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

1.11.2. Lake bottom sediments Table 11. The organic matter contents (LOI, % ) and heavy metal concentra­ tions (iug/g, dry weight) in the surface (0-1cm) and pre-industrial (14-15 cm) sediment layers. Cf and Cd are contamina­ tion factor and degree of contamination values, respectively. The sediments ofLake Pikku-Heynjajarvi have relatively high organic matter contents: the LOI value in the uppermost 1 cm layer is more than 30% (Table 11). The lake is located at a distance of 13 km from the Pechenganikel smelter and is subjected to significant airborne pollution consisting of heavy metals (Ni, Cu, Co) and chalcophile elements (mainly Pb and Hg).The top 2-3 cm layer of the lake sediments is strongly polluted by these elements (Fig. 8). The contamination factor values for these toxic elements range from 2.6 to 17.8 (Table 11), i.e. the values correspond to considerable and high contamination. Nickel has the highest Cfvalue. The degree of contamination value (41.9) for this lake corresponds to high contamination. Lake Layer, cm LOI Cu Ni Zn Co Cd Pb As Hq C h Pikku-Heynjajarvi 0-1 14-15 32.42 21.49 194 29 350 20 101 137 45.1 17.4 0.24 0.25 14.8 1.6 7.26 5.06 0.157 0.061 ..... c, 6.6 17.8 0.7 2.6 0.9 9.2 1.4 2.6 41.9 Fig. 8. Vertical distribution of the concentrations ofNi, Cu, Co and Pb (цд/д, dry weight) in the sediment core of Lake Pikku-Hey- njajarvi. 1.11.3. Hydrobiological studies No direct hydrobiological investigations have been carried out in this lake. The lake is most probably inhabited by pike (Esox lucius), perch (Perea £uviatilis), burbot (Lota lota), and nine-spine stickleback (Pungitius pungitius). 1.12. LAKE POROJARVI Lake Porojarvi (watershed of the River Paz) is located 18 km to the south-west of the town of Nikel and 4 km from the Russian - Norwegian border, along the road to the settlement of Rajakoski. It is a small (area of the lake 4.34 km2), rela­ tively shallow (maximum depth 11.5 m), almost oval lake of glacial origin. The maximum length is 3.8 km and maxi­ mum width 2.0 km. The point of maxi­ mum depth is located in the central part of the lake. Physico-geographical characteristics Watershed RiverMenikkajoki— River Paz Latitude 69°20.953' Longitude 29°47.854' Height above sea level, m 71.4 Maximum length, km 3.8 Maximum width, km 2.0 Maximum depth, m 11.5 Area, m2 4.34 Watershed area, km2 54.7 Study period 1989-2004 38 Catalogue ofLakes in the Russian, Finnish and Norwegian Border Area