Persistent organochlorine residues in harbour porpoise (Phocoena phocoena) from the Black Sea

A wide range of organochlorine residues were determined in the blubber of harbour porpoises from the Black Sea. Concentrations of DDTs (8.3–180 μg g−1 wet weight) were the highest followed by PCBs (1.6–39 μg g−1), HCHs (1.5–17 μg g−1), CHLs (0.11 – 2.4, μg g−1) and HCB (0.057 – 0.61 μg g−1). The composition of DDT and its metabolites was in the order of p,p′-DDT (46%), -DDD (34%), p,p′-DDT (16%) and o,p′-DDT (4%). A similar pattern was also observed in fish from the Black Sea. Relatively higher concentrations of p,p′-DDD in these animals suggested the reductive condition of the Black Sea resulting from organic waste pollution. The residue levels of organochlorines were lower in older female porpoises possibly due to lactational transfer of these contaminants to their calves, while in males the organochlorine concentrations were positively correlated with age. When compared with other cetaceans, the organochlorine residues in harbour porpoises showed a perceptible male-female difference. It is noteworthy that the contamination by DDTs and HCHs in the Black Sea harbour porpoises were elevated amongst a worldwide comparison of organochlorine residues in the same species.