Study on the Characteristic of Adsorption Kinetics of Organochlorine Pesticides in Agricultural Soils

To study the characteristic of adsorption kinetics of BHC and DDT in the unsaturated zone of typical northeastern soil field of China by adopting indoor soil adsorption simulation experiment. The purpose of the study is to reveal the pollution mechanism of BHC and DDT to soil and groundwater and provide a scientific basis for making reasonable and effective groundwater pollution prevention and control measures. The results showed that the adsorption of BHC and DDT in the tested soils were well consistent with the Langmuir kinetics equation. Adsorption can be divided into two processes, namely, rapid reaction phase and slow reaction phase. At the initial stage of reaction, the amount of adsorption increased with time and basically reached equilibrium at about 4 similar to 8 h. The equilibrium adsorption capacity was more than 50% in the first hour and above 90% in the second hour. In addition, the sorption and the desorption process actually occur simultaneously during the adsorption or desorption of organic matter. The adsorption / desorption two-compartment model can describe the two reversible processes at the same time. The fitted value r is from 0.8039 to 0.9651.