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

Hydrochemical properties at the time. The concentrations of these elements, as well as of other elements that characterize the state of the water, are currently still rather high. The annual chemical cycle of the lake is characterized by a drop in total mineralization to 48.3 mg/l, as well as a drop in pH, during flood periods and episodes of high precipitation when the inflow of humic water increases. During low-water periods (mainly in winter and autumn) and when the in­ flow of groundwater increases, the to­ tal mineralization increases slightly to 90.5 mg/l, the oxidizability drops and the pH rises. The concentrations and relation­ ships between species of mineral nu­ trients vary according to the season, and the dynamics is to a greater extent determined by the level of production and, consequently, the trophicity of the water body. The highest total P concen­ trations (up to 60 pg/l) typically occur in the summer, when it is 7-8 times higher than during the flood period. The high­ est total N concentrations (up to 390 pg/l) normally occur during the vegetation period. Based on the concentrations of bio­ genic elements, the lake is classified as eutrophic.The lake also has colour values, and organic matter (up to 5.0 mg/l) and Fe concentrations (mean 85 pg/l) typi­ cal of small water bodies in the region. The trophic status of the water body is primarily regulated by the proximity of the town ofNikel and the smelter on the shore of the lake. The water exchange in­ dex is 1.55, i.e. full water exchange in the lake takes about one year and a half. Sus­ pended particles are strongly deposited in the northern and deepest part of the lake, with the result that the bottom of the lake is completely covered with a thick layer of silt, comprising undecomposed zooplank- ton debris and organic matter. This feature is of primary importance for the feeding of whitefish species. The conditions for the growth of food organisms are obviously highly favourable. The watershed of Lake Kuetsjarvi is subjected to severe pollutant impacts result­ ing from the activities of the Pechenganikel smelter. The water system of the lake is exposed to the direct discharge of pollutants from the metallurgical and smelting pH 7.06 6.71-7.31 Electrical conductivity, 105 mS/cm 67-137 Ca, mg/l 10.2 6.86-13.5 Mg, mg/l 3.54 2.00-4.97 Na, mg/l 4.24 2.66-6.50 K, mg/l 0.83 0.59-1.16 HC03, mg/l 17.5 11.0-21.9 S04, mg/l 28.8 16.8-40.3 Cl, mg/l 3.69 2.40-4.87 Total mineralization, 69.0 mg/l 43.8-90.5 Alkalinity, цед/І 287 180-359 Water colour, deg. 24 12-50 NH4, цд/І 26 2-72 N03, цд/І 39 1-320 Total N, |ag/l 226 134-390 P04, цд/І 4 1-26 Total P, pg/l 18 7-60 Fe, цд/І 85 14-350 Cu, цд/І M 4.5-15.2 106 Ni, цд/І 74-182 36 Al, цд/І 8-126 0.17 Pb, цд/І 0.01-0.78 Catalogue ofLakes in the Russian, Finnish and Norwegian BorderArea