Content and pattern of organic pollutants (PAHs, PCBs and DDT) in blue mussels Mytilus trossulus from the southern Baltic Sea

The objective of this work was to assess the contents and patterns of selected organic pollutants (polycyclic aromatic hydrocarbons - PAHs, polychlorinated biphenyls - PCBs, and chlorinated pesticides - DDT) in the southern part of the Baltic Sea proper, using blue mussels, Mytilus trossulus, as sentinel organisms. The mussels were collected from the Baltic Sea off Poland. The sampling programme focused on the mouths of the rivers Odra and Vistula, located respectively in the Pomeranian Bay and the Gulf of Gdansk, both known to be under anthropogenic pressure. The analyses of PCBs and DDT were performed by GC-ECD, that of PAHs by GC-MS. Mussels from both the Vistula and Odra estuaries were found to contain higher levels of organic contaminants (PAHs, PCBs, DDT; 29.7 ng g-1 w.w. (wet weight), 22.3 ng g-1 w.w., 11.2 ng g-1 w.w. respectively) as compared to the reference point (PAHs - 8.6 ng g-1 w.w., PCBs - 1.9 ng g-1 w.w., DDT - 1.3 ng g-1 w.w.). These results confirm the direct influence of land-based pollution sources on the content of organic pollutants (PAHs, PCBs, and DDT) in the southern Baltic Sea, and point to the Gulf of Gdansk as the area most under threat. P/A and Fluo/Py ratios indicate that in all the mussels analysed, the contaminants were derived mainly from pyrolitic combustion. The mussels collected along the Polish coast of the Baltic contain mostly tetra-aromatic isomers (fluoranthene, pyrene, benzo(a)anthracene and chrysene), penta-aromatic isomers (benzo(b)fluoranthene, benzo(e)fluorene, benzo(a)pyrene and dibenzo(a,h)-anthracene) and hexa-aromatics (indeno(1,2,3-cd)pyrene and benzo(ghi)perylene) rather than di- and tri-aromatics (naphthalene, fluorene, phenanthrene and anthracene). As regards PCBs, the Baltic mussels contain mostly the more highly chlorinated congeners (penta- and hexachlorobiphenyls). The PCB / pp' DDE and PAH / pp' DDE ratios indicate the predominance of PCBs and PAHs over agriculturally derived DDE in both the Pomeranian Bay and the Gulf of Gdansk.