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

According to the landscape type, the watershed area belongs to the forest-tundra zone with a height of up to 206.8 m. The southern lake shore is waterlogged, and the northern shore is higher. Shrubs, birch and pine forests grow along the shoreline. The water of the lake is colourless but, during flood periods and episodes of high precipi­ tation, the colour of the water increases to 34 de. There are some boulder beds in the littoral zone, and they extend down to a depth of about 2 - 2.5 m. The gaps between the boulders are filled with pebbles. 1.12.1. Hydrochemistry The water of the lake is neutral and has higher total mineralization values (av­ erage 37.3 (ig/1) and alkalinity (average 304 |aeq/l) than the other lakes. During flood periods the pH of the water drops to 6.95 and then rises back to 7.38, i.e. oxidation processes do not develop. The lake does not have high concentrations of base cations and anions, but calcium (average 6.12 mg/l) and bicarbonate (av­ erage 18.6 mg/l) are predominant. The annual chemical cycle of the lake is characterized by a significant reduc­ tion in the total mineralization, oxidiz­ ability and pH during flood periods and episodes of high precipitations when the inflow of humic water increases. Phosphorus and nitrogen concen­ trations if water are the main criteria of development of water eutrophication. The concentrations and relationships between these species of P and N 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 concentrations of total P (up to 11 |ig/l) and total N (up to 267 |ig/l) oc­ cur during the vegetation period. According to the concentrations of mineral nutrients, the lake is classified as eutrophic. The lake also has colour values, and organic matter (4.6 mg/l) and Fe concentrations (mean 23 |-ig/l) typical of small water bodies in the region. The water exchange index is 0.95, i.e. full water exchange in the lake takes about 1 year. During flood periods and episodes of high precipitation in the autumn, the concentrations of species of mineral nutrients (P 0 43" and N 0 3") that determine the lake productivity are low. Hydrochemical properties pH 7.19 6.95-7.38 Electrical conductivity, mS/cm 50 46-56 Ca, mg/l 6.12 5.98-6.43 Mg, mg/l 0.94 0.88-1.11 Na, mg/l 1.91 1.71-2.23 K, mg/l 0.61 0.50-0.69 HC03, mg/l 18.6 17.4-19.8 S04, mg/l 67 4.9-12.6 Cl, mg/l 2A 2.1-2.8 Total mineralization, mg/l 37.3 34.0-45.7 Alkalinity, (jeq/l 304 285-325 Water colour, deg. 22 15-34 NH4, цд/І 8 3-15 N03, цд/І 28 1-52 Total N, цд/І 190 139-267 P04, цд/І 1 1-2 Total P, |_tg/l 4 1-11 Fe, цд/І 23 16-26 Catalogue o f Lakes in the Russian, Finnish and Norwegian BorderArea