Ecosystem and human health assessment to define environmental management strategies: the case of long-term human impacts on an Arctic lake / Moiseenko T. I., Gashkina N. A., Voinov A. A. [et al.] // The Science of the Total Environment. - 2006. - Т. 369, № 1-3. - С. 1-20.

T.I. Moiseenko et al. /Science o f the Total Environment 369 (2006) 1-20 5 Anthropogenic influx of nitrogen and phosphorus to the Lake caused an increase of total contents of these elements and their mineral derivatives (in comparison to the reference condition). According to the phosphorus content, most of the lake became mesotrophic by classi­ fication of Vollenweider (1979), and Monche and Belaya Bays, where the domestic sewage is discharged, and some other warm bays became corresponding to the eutrophic status. In general, from Table 1w e can conclude that water chemistry and living conditions for all water inhabitants became different from pristine natural conditions, with a new feature now present, that is, water toxicity. Transformation of economic conditions in Russia at the end of 1980s, beginning of 1990s brought a stop to many industrial activities and, accordingly, slowed down lake pollution. Some revival of the economy in the last decade is spurred by technology modernization and more restrictions on pollution of the lake and the atmosphere. As a result over the 14 year period the influx of nickel with river Nuduaj has dropped by more than 7 times; sulfates and copper have also decreased (see Table 1) . While nitrogen pollution also decreased, phosphorus influx stayed the same. Data show that in general, in 2003 anthropogenic stress on the lake (direct pollution and airborne deposition to the catchment area) has decreased. Calculation of balances between concentrations and flows in reaches show volumes of element accumula­ tions by reaches (see Table 1 ). Nickel and copper accumulation during these years decreased in proportion to levels of lake pollution and were 13.9 and 6.8 t, respectively. If in 1998 the lake accumulated up to 90% of nickel (from total influx volume) and 75% of copper, in 2003 this percent has decreased and was about 50% for both elements. Outflow of sulfate is about the same as the inflow. However phosphorus and nitrogen accumulation in relation to their inflow has increased due to increase of biological use of the element in the trophic structure of the ecosystem. There are no data about the number of species and biomass of phyto- and zooplankton for that period, but by analogy with non-polluted areas of this lake and other lakes of Kola Peninsula we can determine that total biomass of phytoplankton in summer was less than 1 g/m3 and its amount was 160,000 cells/l, while the information index of the species (Shannon's index of biodiversity) during vegetation season was 3.5-4.0 in unpolluted areas. Average value of Chlorophyll-a in the ice-free period was 0.2-0.3 mg/m3. The biomass of zooplankton varied from 0.2 to 1.0 g/m3 and the number of species was from 10 to 100,000 ind/m3; the Shannon index ranged from 2.5 to 3.0 bit/ind. During the period of economic crisis and depopula­ tion, metal concentrations in the water have decreased accordingly. Contents of nickel in Monche Bay became about 25 p,g/l in 2003. Similar tendency is seen for copper and zinc concentrations. We can conclude that toxic properties of water have decreased. The ionic content was stable. Total phosphorus concentrations varied substantially at different times. They were very high in the 1970s, went down in the 1980s, and in 2003 were at about the level of the 1980s. Concentrations of nitrogen fluctuated as well. However both were always higher than one would expect for an oligotrophic lake. Note that while total phosphorus remained quite high, its mineral phase, phosphates, plummeted, along with the concentration of silica (lower than natural conditions). This is likely a result of fast uptake of these elements by developing alga (mostly diatoms), and indicates that the eutrophi- cation processes is well underway. Our results show that water quality has worsened during the period of economic growth and associated intense pollution, and they did not recover completely during last decade despite the reduction of pollution. 3. Effects of water contamination on the lake ecosystem In past the water inhabitants were represented mainly by Arctic cold-water species that are typical for north Fennoscandia. The analysis of phytoplankton structure has shown significant abundance and a variety of diatoms in this early period (Rylov, 1916; Poretskij et al., 1934; Voronikhin, 1935; Rodhe, 1948) . In the dominant complex is presented in Table 2. Among the macro-zoobenthos in the profundal zone of the lake there were more than 70 species and forms of invertebrates, among which by number of species and frequency of occurrence the dominant ones were the larvae of midges (Chironomidae family), bivalves Eu- glesa spp. and relict crustacean (Monoporeia affinis and M. relicta ), which are found in all lakes of Fennoscandia (Gerd, 1949; Dol’nik and Stal’makova, 1975; Sarkka et al., 1990) . Among Oligochaetawe noticed representatives of Lumbriculidae, Naididae and Tubificidae families. It is rather difficult to reconstruct natural parameters of zoobenthos using analogies with non-polluted areas, because of the influence of biotope character on species content and structure of zoobenthos communities. We should notice, that M. affinis predominates in non­ polluted areas of Kola lakes (occurrence in sample up to 100%). For a pre-industrial period, exactly in 1930, average values of biomass of zoobenthos were not more