Degradation of Herbicide Mesotrione in Three Soils with Differing Physicochemical Properties from China

The movement and fate of herbicides in soils under various environmental factors are important in evaluating their mobility and ecological impact. The effects of sterilization, solarization, and soil physicochemical properties on the degradation of herbicide mesotrione in three soils from China were evaluated using laboratory incubation method, and the degradation kinetics were also simulated using pseudo first-order reaction model. The calculated half-lives (t(1/2)) of mesotrione were found to be 3.78- to 5.24-fold increased in sterilized soils than nonsterilized soils, which indicated that the degradation of mesotrione was strongly affected by soil microbial activity. A certain role of promoting degradation effect of natural light was found, and the t(1/2) values appeared to be only 7.90, 15.89, and 25.29 d(-1) in the surface of paddy soil, sandy loess, and silt clay loam, respectively. Correlation analysis between the observed first-order reaction rate constant (k(obs)) values and the selected soil properties revealed that the degradation of mesotrione was highly dependent on soil pH value (r(2) > 0.992) and organic matter content (r(2) > 0.932), but less related with clay content (<0.02 mm) with r(2) < 0.761 and nonrelated with cation exchange capacity (CEC) (r(2) < 0.164). Data obtained in this study are helpful for further research on the prediction of the movement and fate of mesotrione in soils in limiting its environmental impact.