Hundred topsoil (0-20 cm) samples under different land use types were collected from a county in the Tailake Region, China and analyzed for 18 polychlorinated biphenyls (PCBs) including five dioxin-like PCBs. The mean concentration of total PCBs (SigmaPCBs) for all sites was 1.071 microg kg(-1) dry weight (dw) with a range of 0.016 microg kg(-1) to 4.050 microg kg(-1), and the concentration of total Dioxin-like PCBs (SigmaDioxin-like PCBs) was 0.352 microg kg(-1) about 33% of SigmaPCBs. The concentration of SigmaPCBs in paddy field (PF) soils with a mean of 1.63 microg kg(-1) was higher than that in vegetable soil with a mean of 0.882 microg kg(-1), but the concentration of Dioxin-like PCBs in PF soil was lower than that in commercial vegetable production soil. The concentration of heavier weighted molecular PCB congeners (> or = penta-PCBs) in vegetable soil accounted for 98% of SigmaPCBs, while that in Paddy field soil for 65% of SigmaPCBs.
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