Photolytic properties of isoxaflutole on the soil surface and its degradation, leaching properties in soils

To assess the environmental risk of isoxaflutole, the laboratory microcosm studies were conducted to investigate the photolytic properties of isoxaflutole on the red soil surface and its degradation, leaching properties in three contrasting soils (moisture soil, paddy soil and red soil). The results demonstrated that photodegradation of isoxaflutole on the surface of red soil followed the first-order kinetics model, and the equation was as follows: c_t = 4.23e^–0.008t (r = 0.937) with a half-life of 82.5 h. The degradation in three soils (moisture soil, paddy soil and red soil) also followed the first-order kinetics model. The aerobic degradation half-lives in three soils were 10.5, 43.3 and 139 h, respectively, and the anaerobic degradation half-lives were 19.4, 18.4 and 158 h, respectively. The leaching coefficients (R_f) in moisture soil, paddy soil and red soil were 0.417 0, 0.083 3 and 0.083 3, respectively. The results showed that the photodegradation rate of isoxaflutole on the surface of soil was slow. But its degradation rate in soils was fast under aerobic or anaerobic conditions which led to short residue period. The results indicated that it’s not easy for isoxaflutole to cause pollution risk to the surrounding environment and groundwater.