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

1.8. LAKE NJASJUKKAJARVI Lake Njasjukkajarvi (watershed of the river Pechenga) is located 5 km to the west of the settlement of Pechenga and 3 km to the east of the Russian-Norwegian border. An earth road passes by along the lake to the coast of the Barents Sea. It is a rather large (area of the lake 9.5 km2), shallow-water (maximum depth 7 m) elongated oval lake of glacial origin. The maximum length is 6.2 km and maximum width 2.6 km. The point of maximum depth (6 m) is located in the central part of the lake. The River Njasu- kkjajoki flows out of the lake. According to the landscape type, the watershed area belongs to the forest- tundra zone with heights of up to 292 m (Selkjatunturi fell). The eastern shore of the lake is high and covered by shrubs and birch forest. The watershed area is waterlogged in the south. The water in the lake is colourless. There are some boulder beds and sandy beaches in the littoral zone. The gaps between the boulders are filled with sand and pebbles. Physico-geographical characteristics Watershed River Njasukjajokki — River Pechenga Latitude 69°33.939' Longitude ЗГ02.151' Height above sea level, m 65.8 Maximum length, km 6.2 Maximum width, km 2.6 Maximum depth, m 7 Area, m2 9.5 Watershed area, km2 98.0 Study period 2004 1.8.1. Hydrochemistry The water of the lake is neutral, and is characterized by low total mineralization values (average 26.2 mg/l) and alkalinity (average 120). The lake has low concen­ trations of base cations and anions, sodi­ um (average 4.08 mg/l) and bicarbonate (average 7.4 mg/l) predominating. Based on the concentrations of min­ eral nutrients, the lake is oligotrophic. The concentration of total P is 4 |ig/l and total N - 120 pg/l. The lake also has colour values, organic matter concentra­ tions (up to 4.3 mg/l) and Fe concen­ trations (mean 31 pg/1) typical of small water bodies in the region. During high water periods in the summer the con­ centrations of mineral nutrient species (P 0 43 and N 0 3") that determine the lake productivity are low. The water exchange index, which de­ termines the concentrations of mineral nutrients in the lake is 1,8, i.e. full water ex­ change in the lake takes about 2 years. The bottom of the lake is covered with a thick layer of silt, which consists of undecomposed zooplankton debris and organic matter. These properties are ofprimary importance for the feeding of ichthyofauna.The condi­ tions for the growth of food organisms are obviously highly favourable. Hydrochemical properties pH 6.97 6.94-6.99 Electrical conductivity, mS/cm 43 42-44 Ca, mg/l 2.22 2.15-2.29 Mg, mg/l 1.16 1.16-1.16 Na, mg/l 4.08 4.04-4.13 K, mg/l 0.55 0.54-0.57 HC03, mg/l 7Л 7.3-7A S04, mg/l M 4.7-4.9 Cl, mg/l 6.39 6.22-6.55 Total mineralization, mg/l 26.6 26.2-27.0 Alkalinity, |ieq/l 121 120-121 Catalogue of Lakes in the Russian, Finnish and Norwegian BorderArea