Distribution and Risk Evaluation of Organochlorine Pesticides Residues in Surface Sediment from Quanzhou Bay

Concentrations of organochlorine pesticides(OCPs) residues in Quanzhou Bay,were determined based on USEPA 8000 methods and under quality assurance and quality control(QA/QC).The surface sediment was divided into upper sediment(up to 2 cm of the bed sediment) and lower sediment(2～10 cm).The results show that concentrations of OCPs are in the order of inner bay,Xiutu-Shihu and offshore area from high to low.Endosulfan sulfate and heptachlor epoxide which have high adsorptivity tend to accumulate in upper sediment.OCPs residues in surface sediment are mainly degraded under anaerobic condition,while the degree of degradation in upper sediment is obviously higher than that in lower sediment.South-southwestward tidal-current results in long-term residence of organic contaminants in the inner bay,and retards their degradation.According to the corresponding quality guidelines from Ingersoll,the Bay would impose higher ecological risk on the marine biology,particularly on deep-water aquiculture and benthonic mud-eaters.