, in contrast, were associated with a reverse, low (1:3, V/V) ratio of ESA to OXA for SM, and Alphaproteobacteria, Actinobacteria, and Bacillales dominated regardless of the herbicide. Our results emphasize the variability in the extent and modes of SM and BUT dissipation in agricultural soils, and in associated changes in bacterial communities.

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Section: Sm Degradation and But Sorption Are Major Dissipation Processes In Agricultural Soilsmentioning

confidence: 63%

Dissipation of S-metolachlor and butachlor in agricultural soils and responses of bacterial communities: Insights from compound-specific isotope and biomolecular analyses

Torabi

Wiegert

Guyot

et al. 2020

Journal of Environmental Sciences

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“…We assumed a maximum enrichment in 13 C of +20‰, which would correspond to at least 96% of degradation based on previously published carbon fractionation (ε C ) for ATR, ACETO and METO degradation. 5,[39][40][41][42][43][44][45] Applying Eq. (6), we determined that an enrichment in 13 C of +20‰ is associated with an offset between uncorrected and corrected Cl isotope value of -0.22‰ for ATR (fragment m/z 202: one Cl atom and seven C atoms), -0.93‰ for ACETO (fragment m/z 225: one Cl and 12 C) and -1.02‰ for METO (fragment m/z 240: one Cl and 13 C).…”

Section: Resultsmentioning

confidence: 99%

“…This leads to changes in the isotope ratio of the contaminant fraction that has not yet been degraded. Whereas C-CSIA methods are available for many chlorinated organic legacy compounds and even for some chlorine-containing pesticides [5][6][7][8][9] , analytical methods for Cl-CSIA are so far only available for a narrow range of compounds, especially short chain polychlorinated aliphatic hydrocarbons. 10,11 This limited availability is explained by numerous analytical challenges associated with Cl-CSIA.…”

mentioning

confidence: 99%

Compound-Specific Chlorine Isotope Analysis of the Herbicides Atrazine, Acetochlor, and Metolachlor

et al. 2019

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A gas chromatography-single quadrupole mass spectrometry method was developed and validated for compoundspecific chlorine isotope analysis (Cl-CSIA) of three chlorinated herbicides, atrazine, acetochlor and metolachlor, which are widespread contaminants in the environment. For each compound, the two most abundant ions containing chlorine (202/200 for atrazine, 225/223 for acetochlor and 240/238 for metolachlor) and a dwell time of 30 ms were determined as optimized MS parameters. A Limit of Precise Isotope Analysis for ethyl acetate solutions of 10 mg/L atrazine, 10 mg/L acetochlor and 5 mg/L metolachlor could be reached with an associated uncertainty between 0.5 and 1‰. To this end, samples were measured tenfold and bracketed with two calibration standards which covered a wide range of δ 37 Cl values and whose amplitudes matched those of the samples within 20% tolerance. The method was applied to investigate chlorine isotope fractionation during alkaline hydrolysis of metolachlor, which showed a shift in δ 37 Cl of +46‰ after 98% degradation, demonstrating that chlorine isotope fractionation could be a sensitive indicator of transformation processes even when limited degradation occurs. This method, combined with large-volume solid-phase extraction (SPE), allowed application of Cl-CSIA to environmentally relevant concentrations of widespread herbicides (i.e. 0.5 to 5 µg/L in water before extraction). Therefore, the combination of large-volume SPE and Cl-CSIA is a promising tool for assessing the transformation processes of these pollutants in the environment. fractionation associated with reaction mechanisms relevant for field studies. Hence, future studies are warranted to better understand how variable dual isotope slopes are for specific processes in order to identify them unequivocally in the field. ASSOCIATED CONTENT Supporting Information Further details on target analytes, analytical and extraction methods, GC-qMS method performance and results of the validation tests are available in Supporting Information. The Supporting Information is available free of charge on the ACS Publications Website.

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“…In addition, monitoring the changes of isotope signatures of two (or more) elements is recommended to obtain a more reliable assessment of degradation and to derive the extent and relative contribution of different reaction mechanisms. 9,11,12 Although CSIA is in widespread use to study the fate of many contaminants 11,[13][14][15] , applications are still emerging for pesticides. 16 Various analytical methods have been recently developed.…”

Section: Introductionmentioning

confidence: 99%

Solid-phase extraction method for stable isotope analysis of pesticides from large volume environmental water samples

Torrentó

Bakkour

Glauser

et al. 2019

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Carbon and nitrogen stable isotope fractionation during abiotic hydrolysis of pesticides

Cited by 47 publications

References 39 publications

Dissipation of S-metolachlor and butachlor in agricultural soils and responses of bacterial communities: Insights from compound-specific isotope and biomolecular analyses

Dissipation of S-metolachlor and butachlor in agricultural soils and responses of bacterial communities: Insights from compound-specific isotope and biomolecular analyses

Compound-Specific Chlorine Isotope Analysis of the Herbicides Atrazine, Acetochlor, and Metolachlor

Solid-phase extraction method for stable isotope analysis of pesticides from large volume environmental water samples

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