| Abstract
| - Chlorimuron,2-[[[[(4-chloro-6-methoxy-2-pyrimidinyl)amino]carbonyl]amino]sulfonyl]benzoicacidethyl ester, was added to water (pH 7.5, hardness = 110 mg ofCaCO3/L) and soil (sandy loam, pH5.2) to determine the rates of dissipation at 5 and 25 °C.Radioactivity of both pyrimidine- andphenyl-14C-labeled chlorimuron was quantitatively recoveredfrom water after incubation for 112days. Greater than 85% of the radioactivity was recovered fromthe soil treatments after 56 daysof incubation. Extractable radioactivity in the soil decreasedwith time. The rate of degradation ofchlorimuron in water followed zero-order kinetics(R2> 0.95). Less than 7% of thechlorimurondegraded at 5 °C, and the slope of the zero-order constant did notdiffer from zero. Half-life forchlorimuron in water at 25 °C ranged from 388 to 725 days, dependingupon treatment. Dissipationof chlorimuron appeared to be greater in light than dark treatments.In soil, chlorimuron dissipationwas described by first-order kinetics and half-life ranged from 17 to22 days. Probable degradationproducts (saccharin, ethyl benzoate sulfonamide, and pyrimidine amine)in soil and water wereidentified in the methanol eluate by thin layer chromatography.Ethyl benzoate sulfonamide andpyrimidine amine are hydrolysis products of chlorimuron. Less than1% of the radioactivity fromwater was evolved as carbon dioxide. Three to 5% of theradioactivity was evolved as carbon dioxidefrom the nonsterile soil treatment. Temperature appears to be asignificant factor affectingchlorimuron dissipation in soil and water. Light may also enhancechlorimuron dissipation in water. Keywords: Sulfonylurea; environmental fate; biotic and abioticdissipation
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