Persistent organochlorine contaminants and enantiomeric signatures of chiral pollutants in ringed seals (Phoca hispida) collected on the east and west side of the Northwater Polynya, Canadian Arctic

To examine the influence of diet and age on organochlorine contaminant (OC) concentrations in two closely related ringed seal (Phoca hispida) populati ons enantiomeric fractions (EFs) of chiral contaminants and stable isotopes of nitrogen (delta N-15) and carbon (delta C-13) were measured along with OCs in ringed seals collected from the cast and west side of the Northwater Polynya. Seals from these two locations were feeding at the same trophic l evel based on delta N-15 values in muscle but had slightly different source s of carbon based on delta C-13 measurements in muscle. After removing the influence of age, sex, and blubber thickness, OC concentrations did not var y between ringed seals from the cast and west side of the polynya. Sigma PC B, Sigma DDT, and Sigma chlordane were found to increase with age for both male and female seals. The inclusion of older (> 20 years) female seals, wh ich may have a reduced reproductive effort, may influence the relationships in females. Stable isotopes failed to describe OC concentrations in ringed seals suggesting that diet was not a major factor in variation of OC conce ntrations within this ringed seal population. Cis- and trans-chlordane, oxy chlordane, and heptachlor epoxide were all nonracemic in the ringed seal bl ubber but did not vary with age, sex, or collection site. alpha -HCH appear ed racemic (enantiomeric fraction = 0.50 +/- 0.01) in the seals, although t his EF is different than those previously observed in their prey species, a nd was found to vary significantly with age. EF values in the ringed seals varied considerably from other Arctic marine mammals and seabirds, providin g addition evidence that the type(s) and characteristic(s) of the enzymes i nvolved in bio transformation of chiral OCs vary between these organisms.