Research on the influence of the activities of Pechenganickel Mining and Metallurgical Company on sediment heavy-metal geochemistry of the subarctic Lake Kuetsjärvi (north-western Russia) are described. It is estimated that during 60 years of mining/refining activity, 310 t of Ni, 120 t of Cu, 14 t of Co, 19 t of Zn, 0.087 t of Cd, 0.78 t of Pb and 0.053 t of Hg have accumulated in the lake sediments. The latter can be a source of secondary pollution and represent a danger for the lake ecosystem. The sedimentation rate in the lake is estimated to be within the range of 1.5-3 mm year(-1). The average concentrations of Ni, Cu, Hg and Co in superficial sediments have increased 25, 14, 11 and 5 times, respectively in the last century.