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

1.7.2. Lake bottom sediments The sediments of Lake LN-3 have relatively high organic matter contents, with LOI values for the whole sediment core of more than 35% (Table 7). The lake is located at a distance of 9 km from the smelter, and subjected to significant airborne pollution of heavy metals (Ni, Cu, Co) and chalcophile elements (Pb, As, Cd and Hg).The top 3-4 cm of the lake sediments are the most strongly polluted by Ni, Cu and Co, and the top 5-6 cm also by chalcophile elements (Fig. 6), i.e. pollution by these very toxic elements has begun at an earlier date. The contamination factor values for these toxic elements range from 3.2 up to 36.2 (Table 7), which correspond to considerable and high con­ tamination. Hg (one of the most toxic and dangerous elements for hydrobionts) has the largest Cf value. The degree of contamination value (99.8) for this lake corresponds to high contamination. Lake Layer, cm LOI Cu Ni Zn Co Cd Pb As Hg c d LN-3 0-1 36.61 81 103 72 10.6 0.30 10.4 32.40 0.362 30-31 36.56 22 13 54 3.3 0.05 0.7 1.16 0.010 c, 3.6 7.8 1.3 3.2 5.5 14.3 27.9 36.2 99.8 Table 7. The organic matter contents (LOI, % ) and heavy metal concentra­ tions (pg/g, dry weight) in the surface (0-1cm) and pre-industrial (30-31 cm) sediment layers. Cfand Cdare con­ tamination factor and degree of contamination values, respectively. Fig. 6. Vertical distribution of the concentrations of Ni, Cu, Pb, Cd and Hg (pg/g, dry weight) in the sedi­ ment core of Lake LN-3. 1.7.3. Hydrobiological studies Lake LN-2 LN-3 has low biodiversity levels. The dominant species are chironomids, water-bugs and beetles. No fish are present in this lake. Catalogue o f Lakes in the Russian, Finnish and Norwegian BorderArea 29