Catalogue of Lakes in the Russian, Finnish and Norwegian Border Area = [Каталог озер в приграничном районе России, Финляндии и Норвегии] / Nikolay A. Kashulin, Vladimir A. Dauvalter, Sergey S. Sandimirov etc. - Apatity : Institute of the North Industrial Ecology Problems KSC RAS etc., 2008.

tion and inflow of humic water increase. Elevated concentrations of P and N are important criteria when estimating water eutrophication.The concentrations of and relationships between species of P and N vary according to the season and the dynamics is to a greater extent determined by the level of production and, consequently, the trophicity of the water body. The average concentrations of total P and total N during the veg etation period are 10 pg/1 and 307 pg/1, respectively. According to the concentrations of mineral nutgrients, the lake is classified as mezotrophic. The colour values and organic matter (4.9 mg/l) and Fe con centrations (average 39 |ig/l) are typi cal of small water bodies in the region. During flood periods in the summer the concentrations ofP 0 43"and N 0 3",which determine the lake productivity, are low. Although the watershed of Lake Is- alombola is relatively remote from the Pechenganickel smelter (62 km), it is subjected to anthropogenic impacts as a result of emissions from the smelter. The main pollutants are sulphur compounds and heavy metals (Ni, Cu, со, etc.). De spite the fact that emissions from the smelter have fallen to approximately one third of the peak levels of the late 1970s, the deposition of pollutants still affects the water bodies in the area. The average concentrations of Cu and Ni are 1.3 pg/1 and 1.4 pg/1, respectively. 2.7.2. Lake bottom sediments Hydrochemical properties pH 6.79 6.62-6.98 Electrical conductivity, mS/cm 23 21-24 Ca, mg/l 1.71 1.46-1.81 Mg, mg/l 0.58 0.50-0.63 Na, mg/l 1.52 1.46-1.67 K, mg/l 0.47 0.44-0.50 HC03, mg/l 67 6.0-7.1 S04, mg/l 2.16 2.07-2.25 Cl, mg/l 156 1.36-1.85 Total mineralization, mg/l 14.6 13.3-15.8 Alkalinity, peq/l 109 99-117 Water colour, deg. 13 12-15 nh 4, Mg/i 9 7-10 N03, цд/І 2 1-4 Total N, цд/І 188 145-307 po 4, мд/і 2 1-4 Total P, цд/І 6 3-10 Fe, мд/І 39 32-51 Cu, мд/і 13 0 . 5 - 2.7 Ni, мд/1 14 0 . 6 - 2.6 Al, мд/і 17 13-20 Pb, мд/і 03 0.2-0.6 The sediments in Lake Isalombola have relatively high organic matter contents (LOI): in the uppermost 1 cm layer it was about 30% (Table 31). The lake is located at a distance of 59 km from the Pechenganickel smelter. As a result, emissions from the smelter have a relatively minor effect on water quality, and the lake is subjected prima rily to the deposition of chalcophile elements such as Pb, As, Cd and Hg.The top 3-4 cm sediment layer is the most polluted (Fig. 46). The contamination factor values for these toxic chalcophile metals range from 2.1 to 19.9 (Table 31), i.e. the values cor respond to high, considerable and moderate (Hg) contamination. Lead has the highest Catalogue o fLakes in the Russian, Finnish and Norwegian BorderArea