Adsorption and Desorption of Carbendazim and Thiamethoxam in Five Different Agricultural Soils

The adsorption and desorption behaviors of carbendazim (CBD) and thiamethoxam (TMX) were systematically studied in five different agricultural soils. The adsorption and desorption isotherms of CBD and TMX in the five different soils were fitted well by the Freundlich model. The Freundlich adsorption coefficient (K (f) (ads) ) and Freundlich desorption coefficient (K (f) (des) ) of CBD in the five different soils were 1.46-19.53 and 1.81-3.33, respectively. The corresponding values of TMX were 1.19-4.03 and 2.07-6.45, respectively. The adsorption affinity and desorption ability of the five different soils for CBD and TMX depended mainly on soil organic matter content (OMC) and cation exchange capacity (CEC). Desorption hysteresis occurred in the desorption process of CBD and TMX in the five different agricultural soils, especially for TMX. It is concluded that the adsorption-desorption ability of CBD was much higher than that of TMX in the five different agricultural soils, which was attributed to soil OMC and CEC.