Research On Pollution Status Of Polychlorinated Biphenyls And Poly Brominated Diphenyl Ethers In Chinese Surface Soil

Polychlorinated biphenyls(PCBs) and Poly brominated diphenyl ethers(PBDEs) both areglobal persistent organic pollutants, which are widespread in the environment. Currently, thesurvey area of PCBs and PBDEs in China is very limited, it is difficult to estimate thepollution status of PCBs and PBDEs in Chinese surface soil. Therefore, studying the pollutionstatus of PCBs and PBDEs in Chinese surface soil can fill the gaps in this area.In this study，89surface soil samples have been sampled in the nationwide, including3directly governed cities,20provinces and3autonomous regions. The samples have a widedistribution, and cover the large area. They can fully reflect pollution status of PCBs andPBDEs in Chinese surface soil. After the steps of sampling the surface soil samples, soxhletextraction, silica gel column purification, concentration and determination with GC/MS,studied the concentration distribution, congeners composition and homologues distribution ofPCBs and PBDEs in Chinese surface soil.The results showed that：the whole PCBs pollution level in Chinese surface soil was low,but there was evident difference in different areas, some developed cities were showed moreserious PCBs pollution. The concentration of∑PCBs in Chinese surface soil was between48.89and8689.39pg/g dw, and the average concentration was1012.00pg/g dw. Theconcentration distribution of PCBs in different sampling point types in China overall showedthat the city points had the highest concentration, followed by the rural points, theconcentration of background points in remote areas was the lowest. The main PCBscongeners in Chinese surface soil was low chlorine PCBs. Compared with top ten PCBscongeners of transformer oil in China, there were5same congeners, they were CB-17、CB-18、CB-22、CB-31/28、CB-44. The main PCBs homologues in Chinese surface soil wereTri-CBs and Tetra-CBs, the sum of Tri-CBs and Tetra-CBs concentration accounted for53.97%of∑PCBs concentration. Transformer oil in China had the same main PCBshomologues, but they had different proportions.The results also showed that：the whole PBDEs pollution level in Chinese surface soilwas low, but there was evident difference in different areas, some developed cities wereshowed more serious PBDEs pollution. The concentration of∑PBDEs in Chinese surfacesoil was between4.37×102and7.98×105pg/g dw, and the average concentration was 5.35×104pg/g dw. The concentration distribution of PBDEs in different sampling point typesin China overall showed that the city points had the highest concentration, followed by therural points, the concentration of background points in remote areas was the lowest. Themain PBDEs congeners in Chinese surface soil was BDE209(its concentration accounted for98.43%of∑PBDEs concentration.), and the main PBDEs homologues in Chinese surfacesoil was Deca-BDE, followed by Penta-BDEs.By correlation analysis on the concentration of∑PCBs and∑PBDEs with TOC in soil,the results showed that influence of TOC in soil on concentration of∑PCBs and∑PBDEswas very limited.