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

1.6.1. Hydrochemistry The lake is, due to its close proximity to the Pechenganikel smelter, one of the most polluted lakes in the Pechenga area. Airborne industrial pollution has a major impact on the quality of the lake water. The water of the lake is neutral, and its mean total mineralization 164.4 mg/l and mean alkalinity 174 |_ieq/l. During flood periods the pH falls to 6.73 and then increases back to 7.15, i.e. oxidation processes do not develop as a result of the buffering capacity of water. The lake is characterized by high concentrations of base cations and anions, with calcium (average 31.8 mg/l) and sulphate (average 105 mg/l) predominating. The concentrations of most elements in the water, especially sulphate (up to 115 mg/l), and Cu and Ni, are currently at a high level. The annual chemical cycle of the lake is characterized by no significant changes in total mineralization during the flood period and episodes of high precipitation, as well as during low-water periods (mainly in the autumn and winter) when the inflow of groundwater increases. Physico-geographical characteristics Watershed river— Lake Kuetsjarvi — River Paz Latitude 69°25.454' Longitude 30°23.747' Height above sea level, m 210.0 Maximum length, km 0.6 Maximum width, km 0.3 Maximum depth, m 6 Area, m2 0.11 Watershed area, km2 2.5 Study period 2003-2007 The concentrations and relationships between mineral nutrient species vary according to the season, and the dynam­ ics is to a greater extent determined by the level of production and, consequent­ ly, to the trophicity of the water body. The highest total P concentrations in the lake (up to 13 |ig/l) typically occur during the summer, and they are 3 times higher than the concentrations during flood periods. The highest total N con­ centrations (up to 189 |ig/l) also occur during the vegetation period. Based on the concentrations of min­ eral nutrients, the lake is classified as oligotrophic. The colour values, organic matter concentrations (up to 4.9 mg/l) and Fe concentrations (mean 116 ^g/1) are also typical of small water bodies in the region. The water exchange index is 4.3, i.e. full water exchange in the lake takes about 4 years. As the lake is not deep, the circulation of mineral nutrients in the water speeds up during the summer. During high water periods and episodes of high precipitation in the autumn, the concentrations of mineral nutrients (P 0 43_and N 0 3) that determine the lake productivity are low. Hydrochemical properties pH 6.97 6.73-7.15 Electrical conductivity, 252 mS/cm 229-268 Ca, mg/l 31.8 38.1-34.4 Mg, mg/l 8.77 8.06-9.68 Na, mg/l 3.71 3.05-4.00 K, mg/l 0.61 0.50-0.77 HC03, mg/l 10.7 7.6-13.4 S04, mg/l 105 96-115 Cl, mg/l 3.04 2.00-4.75 Total mineralization, 164 mg/l 146-179 Alkalinity, |jeq/l 174 124-220 Catalogue o f Lakes in the Russian, Finnish and Norwegian BorderArea