Acidity and Concentrations of Aluminum in Atmospheric Deposition in Boreal Pine Forest in the Region of Location of an Aluminum Industry Plant in the Kola Peninsula

ABSTRACT

The given paper presents the results of ecological monitoring of atmospheric deposition (snow, rainwater and throughfall), obtained at forest stationary monitoring sites, located at different distances from the Kandalaksha aluminum plant (Kandalaksha area), as well as in some other parts of the Kola Peninsula. Shown is the distribution of the acidity and aluminum concentration at different distances from the aluminum plant. Found are seasonal and parceling differences for the acidity and aluminum contents in the atmospheric deposition. In Kandalaksha area the Al concentration is higher, compared to the one in other areas under study of the Kola Peninsula. Precipitation's pH in Kandalaksha area is higher, whereas in other areas of the Kola Peninsula it is somewhat lower. The higher than usual concentration of aluminum in atmospheric deposition (at distances close to the emission source) may result in its higher contents in the soil and the vegetation lower strata, whereas the high acidity of deposition is capable of increasing its migration activity in various components of its environment. Due to this, a need in additional studies seems to be vital.

INTRODUCTION

The atmospheric depositions are characterized by various chemical compositions in different ecological requirements. Its influence on forest ecosystems amplifies depending on sources of industrial exhausts. The chemical composition of atmospheric deposition can change at passage through crowns of trees [10,16]. Industrial exhaust in an atmosphere, the air pollution, their migration with subsequent precipitation as dry and wet deposition for the Kola Peninsula (Murmansk region) is a vital question.

The industrial development in the Kola Peninsula started in the 1930s and there are now numerous plants, mines and open pits situated there. The Murmansk region is one of the most industrially developed and urbanized areas in the Russian North. The basic sites of human activities in the Kola Peninsula are: Murmansk and Severomorsk (naval shipyards, nuclear vessels), Zapolyarny (open pit Ni mine, Cu-Ni ore roasting), Nikel (the "Pechenganikel" Cu-Ni smelter), Monchegorsk (the "Severonikel" Cu-Ni smelter), Kirovsk (open pit apatite mine, apatite processing), Apatity (coal-fired power plant, nephelene waste, apatite processing), Kovdor and Olenegorsk (iron mine and processing), Polyamye Zory (nuclear power plant), Kandalaksha (aluminum plant) [9,14].

As a result of these long and intensive productions, the environment near these industrial cities is contaminated with different chemical elements and their compounds (in hazardous concentrations for the North terrestrial and water ecosystems and also for the health of people). The most of pollutants (heavy metals and others components) ejected in the shape of polymetal dust and with industrial gases, are deposited near the smelters, but a part of them is capable of being transported by air and precipitated tens or even thousands kilometers away from sources, and polluting the remote territories [2].

The Kandalaksha aluminum plant (established in 1951) is considered as the main source of compounds of aluminum and fluorine (hydrogen fluoride, insoluble fluorides and etc.), 3.4 -benzpyrenes and many other contaminating substances [5,13]. The technologies of production of aluminum, existing today, provoke the hazard of generating occupational diseases and poisonings of the industrial personnel at the given plant. The pollution of atmosphere by aerosols of aluminum could have caused the formation of territories with exuberant content of pollutants in the environment (especially in the regions subject to influence by the aluminum plant).

At increased concentrations in the environment and at low levels of pH aluminum is potential toxic for some organisms (plants, fish, and animals) [1,4,8,11]. Free Al ion is toxic to humans [3,6,7,12]. In human organisms the allocation of Al is capable to change under the influence of increased uptake of ion of fluorine. The people living in polluted areas in the Kola Peninsula and also those immediately participating in different technological processes of Al production are subject to a considerable degree of hazard.

The specific objective of this experimental program was to study and to estimate the air industrial pollution of the environment by compounds of aluminum, in the region of location of the aluminum industry plant in the Kola Peninsula. The research issues were as follows: 1. to carry out monitoring of Al content in atmospheric deposition at various distances from Kandalaksha aluminum plant (with the purpose of revealing probable pollution of the territory of Kandalaksha area); 2. to compare the content of Al in atmospheric deposition in Kandalaksha area with other areas in the Kola Peninsula; 3. to reveal negative consequences of atmosphere pollution and atmospheric deposition with compounds of Al for the North terrestrial ecosystems; 4. to determine probable ways of solutions of existing ecological problems.

MATERIALS AND METHODS

The investigations were carried out, since 2001. The 4 study sites were set up in Kandalaksha area at various distances from the Kandalaksha aluminum plant. The vegetation in these sites is dominated by pine (Pinus sylvestris - subsp. Lapponica Fries (= P. lapponica Mayr.), with small addition of spruce ((Picea obovata Ledeb. (= P. excelsa var. Obovata Ledeb., Picea fennica (Regel.) Kom.), and birch (Betula папа L., Betula tortuosa Ledeb.). The soils are classified as Al-Fe-humic podzols. The bedrock and the underlying till consist of gneiss and granite [17].

The monitoring sites were located at the following distances from Kandalaksha aluminum plant: at the distance of 6 (7.5) km (the coast of the White Sea near Kandalaksha); at the distance of 8 km (Tonnaja Luda Island in White Sea); at the distance of 9 km (Oleni Island in White Sea); at the distance of 120 km (the coast of the White Sea - on Turi Cape). Tonnaja Luda and Oleni Islands and Turi Cape make part of the territory of the Kandalaksha State reserve.

The samples of atmospheric deposition were also selected and analyzed for pH and the content of Al at some forest monitoring sites (with dominated by Pinus sylvestris L.), located in other areas in the Kola Peninsula: at the distance of 10 km from "Severonikel" smelter (near Monchegorsk); at the distance of 31-50 km from Monchegorsk (in the territory of the Lappland Nature Reserve); at the distance of 6 km from Polyamye Zory (near Polyamye Zory); at the distance of 20 km from Alakurtti in the direction of Russian-Finnish State border (near Alakurtti) (Table 1).

Table 1. Location of monitoring sites used in the study

The snow samples were taken at the maximal point of snow cover (April), using a 1-m long polyethylene tube with internal diameter of 14.5-cm. In each study site were selected by 6 samples of snow cover: by 3 samples under the crown and by 3 samples in open areas (between the crown). Thus there was a necessity to check, that together with snow no particles of ground and ground vegetation were taken. Further the samples were stored in polyethylene bags and kept frozen. The bags then that very day were brought to the laboratory, where they were left to melt overnight at room temperature prior to filtration and analysis.

The samples of wet atmospheric deposition were collected monthly from July to September with rain/throughfall collectors. The collectors were systematically established in the each study sites: 3 collectors between the crown of trees (for rainwater, precipitated in open areas) and 3 collectors under the crown of trees (for throughfall). The volume of deposition was determined in field requirements with the help of measuring circles, then spilled in plastic bottles (Volume = 250 ml), and that very day they were hauled at a chemical laboratory, for the analysis.

pH was measured potentiometrically (using Hanna Instruments pH-meter), the water samples were filtered (trough paper filters, with the diameter of pores = 1.5-2 &#;m), and subject to chemical analysis for cation of aluminum (by atomic absorption spectrophotometer, AAS-30, Perkin Elmer 5000 HGA 400). Detection limits of Al - 0.3 &#;g L^-1.

RESULTS AND DISCUSSION

Snow cover

The snow cover, preserved in the investigated region in the average for < 200 days, is capable to accumulate a lot of chemical compounds of natural and anthropogenic origins, owing to that the waters formed at its melting have bigger mineralization, than naturally atmospheric precipitation [10].

Acidity. We suggest that acidity of the snow cover increases with the distance from Kandalaksha aluminum plant (p< 0.05) (Table 2). The least values of acidity of snow were revealed at the distance of 6 km from the plant, and the greatest values at the distance of 120 km. pH under the crown below (by 1 and more) in comparison with the starting ones (p< 0.05). The comparison has shown, that the greatest acidity of the snow cover was observed in the monitoring site near Monchegorsk, and the least acidity in monitoring sites near Kandalaksha (especially at the distance of 6-7.5 km from aluminum plant) (p< 0.05).

Concentrations of aluminum. We show that the snow cover has the highest concentrations of Al at distances of 6-7.5 km from Kandalaksha aluminum plant, and the smallest concentrations at the distance of 120 km (p< 0.05) (Table 2). Concentrations of Al in open areas at distances of 6-7.5 km are 35-45 times higher as compared with the distance of 120 km. Concentrations of Al under the crown at the distance of 8 km are 8 times higher as compared with the distance of 120 km. The concentrations under the crown are higher from 2 to 7 times (p< 0.05), than in open areas, which testifies of the influence of the tree canopy on the enriching of the snow cover with compounds of Al.

Table 2. Values of pH and concentrations of aluminum in snow cover in Kandalaksha area and some other areas in the Kola Peninsula

The comparison has shown, that the greatest concentration of Al in snow cover were found in monitoring sites in Kandalaksha area (near Kandalaksha – 6-7.5 km from the plant), whereas the least concentrations were observed in the monitoring site near Alakurtti (p< 0.05).

Rain and throughfull deposition

Rainwater and throughfall are useful tools for determination of the inputs of elements to terrestrial ecosystems [16]. Their measuring and analyses are useful when assessing and monitoring the air industrial pollution [15].

Acidity. We suggest that acidity of rainwater and throughfall increases with the distance from Kandalaksha aluminum plant (p< 0.05) (Table 3). It is typical for all observed months. The least values of acidity were found at distances of 6-8 km from Kandalaksha aluminum plant, and the greatest values of acidity at the distance of 120 km. pH under the crown below (by 1 and more) at the comparison with pH between the crown (p< 0.05). The comparison has shown, that the greatest acidity of rainwater and throughfall was observed in the monitoring site near Monchegorsk, and the least acidity in monitoring sites near Kandalaksha and Tonnaja Luda Island (p< 0.05).

Table 3. Values of pH and concentrations of aluminum in rain and throughfall deposition in Kandalaksha area and some other areas in the Kola Peninsula

Concentrations of aluminum. We show that concentrations of Al in rainwater and throughfall are highest at the distance of 6 km from Kandalaksha aluminum plant. Concentrations of Al in deposition decrease with increasing distance from aluminum plant (p< 0.05) (Table 3).

July. Concentrations of Al in open areas at the distance of 8 km are 1.5-3 times higher as compared with concentrations at other distances. Concentrations of Al in throughfall at the distance of 8 km in 2-6 times higher as compared with concentrations on other distances. The concentrations in throughfall are from 7 to < 50 times (p< 0.05) higher than in open areas which testifies of accumulation of Al compounds by crown of pine trees and the enriching of atmospheric deposition under the crown by Al.

August. Concentrations of Al in open areas at the distance of 6 km are 1.5-5 times higher as compared with concentrations at other distances. Concentrations of Al in throughfall at the distance of 8 km are 1.5-3 times higher as compared with concentrations at other distances. The concentrations in throughfall are from 13 to 40 times higher than in open areas (p< 0.05).

September. Concentrations of Al in open areas at the distance of 6 km are 1.5-3 times higher as compared with concentrations at other distances. Concentrations of Al in throughfall at the distance of 8 km are 2.5-3 times higher as compared with concentrations at other distances. The concentrations in throughfall are from 6 to 16 times higher than in open areas (p< 0.05). However concentrations of Al in throughfall in each observed month are slightly decreased at the distance of 9 km from the aluminum plant (as compared with the distances of 8 and 120 km). It testifies about probable distribution of the air industrial pollution and also of unequal influence of the crown of pine trees on concentrations of Al in throughfall at various distances from the plant.

The comparison has shown that the greatest concentration of Al in rainwater and throughfall were observed in monitoring sites in Kandalaksha area (near Kandalaksha and Tonnaja Luda Island). It is noticed for rainwater and throughfall in all observed months. The least concentrations of Al in open areas were observed; in July in monitoring site Turi Cape, and in August - September in monitoring site near Alakurtti. It can be connected with their removal from sources of air industrial pollution. The least concentrations of Al in throughfall were observed from July to September in the monitoring site near Monchegorsk. It can be connected with the damage of pine crown by industrial exhausts from “Severonikel” smelter, and hence a very small enriching of atmospheric deposition with Al compounds under the crown of trees.

The atmospheric deposition with increased concentrations of Al compounds (especially in immediate proximity from Kandalaksha aluminum plant) can result in collecting and accumulating of Al mainly by soil horizons, tissues of some plants (e.g., moss, club-moss, etc.), and water ecosystems. The influence of the tree canopy can result in intensification of Al migrations, but such situation (in natural background conditions) is supported by particular equilibrium between various components of the environment. Under the influence of air industrial pollution this equilibrium can be broken.

CONCLUSION

Problems of distributions and accumulation of Al compounds are especially urgent for the region of location of the aluminum industry plant and some other areas, subject to influence of the industrial factors in the Kola Peninsula. Acidity of the snow cover and rainwater / throughfall increased with distances from aluminum plant (in Kandalaksha area). Acidity of atmospheric deposition in Kandalaksha area was less, compared with Monchegorsk area, and some other areas in the Kola Peninsula. The values of pH do not exceed values of 5-5.5 (between the crown) and values of 4-4.2 (under the crown) at all distances from aluminum plant. Acidity under the crown is very higher as compared with acidity between the crown of pine trees. Concentrations of Al in atmospheric deposition in winter and in vegetation period increased at close distances from Kandalaksha aluminum plant. Especially well it is noticeable at distances of 6-8 (up to 9) kms from the plant (in Kandalaksha area). Concentrations of Al in other areas in the Kola Peninsula were less than that. Concentrations of Al become less with the increasing distances from the aluminum plant. Compounds of Al, acting from the atmosphere, precipitate on the surface of needles, branches, and trunks of pine trees, and with atmospheric deposition they get in soil surface, because deposition under the crown becomes more saturated with Al. In North forest ecosystems in winter and in vegetation period the transformation of atmospheric deposition by crowns of pine trees is observed. However, the degree of transformation of deposition is different, - a stronger transformation occurs in vegetation period. Pollution of the atmosphere and atmospheric deposition with Al compounds (in high concentrations) can cause the accumulation of this element in soil and other components of the environment. High acidity of deposition can result in strengthening mobility and activity of Al in terrestrial ecosystems. Because need in additional studies seems to be vital.

The ways of solutions of these problems are:1. increase of the investments into modernization of existing inventory; 2. making environment friendly technologies in productions of Al, including build modem electrolysis shops, adopting the direction to diminution of the content of harmful substances in the air of industrial premises and decrease of harmfulness of industrial exhausts in the atmosphere. Also is necessary complex estimation and monitoring of states of environment.

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