Organic halogen compounds, EOX, in mussels from a clean lake and a pulp mill recipient

Abstract

The extractable organic halogen (EOX) residue of duck mussels, Anodonta anatina, from the unpolluted Lake Höytiäinen, Finland, was found to be 690 μg/g of lipids. The residue was characterized by analyzing chlorinated phenols, hydrocarbons and fatty acids. These compound classes accounted only for 1.9% of the EOX. Mussels from the same lake were incubated in a lake receiving pulp and paper mill effluents for 12 months to study the bioaccumulation of organochlorine compounds. The EOX of these mussels was 2045 μg/g lipids and only 1.1% of the residue was explained by the low molecular weight compounds. Thus, the majority of EOX remains undefined. However, potential differences in composition are suggested by the relative proportion of defined compounds and the differences among the measured compound classes. These halogen compounds may be of natural origin or reaction products of anthropogenic compounds with humic substances. The presence of such compounds should be taken into account when evaluating the accumulation of pulp mill effluent-related EOX in mussels. No difference was found in the EOX between male and female mussles caged close to a pulp mill, but, on dry weight basis, mussels infected by a digenean parasite had higher EOX concentration than healthy females.