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

the water body. The highest concentra­ tion of total P in the lake (up to 22 |ig/l) and of total N (up to 311 fag/1) are typical for the vegetation period. According to the concentrations of mineral nutrients, the lake is classified as eutrophic. The lake also has colour val­ ues, and organic matter (7.4 mg/l) and Fe concentrations (mean 176 |ig/l) typi­ cal for water bodies in the region. The water exchange index, which regulates the concentration of mineral nutrients in the lake, is 0.82, i.e. full wa­ ter exchange in the lake takes about 1 year. During flood periods and episodes of high precipitation in the autumn, the con­ centrations of species of mineral nutrients (P 0 43 and N 0 3') that determine the lake productivity are low. Water colour, deg. 31 18-44 NH4, (jg/l 20 2-103 N03, мд/І 2 1-5 Total N, мд/І 216 161-311 po 4, мд/і 2 1-10 Total P, цд/І И 4-22 Fe, мд/І 176 98-360 Cu, мд/і M 0.9-4.5 Ni, мд/і 17.2 3.6-41.4 Ai, мд/і 45 11-139 Pb, цд/І 0.67 0.01-2.37 The maximum pollution of the lake occurred in the middle of the 20th century, when the mine near the settlement of Prirechny was operating. At the present time the watershed of Lake Alla-Akkajarvi is subjected to anthropogenic impacts from the Pechenganikel smelter. The water system of the lake is also subjected to the effect of the smelter emissions. The main pollutants are sulphur compounds and heavy metals (Ni. Cu etc.). Due to the substantial size of the watershed, the impact of reduced emissions still results in higher concentrations of Cu (up to 4.5 |_ig/l) and Ni (up to 41.4 |ig/l) during periods of high water. 1.15.2. Lake bottom sediments The sediments of Lake Alla-Akkajarvi have relatively high organic matter contents: the LOI value in the uppermost 1 cm layer is 35% (Table 15). The lake is located at a distance of 45 km from the “Pechenganikel”smelter. The lake is affected by heavy met­ al (Ni, Cu, Co) and chalcophile elements (Pb, As, Cd and Hg) in the form of airborne emissions from the smelter and effluent from the Cu-Ni mine. The top 3 cm layer of the lake sediments is the most polluted by Ni, Cu and Co. Pollution by chalcophile ele­ ments began earlier because the top 10 cm layer of the sediments is especially polluted by these elements (Fig. 12). The contamination factor values for these toxic elements range from 2.5 to 13.5 (Table 15), i.e. the values correspond to high and considerable contamination. The most toxic chalcophile element, Hg, has the highest Cfvalue. The contamination factor values for the other heavy metals correspond to moderate con­ tamination. The degree of contamination value (72.7) for this lake corresponds to high contamination. Catalogue o f Lakes in the Russian, Finnish and Norwegian BorderArea