Adsorption and leaching behavior of florasulam in different soils

The adsorption and leaching of pesticides in soils are important evaluation index which can be used to describe it's environmental behavior. In this study, the adsorption and leaching of florasulam in different soils were conducted by batch equilibrium and column leaching experiments. The results showed that the adsorption of florasulam in the tested soils was better fitted by the empirical Freundlich adsorption isotherm, and the adsorption constants (Kf) in Anhui clay, Shandong sandy loam and Henan sandy clay loam were ranged from 0.39 to 0.62. The organic carbon partition coefficients (Koc) were ranged from 66.91 to 81.35, which demonstrated that florasulam was rather difficult to be adsorbed on the tested soils. The values of adsorption free energy (ΔG) in the three soil samples were ranged from -10.90 to -10.42 kJ/mol. And the adsorption belonged to spontaneous and physical process. In the three soils, the leaching rates were ranged from 71.7% to 74.1%, and florasulam showed comparatively high mobility and leaching degree. The initial addition and humic acid had some effect on the leaching rate. The adsorption and migration of florasulam could be influenced by the combined effects of organic matter content, clay content, C.E.C and pH value of soil. Thus attention should be paid to the pollution problem of groundwater caused by florasulam.