Degradation and persistence of metolachlor in soil: Effects of concentration, soil moisture, soil depth, and sterilization

Rice, Pamela J.; Anderson, Todd A.; Coats, Joel R.

doi:10.1002/etc.5620211216

Cited by 67 publications

(42 citation statements)

References 39 publications

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“…Although rhizosphere microbes may be important in biodegradation, plant uptake appears to be the main mechanism of phytoremediation of metolachlor in this prairie grass system. Levels of volatilization, mineralization, and metabolites in soil were comparable to those described by Rice et al (6), and metolachlor ESA was the major metabolite in soil and in grass tissue. Levels of metolachlor and key metabolites in grasses were slightly below the tolerance limits set by the U.S. EPA.…”

Section: Mg/kg; 419 µCi)supporting

confidence: 83%

“…Radiopurity was 97.6%, and chemical purities for the radiolabeled and analytical-grade compound were 96.4 and 99%, respectively. Purity was determined using thin-layer chromatography as described by Rice et al (6).…”

Section: Methodsmentioning

confidence: 99%

“…Forced air was pumped through each 5 L chamber at 23 L/h (SE )1 L/h). [ 14 C]CO2 and volatile [ 14 C]organic metabolites were collected using a flow-through system consisting of two 30 mL 2 N KOH traps, one 30 mL ethylene glycol trap, and three polyurethane foam traps, similar to the method described by Rice et al (6) (Figure 1). Throughout the study, the temperature was maintained at 27 ( 3°C, and the soil moisture was maintained at 15% moisture (field capacity) using a HoldAll moisture meter (AmerTac, Monsey, NY).…”

Section: Methodsmentioning

confidence: 99%

“…Extraction efficiency was 94%. Methods for these traps were similar to those described by Rice et al (6). Radioactivity in CO2 and volatile traps was quantified using a Beckman LS 6500 liquid scintillation counter (Beckman Coulter, Inc., Fullerton, CA).…”

Section: Methodsmentioning

confidence: 99%

“…Once applied, metolachlor has an estimated half-life of 16-289 days in soil, depending on soil characteristics, moisture, temperature, and depth, as well as microbial activity (5)(6)(7). Metolachlor and its metabolites are also slightly mobile in soil (8); in several leaching studies, approximately 1% of applied metolachlor leached through soil columns, while selected metolachlor degradates appeared to be more mobile in soil (9,10).…”

Section: Introductionmentioning

confidence: 99%

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Mass Balance of Metolachlor in a Grassed Phytoremediation System

Henderson

Belden

Coats

2007

Environ. Sci. Technol.

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Metolachlor is a point-source pollutant at agrochemical dealerships in the Midwest, as well as a non pointsource contaminant of surface waters caused by runoff. Prairie grasses have been used in filter strips to control runoff and are also useful for phytoremediation; however, little is known about the fate of metolachlor and its metabolites within a grassed system. Effects of uptake by prairie grasses on the formation and fate of degradation products are not known. In this study, [U-ring-14C]metolachlor was added to enclosed systems to determine the fate of the parent compound and its metabolites in soil and plants. Mineralization and volatilization were monitored over the 97 day study and found to be 1.05 and 0.2%, respectively, for vegetated systems. At the end of the study, soil and plant material was evaluated for the presence of parent metolachlor and selected metabolites, as well as bound residues. Metolachlor ethane sulfonic acid was the dominant metabolite in soil and plant tissue. Over 7% of applied radioactivity was taken up by the grasses, and plant uptake/metabolism appeared to be the main mechanism for phytoremediation of metolachlor. Vegetation significantly reduced the amount of metolachlor in soil by 9%, indicating potential success as a remediation tool. Metolachlor is a point-source pollutant at agrochemical dealerships in the Midwest, as well as a non point-source contaminant of surface waters caused by runoff. Prairie grasses have been used in filter strips to control runoff and are also useful for phytoremediation; however, little is known about the fate of metolachlor and its metabolites within a grassed system. Effects of uptake by prairie grasses on the formation and fate of degradation products are not known. In this study, [U-ring-14 C]metolachlor was added to enclosed systems to determine the fate of the parent compound and its metabolites in soil and plants. Mineralization and volatilization were monitored over the 97 day study and found to be 1.05 and 0.2%, respectively, for vegetated systems. At the end of the study, soil and plant material was evaluated for the presence of parent metolachlor and selected metabolites, as well as bound residues. Metolachlor ethane sulfonic acid was the dominant metabolite in soil and plant tissue. Over 7% of applied radioactivity was taken up by the grasses, and plant uptake/metabolism appeared to be the main mechanism for phytoremediation of metolachlor. Vegetation significantly reduced the amount of metolachlor in soil by 9%, indicating potential success as a remediation tool. Disciplines Agronomy and Crop Sciences | Entomology Mass Balance of Metolachlor in a Grassed Phytoremediation System

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Section: Mg/kg; 419 µCi)supporting

confidence: 83%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Mass Balance of Metolachlor in a Grassed Phytoremediation System

Henderson

Belden

Coats

2007

Environ. Sci. Technol.

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Leaching potential of nonsteroidal anti‐inflammatory drugs in soils

Chen

et al. 2010

Enviro Toxic and Chemistry

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Abstract-Nonsteroidal anti-inflammatory drugs (NSAIDs) in soils resulting from application of municipal wastewater or biosolids may migrate through soils intact or be transformed and reach groundwater. In the present study, the leaching potential of four NSAIDs (ibuprofen, naproxen, ketoprofen, and diclofenac sodium) in three U.S. cropland soils was evaluated, and the effect of CaCl 2 solution (as an index of salinity), dissolved organic matter (DOM), and polyacrylamide (PAM) amendment was investigated. The soils were spiked with selected NSAIDs, incubated for 24 h followed by 7-d storage in glass flasks, and then packed into stainless steel columns and leached with deionized water (DIW), 10 mM CaCl 2 , DOM (DOC 34 mg/L), and PAM solution (1.0 mg/L) by gravity. Initial concentrations of ibuprofen, naproxen, ketoprofen, and diclofenac sodium in the three packed soils were 1

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Persistence of acetochlor, atrazine, and S‐metolachlor in surface and subsurface horizons of 2 typic argiudolls under no‐tillage

Bedmar

Giménez

Costa

et al. 2017

Enviro Toxic and Chemistry

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Variations in soil properties with depth strongly influence the degradation and persistence of herbicides, underlining the importance of studying these processes in soil horizons with distinctively different properties. The persistence of the herbicides acetochlor, atrazine, and S-metolachlor was measured in samples of the A, B, and C horizons of 2 Typic Argiudolls from Argentina under no-till management. The soils studied differed in soil organic carbon (OC) content, pH, particle size distribution, and structure. Quantification of herbicides in soil was done through high-performance liquid chromatography with diode array detector. There were interactions of herbicide × horizon (p < 0.01) that resulted in degradation rates (k) of all herbicides decreasing, and their corresponding dissipation half-life (DT50) values increasing, with soil depth. Herbicide persistence across all soils and horizons ranged from 15 to 73 d for acetochlor, 13 to 29 d for atrazine, and 82 to 141 d for S-metolachlor, which had significantly (p < 0.01) greater persistence than atrazine and acetochlor. The DT50 values of herbicides were negatively correlated with the contents of OC (correlation coefficients ranging from -0.496 to -0.773), phosphorus (-0.427 to -0.564), and nitrogen-nitrate (-0.507 to -0.662), and with microbial activity (-0.454 to -0.687) and the adsorption coefficient (-0.530 to -0.595); DT50s were positively correlated with pH (0.366 to 0.648). Adsorption was likely the most influential process in determining persistence of these herbicides in surface and subsurface horizons. The present study can potentially improve the prediction of the fate of acetochlor, atrazine, and S-metolachlor in soils because it includes much needed information on the degradation of the herbicides in subsurface horizons. Environ Toxicol Chem 2017;36:3065-3073. © 2017 SETAC.

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Degradation and persistence of metolachlor in soil: Effects of concentration, soil moisture, soil depth, and sterilization

Cited by 67 publications

References 39 publications

Mass Balance of Metolachlor in a Grassed Phytoremediation System

Mass Balance of Metolachlor in a Grassed Phytoremediation System

Leaching potential of nonsteroidal anti‐inflammatory drugs in soils

Persistence of acetochlor, atrazine, and S‐metolachlor in surface and subsurface horizons of 2 typic argiudolls under no‐tillage

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