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

of glacial origin. The maximum length is 3.4 km, maximum width 2.4 km, and the maximum depth occurs in the central part of the lake. According to the landscape type, the watershed area belongs to the forest-tun- dra zone with altitudes of up to 351.5 m (Kaskama hill). The south-eastern shore is waterlogged, and the other shores are high and abrupt. Shrubs and birch and pine forests grow along the shoreline. The water of the lake is colour­ less. Boulder beds, extending to a depth of about 2-2.5 m, occur in almost all parts of the littoral zone. The gaps between the boul­ ders are filled with silt and peb­ bles. pH 6.95 6.88-7.09 Electrical conductivity, mS/cm 34 32-37 Ca, mg/l 3.22 2.88-3.57 Mg, mg/l 0.77 0.70-0.89 Na, mg/l 1.92 1.88-1.95 K, mg/l 0.39 0.36-0.40 HC03, mg/l 9A 9.2-9.6 S04, mg/l 4.19 4.05-4.29 Cl, mg/l 2.06 1.84-2.39 Total mineralization, mg/l 21.9 21.3-22.4 Alkalinity, peq/l 153 151-157 Water colour, deg. 24 22-25 nh 4, мд/і 12 8-17 no 3, мд/і 9 1-17 Total N, мд/І 164 123-198 P04, мд/і 1 1-1 Total P, мд/і 4 3-5 Fe, мд/І 36 34-41 1.2.1. Hydrochemistry The water of the lake is neutral and is characterized by low total mineralization (average 21.9 mg/1) and alkalinity (average 153 |ieq/l). The lake has low concentrations of base cations and anions, cal­ cium (average 3.22 mg/1) and bicarbonate (average 9.4 mg/1) predominating. The total P and N concentra­ tions are the main criteria used in assessing the development of water eutrophication. The con­ centrations and relationships between P and N species vary according to the season, and the dynamics is to a greater extent determined by the level of pro­ duction and, consequently, the trophicity of the water body. The concentrations of these mineral nutrients during the vegetation period are: total P up to 5 |ig/l, and total N up to 198 |_ig/l. Based on the concentrations of nutrient elements, the lake is oligotrophic. The lake also has colour values, organic matter concentrations (up to 4.6 mg/1) and Fe concentrations (mean 36 |ig/l), typical of small water bodies in this region. The water exchange index is 0.61, i.e. full water exchange in the lake takes about 6 months. The bottom of the lake is covered with a thick layer of silt comprised of undecomposed zooplankton debris and organic matter; this is of primary importance for the feeding of ichthyofauna. The conditions for the growth of food organisms are Cu, мд/і L9 1.5-2.4 2.9 Ni, мд/і 2.1-3.8 42 Al, цд/І 38-45 Pb, мд/і O l 0.1-0.2 Catalogue ofLakes in the Russian, Finnish and Norwegian Border Area