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

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

doi:10.1021/acs.est.7b02297

Cited by 28 publications

(11 citation statements)

References 69 publications

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“…The detected TP suggested that degradation pathways involving 4-(2-ethyl-6-methylphenyl)-5-methyl-3-morpholinone, a major photolysis product ( Mathew and Khan, 1996 ), or hydroxymetolachlor, an important fungal and bacterial degradate ( Sanyal et al, 2000 ), were operative in our microcosms and thus potentially also in groundwater. Alternative degradation pathways that do not involve OXA and ESA as intermediates were previously observed in artificial wetlands ( Elsayed et al, 2015 ) and at the agricultural catchment scale ( Marie et al, 2017 ).…”

Section: Resultsmentioning

confidence: 73%

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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Section: Resultsmentioning

confidence: 73%

Toward Integrative Bacterial Monitoring of Metolachlor Toxicity in Groundwater

et al. 2018

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“…On entering the environment, pesticides can undergo processes such as transfer (or movement) and degradation [31][32][33]. Pesticide degradation in the environment produces new chemicals [34]. Pesticides relocate from the target site to other environmental media or non-target plants by transfer processes including adsorption, leaching, volatilization, spray drift, and runoff (Figure 2) [35].…”

Section: Pesticide Behavior In the Environmentmentioning

confidence: 99%

“…Pesticide degradation processes control pesticide persistence in soils and yield different metabolites [40]. It also provides the concept of a half-life of the pesticides in the environment [34]. For example, in the case of chlorpyrifos, the major metabolite 3, 5, 6-trichloro-2-pyridinol (TCP) of chlorpyrifos is much more mobile and toxic than its parent chlorpyrifos [41].…”

Section: Pesticide Degradationmentioning

confidence: 99%

Agriculture Development, Pesticide Application and Its Impact on the Environment

Tudi

Ruan

Wang

et al. 2021

IJERPH

1,156

481

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Pesticides are indispensable in agricultural production. They have been used by farmers to control weeds and insects, and their remarkable increases in agricultural products have been reported. The increase in the world’s population in the 20th century could not have been possible without a parallel increase in food production. About one-third of agricultural products are produced depending on the application of pesticides. Without the use of pesticides, there would be a 78% loss of fruit production, a 54% loss of vegetable production, and a 32% loss of cereal production. Therefore, pesticides play a critical role in reducing diseases and increasing crop yields worldwide. Thus, it is essential to discuss the agricultural development process; the historical perspective, types and specific uses of pesticides; and pesticide behavior, its contamination, and adverse effects on the natural environment. The review study indicates that agricultural development has a long history in many places around the world. The history of pesticide use can be divided into three periods of time. Pesticides are classified by different classification terms such as chemical classes, functional groups, modes of action, and toxicity. Pesticides are used to kill pests and control weeds using chemical ingredients; hence, they can also be toxic to other organisms, including birds, fish, beneficial insects, and non-target plants, as well as air, water, soil, and crops. Moreover, pesticide contamination moves away from the target plants, resulting in environmental pollution. Such chemical residues impact human health through environmental and food contamination. In addition, climate change-related factors also impact on pesticide application and result in increased pesticide usage and pesticide pollution. Therefore, this review will provide the scientific information necessary for pesticide application and management in the future.

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“…Moreover, excessive and inappropriate use of herbicides habituated from long-term conventional tillage leads to inevitable residual pollution and frequent herbicide resistance that undermines productivity, sustainability and profitability in agroecosystems [5,6]. In particular, many studies have warned that herbicides are among the key contributors to pollution stress on non-target organisms with respect to their survival, function and biodiversity since the active ingredients of herbicides and their metabolites have been ubiquitously detected in aquatic, marine and edaphic environments [7][8][9]._ENREF_9 Nevertheless, microorganisms possess attractive potential to accelerate the breakdown and transformation of organic xenobiotic compounds present in environmental matrices via enzymatic metabolism [10,11]. In fact, taking advantage of molecular biology, novel bioreactors and immobilization techniques, biodegradation treatments are being remarkably improved due to the enhanced survival of the applied microbes and their ability to degrade, which facilitates the in situ removal of target pollutants [12,13].…”

Section: Introductionmentioning

confidence: 99%