Composition of littoral bottom sediments from the Kandalaksha Bay (Whire Sea), labile and lithogenic forms of metals

According to results of a comparative study carried out on sediment sampled from littoral zones of small inlets in the Kandalaksha Bay (White Sea) metals (Fe, Mn, Cu, Zn, Pb, Cr, and Li) occur mainly in biogeochemically stable mineral incorporated forms that comprise 77-99% of total metal concentrations. Average percentages of labile forms easily extracted by weak acid of total concentrations are 3.2% for Fe, 2.0% for Mn, 1.7% for Cr, 5.6% for Pb, 5.8% for Zn, 6.5% for Cu, and is negligible for Li. Concentrations of the most studied trace metals are below the threshold level according to environmental quality guidelines (sediment analysis). The percentages of metal forms evidence natural origin of elevated concentrations of both Zn and Cr in studied sediments.