Persistent organic pollutants in the Pechora Sea walruses

Abstract

Until 2011, walrus (Odobenus rosmarus rosmarus) population inhabiting the Pechora Sea remained among the less-studied parts of the Atlantic subspecies. Composition and level of anthropogenic pollutants in these walruses have never been studied before the present work. We collected samples of skin and subcutaneous tissues from 15 adult males in the Pechora Sea and from 1 adult female from adjacent White Sea during the years 2011–2017. These samples were analyzed for polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and organochlorine pesticides. The highest concentrations were found for PCBs (∑PCB: \(\stackrel{-}{x}\) ± SE = 5700 ± 3090 ng g−1 lipid; range 40–50,400 ng g−1 lipid, n = 16), followed by pesticides oxychlordane (\(\stackrel{-}{x}\) ± SE = 1090 ± 412 ng g−1 lipid; range 31–5070 ng g−1 lipid, n = 16), and 4,4′-DDE (\(\stackrel{-}{x}\) ± SE = 460 ± 300 ng g−1 lipid; range 2.5–4920 ng g−1 lipid, n = 16). PBDEs showed the lowest concentrations (∑PBDE: \(\stackrel{-}{x}\) ± SE = 13 ± 6.5 ng g−1 lipid; range 0.7–104 ng g−1 lipid, n = 16). Compared with walruses from Svalbard, the studied animals have considerably lower levels of oxychlordane, comparable levels of PBDEs, and exceeding burden of PCBs. Concentrations found in walruses are closer to polar bears than to other pinnipeds from this region (ringed and harp seals). Although all walruses in the sample group were mature males with exception of one mature female from the same location, concentrations of pollutants varied in very broad range. Three groups of walruses were distinguished by concentrations of analyzed persistent organic pollutants (POPs): low POP concentrations; high POP concentrations; intermediate POP concentrations.