Microbial and Photolytic Degradation of the Herbicide Acetochlor

Abstract Time-course of the microbial degradation of the herbicide acetochlor was studied in commercial black mold and products of degradation were followed using gas chromatography-mass spectrometry (GC-MS). After 1-year-exposure in soil only 9% of the parent molecule was found and two metabolites were identified. The estimated half-life (t1/2) of the acetochlor was approximately 90 days. In photolytic degradation studies irradiation of acetochlor resulted in 50% conversion of the parent molecule yielding at least six products, of which five photoproducts accounted for 43 % were tentatively identified using GC-MS and their structures were confirmed by chemical synthesis. Products formed by microbial degradation were less phytotoxic to maize, oat and ryegrass seedlings than parent acetochlor.