Heavy Metals in Eight 1965 Cores from the Novaya Zemlya Trough, Kara Sea, Russian Arctic

The concentration and distribution of 18 chemical elements were determined in 86 samples from eight sediment cores, 89–131 cm long, collected during 1965 along a 650 km traverse in the Novaya Zemlya Trough, Kara Sea, Russian Arctic. These include potentially toxic elements followed by the Arctic monitoring and assessment program (AMAP) (e.g., As, Cr, Hg, Pb) and elements that may be related to the fine size minerals in these cores (e.g., Al, K, Mg). Arsenic and Hg had high concentrations (to 212 ppm – baseline 20 ppm, and to 875 ppb – baseline 338 ppb, respectively) in upper sections of cores. This suggests possible anthropogenic input in the Kara Sea before 1965. In contrast, most of the metals analysed had baseline contents throughout the cores. High As values in the sediments probably reflect a combination of diagenetic mobilization from depth to surface/near-surface sediments and input from human activities such as dumped military materials in the trough, mining and smelting effluents and emissions, and the burning of fossil fuel (especially coal). High Hg contents cannot be the result of the diagenetic path followed by As and may reflect an anthropogenic addition of Hg to high natural baseline values from atmospheric deposition of industrial emissions as well as from decomposition of dumped wastes (e.g., lewisite) and naval reactor coolant discharged into the sea. Arsenic and Hg discharged into the southern Kara Sea from Siberia and the Novaya Zemlya archipelago move with oceanic currents and ice-floes as suspensates or adhered particulates for deposition in the trough. Arsenic is likely mobilized in particulates as the arsenate species sorbed to ferric oxy/hydroxides whereas Hg can be mobilized in organisms as the biomethylated form or Hg species (e.g., Hg2+, HgCl42−) sorbed onto organic and/or inorganic (clay mineral) particulates. High concentrations of Mn and Mo in upper core sediments result from post-depositional mobilization from reduced deeper sediments to oxic surface sediments.