Accumulation Features and Temporal Trend of Dioxins and Related Compounds in Baikal Seal(Pusa sibirica)

摘要

This study determined the concentrations of polychlorinated dibenzo-p-dioxins(PCDDs),polychlorinated dibenzofurans(PCDFs),and coplanar polychlorinated biphenyls(Co-PCBs)in blubber of Baikal seals(Pusa sibirica)collected on 2005.PCDD/DFs and co-PCBs were detected in all the samples and mono-ortho PCBs(mean:1600 ng/g fat wt.)were dominant,followed by non-ortho PCBs(1300 pg/g fat wt.)>PCDDs(74 pg/g fat wt.)>PCDFs(35 pg/g fat wt.)in males,and mono-ortho PCBs(440 ng/g fat wt.)>non-ortho PCBs(730 pg/g fat wt.)>PCDFs(26 pg/g fat wt.)>PCDDs(15 pg/g fat wt.)in females,respectively.Concentrations of PCDDs and co-PCBs in males were significantly higher than those in females,but not PCDFs.This result suggests that PCDDs and co-PCBs are transferred from mother to pup via placenta and milk.PCDFs might be metabolised by drug metabolising enzymes in males,which accumulate dioxins and related compounds to higher levels than females.In addition,age-dependent accumulation of PCDDs and mono-ortho PCBs was observed in males,but not PCDFs and non-ortho PCBs.When the concentrations of dioxins and related compounds in Baikal seals analyzed in this study were compared with the data in 1992,a decreasing trend was observed,especially in the case of PCDFs and non-ortho PCBs.However,TEQ levels in Baikal seals were higher than the values in pinniped species from other areas and exceeded the immunosuppression value observed in harbour seals,implying that Baikal seals may be at high risk of dioxins and related compounds.