Airborne contamination by heavy metals and aluminum in the freshwater ecosystems of the Kola subarctic region (Russia) / Moiseenko T. I., Kudryavtseva L. P., Rodyushkin I. V. [et al.] // The Science of the Total Environment. - 1995. - Т. 160/161. - С. 715-727.

T.I. Moiseenko et al. / Sci. Total Environ. 160/161 (1995) 715-727 717 pre-industrial background values were de­ termined from the lowest core layers (usually between 20 and 25 cm) of 120 lakes, plus one standard deviation (1 S.D.) of the substance (Hakanson 1980,1984). The degree of contamina­ tion (C d ) values were defined as the sum of all contamination factors for a given lake. Heavy metal concentrations in the tissues and organs of fish were determined for five individual fish from every collection site. Samples were placed in plastic bags and quickly frozen in liquid nitrogen for further analysis at the laboratory. These samples were dried to constant weight at 105°C. Organic matter was removed using con­ centrated nitric acid (HNO 3 ). In organs and tis­ sues, concentrations of Ni, Cu, Zn, Co, Mn, Al, and Sr were determined using the atomic absorp­ tion method (Seiler, 1993). To determine spatial variability in concentra­ tions of metals in lake water and sediments, four subregions were defined in the area being investi­ gated: 1, within a 30-km zone around the Pechen- ganikel plant; 2, within a 30-km zone around the Severonikel plant; 3, within a distance of 30-100 km around the smelters; 4, background subregion (Fig. 1). 3. Results and discussion 3.1. Metals in lake water In fresh waters of the Kola North, the most common metal pollutant is Ni. The regions with high contents of Ni in lake waters are limited to 30-km zones around the copper and nickel smelters. Maximum concentrations, up to 145 /xg/1, are found in the acidic lakes in subregion 1 (Table 1). An increase in background values (from 1 to 10 /xg/1) is retraced over one-third of the Kola North territory and spreads into the terri­ tory of contiguous countries, Norway and Finland (Traaen et al., 1991). The region around smelters in Sudbury, Ontario, is characterized by a similar dispersion of concentrations of heavy metals in water bodies (Keller and Pitblado, 1986). The background values remain unchanged in the re­ mote eastern regions of the Kola Peninsula (sub- region 4). Copper pollution covers a small area. Its me­ dian concentration in the 30-km zone is less than one-half the Ni concentration and seldom ex­ ceeds 10 /xg/1. Typical Cu concentrations are < 1 /xg/1. An exception is a high concentration of Cu in waters of Babye lake and other small water bodies in the southeastern region. The con­ centration here amounts to 20 /xg/1. Concentra­ tions of Zn, Mn, and Sr in lake waters of the Kola North show no distinct pollution areas, but there is evidence of a twofold increase over background levels observed in subregions 3 and 4 (Table 1). Concentrations of other elements (Cd, Cr, Co, Pb) in the waters of small lakes are below the detection threshold. Higher values are typical only for the polluted water in the 30-km zones around the smelters. An interesting relationship emerged among heavy metal concentration, pH, and basic cation concentrations in the water. In the 30-km zones around the smelters, Ni and Cu concentra­ tions had a positive correlation (r = 0.54; n = 136) with Ca + Mg concentration, which indi­ cates the spread of these elements in alkaline aerosol compounds or their release from catch­ ments that have high base cation concentrations. The highest heavy metal concentrations were typical for waters with high acid neutralizing ca­ pacity (ANC > 200 /xequiv./l), which apparently somewhat decreases the toxic properties of the heavy metals. In remote regions, a negative rela­ tionship existed between heavy metals and pH and ANC, demonstrating the washout of heavy metals into water bodies through acidic precipita­ tion or the mobilization of heavy metals from within the watershed by acidic precipitation (cor­ relation coefficient between pH and Ni in subre­ gion 3: r — —0.57; n = 89). In acidified lakes, an increase in the concentra­ tion of all rare elements can be demonstrated. In particular, we observed the dispersal of Al in surface waters, where its concentration has a high negative correlation with pH (r = —0.84; n = 89). This relationship is shown in the following equation: Сді = 376.2 - 49.9-pH, F-ratio = 65.4, F = 0.0000