Occurrence of Alachlor and Its Sulfonated Metabolite in Rivers and Reservoirs of the Midwestern United States:  The Importance of Sulfonation in the Transport of Chloroacetanilide Herbicides

• Published in: Environmental science & technology Vol. 30; no. 2; pp. 569 - 574
• Main Authors: Thurman, E. M, Goolsby, D. A, Aga, D. S, Pomes, M. L, Meyer, M. T
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.02.1996
• Subjects: Applied sciences; Biodegradation of pollutants; Biological and medical sciences; Biological and physicochemical phenomena; Biotechnology; Chemistry; Chromatography; Environment and pollution; Environmental monitoring; Exact sciences and technology; Freshwater; Fundamental and applied biological sciences. Psychology; Herbicides; Industrial applications and implications. Economical aspects; Natural water pollution; Pollution; Reservoirs; Rivers; Water pollution; Water treatment and pollution; United States; North America; America; Midwest states; USA, Midwest; Biodegradation; Alachlor; Metabolite; Cultivated soil; Check; Reservoir; Runoff water; Rivers; Herbicide; Sulfonate; Chlorine Organic compounds; Content; Reaction mechanism; Water pollution
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es950341q

Alachlor and its metabolite, 2-[(2‘,6‘-diethylphenyl)(methoxymethyl)amino]-2-oxoethanesulfonate (ESA), were identified in 76 reservoirs in the midwestern United States using immunoassay, liquid chromatography, and gas chromatography/mass spectrometry. The median concentration of ESA (0.48 μg/L) exceeded the median concentration of alachlor (<0.05 μg/L), with highest values in the upper Midwest. ESA also was detected in the Mississippi River from the mouth to the headwaters at concentrations of 0.2−1.5 μg/L, exceeding the concentration of alachlor. In a field runoff study, alachlor rapidly formed ESA. It is hypothesized that a glutathione conjugate forms, which later oxidizes in soil to ESA. The removal of the chlorine atom lessens the toxicity of the parent compound and increases runoff potential. It is hypothesized further that sulfonic acid metabolites of other chloroacetanilides, including acetochlor, butachlor, metolachlor, and propachlor, also occur in surface water.