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

1.15. LAKE ALLA-AKKAJARVI Lake Alla-Akkajarvi (watershed of the River Lotta) is located 44 km to the south of the town of Nikel. It is a relatively large (area of the lake is 19.88 km2), not deep (max. depth 15 m) elongated lake of glacial origin. The maximum length is 14.6 km and maximum width 2.8 km. The deepest points in the lake are to be found in its western part. The lake is intensively used by inland water transport. According to the landscape type, the watershed belongs to the tundra zone with heights of up to 288 m (Kuotes- varr fell). The northern shore of the lake is waterlogged. The southern shore is higher but, despite this, it is also water­ logged in places. Shrubs, and birch and pine stands grow along the shores. The water of the lake is yellowish and, during the flood period and episodes of high precipitation, the colour of the water in­ creases to 44 deg. The shores are rocky. An uninhabited settlement (Prirechny), country houses and the slag heaps from an abandoned mine are located along its eastern shore. Physico-geographical characteristics Watershed River Akkim— River Lotta— RiverTuloma Latitude 69°00.987' Longitude 30°15.884' Height above sea level, m 154.5 Maximum length, km 14.6 Maximum width, km 2.8 Maximum depth, m 15 Area, m2 19.88 Watershed area, km2 315.0 Study period 1995-2007 1.15.1. Hydrochemistry The water of the lake is close to neu­ tral and has a low total mineralization (mean 18.1 mg/l) and alkalinity (mean 139 (ieq/1). During the flood period the pH falls to 6.59 and then rises back to about 6.83, i.e. oxidation processes do not develop due to the buffering capac­ ity of the water. The lake has low con­ centrations of base cations and anions, with calcium (average 2.16 mg/l) and bicarbonate (average 8.5 mg/l) predomi­ nating. The annual chemical cycle of the lake is characterized an insignificant decrease in mineralization, oxidizability and pH during flood periods and episodes of high precipitation when the inflow of humic water increases. The P and N concentrations in water are the main criteria used for assessing the de­ velopment of water eutrophication. The concentrations and relationships between the species of these mineral nutrients vary according to the season, and the dynamics is to a greater extent regulated by the level of production and, consequently, the trophicity of Hydrochemical properties pH 6.75 6.59-6.83 Electrical conductivity, 28 mS/cm 23-33 Ca, mg/l 2.16 1.76-2.43 Mg, mg/l 0.88 0.74-1.05 Na, mg/l 1.52 1.31-1.74 K, mg/l 0.50 0.41-0.59 HC03, mg/l M 6.5-10.7 S04, mg/l 2.96 2.51-3.81 Cl, mg/l 1.51 1.17-2.00 Total mineralization, mg/l 18.1 15.2-21.2 Alkalinity, цед/І 139 106-175 Catalogue o fLakes in the Russian, Finnish and Norwegian BorderArea