Organochlorine contaminants in a local marine food chain from Jarfjord, Northern Norway

Polychlorinated biphenyls (PCBs; 17 congeners), ΣDDT (p,p′-DDT, p,p′-DDD, p,p′-DDE and o,p′-DDD), chlordanes (oxychlordane and trans-nonachlor), hexachlorocyclohexanes (HCHs; α-, β- and γ-isomers) and hexachlorobenzene (HCB) have been determined in a local marine food chain including the lesser sandeel (Ammodytes marinus), cod (Gadus morhua), harbour seal (Phoca vitulina) and grey seal (Halichoerus grypus), caught in Jarfjord, Northern Norway. The concentrations of the pollutants generally increased with trophic level. The highest biomagnification factor (36.9) was found for ΣDDT from sandeel to harbour seal. The compositional patterns of accumulated organochlorines also differed between the species. The proportions of highly chlorinated biphenyls, p,p′-DDE and oxychlordane increased with higher trophic level, while the proportions of mono-ortho substituted and meta–para unsubstituted PCB congeners, together with DDD decreased from fish to seal. The data suggest that the bioaccumulation mechanisms at lower trophic levels (fish) depend primarily on physicochemical factors, such as the water solubility and lipophilicity of the pollutants. At higher trophic levels (seals), the bioaccumulation mechanisms are primarily affected by biochemical factors, such as the metabolic capacity of the organisms. Prey preference may also influence the patterns of accumulated pollutants in the different species.