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

Water colour, deg. 19 10-32 nh 4, pg/1 7 1-22 N03, цд/І 16 1-98 Total N, ng/l 192 100-597 P04, цд/І 1 1-2 Total P, цд/І 4 2-6 Fe, ng/1 123 5-1571 covered with a thick layer of silt, com­ prising undecomposed zooplankton de­ bris and organic matter. This feature is of primary importance for the feeding of ichthyofauna. The conditions for the growth of organisms are obviously high­ ly favourable. Due to the fact that most of the lake is not deep, the circulation of mineral nutrients in the water is faster in the summer; this also increases the production capacity of the water body. During high water periods and high precipitation episodes in the autumn, the concentrations of species of mineral nutrients (P 0 43_ and N 0 3') that deter­ mine the lake productivity are low. The watershed of Lake Shuonijaur is subjected to the impact of pollutants emitted by the “Pechenganikel” smelter. The main pollutants are sulphur com­ pounds and heavy metals (Ni, Cu etc.). Maximum concentrations of Cu (up to 7.5 pg/1) and Ni (17 pg/1) were recorded in the water in the 1990s. At the present time, due to the reduction in the airborne pollution load, higher Cu (up to 11 pg/1) concen­ trations occur during the flood period when the snow melts in the watershed, and of Ni (up to 182 pg/1) during flood periods and the autumn low-water periods. Cu, ng/l 47 2.0-11.0 7.4 Ni, ng/l 4.7-17.0 40 Al, цд/І 14-194 0.22 Pb, ng/l 0.10-0.56 1.18.2. Lake bottom sediments Table 20. The organic matter contents (LOI, %) and heavy metal concentra­ tions (цд/д, dry weight) in the surface (0-1 cm) and pre-industrial (14-15 cm) sediment layers. Cf and Cdare contamina­ tion factor and degree of contamination values, respectively. The sediments of Lake Shuonijaur have somewhat lower organic matter contents: the LOI value in the uppermost 1 cm layer is slightly less than 30% (Table 20). The lake is located at a distance of 20 km from the Pechenganikel smelter, and is subjected to airborne pollution by heavy metals (Ni, Cu, Co) and chalcophile elements (Pb, As, Cd and Hg).The top 3-4 cm layer of the lake sediments is the most polluted by Ni, Cu and Co. Pollution by chalcophile elements started earlier: these elements are present in the top 6-7 cm layer especially (Fig. 25). Lake Layer, cm LOI Cu Ni Zn Co Cd Pb As Hg Cd Shuonijaur 0-1 29.76 100 117 63 7.8 0.47 12.1 2.03 0.040 14-15 21.97 14 13 47 1.7 0.06 0.8 0.74 0.013 cf 7.3 9.3 1.3 4.6 8.5 14.9 2.7 3.1 51.7 62 Catalogue o f Lakes in the Russian, Finnish and Norwegian BorderArea