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

Table 30. The organic matter con­ tents (LOI, %) and heavy metal concentrations (цд/д, dry weight) in the surface (0-1 cm) and pre-industrial (12-13 cm) sediment layers. Cfand Cdare the contamina­ tion factor and degree of contamination values, respectively. riods in the summer the concentrations o fP 0 43 and NO,', which determine the lake productivity, are low. The low micronutrient concentra­ tions of the water entering the water body reflect the low level of chemical weathering of the minerals present in the watershed area. Although the water­ shed of Lake Holmvatn is relatively dis­ tant from the Pechenganickel smelter (32 km), it is still subjected to the im­ pacts of pollutants from thr smelter. The main pollutants are sulphur compounds and heavy metals (Ni, Cu, Co etc.). De­ spite the fact that emissions from the smelter have been reduced to approxi­ mately one third of the peak levels of the late 1970s, the deposition of pollutants still has an impact on the water bodies in the area. The average concentrations of Cu and Ni are 2.8 |_ig/l and 5.8 |ag/l, respectively. Cu, цд/І 28 1.6-3.5 Ni, цд/І 5Я 5.0-7.3 Al, цд/І 28 25-33 Pb, цд/І 03 0.2-0.3 Water colour, deg. 6 6-6 NH4, цд/І 6 4-9 N03, цд/І 2 1-3 Total N, цд/І 9Z 95-100 P04, цд/І 1 1-1 Total P, цд/І 4 4-5 Fe, цд/І 11 5.5-9.3 2.6.2. Lake bottom sediments The sediments in Lake Holmvatn have very low organic matter contents (LOI): in the uppermost 1 cm layer LOI is less than 20% (Table 30). As the lake is located at a distance of 37 km from the “Pechenganickel”smelter, emissions from the smelter have a relatively small impact on the lake. Pollution by chalcophile elements is also low. De­ spite this, the maximum concentrations of almost all metals (Ni, Zn, Co, Cd and Hg) occurred in the 2-5 cm sediment layer (Fig. 45). The accumulation of metals in this layer is presumably due to strong pollution from an unknown source. The contamina­ tion factor values for these heavy metals range from 0.4 to 3.6 (Table 30), i.e. the values correspond to low and moderate contamination. The degree of contamination value (13.0) for this lake corresponds to moderate contamination. Lake Layer, cm LOI Cu Ni Zn Co Cd Pb As Hg cd Holmvatn 0-1 19.45 62 37 98 48 0.16 25.6 1.60 0.048 12-13 13.49 67 20 59 13 0.08 21.9 3.94 0.035 c, 0.9 1.9 1.6 3.6 2.1 1.2 0.4 1.4 13.0 88 Catalogue of Lakes in the Russian, Finnish and Norwegian BorderArea