Catalogue of Lakes in the Russian, Finnish and Norwegian Border Area = [Каталог озер в приграничном районе России, Финляндии и Норвегии] / Nikolay A. Kashulin, Vladimir A. Dauvalter, Sergey S. Sandimirov etc. - Apatity : Institute of the North Industrial Ecology Problems KSC RAS etc., 2008.

The P and N concentrations ofwater are the main criteria used for assessing the development of water eutrophica- tion. The concentrations and relation ships between the species of P and N vary according to the season, and the dy namics is to a greater extent determined by the level of production processes and, consequently, the trophicity of the wa ter body. The concentrations of total P and total N during the vegetation period reach 10 pg/l and 350 |ig/l, respectively. According to the concentrations of mineral nutrients, the lake is classified as mesotrophic. The lake also has col our values and organic matter (up to 8.0 mg/l) and Fe concentrations (mean 431 |ig/l) typical of small water bodies in the region. During high water periods in the summer the concentrations of PO,3' and N 0 3",which determine the lake produc tivity, are low. Although the watershed of Lake Suovaselkajarvi is relatively remote from the Pechenganickel smelter (76.3 km), it is nevertheless subjected to anthro pogenic impacts. The water system of the lake is exposed to the deposition of airborne pollutants derived from the smelter. The main pollutants are sulphur compounds and heavy metals (Ni, Cu, Al, etc.) Despite the fact that emissions from the smelter have decreased to ap proximately one third of the maximum levels during the late 1970s, the deposi tion of pollutants still has an impact on the water body. The average Cu, Ni and Al concentrations are 0.8 pg/l, 1.7 pg/l and 63 pg/l, respectively. Hydrochemical properties pH 6.48 6.19-7.00 Electrical conductivity, 35 mS/cm 21-53 Ca, mg/l M 22-5.7 Mg, mg/l 08 0.5-1.2 Na, mg/l 15 1 . 2 - 2.0 K, mg/l 06 0.4-0.8 HC03, mg/l 14.1 6.5-22.0 S04, mg/l 22 1.8-2.9 Cl, mg/l 15 1 . 0 - 2.0 Total mineralization, 24.6 mg/l 13.6-36.6 Alkalinity, (jeq/l 230 107-360 Water colour water. 30 deg. 20-35 nh 4, мд/і 74 6-140 N03, цд/І 5 4-7 Total N, ng/l 350 270-410 Total P, цд/І & 4-10 Fe, цд/І 431 33-850 Cu, цд/І 08 0.5-1.1 Ni, цд/І 1Z 0.3-4.6 Al, цд/І 62 42-88 Pb, ng/l 0.08 0.04-0.14 3.5.2. Lake bottom sediments The sediments of Lake Suovaselkajarvi have high organic matter contents: the LOI value in the uppermost 1 cm sediment layer is about 60% (Table 48). The lake is lo cated at a distance of 87 km from the Pechenganickel smelter. Airborne pollution from the smelter has slight effect on the lake: there is a gradual increase in Ni concentrations in the uppermost 6 cm layer of the sediments (Fig. 75). The uppermost 5-7 cm layer of the sediments has elevated concentrations of chalcophile elements (Pb, As and Cd) 130 Catalogue o f Lakes in the Russian, Finnish and Norwegian BorderArea