Persistent organic pollutants in two Finnish watercourses: Levels, congener profiles and source estimation by mussel incubation

Mussel incubation was used to compare two Finnish watercourses, which have been contaminated by effluents from pulp mills and are known to be polluted with polychlorinated biphenyls (PCBs). Lake mussels (Anodonta Piscinalis) incubated in 1998 and 2004 in the rivers Kymijoki and Vuoksi were analysed for PCBs and polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), naphthalenes (PCNs), diphenyl ethers (PCDEs), hydroxy diphenyl ethers (HO-PCDEs), methoxy diphenyl ethers (MeO-PCDEs), and polybrominated diphenyl ethers (PBDEs). The contamination of the River Kymijoki, which descends to the Baltic Sea, proved significantly greater than that of the River Vuoksi, with no decreasing apparent trend, except for the PBDEs. The River Vuoksi represented more a background area compared to the River Kymijoki, excluding the PCBs. The concentration of the PCDD/PCDFs in the Kymijoki mussels exceeded the EU’s maximum permissible level for PCDD/PCDFs in foodstuffs (4 pg g−1 fresh weight). Analyses of perfluorooctanesulphonate and perfluorooctanoate in the mussels incubated in 2005 and 2006 in the River Kymijoki revealed no significant contamination of the river with these compounds. Comparison of the data of the mussels with that of sediments and commercial formulations showed that the past manufacture of a chlorophenol-based wood preservative has remained a significant source of the PCDD/PCDFs, HO-PCDEs and PCDEs in the River Kymijoki. PCB formulations are believed to represent the major sources of the PCBs and PCNs in both watercourses, though situation in the River Kymijoki had been influenced by a chlor-alkali plant. Municipal wastewaters are believed to represent the major source of the PBDEs.