Herbicide concentrations in the Mississippi River Basin—the importance of chloroacetanilide herbicide degradates

Rebich, Richard A.; Coupe, Richard H.; Thurman, E. Michael

doi:10.1016/j.scitotenv.2003.09.006

Cited by 98 publications

(57 citation statements)

References 17 publications

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“…Due to its extensive usage and moderate persistence, both alachlor and its metabolites could be accumulating in agriculturally related waters and the peak concentrations for alachlor of 25 lg L À1 in Kansas River and 4.8 lg L À1 in US groundwater were reported (Potter and Carpenter, 1995;Galassi et al, 1996;Thurman et al, 1996;Scribner et al, 2000;Squillace et al, 2002;Rebich et al, 2004). Concerns have been rising regarding the health risks associated with its occurrence in natural waters because alachlor is toxic and mutagenic (Tessier and Clark, 1995).…”

Section: Introductionmentioning

confidence: 99%

Degradation mechanism of alachlor during direct ozonation and O3/H2O2 advanced oxidation process

et al. 2010

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a b s t r a c tThe degradation of alachlor by direct ozonation and advanced oxidation process O 3 /H 2 O 2 was investigated in this study with focus on identification of degradation byproducts. The second-order reaction rate constant between ozone and alachlor was determined to be 2.5 ± 0.1 M À1 s À1 at pH 7.0 and 20°C. Twelve and eight high-molecular-weight byproducts (with the benzene ring intact) from alachlor degradation were identified during direct ozonation and O 3 /H 2 O 2 , respectively. The common degradation byproducts included N-(2,6-diethylphenyl)-methyleneamine, 8-ethyl-3,4-dihydro-quinoline, 8-ethyl-quinoline, 1-chloroacetyl-2-hydro-3-ketone-7-acetyl-indole, 2-chloro-2 0 ,6 0 -diacetyl-N-(methoxymethyl)acetanilide, 2-chloro-2 0 -acetyl-6 0 -ethyl-N-(methoxymethyl)-acetanilide, and two hydroxylated alachlor isomers. In direct ozonation, four more byproducts were also identified including 1-chloroacetyl-2,3-dihydro-7-ethyl-indole, 2-chloro-2 0 ,6 0 -ethyl-acetanilide, 2-chloro-2 0 ,6 0 -acetyl-acetanilide and 2-chloro-2 0 -ethyl-6 0 -acetyl-N-(methoxymethyl)-acetanilide. Degradation of alachlor by O 3 and O 3 /H 2 O 2 also led to the formation of low-molecular-weight byproducts including formic, acetic, propionic, monochloroacetic and oxalic acids as well as chloride ion (only detected in O 3 /H 2 O 2 ). Nitrite and nitrate formation was negligible. Alachlor degradation occurred via oxidation of the arylethyl group, N-dealkylation, cyclization and cleavage of benzene ring. After O 3 or O 3 /H 2 O 2 treatment, the toxicity of alachlor solution examined by the Daphnia magna bioassay was slightly reduced.

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Section: Introductionmentioning

confidence: 99%

Degradation mechanism of alachlor during direct ozonation and O3/H2O2 advanced oxidation process

et al. 2010

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“…The fingerprints that represented communities exposed to the control treatment (0 mg l À1 ) and the environmentally relevant acetochlor concentrations (1 and 5 mg l À1 ) clustered with relatively high (88%) similarity. Therefore, since acetochlor is most often detected in environmental waters at concentrations less than 25 mg l À1 (Kolpin et al, 1996;Clark et al, 1999;Battaglin et al, 2000;Rebich et al, 2004), our fingerprinting analyses suggest that exposure to relevant levels of environmental contamination will result in limited detectable alteration to the indigenous bacterial community. In contrast, exposure to acetochlor at concentrations that were (i) higher than environmentally relevant (50 and 100 mg l À1 ) and (ii) extreme (500 mg l À1 ) resulted in bacteria communities that were less than 80 and 35% similar, respectively, to the control communities.…”

Section: Discussionmentioning

confidence: 92%

“…As a result of its propensity for off-site movement, acetochlor is the third most frequently detected herbicide in natural waters behind atrazine and metolachlor (Rebich et al, 2004). In natural waters, chloracetanilide herbicides are degraded primarily by photolytic- (Houston and Pignatello, 1999;Zheng and Ye, 2003) and to a lesser extent, microbial (Ensz et al, 2003) activities.…”

Section: Introductionmentioning

confidence: 99%

“…Degradation of chloracetanilide compounds results in the removal of a chlorine atom and the addition of a sulfonic acid functional group, which greatly increases its water solubility relative to the parent compound. In the case of acetochlor, commonly detected degradation products include its ethane sulfonic (ESA) and oxanilic (OA) acids, which are commonly detected in surface waters (Kalkhoff et al, 1998;Rebich et al, 2004). ESA is likely a by-product of glutathione conjugation occurring in plants, algae and microorganisms (Kalkhoff et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

“…The movement of acetochlor and its transformation products is mediated through several pathways including leaching, soil erosion (Baran et al, 2004) and surface runoff, which has been shown to facilitate the movement of up to 1% of applied acetochlor following natural rainfall conditions (Ferenczi et al, 2002). As a result of these transport mechanisms, it is estimated that up to 96% of freshwater streams in agricultural environments contain detectable quantities of acetochlor (Kolpin et al, 1996;Battaglin et al, 2000;Rebich et al, 2004). The widespread prevalence of acetochlor (and related compounds) in natural waters likely results from the herbicide's high stability and persistent nature in the aquatic environment.…”

Section: Introductionmentioning

confidence: 99%

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A multiphasic characterization of the impact of the herbicide acetochlor on freshwater bacterial communities

2007

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Acetochlor is the third most frequently detected herbicide in natural waters; however, it is unknown if exposure to environmentally relevant concentrations of acetochlor will impact bacterial community structure and function. This study examined the impact of acetochlor on freshwater heterotrophic bacteria number, and community structure and function using direct counting, community level physiological profiling (CLPP) and denaturing gradient gel electrophoresis (DGGE) analysis. Acetochlor concentration did not appear to correlate with the number of total (P ¼ 0.69) and viable (P ¼ 0.80) bacteria, even at concentrations up to 500 lg l À1 . However, CLPP indicated that acetochlor increased functional diversity as shown by (i) an increase in the number of carbon sources utilized by the microbial community, relative to nonexposed controls and (ii) increased functional evenness within the heterotrophic bacterial community. Conversely, DGGE fingerprints suggested that exposure to acetochlor generally decreased the community complexity, as the average number of DGGE bands in most treatments was significantly less than in the control treatment. Cluster analysis of DGGE fingerprints revealed three distinct, dose-dependent clusters (i) communities exposed to 0, 1 and 5 lg l À1 ; (ii) 50 and 100 lg l À1 and (iii) 500 lg l À1, indicating a relationship between acetochlor concentration bacterial community changes. This study indicated that while exposure to environmentally relevant concentrations of acetochlor resulted in no significant impact to the number of freshwater bacteria, impacts to the function and structure of the community were revealed by adopting a multiphasic approach.

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Residual herbicide concentrations in on‐farm water storage–tailwater recovery systems: Preliminary assessment

Grantz¹,

Leslie

Reba

et al. 2020

Agricultural & Env Letters

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On-farm water storage-tailwater recovery systems reduce groundwater usage and intercept agrochemical loads, but pesticide residue dynamics in these systems are not well understood. This study monitored concentrations of seven herbicides in seven northeast Arkansas tailwater recovery systems (April 2017-March 2018). Clomazone, glyphosate, metolachlor, and quinclorac were frequently detected, with minimal detections of 2,4-D, dicamba, and propanil. Concentrations peaked during the growing season (1 Apr.-15 Sept.), reflecting an interaction of application and precipitation. Clomazone, glyphosate, and quinclorac concentrations were greater in ditches (<0.80-67, <0.50-6.2, and <0.40-62 μg L −1 , respectively) than in the associated reservoir (<0.80-6.0, <0.50-4.1, and <0.40-6.0 μg L −1 , respectively), but metolachlor concentrations were not different between structure types (maximum 22-32 μg L −1 ). Off-season concentrations were mostly below detection, except for quinclorac. Cycling recovered tailwater through the system and irrigating from reservoirs may minimize risk of cross-crop contaminations with residual herbicides. Managed groundwater recharge should use reservoir water during winter to protect groundwater quality.Abbreviations: BMP, best management practice; MAR, managed aquifer recharge; OFWS-TWR, on-farm water storage-tailwater recovery; SPE, solid phase extraction.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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Herbicide concentrations in the Mississippi River Basin—the importance of chloroacetanilide herbicide degradates

Cited by 98 publications

References 17 publications

Degradation mechanism of alachlor during direct ozonation and O3/H2O2 advanced oxidation process

Degradation mechanism of alachlor during direct ozonation and O3/H2O2 advanced oxidation process

A multiphasic characterization of the impact of the herbicide acetochlor on freshwater bacterial communities

Residual herbicide concentrations in on‐farm water storage–tailwater recovery systems: Preliminary assessment

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