Distribution, Sources And Risk Assessment Of Ocps In Sediments From Coastal Area Of Qinzhou Bay

Organochlorine pesticides (OCPs) is the first group of Persistent Organic Pollutants (POPs) to be controlled as specified in the Stockholm Convention on POPs. OCPs have the characteristics of environmental persistence, semi-volatility, highly toxicity and bioaccumulation. Once OCPs presente at the environmental media, they can remain in the environment for a long time and transporte far away from their places of release, where they accumulate and magnification through the food chain. Pose a great threat to the environment security and human health.35sediment samples were collected from Qinzhou Bay and its tributary rivers. OCPs was analyzed by using the GC-ECD apparatus, and the distribution, sources and risk assessment in the surface sediment are studied.The following resuts were obtained:total OCP concentration in surface sediments of Qinzhou Bay ranged from1.54to129ng/g dry weight, with a mean concentration of26.0ng/g dry weight. When compare to those reported in other regions of the world, the contamination of OCPs in surface sediments from Qinzhou Bay is at the low to medium level. OCPs distribution in sediments of Qinzhou Bay showed a higher level in Maowei Sea than Qinzhou Outer Bay and in eastern coast than western coast in Maowei Sea. Total OCP concentration in surface sediments of the tributary rivers ranged from10.1to64.8ng/g dry weight, with a mean concentration of23.4ng/g dry weight. When compare to those reported in other rivers of the world, the contamination of OCPs in sediments from the tributary rivers is at the low to medium level. The highest concentration was found in sediments from the Maoling River, while the lowest concentration was found in the Jingu River.Component analysis of OCPs showed that DDT and HCH in sediments from Qinzhou Bay was mainly originated from historical usage, but in some sampling areas showed new input of DDT and lindane. DDTs in sediments from the tributary rivers of Qinzhou Bay was mainly originated from historical usage and the degradation has occurred, HCHs in upstream of the Jingu River showed new input of lindane and in other areas of the tributary rivers was mainly originated from historical usage. Chlordane in sediments of Qinzhou Bay and its tributary rivers was mainly originated from the fresh use of technical chlordane.Risk assessment according to Effects Range Low and Effects Range Median (ERL/ERM) values and Threshold Effects Level and Probable Effects Level (TEL/PEL) showed that the potential ecological risk of chlordane, Heptachlor and lindane in sediments of Qinzhou Bay and its tributary rivers was relatively low while ecological risk of DDTs was high and great concern should be paid on the contamination of DDTs in the study area.