Correction to Degradation and Transport of the Chiral Herbicide <i>S</i>-Metolachlor at the Catchment Scale: Combining Observation Scales and Analytical Approaches

Lefrancq, Marie; Payraudeau, Sylvain; Guyot, Benoît; Millet, Maurice; Imfeld, Gwénaël

doi:10.1021/acs.est.8b01118

Cited by 5 publications

(3 citation statements)

References 65 publications

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“…The 47 ha catchment is located 30 km north-east of Strasbourg France;48 47 19,56 N;7 35 2,27 E) and has been previously described by Lefrancq et al, (2017b). The mean catchment slope is 6.7 ± 4.7% with altitude ranging between 190 and 230 m. Catchment water flows in ditches to a 50 cm diameter pipe at a single outlet.…”

Section: Catchment Descriptionmentioning

confidence: 99%

“…3C), inferred top soil nondestructive losses (e.g., sorption, infiltration, run-off and volatilization) were estimated to have reached 8% of the applied product. Plant uptake was considered to be negligible, as no correlation was found between remaining mass and crop growth (from 0 to 40 cm) or surface cover (from 0 to 100%) (Lefrancq et al, 2017b). Although S-met is considered to be a non-volatile compound (VP ¼ 1.73 mPa) (Corbin et al, 2006), based on environmental conditions (e.g., Prueger et al, 2005) and model based calculations (Lefrancq et al, 2017b) we estimate volatilization to have accounted for 5% of the applied product.…”

Section: Validation Of the Csia Approachmentioning

confidence: 99%

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Pesticide degradation and export losses at the catchment scale: Insights from compound-specific isotope analysis (CSIA)

et al. 2018

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Although pesticides undergo degradation tests prior to use, determining their export, degradation and persistence under field conditions remains a challenge for water resource management. Compound specific isotope analysis (CSIA) can provide evidence of contaminant degradation extent, as it is generally independent of non-destructive dissipation (e.g., dilution, sorption, volatilization) regulating environmental concentrations. While this approach has been successfully implemented in subsurface environments, its application to pesticides in near-surface hydrological contexts at catchment scale is lacking. This study demonstrates the applicability of CSIA to track pesticide degradation and export at catchment scale and identify pesticide source areas contributing to changes in stable isotope signature in stream discharge under dynamic hydrological contexts. Based on maximum shifts in carbon stable isotope signatures (ΔδC  = 4.6 ± 0.5‰) of S-metolachlor (S-met), a widely used herbicide, we estimate maximum degradation to have reached 96 ± 3% two months after first application. Maximum shifts in nitrogen isotope signatures were small and inverse (ΔδN=-1.3±0.6‰) indicating potential secondary isotope effects during degradation. In combination with a mass balance approach including S-met main degradation products, total catchment non-destructive dissipation was estimated to have reached 8 ± 7% of the applied product. Our results show that CSIA can be applied to evaluate natural attenuation of pesticides at catchment scale. By providing a more detailed account of pesticide dissipation and persistence under field conditions we anticipate the contribution of pesticide CSIA to the improvement of regulatory and monitoring strategies.

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Section: Catchment Descriptionmentioning

confidence: 99%

Section: Validation Of the Csia Approachmentioning

confidence: 99%

Pesticide degradation and export losses at the catchment scale: Insights from compound-specific isotope analysis (CSIA)

et al. 2018

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“…Surface runoff is a major driver of pesticide transport from agricultural land into aquatic ecosystems. It exports up to 5% of solid-bound and dissolved pesticides during rainfall-runoff events (Herrero-Hernández et al, 2017;Parajulee et al, 2018;Lefrancq et al, 2018). Pesticide export eventually affects drinking water resources and the health of aquatic ecosystems (e.g., Zubrod et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Do rainfall characteristics affect the export of copper, zinc and synthetic pesticides in surface runoff from headwater catchments?

Imfeld

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Wiegert

et al. 2020

Science of The Total Environment

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Rainfall and runoff characteristics may influence off-site export of pesticides into downstream aquatic ecosystems. However, the relationship between rainfall characteristics and pesticide export from small headwater catchments remains elusive due to confounding factors including the application dose and timing and the variation of pesticide stocks in soil. Here we examined the impact of rainfall characteristics on the export of copper (Cu), zinc (Zn) and 12 legacy and currently used synthetic pesticides in surface runoff from a headwater vineyard catchment. Cluster analysis of rainfall intensity, depth and duration of 78 events revealed four distinct rainfall categories, i.e., Small, Long, Moderate and Intense (p<0.001). Event mean concentrations of pesticides did not differ among rainfall categories (p>0.05). In contrast, event loads of both dissolved and solid-bound Cu and Zn significantly differed among rainfall categories (p<0.001). Rainfall depth and intensity significantly correlated with both Cu and Zn loads in runoff (ρ s = 0.33 to 0.92, p<0.002), and might be the main drivers of Cu and Zn export at the catchment scale. In contrast, rainfall depth, intensity or duration did not influence the loads of synthetic pesticides in runoff, even when weekly variations of pesticide stocks in the soil were accounted for. However, intense rainfall-runoff events, that can fragment soil, may control the export of persistent and hydrophobic legacy pesticides stocks in the soil, such as simazine and tetraconazole. Our results emphasise that rainfall characteristics controlled the off-site export of Cu, Zn and legacy synthetic pesticides in a small headwater catchment, whereas the application timing drove the export of currently used synthetic pesticides in runoff. We anticipate our results to be a preliminary step to forecast the influence of regional rainfall patterns on the export of both metallic and synthetic pesticides by surface runoff from small headwater catchments.

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Toward Integrative Bacterial Monitoring of Metolachlor Toxicity in Groundwater

et al. 2018

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Common herbicides such as metolachlor (MET), and their transformation products, are frequently detected in groundwater worldwide. Little is known about the response of groundwater bacterial communities to herbicide exposure, and its potential use for ecotoxicological assessment. The response of bacterial communities exposed to different levels of MET from the Ariège alluvial aquifer (Southwest of France) was investigated in situ and in laboratory experiments. Variations in both chemistry and bacterial communities were observed in groundwater, but T-RFLP analysis did not allow to uncover a pesticide-specific effect on endogenous bacterial communities. To circumvent issues of hydrogeochemical and seasonal variations in situ, groundwater samples from two monitoring wells of the Ariège aquifer with contrasting records of pesticide contamination were exposed to different levels of MET in laboratory experiments. The standard Microtox® acute toxicity assay did not indicate toxic effects of MET, even at 5 mg L-1 (i.e., 1000-fold higher than in contaminated groundwater). Analysis of MET transformation products and compound-specific isotope analysis (CSIA) in laboratory experiments demonstrated MET biodegradation but did not correlate with MET exposure. High-throughput sequencing analysis (Illumina MiSeq) of bacterial communities based on amplicons of the 16S rRNA gene revealed that bacterial community differed mainly by groundwater origin rather than by its response to MET exposure. OTUs correlating with MET addition ranged between 0.4 to 3.6% of the total. Predictive analysis of bacterial functions impacted by pesticides using PICRUSt suggested only minor changes in bacterial functions with increasing MET exposure. Taken together, results highlight MET biodegradation in groundwater, and the potential use of bacterial communities as sensitive indicators of herbicide contamination in aquifers. Although detected effects of MET on groundwater bacterial communities were modest, this study illustrates the potential of integrating DNA- and isotopic analysis-based approaches to improve ecotoxicological assessment of pesticide-contaminated aquifers. GRAPHICAL ABSTRACTAn integrative approach was develop to investigate in situ and in laboratory experiments the response of bacterial communities exposed to different levels of MET from the Ariége alluvial aquifer (Southwest of France).

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Correction to Degradation and Transport of the Chiral Herbicide S-Metolachlor at the Catchment Scale: Combining Observation Scales and Analytical Approaches

Cited by 5 publications

References 65 publications

Pesticide degradation and export losses at the catchment scale: Insights from compound-specific isotope analysis (CSIA)

Pesticide degradation and export losses at the catchment scale: Insights from compound-specific isotope analysis (CSIA)

Do rainfall characteristics affect the export of copper, zinc and synthetic pesticides in surface runoff from headwater catchments?

Toward Integrative Bacterial Monitoring of Metolachlor Toxicity in Groundwater

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