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.

age background concentration o f researched polluting elements in investigated Norwegian, Fin­ nish and Russian lakes differed not many, maximum in 2 times. The maximal background values o f heavy metals and As are marked in sediments o f the Paz River (Ruskebukta, Skrukkenbukta, Vaggatem), LN-2, Porojarvi, Kuetsjarvi, Langvatn, Kobbholmsvatn, Nammijarvi, Nitsijarvi and other lakes located close to deposits o f copper- nickel ores (territory o f "Pechenhanickel" Company). These increased concentration, probably, are connected with geochemical and morphometrical features as lake watersheds, and lakes themselves as well. Background concentration o f heavy metals and As in these lakes at 2 - 10 times more, than in lakes o f the southwest part o f researched territory o f Russia and the adjoin­ ing southeast part o f researched territory o f Finland. Basically average background concentra­ tion o f investigated elements in lake sediments o f the Paz River basin are similar to earlier de­ termined average background concentrations for lakes o f Northern Fennoscandia (Myllymaa, Murtoniemi, 1986; Rognerud, Fjeld, 1990; Dauvalter, 1994, 1999; Dauvalter, Rognerud, 2001). Long-term anthropogenic loading on lake watersheds has resulted in change o f environment and sediment formation. Therefore, background concentrations o f heavy metals and As are very im­ portant for definition o f anthropogenic influence on fresh-water ecosystems. 1.3.2. Vertical distribution of elements in lake sediment cores Investigations o f vertical distribution of elements in sediments cores allow to reconstruct the succession o f geochemical events within the drainage basin o f lakes, as well as to assess back­ ground concentrations o f elements and variations in their influx. These investigations are o f special importance for regions in which the anomalous distribution o f heavy metals is due to the combination o f specific geochemical features and environmental pollution owing to a highly developed mining and smelting industry. The knowledge o f the vertical distributions o f heavy metals in lake sediments is the basis for investigating the effect o f various anthropogenic factors on the evolution o f contamination by heavy metals through time. The period o f intense accumu­ lation o f heavy metals started concurrently with industrial activity in the northern part o f Fenno- scandia. Significant changes in vertical distribution of concentrations o f Ni, Cu, Co and Zn in sediment o f headwaters o f the Paz River (Hestefoss, Ruskebukta), and also in lakes o f the southwest part o f researched territory o f Russia and the adjoining southeast part o f researched territory o f Finland, and also practically in all Norwegian lakes, have not been noticed. In these lakes the increase in concentrations of Pb, Cd, Hg and As in superficial layers o f sediments was revealed. Input o f Pb in many lakes is connected, first o f all, with the deposition o f atmospheric Pb from automobile exhaust. The increase in accumulation rate o f Pb, Cd, Hg and As, most probably, is connected to global pollution by these elements o f an atmosphere o f Northern hemisphere (Nor­ ton et al., 1990). In the Russian lakes removed from "Pechenganickel" Company (for example in the lake Kochejavr which is taking place on distance more 100 km), the increase in concen­ trations o f Pb, Cd, Hg and As in superficial layers o f sediments is also observed. In lakes close to the main source o f pollution in this region - "Pechenganickel" Company - con­ centrations o f Ni, Cu, Co and Zn in the top 4 - 7 cm of sediments are much higher than back­ ground values. Taking into account the fact, that "Pechenganickel" Company is the main source o f pollution o f surface waters o f this region and that this pollution takes place during 60 years, it is possible to calculate (certainly, approximately) the sedimentation rate which is equal ~ 1 mm/year. Contents o f Ni, Cu, Co and Zn decrease in younger sediments on the direction o f the north and south from these lakes. In vertical distribution o f heavy metals in sediments o f the lake Kuetsjarvi, accepting sewage waters o f "Pechenganickel" Company, the maximal values o f contents o f Ni, Cu, Со and Zn are 6