Study on Kinetics of Adsorption and Desorption of Imazethapyr on Soil

The behavior characteristics of sorption-desorption kinetics of imazethapyr in soil were studied with the batch equilibrium method, when the slight alkaline soil (Meadow saline Soil) and weak acid soil (Black paddy soil) was used as soil samples which had the similar organic matter content. It was shown that the adsorption and desorption of imazethapyr in soils can almost achieve equilibrium within 24 hours in the experimental conditions. We found that adsorption and desorption kinetics of imazethapyr in Meadow saline soil and Black paddy soil can be well describe with dual constant equation (r=0.868-0.940, SE<;0.023), the processes of adsorption and desorption were approximated to non-homogeneous diffusion processes. The desorption rate of imazethapyr had same change trend in different types of soils. Desorption rate of imazethapyr with the higher initial concentration was larger than that with the lower initial concentration. The desorption rate of imazethapyr in Meadow saline Soil was higher than that in Black paddy soil. In slight alkaline soil, adsorption capacity of imazethapyr was relatively weak, whereas desorption capacity was relatively easy, so that it was of fluidity and easy to contamination groundwater.