Activity 5: Assessment report of the toxic substances on the small lake sediments
Trilateral cooperation on Environmental Challenges in the Joint Border Area
Vladimir A. Dauvalter
InstituteofNorthIndustrialEcologyProblems, Kola Science Center, RAS
This publication has been produced with the assistance of the European Union, but the contents of this publication can in no way be taken to reflect the views of the European Union.
Introduction
The border area between Russia, Norway, and Finland is exposed to serious industrial impact, including that by the Pechenganikel integrated plant. Lake Kuetsjarvi and the lower watercourse of the Pasvik River receive wastewater from smelting and by-processes located in the settlement of Nikel. The whole system of the Pasvik River as well as lakes and rivers of this area not belonging to the system are exposed to pollution via atmospheric depositions. The major pollutants include compounds of sulfur and heavy metals (HM’s) – Ni, Cu, Cd, Cr, Zn, As, Hg, etc., polycyclic aromatic hydrocarbons (PAH’s), and persistant organic pollutants (POP’s). Sulfur dioxide emissions from the intergrated plant result in acidification of the surface water and its pollution due to intensification of rock desalination processes.
Industrial development of copper-and-nickel ore deposits was started in 1932 by a joint Canadian-Finnish company (after the October Revolution the today’s territory of Pechenga region belonged to Finland and after the war between the USSR and Finland in 1939-1940 it was annexed by the USSR). The Pechenganikel integrated plant has been in operation since 1946 when processing of the local sulfide-and-nickel ore was resumed in the settlement of Nikel. In 1959 ore extraction at Zhdanovskoye Field and its processing in the town of Zapoliarny began. The combine plant’s emissions include sulfaric gas, Ni, Cu, other HM’s, dust, as well as nitrogen oxides and carbon oxides from boiler houses.
Materials and methods
For the study of ecological status of the lakes in the border area between Russia, Norway, and Finland columns of bottom sediments (BS) were sampled from 16 lakes (Fig.1): 4 lakes in Finland: 1 – Lampi 222 , 2 – Harrijärvi, 3 – Pitkä-Surnujärvi, 4 – Sierramjärvi, 8 lakes in Russia: 5 – Pikkujarvi, 6 – Shuonijaur, 7 – Ila-Nautsijarvi, 8 – Ala-Nautsijarvi, 9 – Toartesjaur, 10 –Virtuovoshjaur, 11 – Riuttikjaure, 12 – Kochejaur, and 4 lakes in Norway: 13 – Gardsjøen, 14 – Holmvatnet, 15 – Rabbvatnet, 16 – Durvatn.
The BS columns were sampled in the deepest areas of the water bodies under study by an open gravity type column sampler (internal diameter 44mm) with automatically closing diaphragm. The sampler is made of plexiglass by template desined by Skogheim (Skogheim, 1979) to transport the columns intact for further use. The BS columns were 15 to 45cm long depending on the conditions of their formation and their physical-and-chemical properties. The BS columns were divided into 1sm layers (in specific cases 0.5cm), placed in polyethelene containers and sent to laboratory for analysis where they were stored at a temperature 4°С until analyzed.
Fig.1. Locationofthelakesunderstudy (2012-2013) – Finnishlakes:1 – Lampi 222, 2 – Harrijärvi, 3 – Pitkä-Surnujärvi, 4 – Sierramjärvi;Russianlakes: 5 – Pikkujarvi, 6 – Shuonijaur, 7 – Ila-Nautsijarvi, 8 – Ala-Nautsijarvi, 9 – Toartesjaur, 10 –Virtuovoshjaur, 11 – Riuttikjaure, 12 – Kochejaur;Norwegianlakes: 13 – Gardsjøen, 14 – Holmvatnet,15 – Rabbvatnet, 16 – Durvatn.
The primary treatment of the BS samples (drying, humidity measurement, ignition, and measurement of loss during ignition) and measurement of elements content (Ni, Cu, Co, Zn, Cd, Pb, Hg, Mn, Fe, Ca, Mg, Na, K, Al, Cr, P, and Sr) was performed in the laboratories of Institute of North Industrial Ecology Problems (INEP), Kola Science Center, RAS, Apatity, Russia, and the Norwegian Institute of Water Research (NIVA), Oslo, Norway.
The samples (ca. 5g) were dried in a drying box under a temperature 105ºС for 6 h, and sample humidity was determined. (Håkanson, 1984). Then the samples were baked in a muffle furnace at a temperature 450-500ºС for 4 h in order to determine the loss on ignition (LOI) as indirect indicator of organic matter content. Then, the samples were milled in a jasper mortar and kept under a temperature 4ºС before chemical analysis.
To determine the gross metal concentrations 0.3g sample weight was treated with 3ml concentrated nitric acid (HNO3) of ultra high purity class in autoclave with a teflon insert at a temperature 140ºС for 5 h. The autoclave content was then cooled down to room temperature and 2.5 ml aliquot was placed into a 60 ml plastic bottle and diluted with deionized water up to volume 25 ml.
The resultant BS solutions were analyzed by atomic absorption spectrophotometer AAS-30 in the flame acetylene-air (Cr, Co, Fe, and Mn), in the flame acetylene-nitrogen monoxide (Sr and Al); Perkin-Elmer-360) in the flame acetylene-air (Ni, Cu, and Zn), in the flame propane-butane-nitrogen monoxide (Ca and Mg), in the flame propane-air (Na and K). Concentrations of Cd, Pb, and As were determined with the device AAN-800 (electrothermal atomization). Concentrations of Hg were determined by way of cold steam atomic absorption with the help of Perkin-Elmer FIMS 100 device. Quality control was performed by analysis of standard samples PACS-2 (Canada) and L6M (Finland). The deviations from standardized values did not exceed the acceptable error for the elements under study (20-25%). All the metal concentrations are given in microgram per gram (µg/g) of dry weight.
The level of industrial load on the lakes’ ecosystems was determined according to the estimated pollution factor (Cf) for each of the priority HM contaminant (Ni, Cu, Co, Zn, Pb, Cd, Hg, and As). The Cf value was found by dividing HM concentration in the surface (present-day) layer )0-1cm) by its background content in the deepest layer formed in the pre-industrial period(Håkanson, 1980,). The BS contamination degree (Cd) was determined by the sum of all Cf values for the eight HM in a particular lake.
Background concentrations of elements in bottom sediments
The study of background HM concentrations in the BS is one of the central issues in the study of lakes pollution. Samples of BS taken from the deepest layers of the columns (usually, over 20cm) allow finding background HM concentrations in the course of lakes pollution study. According to earlier studies (Norton et al., 1992, 1996; Rognerud et al., 1993), these layers were formed over two hundred years ago, i.e. before industrial development of North Fennoscandia. The background HM concentrations reflect the geo-chemical peculiarities of the catchment area, provide information about quantitative values of water bodies’ pollution degree, and help determine anomalies for the purpose of mineral resources exploration (Tenhola, Lummaa, 1979).
The background HM concentrations in BS of the lakes under study are fairly volatile which reflects considerable variations in the catchment area geochemistry (bedrock and quaternary rock, and soils covering them), the erosion processes rate, drainage module (water, ion, and solid matter), i.e. all conditions of formation of the lakes’ BS chemical composition.
The maximum background HM concentrations in BS (Table 1) were found in different lakes: Cu and Hg in Lake Lampi 222, Zn and Cd in Lake Ala-Nautsijarvi, Co in Lake Ila-Nautsijarvi, Ni in Lake Pikkujarvi, Pb in Lake Holmvatnet, and As in Lake Gardsjøen, which is accounted for by the geochemical and morphometrical peculiarities of the catchment area and the lake itself, as it was noted above. For example, in the catchment areas of Lakes Pikkujarvi, Ala-Nautsijarvi and Ila-Nautsijarvi copper-and-nickel sulfide deposites are represented by such minerals as pentlandite (Fe,Ni)9S8, copper pyrite CuFeS2, white cobalt (Co,Ni)AsS, nicolite NiAs and others (Gregurek et al., 1999), which explains the fairly high concentrations of almost all HM in the BS background layers of the lakes under study.
Table 1. Background concentrations (µg/g of dry weight) of elements in BS of the lakes under study.
Average* – average background concentrations in BS in the North-West of Murmansk Region and border areas of the neighboring countries (Kashulin et al., 2009).
Lakes / Layer, cm / LOI / Cu / Ni / Zn / Cd / Co / Pb / As / HgLampi 222 / 29-30 / 31.30 / 200 / 21 / 145 / 0.54 / 11 / 7.0 / 1.9 / 0.318
Harrijärvi / 29-30 / 24.24 / 24 / 16 / 123 / 0.20 / 4 / 6.9 / 1.7 / 0.046
Pitkä-Surnujärvi / 29-30 / 17.91 / 64 / 20 / 98 / 0.45 / 9 / 4.4 / 1.8 / 0.068
Sierramjärvi / 29-30 / 18.51 / 18 / 26 / 83 / 0.25 / 7 / 4.8 / 1.8 / 0.032
Shuonijaur / 15-16 / 33.03 / 23 / 27 / 73 / 0.16 / 7 / 2.8 / 1.6 / 0.064
Ala-Nautsijarvi / 24-25 / 27.24 / 58 / 75 / 254 / 1.06 / 43 / 12.5 / 4.6 / 0.178
Ila-Nautsijarvi / 14-15 / 29.32 / 18 / 35 / 169 / 0.29 / 13 / 2.3 / 2.6 / 0.048
Pikkujarvi / 13-14 / 20.8 / 59 / 78 / 96 / 0.13 / 11 / 5.8 / 2.6 / 0.056
Toartesjaur / 22-23 / 30.21 / 13 / 19 / 63 / 0.11 / 8 / 1.5 / 1.6 / 0.042
Virtuovoshjaur / 14-15 / 52.51 / 14 / 36 / 100 / 0.23 / 14 / 8.2 / 2.1 / 0.088
Riuttikjaure / 16-17 / 25.1 / 15 / 29 / 90 / 0.19 / 5 / 3.1 / 1.4 / 0.010
Kochejaur / 17-18 / 37.8 / 17 / 27 / 100 / 0.17 / 11 / 3.7 / 1.7 / 0.092
Gardsjøen / 29-30 / 34.85 / 69 / 41 / 86 / 0.47 / 14 / 3.6 / 5.4 / 0.108
Holmvatnet / 29-30 / 23.92 / 79 / 41 / 178 / 0.82 / 31 / 26.1 / 3.8 / 0.100
Rabbvatnet / 42-43 / 32.40 / 76 / 24 / 106 / 0.21 / 5 / 3.1 / 3.1 / 0.078
Durvatn / 29-30 / 31.15 / 31 / 22 / 59 / 0.34 / 30 / 2.9 / 5.1 / 0.062
Average / 29.39 / 49 / 34 / 114 / 0.35 / 14 / 6.2 / 2.7 / 0.087
Median / 29.77 / 28 / 27 / 99 / 0.24 / 11 / 4.0 / 2.0 / 0.066
Mininun / 17.91 / 13 / 16 / 59 / 0.11 / 4 / 1.5 / 1.4 / 0.010
Maximum / 52.51 / 200 / 78 / 254 / 1.06 / 43 / 26.1 / 5.4 / 0.318
St.deviation / 8.44 / 47 / 18 / 51 / 0.27 / 11 / 6.0 / 1.3 / 0.073
Average* / 33 / 41 / 96 / 0.17 / 16 / 3.2 / 4.6 / 0.040
Lakes / Mn / Fe / P / K / Nа / Ca / Mg / Sr / Al
Lampi 222 / 313 / 57714 / 2270 / 571 / 88 / 2815 / 1060 / 14 / 32573
Harrijärvi / 77 / 67276 / 754 / 381 / 67 / 1630 / 526 / 15 / 13198
Pitkä-Surnujärvi / 926 / 46190 / 1454 / 797 / 253 / 3221 / 2500 / 17 / 15331
Sierramjärvi / 268 / 44444 / 2240 / 777 / 263 / 3171 / 1538 / 21 / 14152
Shuonijaur / 157 / 16364 / 768 / 1429 / 343 / 4703 / 3810 / 21 / 13152
Ala-Nautsijarvi / 1000 / 82837 / 2238 / 1702 / 179 / 3472 / 2526 / 37 / 23400
Ila-Nautsijarvi / 406 / 46000 / 874 / 923 / 194 / 5185 / 2742 / 27 / 14929
Pikkujarvi / 263 / 25333 / 528 / 4077 / 588 / 8552 / 8318 / 33 / 20812
Toartesjaur / 118 / 7797 / 694 / 409 / 94 / 4524 / 1333 / 15 / 10127
Virtuovoshjaur / 390 / 20597 / 798 / 1143 / 164 / 4054 / 2095 / 31 / 18429
Riuttikjaure / 167 / 7742 / 720 / 1037 / 129 / 4202 / 2000 / 23 / 13583
Kochejaur / 138 / 6498 / 448 / 337 / 127 / 5167 / 1029 / 48 / 11364
Gardsjøen / 167 / 31579 / 2442 / 882 / 218 / 5000 / 2543 / 23 / 20867
Holmvatnet / 908 / 44776 / 1944 / 1176 / 233 / 3724 / 3078 / 21 / 21178
Rabbvatnet / 120 / 18000 / 1412 / 1600 / 352 / 4850 / 3810 / 28 / 16668
Durvatn / 250 / 20000 / 1692 / 588 / 158 / 3378 / 1674 / 22 / 6931
Average / 354 / 33947 / 1330 / 1114 / 216 / 4228 / 2536 / 25 / 16668
Median / 256 / 28456 / 1143 / 903 / 187 / 4128 / 2298 / 22 / 15130
Mininun / 77 / 6498 / 448 / 337 / 67 / 1630 / 526 / 14 / 6931
Maximum / 1000 / 82837 / 2442 / 4077 / 588 / 8552 / 8318 / 48 / 32573
St.deviation / 308 / 22699 / 714 / 894 / 130 / 1511 / 1810 / 9 / 6150
Generally, the average background HM concentrations in BS of the lakes under study (Table 1) are similar to the average background concentrations in water bodies of the North-West of Murmansk Region estimated earlier (Kashulin et al., 2009). Chalcophylic elements Cd, Pb and Hg make an exception with their background concentrations in BS of the lakes under study two times higher, and As – 2 times lower than established before (Kashulin et al., 2009). The discrepancies between the calculated values of average background HM concentrations may be associated with changes of the list of lakes for BS sampling in different years.
The concentrations of Hg in the background BS of the lakes under study stay within the range 0.010 to 0.318 µg/g, the average value being 0.087 µg/g. For comparison, Table 2 presents background Hg concentrations in BS of Fennoscandia and North America. Comparing the results, a conclusion may be made that the Hg background values in other author’s studies are consistent with our data (Table 2). The best consistence is observed with studies of Swedish and Finnish boreal lakes except for Lake Lampi 222 where the maximum Hg concentration was discovered in the background layers of BS.
Table 2. Background Hg values (µg/g of dry weight)in BS of lakes in Fennoscandia and North America.
Country / Lake/Territory / Hg / SourceNorway / Lake Tirifjorden / 0.050 / Abry et al., 1982
Norway / Lake Mjessa / 0.070-0.090 / Rognerud, 1985
Sweden / Boreal lakes / 0.030-0.095 / Håkanson, Jansson, 1983
Sweden / Boreal lakes / 0.050-0.120 / Johansson, 1988
Finland / Boreal lakes / 0.020-0.050 / Rekolainen et al., 1986
The US / Wisconsin / 0.040-0.070 / Rada et al., 1989
The US / North Minnesota / 0.030-0.060 / Megar, 1986
Canada / Ontario / 0.100 / Douglas, 1986
The US/Canada / The Great Lakes / 0.030-0.080 / Mudroch et al., 1988
The concentration of elements in BS depends on morphometrical parameters and a number of geological, geochemical, physical, chemical, and biological factors of the lakes (Strakhov et al., 1954). To identify the factors having the greatest impact on the chemical composition formation of the lakes’ BS factor analysis was performed (Table 3) which determined the first factor of the largest weight (27%) comprising the HM contained in higher concentrations in the bedrock and Quarternary rock in the North-West of Murmansk Region and border area – Zn, Co, Cd, as well as elements which behaviour depends on physical and chemical conditions in the BS and water column (primarily, the redox potential) and the lake’s trophic status – Fe,Mn, and P. Other HM under study – Cu, Ni, Pb, As, and Hg –have fairly high coefficients in this factor, which confirms the relation between practically all the HM under study. The first thing in common is presence of HM deposits in sulfide minerals in the territory under study which was noted before (Gregurek et al., 1999).Alkaline and alkaline-earth metals (K, Na, Ca, Mg), have the highest coefficients in the second factor; these are the major rock-forming metals in the bedding magmatic and metamorphic rocks constituting the lakes catchment area. This confirms the influence by bedrock geochemical composition on the formation of the BS background layers chemical composition. The absolute elevation of the lake water line has a high negative coefficient in this factor, i.e. the elements’ content in the background BS layers decreases when the elevation above the sea level increases. Humidity as a physical factor also has an impact on the BS chemistry, which is reflected by the high coefficient of this indicator in the third factor.
Table 3. Factor model of chemical composition of the BS background layers in the lakes under study. The most important parameters with coefficients over 0.7 are highlighted in bold.
Factor 1 / Factor 2 / Factor 3Layer / 0.359 / -0.397 / -0.500
Catchment / 0.203 / 0.184 / 0.510
area / -0.343 / 0.082 / 0.566
masl / -0.193 / -0.726 / 0.092
Distance / -0.293 / -0.515 / 0.414
H2O / -0.251 / -0.181 / 0.754
LOI / -0.246 / -0.084 / 0.398
Cu / 0.641 / -0.108 / -0.492
Ni / 0.507 / 0.707 / 0.352
Zn / 0.772 / -0.045 / 0.443
Co / 0.722 / -0.009 / 0.503
Cd / 0.927 / -0.186 / 0.264
Pb / 0.692 / -0.040 / 0.176
As / 0.571 / 0.104 / 0.144
Hg / 0.642 / -0.242 / -0.065
Mn / 0.752 / -0.020 / 0.233
Fe / 0.750 / -0.262 / 0.048
P / 0.732 / -0.355 / -0.219
K / 0.229 / 0.928 / -0.096
Nа / 0.088 / 0.889 / -0.275
Ca / -0.183 / 0.905 / 0.040
Mg / 0.151 / 0.962 / -0.185
Sr / -0.032 / 0.432 / 0.704
Al / 0.523 / 0.072 / -0.429
Factor weight, % / 26.9 / 22.6 / 14.9
Cluster analysis (Fig.2) clearly identified three groups of water bodies: the first group includes Finnish lakes (Pitkä-Surnujärvi and Sierramjärvi) and a similar Russian lake Ila-Nautsijarvi, the second group includes the Russian lakes (Shuonijaur and Virtuovoshjaur) and the Norwegian lake Rabbvatnet, and the third group includes the Russian lakes Toartesjaur, Kochejaur, and Riuttikjaure. The specified lakes in the groups defined by cluster analysis are believed to be similar in terms of the natural conditions of BS chemistry formation. A large number of lakes not belonging to any of the three groups shows the large diversity of these conditions, which is reflected by a considerable range of background concentrations in BS of the lakes under study.
Fig.2. Cluster analysis dendrogram of the chemical composition of BS in the water bodies under study.
It was also established that the average background concentrations of elements in BS of the lakes under study are similar to average concentrations of chemical elements in the crust of earth (percentage abundance) and in the rocks and soils according to estimation of different researchers (Tables 4 and 5). The calculations by A.P. Vinogradov (1962) show the closest match with the percentage abundance in the bedrocks and soils.
Table 4. Data on average concentration of chemical elements in the crust of earth (µg/g) according to estimates of different researchers (Alexeenko, 2000)
Researchers / Ni / Cu / Co / Zn / Cd / Pb / As / HgF. Clark and G. Washington / 180 / 100 / 100 / 40 / 0.10 / 20 / 1.0 / 0.100
A.P. Vinogradov / 58 / 47 / 18 / 83 / 0.13 / 16 / 1.7 / 0.083
S.R. Tailor / 75 / 55 / 25 / 70 / 0.20 / 12.5 / 1.8 / 0.080
A.A.Beus / 95 / 65 / 34 / 87 / 0.19 / 9 / 1.9 / 0.046
Table 5. Data on average concentration of chemical elements (µg/g) in the rocks and soils (Alexeenko, 2000)
Type of rock and soil / Ni / Cu / Co / Zn / Cd / Pb / As / HgUltrabasic rocks / 20 / 10 / 150 / 50 / 0.10 / 1 / 1.0 / 0.010
Basic rocks / 130 / 87 / 48 / 105 / 0.22 / 6 / 2.0 / 0.090
Medium rocks / 4 / 5 / 1 / 130 / 0.13 / 12 / 1.4 / 0.010
Acidic soils rich in Ca / 15 / 30 / 7 / 60 / 0.13 / 15 / 1.9 / 0.080
Acidic soils poor in Ca / 4.5 / 10 / 1 / 39 / 0.13 / 19 / 1.5 / 0.080
Slates / 68 / 45 / 19 / 95 / 0.30 / 20 / 13.0 / 0.400
Slates+clays / 95 / 57 / 20 / 80 / 0.30 / 20 / 6.6 / 0.400
Sandstone / 2 / 1 / 0.3 / 15 / 0.10 / 7 / 1.0 / 0.030
Carbonates / 20 / 4 / 0.1 / 20 / 0.035 / 9 / 1.0 / 0.040
Soils (A.P. Vinogradov) / 40 / 20 / 8 / 50 / 0.50 / 10 / 5.0 / 0.010
Changes of elements concentration in BS in time
The study of chemical composition of the BS column allows reconstructing the history of their formation conditions for particular lakes based on determination of background values of different elements concentration in BS and changes in their incoming during a long period of time. They become especially important when the sedimention rate is known which allows reconstructing the chronology of the system transformation processes.
In assessment of the catchment basins’ regional pollution history, in the framework of international projects paleolimnological method was used (Norton et al., 1992, 1996; Rognerud et al., 1993) and radiometric (age determination according to 210Pb chronology using dating models CRSand CIC)dating of the columns sample (Appleby, Oldfield, 1978). Based on the BS dating results, the sedimentation rates were determined, as well as the sedimented material flow and accumulation of specific elements in the BS. 210Pb chronology may be relied upon only within 150 years because this isotop’s half-life is 22 years. The BS age was extrapolated further in time based on the sedimentation rate in 1850-1900, and thus was accurately determined. The average rate of sedimentation in the latest hundred and fifty years in the lakes was fairly stable within 0.3-0.6 mm/year except for two Finnish lakes Nitsijarvi and Pahtajarvi where these values on an average amount to 1.0 and 1.25 mm/year, respectively.
Earlier research (Dauvalter, 1999; Dauvalter et al., 2012) inverse proportion was noted: the sedimentation increases where the depth of the lake decreases. This is associated with morphometrical peculiarities of lakes: usually, small lakes are less deep, and, consequently, the ration of the lake area and its catchment increases.
Increased concentrations and sedimentation rates of Ni, Cu, and Co in the BS dated back to XX century were observed in the Norwegian lakes (Norton et al., 1992, 1996; Rognerud et al., 1993). Higher concentrations of Pb in the BS, generally, arenot related to the Pechenganikel smelters’ emissions. The increase in Pb concentrations dates back to the time too early to be related to any industrial activities in this area. Data based on BS in South Sweden’s lakes confirms Pb atmospheric pollution resulting from its intensive production and use in Europe beginning from the time of Ancient Greek and Roman civilizations (Renberg et al., 1994). It has been noticed that atmospheric deposition of Pb increased as compared to the background values over 2,600 years ago (at a depth of BS 1.5 to 4 meters). Slight but noticeable increase of Pb deposition took place ca. 2,000 years ago; still more significant increase began ca. 1,000 years ago; sedimentation accelerated in XIX, and, especially, in XX century. The accumulation reached its maximum in the 1970’s. Before the industrialization in XIX, concentration of Pb in South Sweden’s lakes BS had already increased due to atmospheric depositions 10-30 times compared to the background level. The background concentrations of Pb (at a depth of BS over 1 meter) in 19 Swedish lakes were found within 2-15 µg/g (dry weight), were usually less than 10 µg/g (Renberg et al., 1994). These values coincide with our investigation of background values.
In North America the rate of Pb accumulation in lakes’ BS gradually increased from 1850-1875 to 1975, and then it has been decreasing until the present time (Norton et al., 1990). In Europe the increase was similar to that described above, but a dramatic increase began 50-75 years earlier. Antropogenic origin of Pb may have numerous sources including smelting, glass factories, and use of tetraethyl Pb as addition to petrol. Cessation of use of the latter resulted in Pb deposition amount decrease in North America. Increase of Pb concentrations may be associated with cross-border Pb transport from its source in North America and southern areas of Europe. Absolute values of Pb accumulation rates are lower in northern areas than those in Southern Norway (Norton, Hess, 1980) or in the south of North America (Norton et al., 1990). A slight increase in Pb concentrations in BS in East Finnmark, Norway is found due to a relatively low BS accumulation rate in the both lakes and very low Pb background concentrations.
Ni, Cu, Co andotherHM’sare delivered into the atmosphere with the emissions from the Pechenganikel integrated plant. This is clear from the studies of water and terrestrial ecosystems of the region (Traaen et al., 1990; Rognerud, 1990; Cariat et al., 1996a, 1996b; Dauvalter, 1992, 1994, 1998b; 2003; Dauvalter, Rognerud, 2001; Gregurek et al., 1999; Lukin et al., 2003; Moiseenko et al., 1995; Reimann et al., 1999; Rognerud, Fjeld, 1993; Rognerud et al., 1993, 1998; Äjräs et al., 1995, 1997). Growth of the concentrations and rates of accumulation dates back one decade prior to the beginning of the industrial activitiesatthe Pechenganikel integrated plant. The growth wasusuallydetectedinthe BS, dated the 1920s and 1930s. Thisphenomenonhasthreeexplanations. First, regionalpollutionwithCo, Cu and Ni possiblyexistedasaresultofthe activity of metallurgical plants in the industrial areas of Russia. Until1940,thePechengaareawas the territory of Finland, where mining resources were already beginning to be explored.Second, the HM’sfromthewaterlayeroflakescansettle and redistribute inthe BS, which date back prior to introduction of anthropogenic loads. Suchdiageneticprocesseswerealready described for Zn (Carignan, Tessier, 1985) and other HM. And, third, intheBSdatedthe1920s-1930s, the content of organic substance grows(in LakeDalvatnthe values of PPP grow from 29 to 38%, inLakeDurvatn – from 27 to 30%), which is an essential reason forincrease of HMadsorption by sediments (Norton et al., 1992). Synchronyofthe increaseofHMconcentrations towardsthesurface in theBSof isolated lakes, having similar geochemical nature, probably indicates that it is the atmospheric depositionsrather than specific catchment processesthat are the reason of higher accumulation of HM’s.