Residues of polychlorinated biphenyls in agricultural fields of Chongming Island in Shanghai

Residues concentration of 8 polychlorinated biphenyls (PCBs) congeners in 101 soil samples collected at Chongming Island of Shanghai were determined by GC-μECD. Concentrations of PCBs were between ND and 261 ng/g with average of 56.0 ng/g. Concentration and detection rate of low chlorinated homologues of PCBs were higher than high chlorinated homologues. Concentrations of PCBs varied with the changes of agricultural land use. Depended on the residue concentration level, the series of land use appeared as following: paddy soil > green house vegetable and watermelon soil > traditional vegetable and watermelon soil. Principal component analysis (PCA) and correlation analysis were introduced to investigate source of PCBs. The result showed that lower chlorinated homologues of PCBs were well correlated and implies that they maybe originate from similar sources.