Bioaccumulation of PCBs and chlorinated pesticides in seals, fishes and invertebrates from the White Sea, Russia

Abstract

Persistent organochlorines (OC) contaminants, including polychlorinated biphenyl (PCB) congeners, Dichlorophenyltrichloroethane (DDT)- and chlordane (CHL) related compounds, hexachlorocyclohexanes (HCH) isomers and chlorobenzenes (CBz) were determined in blubber of harp seals ( Phoca groenlandica), ringed seals ( Phoca hispida) and bearded seals ( Eringnathus barbatus) as well as in fishes and invertebrates from the White Sea, in northwest Russia. Highest ∑PCB and ∑DDT concentrations were found in samples from two male bearded seals (means of 4150 ng/g lw and 3950 ng/g lw, respectively). Female harp seals had mean ∑PCB and ∑DDT concentrations of 1070±504 ng/g lw and 619±328 ng/g lw, respectively. Male and female adult ringed seals had similar mean ∑PCB concentrations as harp seals (955±385 ng/g lw and 999±304 ng/g lw, respectively). ∑CHL concentrations ranged from 63±29 ng/g lw in blubber of female adult ringed seals, to 322±156 ng/g lw in adult harp seals and averaged 465 ng/g lw in bearded seals. HCH isomers, mirex and chlorobenzenes were detected in all seal samples but were present at lower levels than ∑CHL, ∑DDT and ∑PCB. Concentrations of ∑CHL, ∑DDT and ∑PCB in ringed seals from the White Sea were within the range reported for the Barents Sea but lower than in ringed seals from the Kara Sea. Temporal trends were investigated by comparing concentrations of OCs in blubber of harp seal pups collected in 1992 with pups of the same age collected in 1998. The declines over the 6 year period ranged from approximately 33% for ∑DDT to 60% for ∑PCB. These declines are consistent with reports of declining concentrations ∑DDT in seawater from the White Sea and inflowing rivers in the 1980's and early 1990s. The major OC contaminants in fishes from the White Sea were DDT-related compounds and PCBs. Navaga ( Eleginus navaga) had the highest concentrations of the 5 fish species studied with mean ∑PCB of 41±6 ng/g wet wt. while lowest mean concentrations were present in cod muscle (16±8 ng/g ww). Concentrations of hexachlorobenzene (HCB), DDT, CHL—related compounds and PCB congeners were strongly correlated with trophic level of the organisms assigned using δ 15N values, while β-HCH, γ-HCH and cis-chlordane showed no relationship with trophic level. Food web magnification factors (FWMFs) for p,p′-DDE, α-HCH, oxychlordane and trans-nonachlor the White Sea were similar to those from marine food webs in the Barents Sea and the Canadian arctic, while FWMFs for HCB and PCBs were generally lower. Overall the results suggest that the White Sea marine food differs in terms of the availability of contaminants in comparison to studies of open ocean arctic food webs due to proximity to urban/industrial areas and greater importance of benthic food sources.