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Formation and Transport of the Sulfonic Acid Metabolite of Alachlor and Metolachlor in SoilBy D.S. Aga and E.M. ThurmanABSTRACTAlachlor and metolachlor are dechlorinated and transformed into their corresponding ethane sulfonic acie (ESA) metabolites in soil. In a field-disappearance study, it was shown that alachlor ESA was formed at a faster rate and at concentrations 2-4 times higher than metolachlor ESA, conforming with the observed longer disappearance half-life of metolachlor (15.5 d) in the field as compared to alachlor (8 d). Runoff data also showed higher concentrations of alachlor ESA as compared to metolachlor ESA, even though they were applied at the same levels. Data from soil cores showed transport of the ESA compounds in soil to as far down as 75-90 cm below the surface, at concentrations ranging from less than 0.5 Î/L to about 50 Î/L. In contrast, no parent herbicide was detected at these depths. This observation correlates with the higher log Koc values for alachlor (3.33) and metolachlor (3.01) relative to their corresponding ESA metabolites, alachlor ESA (2.26) and metolachlor ESA (2.29). Additional information about the Organic Geochemistry Research Laboratory can be found at: http://ks.water.usgs.gov/studies/reslab/Aga, D.S., and Thurman, E.M., 2001, Formation and transport of the sulfonic acid metabolites of alachlor and metolachlor in soil: Environmental Science and Technology, v.35, p. 2455-2460. To request a paper copy of this journal article, email: scribner@usgs.gov |
U.S. Department of the Interior |
U.S. Geological Survey
URL: /pubs/abstracts/dsaga.est.v35.html
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The USGS has collected hydrologic information in Kansas since 1895 with the first USGS Cooperative
Water Program funding agreement for 6 streamflow gages with the Kansas Water Board. USGS collects streamflow
and gage-height data; reservoir content; water-quality and water-quantity data; suspended-sediment data;
and groundwater levels. Hydrologic studies are conducted on national, regional, statewide, and local levels.
The USGS in Kansas works cooperatively with 31 Federal, State, and local agencies, such as the Kansas Water Office, the U.S.Army Corps of Engineers, and the City of Wichita