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.

Over the subsequent years, the gradual increase o f heavy metals concentrations is marked, and the sharp increase at 5, 5 and 4 cm depth (respectively) can be connected to the beginning o f the processing o f Norilsk ores in 1971, when production volume and thus anthropogenic loading to the lake increased significantly. Taking into account that the sediment cores o f sampled stations were collected in 2003 - 2004, it is possible to estimate that for the past 70 year period repre­ sented in the core, the average sedimentation rate approaches 1.57, 1.71 and 1.14 mm/year for Gulf Stream, Salmijarvi and White Stone aquatories o f the Kuetsjarvi, respectively, and for the last 30 years it is 1.67, 1.67 and 1.33 mm/year, respectively. This is consistent with compaction at higher depth. Besides increase in concentration o f the basic polluting heavy metals (Ni, Cu, Co, Zn), in sediments cores o f lake Kuetsjarvi the increase in concentration towards the sedi­ ment surface other researched heavy metals and As is observed (Fig. 5). This fact suggests that sewage waters o f the “Pechenganikel” Company also are polluted by Cd, Pb, As and Hg. Sedimentation rate estimates for Lake Shuonijarvi (23 km to the south-west o f Nikel), from which the Shuonijoki river flows, based on 210Pb using CRS and CIC dating models (Appleby, Oldfield, 1978) for the past 20 years was 0.68 mm/year and 0.45 mm/year over the past 60 years (Norton et al., 1993). The smaller sedimentation rate in Lake Shuonijarvi is likely related to lower runoff o f mineral particles into the lake, which is consistent with a higher content o f or­ ganic material (15 - 20 %) than observed for Lake Kuetsjarvi. In the other lake on the border be­ tween Russia and Norway, Hundvatn (24 km to northeast o f Nikel), the sedimentation rate is a little bit higher namely 0.88 and 0.57 mm/year for the last 20 and 60 years, respectively (Norton et al., 1996). In Lake Hundvatn sediments, the content o f organic material is also within the range 15 - 20 %. Substantial increasing o f concentration Ni, Cu, Co, Zn is marked also in superficial layers o f sediments o f lakes close to Pechenganikel Company (Fig. 6). The greatest increase is noticed in lakes Zapoljarny, LN-2, LN-4, located in several kilometers from the smelters. In lakes more removed from the point sources the basic polluting heavy metals are Cd, Pb and Hg (Fig. 6). 3.3. Distribution of Heavy Metals in the Top Layers of Lake Sediments Emissions of heavy metals and wastewater from melting furnaces, slime pits, tailing dumps, and mines o f the Pechenganikel’ Plant are the main sources o f increased concentrations o f Ni, Cu, Co and Zn in the top layers o f sediments p f lakes close to the sources (Lakes Kuetsjarvi, LN-2, LN-4, Palojarvi, Zapoljarny, Alla-Akkajarvi and Peschanoe). The prevailing southwestern winds mainly spread the emission plume in the north-eastern and southern direction (bottom sediments in lakes located 40 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” Plant. Within 10 to 40 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, which is in­ dicative o f the effect o f emissions from melting furnaces. The bulk o f the industrial wastewater from the “Pechenganickel” Plant enters Lake Kuetsjarvi, where the maximum concentrations o f Ni, Cu, Co, Zn, and Cd were recorded within top layers o f bottom sediments (Fig. 5). 19