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

lake is characterised by a reduction in the total mineralization to 23.1 mg/l and fall in pH during flood periods and episodes of high precipitation. During low-water periods, mainly in the autumn and winter, and when the inflow of ground water increases, the total mineralization of the water increases slightly to 37.4 mg/l, the oxidizability is reduced and the pH rises. The concentrations and relationships between species of mineral nutrients vary ac­ cording to the season, and the dynamics is to a greater degree determined by the level of production and, consequently, the trophicity of the water body. The highest total P concentration (up to 17 pg/l) typically occurs during flood periods, when it is 2-3 times higher than the total P concentrations during low-water periods. The highest total N concentrations (to 340 pg/l) occur during the winter period. According to the concentrations of mineral nutrients, the lake is classified as mezotrophic. The lake also has colour values and organic matter concentrations (up to 5.4 mg/l) typical of small water bodies in the region. The mean Fe con­ centration is 193 pg/l. The trophic type of the water body is to a considerable extent regulated by its close proximity to the town of Zapolyarny and the smelter. The water exchange index is 4.9, i.e. full water exchange in the lake takes about 5 years. The bottom of the lake is covered with a thick layer of silt, which consists of undecomposed organic matter debris. Water colour, deg. 26 15-38 nh 4, мд/і 19 6-40 N03 pg/l 15 1-88 Total N, цд/І 200 116-340 P04, мд/і 2 1-2 Total P, мд/І 10 1-17 Fe, мд/І 193 30-500 The watershed of Lake Palojarvi is subjected to major anthropogenic im­ pacts from the Pechenganikel smelter. The main pollutants are sulphur com­ pounds and heavy metals (Ni. Cu, Co etc.). S 0 2 emissions from the smelter have caused the oxidation of surface wa­ ter and the pollution of ground water owing to the leaching of elements from the surface soil. Maximum Cu (11 pg/l) and Ni (36 pg/l) concentrations were reported in the water in 1990s. Despite the reduction in emissions from the smelter, elevated Cu (up to 17.4 pg/l) and Ni (up to 62 pg/l) concentrations occurred throughout the study period. Cu, мд/і 11.1 7.0-17.4 Ni, мд/і 40 25-62 Al, цд/І 26 14-47 Pb, мд/і 02 0.1-0.6 1.9.2. Lake bottom sediments The sediments of Lake Palojarvi are characterized by relatively high organic matter contents: the LOI value in the uppermost 1 cm layer is more than 65% (Table 9). The lake is located at a distance of 20 km from the Pechenganikel smelter and is subjected to high deposition of heavy metals (Ni, Cu, Co) and chalcophile elements (Pb, As, Cd and Hg). The contamination factor values of these toxic elements range from 2.3 to 36.3 (Table 9), i.e. the values correspond to considerable and high contamination. Catalogue o f Lakes in the Russian, Finnish and Norwegian BorderArea