Speciation of heavy metals in marine sediments vs their bioaccumulation by mussels

Total contents and speciation of selected heavy metals, including Al, Fe, Co, Ni, Pb, Zn, Cu, Cr, were measured in sediment samples and mussels Mya arenaria and Astarte borealis collected in the Horsund Fjord off Spitsbergen (Norwegian Sea) and the Bay of Gdansk (Baltic Sea). The investigation aimed at revealing differences in the accumulation pattern of heavy metals in mussels inhabiting sediments characterized by varying metal bioavailability. The contents of metals adsorbed to sediments and associated with iron and manganese hydroxides, which were obtained by sequential extraction, were utilized as a measure of metal bioavailability. The contents of Cd, Pb, Zn, Cu and Cr in mussels collected off Spitsbergen were generally lower than those in mussels from the Baltic Sea. In sediments collected off Spitsbergen the bioavailable fraction represented a small proportion (0–3.7% adsorbed metals and 0–11% associated with metals hydroxides) of total heavy metal contents. In sediments from the Baltic Sea the percentages of metals adsorbed and bound to hydroxides were 1–46% and 1–13%, respectively. The differences in bioavailable metal contents measured in sediments were utilized to explain the different contents of metals in mussels collected in the corresponding sites.