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

1.14.2. Lake bottom sediments The sediments of Lake Trifonajarvi have extremely low organic matter contents: the LOI value in the uppermost 1 cm layer is slightly more than 6% (Table 14). The lake is located at a distance of 27 km from the Pechenganikel smelter and is subjected to airborne pollution by heavy metals (Ni and Cu) and chalcophile elements (Pb, Cd and Hg).The top 3-4 cm of the lake sediments are the most strongly polluted by these ele­ ments (Fig. 11). The contamination factor values for these toxic elements range from 2.8 to 5.5 (Table 14), i.e. the values correspond to considerable contamination. The chalcophile elements, Pb and Hg, have the highest Cfvalues. The degree of contamina­ tion value (22.6) for this lake corresponds to considerable contamination. Lake Layer, cm LOI Cu Ni Zn Co Cd Pb As Hg cd Trifonajarvi 0-1 6.51 164 164 144 46 0.26 20.9 7.41 0.138 9-10 6.94 54 58 140 40 0.10 3.9 7.17 0.025 cf 3.1 2.8 1.0 1.1 2.6 5.4 1.0 5.5 22.6 1.14.3. Hydrobiological studies According to earlier data (Yakovlev et al., 1991), the benthic fauna of this lake is rela­ tively abundant and includes organisms of different systematic groups (amphipoda, chironomids, caddis flies, oligohaets and mayfly). The plankton community is repre­ sented by cladocera and copepods. Despite the absence of ichthyologic data, this lake is a typical salmonid (trout and arctic char) water body. Table 14. The organic matter contents (LOI, %) and heavy metal concentra­ tions (цд/д, dry weight) in the surface (0 1cm) and pre-industrial (9-10 cm) sediment layers. Cf and Cdare contamina­ tion factor and degree of contamination values, respectively. Fig. 11. Vertical distribution of the concentrations ofNi, Cu, Cd and Hg (цд/д, dry weight) in the sediment core of Lake Trifonajarvi. Catalogue o f Lakes in the Russian, Finnish and Norwegian Border Area 45