Sandimirov S.S. Catalogue of lakes in the Russian, Finnish and Norwegian Border Area. Finland, Jyvaskyla: Kopijyva Oy, 2008.

obviously very favourable. Due to the fact that most of the lake is not deep, the circula­ tion of mineral nutrient material in water is at its greatest in the summer, which also increases the food producing capacity of the water body. At the present time the watershed area is subjected to relatively small anthropo­ genic impacts from the smelter. The main pollutants are sulphur compounds and heavy metals (Ni, Cu etc.). Now that emissions have decreased, the mean concentration of Cu is 1.9 |ag/l and of Ni - 2.9 pg/1. 1.2.2. Lake bottom sediments The sediments in Lake Kaskamajarvi are characterized by low organic matter contents: the LOI value in the uppermost 1 cm layer is less than 20 % (Table 2). The lake is located at a distance of 35 km from the Pechenganikel smelter and is exposed to the deposition of heavy metals (Ni, Cu, Co) and chalcophile elements (Pb, As, Cd and Hg) emitted by the smelter. The uppermost 1 - 2 cm layer is the most strongly pol­ luted with Ni, Cu and Co. Pollution by chalcophile elements occurred earlier: the 3-4 cm sediment layer is strongly polluted by these elements (Fig. 2). The contamination factor (Cf) values for these toxic elements range from 1.4 to 5.6 (Table 2), i.e. they cor­ respond to moderate and marked contamination. Lead (Pb) has the highest Cfvalue. The degree of contamination (Cd) value (20.2) for this lake corresponds to considerable contamination. Lake Layer, cm LOI Cu Ni Zn Co Cd Pb As Hg c d Kaskama­ jarvi 0-1 19.32 77 70 107 32.4 0.30 12.0 7.63 0.116 19-20 15.24 53 26 115 13.9 0.09 2.1 4.83 0.057 c f 1.4 2.7 0.9 2.3 3.6 5.6 1.6 2.0 20.2 2.3. Hydrobiological studies No direct hydrobiological investigations have been carried out in this lake. As regards the fish fauna, Lake Kaskamajarvi is a typical reservoir for species such as trout ( Salmo trutta), whitefish ( C oregonu s lavaretus), grayling ( Thumallus thumallus ), pike ( Esox lucius), perch ( Perea Лиviatilis), burbot ( Lota lota), minnow ( Phoxinus phoxinus), and nine-spine stickleback ( Pungitius pungitius). Catalogue o f Lakes in the Russian, Finnish and Norwegian BorderArea Table 2. The organic matter contents (LOI, %) and heavy metal concentra­ tions (цд/д, dry weight) in the surface (0-1cm) and pre-industrial (19-20 cm) sediment layers. Cf and C, are contamina- a tion factor and degree of contamination values, respectively. Fig. 2. Vertical distribution of the concentrations ofNi, Pb, Cd and Fig fag/g, dry weight) in the sediment core ofLake Kaskamajarvi.