Aerobic soil metabolism of metsulfuron-methyl

✍ Scribed by Li, Yutai; Zimmerman, W T; Gorman, M K; Reiser, R W; Fogiel, A J; Haney, P E

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 259 KB
• Volume: 55
• Category: Article
• ISSN: 1526-498X
• DOI: 10.1002/(sici)1096-9063(199904)55:4<434::aid-ps909>3.0.co;2-z

✦ Synopsis

A laboratory study was conducted to determine the degradation rates and identify major metabolites of the herbicide metsulfuron-methyl in sterile and non-sterile aerobic soils in the dark at 20ÄC. Both [ phenyl-U-14C ] -and [ triazine-2-14C ] metsulfuron-methyl were used. The soil was treated with [ 14C ] metsulfuron-methyl (0.1 mg kg-1) and incubated in ýow-through systems for one year. The degradation rate constants, and were obtained based on the ürst-order and biphasic DT 50 , D T 90 models. The (time required for 50% of applied chemical to degrade) for metsulfuron-methyl, DT 50 estimated using a biphasic model, was approximately 10 days (9-11 days, 95% conüdence limits) in the non-sterile soil and 20 days (12-32 days, 95% conüdence limits) in the sterile soil. One-year cumulative carbon dioxide accounted for approximately 48% and 23% of the applied radioactivity in the [ phenyl-U-14C ] and [ triazine-2-14C ] metsulfuron-methyl systems, respectively. Seven metabolites were identiüed by HPLC or LC/MS with synthetic standards. The degradation pathways included O-demethylation, cleavage of the sulfonylurea bridge, and triazine ring opening. The triazine ring-opened products were methyl 2-[ [ [ [ [ [ [(acetylamino)carbohyl ] amino ] carbonyl ] amino ] carbonyl ] -amino ] sulfonyl ] benzoate in the sterile soil and methyl 2-[ [ [ [ [amino [ (aminocarbonyl)imino ] methyl ] amino ] carbonyl ] amino ] sulfonyl ] benzoate in the non-sterile soil, indicating that diþ erent pathways were operable.