Sandimirov S. Pollution of the Sediments of the Paz River basin / In State of the environment in the Norwegian, Finnish and Russian border area. The Finnish Environment. Finland, Jyvaskyla: Kopijyva Oy. 2007, №6, 98p.

marked in an interval 2 - 4 cm. Reduction o f concentration in the top 2 cm, probably, can be ex­ plained by changes o f physical and chemical conditions in lake and in territory o f watersheds, as well as reduction o f atmospheric emissions o f the smelters. Sedimentation rate in lake Kuets­ jarvi, according to indirect determinations, is equal on the average on all researched water areas 1.5 mm/year. Sedimentation rate in the Shuonijarvi lake, determined by results o f models o f dat­ ing on 210Pb, is equal 0.68 mm/year for last 20 years and 0.45 mm/year for last 60 years (Norton et al., 1996). The difference in sedimentation rate is connected, most likely, that lake Shuoni­ jarvi becomes soiled by only air way, and in lake Kuetsjarvi a plenty o f the suspended particles that increases input o f mineral particles in lake acts also, and respectively increases the sedi­ mentation rate. The average sedimentation rates o f the Norwegian lakes Hundvatn, Durvatn and Dalvatn are equal 0.4, 0.6 and 0.54 mm/year, respectively (Norton et al., 1992, 1996), Finnish lakes Lampi 222, Nitsijarvi, Sierramjarvi and Pahtajarvi - 0.4, 1.0, 0.5 and 1.25 mm/year (data o f Dr. Jaakko Mannio, Finnish Environment Institute). Therefore, it is possible to accept, that the average sedimentation rate in lakes o f the Paz River basin is equal 1 mm/year. The knowledge o f the vertical distributions o f heavy metals in lake sediments is the basis for in­ vestigating the effect o f various anthropogenic factors on the evolution o f contamination by heavy metals through time. The period o f intense accumulation o f heavy metals started concur­ rently with industrial activity in the northern part o f Fennoscandia. Global transfer o f air masses to Northern hemisphere is reflected in increase in accumulation o f Pb Cd, Hg and As in surface sediment layers o f the lakes removed from the main source o f pollution. 1.3.3. Distribution of elements in the surface sediments Emissions of heavy metals and wastewater from melting furnaces, slime pits, tailing dumps, and mines o f the “Pechenganickel” Company are the main sources o f increased concentrations o f Ni, Cu, Со, Cd, Zn and Hg in the top layers o f sediments o f the Kuetsjarvi Lake. Significant ac­ cumulation o f Ni, Cu, Co, Zn, Cd, connected mainly with input of sewage waters o f the "Pechenganickel" Company through the Kuetsjarvi Lake, is marked on the middle current o f the Paz River (Bjornevatn). The analysis o f accumulation o f Ni, Cu, Co, Zn in sediments o f the up­ per and lower current o f the Paz River has not shown any influence o f atmospheric emissions o f smelters. The water o f the Paz water system features neutral pH values and considerable neu­ tralizing capacity with respect to acid compounds, which abundantly arrive from the Pechengan­ ickel Company. This greatly favours the capture and accumulation o f mobile heavy metals (e.g., Ni, Cu, and Cd) in lake sediments. The prevailing south-western winds mainly spread the emis­ sion plume in the north-eastern and southern direction (bottom sediments in lakes located 50 km and farther south o f Nikel’ are contaminated only slightly). In northern areas o f Norway and Finland, deposition o f these elements with precipitation is low. In these places, emissions o f the plant only slightly affect the heavy metal content o f top layers o f lake sediments. The maximum Ni and Cu concentrations, which exceed their background values by a factor o f 10 to 130, were recorded within 10 km o f the “Pechenganickel” Company. Within 10 to 30 km o f the source o f contamination, these concentrations are only 3-7 times as high as their back­ ground values. Concentrations o f Co were 4-10 times greater than their background values within 15 km o f the contamination source and up to 3 times greater in other lakes on the dis­ tance more than 15 km, which is indicative o f the effect o f emissions from melting furnaces. Lakes Kuetsjarvi, LN-2, LN-3, LN-4 receive the basic part o f emissions o f the “Pechengan­ ickel” Company and have maximal concentration o f Ni, Cu, Co, Zn, Cd, Hg and As in superfi­ cial layers o f sediments. High concentrations o f Cd, Pb, Hg and As are marked as well in some lakes removed from the “Pechenganickel” Company that is connected to global pollution by these elements last decades. 7