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.

4 TI. Moiseenko et at. /Science o f the Total Environment 369 (2006) 1-20 2. Anthropogenic loads and changes in water chemistry Once Lake Imandra was a typical ultra-fresh and oligotrophic lake, with low concentrations of suspended material (0.7-1.0 mg/l), microelements (<1 Mg/l), and nutrients. Concentration of total phosphorus was less than 2 Mg/l; phosphates during the vegetation period were practically completely utilized in the production processes. Water transparency was about 8 m. The lake was characterized by high saturation of waters by oxygen (up to the bottom) due to mountain ice-free rivers falling into the lake (Rikhter, 1934; Krokhin and Semenovich, 1940) . In the past the local population, mostly Saami historically living along the coasts of the lake, was very small, and before 1930 there was practically no human effect on the lake ecosystem. Rich mineral deposits found on the coast of the lake (apatite-nepheline, iron, manganese, copper-nickel ore) brought big mining industries. In the 1930-40s mining and enrichment of the apatite-nepheline ore began, and the “Apatit” industrial complex was built. In the 1940-50s — “Severonickel” combinat was built for nickel extraction; in the 1950-60s — Olenegorsk mining operations started producing iron-manganese ore; and in 1974 — the Kola nuclear power station started to provide local industries with energy. For map of sites of main industries see Fig. 1. Accordingly during these periods the industries became the main factors for building of towns and cities: so the cities of Monchegorsk, Olenegorsk, Apatity, and Polyarnye Zori appeared. Now increasing human population, and industrial and household pollution were affecting the lake. Yet still, paradoxically, Lake of Imandra was and still is used as a sink of industrial and domestic wastewater, as well as a source of drinking water for several cities. Table 1 p resents the annual influx of main con­ taminants during two periods: intense pollution (1989) and when pollution was in decline (2003). Most of the metals were entering the lake by river Nyuduaj, nutrients — came with rivers Belaya and Monche. The lake catchment and waters were also receiving airborne pollutions, which amount was quite significant at times. Over many years these anthropogenic loads, which started in the 1940s and reached maximum in the 1980s, caused serious changes in water chemistry: transparence decreased, salt concentrations increased, pH moved towards alkaline condition in comparison to the reference condition (Table 2) . As a result of influx of salts the ionic composition of waters changed. Techno­ genic sulfates in ionic composition of waters have dominated over hydro-carbonates. The pollution from the metallurgical enterprise has increased the content of heavy metals and especially that of nickel, copper and zinc. Table 2 Dynamics of water chemistry (basic ions, nutrients, trace elements) in Bol’shaya Imandra during different periods (numerator — average values, denominator — minimum and maximum values) Parameters Reference condition* Periods 1972­ 1982 1983­ 1992 1993­ 1998 2003 pH 6.4-7.2 7.2 7.4 7.2 7.4 6.9-7.5 6.7-7.9 7.1-7.3 6.9-7.7 Total ion 20 - 30 60 87 80.5 81.3 content, mg/l Ca, mg/l 2 - 5 4.2 4.7 4.1 3.8 Mg, mg/l 1-2 2.2 1.6 1.1 1.2 Na, mg/l 15.0 20.1 14.8 17.4 K, mg/l 3.4 3.3 2.4 2.5 HCO 3 , mg/l 13-18 20.3 20.9 20.2 22.6 SO 4 , mg/l 1-3 16.1 29.7 24.2 28.5 Cl, mg/l 1-2 4.2 7.7 5.5 5.4 PO 4 , Mg/l 0-8 - 11 9 3 2-26 1-37 0-12 TP, Mg/l 2-18 124 27 38 26 22-660 4-100 8-114 13-68 NH4, Mg/l 0-20 - 48 36 21 33-75 8-120 2-76 NO3, Mg/l 0-35 - 23 24 20 8-55 2-230 1-158 TN, Mg/l 30-300 - 298 263 188 170-460 97-435 106-402 Si, mg/l 0.6-0.8 1.1 1.0 0.9 0.4 0.2-2.2 0.1-4.6 0.1-2.8 0.1-1.4 Permanganate 3-5 3.9 3.2 3.3 2.8 consumption, 2.0-6.1 1.4-4.5 2.5-4.5 2.3-3.8 MgO/l Ni, Mg/l < 1 42 61 15 10 16-84 13-290 13-19 7-27 Cu, Mg/l < 1 3 18 6 5.5 0-5 5-28 5-8 4-10 Sr, Mg/l <30 - 66 69 59 54-83 60-80 32-72 Al, Mg/l < 10 - 41 38 61 19-80 20-80 14-145 Fe, Mg/l < 15 - 27 29 35 13-40 16-50 9-60 Mn, Mg/l <5 - 9.3 10.4 13.2 1-17 6-18 6-35 Zn, Mg/l <2 - 11 2.8 2.5 2-27 1-6 1-15 Cd, Mg/l - - 0.3 <0.05 0.1-0.6 Pb, Mg/l - - - <0.3 Reference conditions are established based on Rikhter, 1934; Vereshagin, 1930; Krokhin and Semenovich, 1940, with corrections based on representative unpolluted lakes of the Kola North.