Spatial Distribution Of Polychlorinated Biphenyls In Sediments From Qinzhou Bay, Beibu Gulf Of South China

Polychoririated biphenyls (PCBs) are one important group of Persistent Organic Pollutions (POPs) which had been expressed provision in the Stockholm Convention. PCBs have the characteristics of POPs and cause great threat to human health and ecological environment. Therefore, it’s been paid much attention to the study of PCBs in academia. Qinzhou Bay is an important estuary in Beibu Gulf, and its sediment is the main accumulation of the pollutions. The residual level of polychlorinated biphenyls (PCBs) was determined in the surface sediments collected from the Qinzhou Bay, Beibu Gulf of Southern China in April2011. About thirty-nine surface sediment samples were collected and analysed for polychlorinated biphenyl (PCBs) with gas chromatography-electron capture detector(GC-ECD) to get the concentrations. And pollution level, sources and risk assessment in these surface sediments are studied.The results showed that:the total concentration of PCBs in surface sediment of Qinzhou Bay ranged from1.62to62.63ng/g dry wt, with a mean of9.87ng/g dry wt. The contamination of PCBs in surface sediments from Qinzhou Bay is at the low level when compared to those reported in other regions of the world. Generally from the pollutant concentration trend, the average PCBs concentrations descended in this order:inner bay>outer bay. And there were higher PCBs concentrations in the eastern coast than those in the western coast. On a mean level, with respect to the PCBs homologue profiles, the analysis suggested that tetrachlorinated biphenyls was the most abundant PCB, accounting for about41.57%of the total PCBs. And among the homologous series, the percentage of them descended as the following orders:tetrachlorinated biphenyls> hexachlorinated biphenyls> pentachlorinated biphenyls>decachlorinated biphenyls>octachlorinated biphenyls. PCB profiles varied according to the nature of the site and its proximity to the sources. PCA with multiple linear regression analysis indicated that the PCBs in Qinzhou Bay were mixed pollution and Aroclor products had made great contribution. And it could be speculated that the pollution mainly come from the continental input and long distance transportation. To evaluate the risk assessment of the PCBs in sediment of Qinzhou Bay, different methods had carried out to ensure the accuracy of the data. Risk assessments conducted on the levels indicated that PCBs in sediments of Qinzhou Bay posed no significant risk to human health and environment. However, considering the bioconcentration of the PCBs, attentions should be paid on PCBs.