Chemical composition of lake sediments along a pollution gradient in a Subarctic watercourse / Dauvalter V., Kashulin N., Sandimiriv S. [et al.] // Journal of Environmental Science and Health. Part A. - 2011. - Vol. 46. - P. 1020-1033.

Downloaded by [Vladimir Dauvalter] at 21:54 24 November 2013 Lake sediment composition in Subarctic watercourse 1021 Fig. 1. The scheme of sediment sampling in the Inari-Pasvik watercourse. Here and in other figures the numbers of stations correspond to the numbers in Tables 1, 2 and 3. The main polluting substances are heavy metals (Ni, Cu, Zn, Co, Cd, As), sulphates and organic substances that are applied during the flotation enrichment o f ores. A number o f studies have explored the influence o f the Pechenganickel smelters on terrestrial and freshwater ecosystems in the re­ gion, including descriptions o f the volume and dynamics o f the emissions o f polluting substances.[5-8,11-22] Development o f the Pechenga copper-nickel deposits be­ gan in 1932 by a jo in t Canada-F innish Company (after the October Revolution in 1917 the territory o f present area o f the Pechenga district was departed to Finland, but af­ ter the Soviet-Finnish War in 1939-1940 it was again a p a rt o f the USSR). The Pechenhanickel Company came in function from 1946 when the Nickel processing settlement using local sulphide-nickel ores was renewed. In 1959, ex­ traction o f ores from the Zhdanov deposit was initiated and their processing at the factory in Zapoljarnij was de­ veloped. The emissions o f the Pechenganickel Company include sulphur dioxide, Ni, Cu, a dust, and also nitrogen oxides and carbon oxide from boiler-houses. The pollution plume o f the copper-nickel Company smelters is distributed by prevailing southwesterly winds mainly in a no rtheast­ erly direction, leaving the sediments in lakes more 20 km distant, southwest o f the smelters, almost unaffected.[8,20] Therefore, waste waters o f the Pechenganickel Company, rather than the atmospheric emissions, are assumed to be the main contam ination sources o f the Pasvik watercourse, particularly downstream current. Two main environmental problems connected with reg­ ulation o f water flow and influence o f the Pechenhanickel Company activity, are characteristic for the Inari-Pasvik system: pollution by heavy metals and eutrophication.[23] The first problem is connected with emissions and sewage o f the Pechenhanickel Company and transboundary air transfer, mainly from industrially developed regions o f the country and the Europe. The second problem is caused by regulation o f water flow o f Lake Inari and the Pasvik watercourse, and also the entrance o f household waste wa­ ter o f the settlements located on the watershed o f the River Pasvik. Metals enter the watercourse through runo ff from the catchment area and through atmospheric precipitation. The contents o f dissolved forms o f metals in water o f lakes are limited. They are acquired by hydrobionts and adsorbed by the suspended particles settling on bo ttom and forming lake sediments. Metals can also be adsorbed directly by sediments.[24] Hence, sediments, especially in deep parts of lakes, characterize the degree o f environmental contam ­ ination by metals and are therefore a suitable target for pollution studies. The aim o f the present study was to explore the chemical composition o f sediments in the Inari-Pasvik system and provide an estimate o f pollution by heavy metals in view o f their background concentration, and vertical and spatial distribution in sediment columns and in the surficial layers o f sediments. Materials and methods The Inari-Pasvik watercourse drains north-east into the Barents Sea (Fig. 1), and is one o f the larger watersheds in Fennoscandia with its 380 km maximum river length and mean flow o f 175 m 3/ s at the outlet. Lake Inari is the third largest lake in F inland and the World’s largest lake located to the no rth o f the polar circle. The area o f the Lake is 1040 km2. The maximum depth is 92 meters and the total volume o f the lake is 15.9 km3. It is located 119 m above sea level. The Pasvik watercourse (length o f 167 km) is the outlet river o f Lake Inari. The catchment area is 20,890 km2 from which 69.8 % belong to Finland, 27.2 % o f Russia and 5 % o f Norway. The watercourse constitutes the border between