Adsorptionanddesorptionbehaviorofrotenoneinthreedifferentsoils

Static equilibrium experiments were conducted to investigate the adsorption and desorption behavior of rotenone in three different agricultural soils including sandy loam, clay loam and loam. All adsorption and desorption isotherms could be best described by the Freundlich model (R²≥0.946 8). The results showed that the adsorption constant (K_f-ads) of rotenone in three soils were from 1.52 to 11.39. The order of the adsorption capacity of the soils to rotenone was: clay loam> sandy loam> loam. The desorption constant (K_f-des) of rotenone were from 1.02 to 4.55. The order of the desorption capacity was: loam> clay loam> sandy loam. The organic carbon distribution constant (K_OC) of rotenone in three soils were 982, 1 017 and 219 while the hysteresis index (H) were 0.687 3, 0.556 9 and 0.892 3, respectively. The research indicated that rotenone was not easy to migrate in clay loam and sandy loam which exhibits hysteresis. On the contrast, it can migrate easily in loam with no hysteresis. The research provides theoretical guidance for the safety evaluation of rotenone in soils.