Arsenic and other trace metals in sediments from the Kara Sea and the Ob and Yenisey estuaries, Russia

Major (Al and Fe), minor (Mn) and trace (As, Cd, Co, Cr, Cu, Hg, Li, Mo, Ni , Pb, Sb, V and Zn) metals along with material of grain size < 63 mu m, TOC and TN have been determined in sediment grab and core samples from the Kar a Sea, and the Ob and Yenisey estuaries, Russia. Surprisingly, the levels o f trace metals, with the exception of As, were much lower than was anticipa ted from speculative reports of extensive contamination in the Arctic marin e areas adjacent to the Siberian coastline of Russia. Lithium normalization indicates that the abundance and distribution of the metals, with the exce ption of As and Mo, are controlled by the accumulation of their fine graine d aluminosilicate host minerals at sites determined by hydrodynamic conditi ons in the Kara Sea and in the estuaries. Metal levels in the Kara Sea and the Ob and Yenisey estuaries, except for some anomalous As, Cu and Ni value s, are close to natural baseline levels of other Eurasian Arctic shelf sedi ments. High levels of As, however, occur in surface and subsurface sediment s. The accumulation of As, as well as Mo, can be attributed to the post-dep ositional diagenetic effects of Fe-Mn cycling both at and near the sediment water interface. Subsurface As and Fe maxima and minima suggest alternatin g oxic and anoxic water conditions during post-glacial rises in sea level. In contrast to the results from the adjacent Pechora Sea, in the Kara Sea t here is no correlation between the levels of As and radionuclides in the se diments.