Studies on photodegradation of chlorimuron-ethyl in soil

Photolysis of chlorimuron-ethyl was studied on a soil surface under sunlight and UV light. Eight photoproducts were isolated and characterised by spectroscopic methods. Major photoproducts are formed by cleavage of the sulfonylurea bridge and minor products are formed via dechlorination, hydrolysis and cyclisation. The rates of photodegradation of chlorimuron-ethyl on different soils followed first-order rate kinetics, with half lives of 22.3 h, 9.4 h, 4.9 h (UV) and 20.7 days, 11.1 days and 11.1 days (sunlight) for alluvial, red and laterite soils, respectively. The differences in rates of photodegradation were dependent upon the soil pH.