Distribution and Ecological Hazard of Organochlorine Pesticides Residues in Surface Sediment from Pai Lake

Concentrations of organochlorine pesticides(OCPs) residues in Pai Lake are determined by USEPA 8000 methods under quality assurance and quality control(QA/QC).The method of dividing sediment into upper sediment(up to 2 cm of the bed sediment) and lower sediment(2~10 cm) is applied.The results show that concentration of OCPs is 9.71~123.62 ng·g-1 in sediment.OCPs content of sediments in the upper is higher than that in the lower part,which results from the steady hydrodynamic conditions of the lake.DDD/DDE ratio indicates that degradation of DDT at the upper sediment is mainly under anaerobic conditions,and under aerobic conditions at lower sediment.Low α-HCH/γ-HCH ratio indicates new Lindane might be used recently.Compared with the corresponding quality guidelines from Ingersoll,the lake would impose high ecological risk on aquaculture,particularly on benefic fauna and soil-feeders.