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Metallurgic industry is a source of serious environmental pollution related to the emission of heavy metals. Freshwater systems are focal points for pollution, acting as sinks for contaminants that may end up in fish and humans. The Pasvik watercourse in the border area between Finland, Norway and Russia is located in the vicinity of the Pechenganickel metallurgic enterprises, and the lower part of the watershed drains the Nikel smelters directly through Lake Kuetsjarvi. Heavy metal (Ni, Cu, Cd, Zn, Pb and Hg) concentrations in environment (water and sediments) and whitefish Coregonus lavaretus tissue (gills, liver, kidney and muscle) were contrasted between five lake localities situated along a spatial gradient of increasing distance (5-100 km) to the smelters. The heavy metal concentrations, in particular Ni, Cu and Cd, were highly elevated in Kuetsjarvi, but steeply declined with increasing distance to the smelters and were moderate or low in the other four localities. The study demonstrates that the majority of metal emissions and runoffs are deposited near the pollution source, and only moderate amounts of the heavy metal contaminants seem to be transported at further distances. Bioaccumulation of Hg occurred in all investigated tissues, and higher Hg concentrations in planktivorous versus benthivorous whitefish furthermore indicated that pelagic foraging is associated with higher levels of Hg biomagnification. Potential population ecology impacts of high heavy metal contaminations where mainly observed in whitefish in Kuetsjarvi, which showed depletions in growth rate, condition factor and size and age at maturation.

Aspects of reducing the resource potential of surface waters of the Murmansk region in the global climate change and the environment and their irrational use have been considered. Increase of aquatic environment toxicity, drastic restructuring of the structural and functional characteristics of aquatic communities, changes in trophic status of lakes, reducing the stability of freshwater ecosystems, increasing the risk of catastrophic degradation have been shown. Taking into account the regional peculiarities, some indicators of surface water quality in the Murmansk region have been proposed.

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Sediment cores were collected from seven lakes in the Subarctic Pasvik watercourse, polluted by sewage waters and air emissions from the Pechenganickel Metallurgical Company, in order to study chemical composition and estimate the intensity of pollution by taking into account background concentration of elements and the vertical and spatial distribution of their contents in cores and surficial layers of sediments. Sediment samples were analysed by atomic-absorption spectrophotometry for 18 elements (Ni, Cu, Co, Zn, Cd, Pb, Hg, As, Cr, Sr, Mn, Fe, Ca, Mg, Na, K, Al, P). Maximum concentrations of all investigated heavy metals (Ni, Cu, Co, Zn, Cd, Pb, Hg, As) were found in the surficial sediment layers of Lake Kuetsjarvi situated directly below the metallurgic smelters. Decreased contents of heavy metals were observed in surficial sediment layers further downstream in the Pasvik watercourse, although pollution remained rather high. Considerable increase in the contents of the heavy metals emitted into the atmosphere in significant amounts by the Pechenganickel Company (Ni, Cu, Co, Zn), was not observed in surficial sediment layers of lakes upstream in the watercourse polluted only by air contamination and household sewage, but substantial increase of the concentrations of chalcophile elements (Pb, Cd, Hg, As) was revealed. The increase in P contents towards the sediment surface in some lakes may suggest a development of eutrophication processes. Our studies reveal that the metallurgic processing of the Pechenganickel Company has resulted in comprehensive heavy metal pollution and contaminations of lakes sediments in the Inari-Pasvik watercourse. The pollution impact on the sediments is most severe in Lake Kuetsjarvi in the vicinity of the smelters, intermediate in lake localities in the main watercourse downstream the metallurgic enterprises and least in lake localities in the upstream part of the watercourse.