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

The annual chemical cycle of the lake is characterized by no significant changes in the total mineralization of the water during flood periods and episodes of high precipi­ tations, and during low-water periods (mainly in the winter and autumn) and when the inflow of groundwater increases. The composition and relationships between mineral nutrient species vary according to the season, and the dynam­ ics is to a greater extent determined by the level of production and, consequent­ ly, the trophicity of the water body. The highest total P concentration in the lake (up to 11 [ig/1) typical occurs during the summer, and the total P concentration is 1.5-2 times higher than during flood periods. The highest total N concentra­ tions (up to 381 |ig/l) also typically oc­ cur during the vegetation period. Based on the concentrations of min­ eral nutrients, the lake is classified as oli- gotrophic. The lake also has colour val­ ues, and organic matter (up to 4.6 mg/l) and Fe concentrations (mean 93 |ig/l) typical of the small water bodies in this region. The water exchange index is 1.5, i.e. full water exchange in the lake takes about one year and a half. As the lake is not deep, the circulation of mineral nu­ trients in the water is faster during the summer. During flood periods and high precipitation episodes in the autumn, the concentrations of mineral nutrient species (P 0 43 and N 0 3") that determine the lake productivity are low. The watershed of lake LN-3 is sub­ jected to severe anthropogenic impacts from the smelter. The main pollutants are sulphur compounds and heavy met­ als (Ni. Cu, Cd, Cr, Zn, As, Hg etc.). In spite of the fact that emissions from the smelter have been reduced to approxi­ mately one third of the peak levels in the late 1970s, the deposition of pollutants still has a considerable impact on the water body. Copper (up to 26.5 [ig/1) and Ni (up to 150 |ig/l) concentrations in the vicinity of the smelter are substantially higher than in other parts of the region. Hydrochemical properties pH 6.75 6.56-6.99 Electrical conductivity, mS/cm 50 46-55 Ca, mg/l M 4.2-5.7 Mg, mg/l 0.90 0.80-1.03 Na, mg/l 2.62 2.42-2.87 K, mg/l 0.30 0.19-0.58 HC03, mg/l 6 1 4.9-8.0 S04, mg/l 10.1 8.65-10.4 Cl, mg/l 4.14 3.45-4.95 Total mineralization, mg/l 29.5 26.9-32.8 Alkalinity, neq/l 109 81-131 Water colour, deg. 4 2-5 nh 4, мд/і 12 1-53 N03, цд/І z 1-36 Total N, ng/l 187 131-381 P04, (ig/1 1 1-2 Total P, ng/l 6 2-11 Fe, мд/І 93 37-230 Cu, цд/І 13.6 7.90-26.5 111 Ni, цд/І 76-159 12 Al, цд/І 4.5-36 Pb, цд/І 03 0.1-0.7 Catalogue o fLakes in the Russian, Finnish and Norwegian BorderArea