Sandimirov S.S. Catalogue of lakes in the Russian, Finnish and Norwegian Border Area. Finland, Jyvaskyla: Kopijyva Oy, 2008.

able supply of base cations. Thus, despite the high sulphur deposition, the soils in the catchment area contribute sufficient base cations to prevent acidification.This is clearly reflected in the water quality; lakes with relatively high sulphate concentrations also have high base cation concentrations and high alkalinity. The emission of alkaline dust from the smelter, power station and mining activities also undoubtedly contributes to the high base cation concentrations in the lakes. The Jarfjord and Vatsari areas have more weakly buffered lakes. This is also the case in Vatsari and in Sor-Varanger, to the east of Vatsari. Jarfjord and S 0 r-Varanger are situated relatively close to the smelter, and are therefore subjected to relatively high sulphur deposition. Strong signs of acidification have earlier been recorded in the lakes in the Jarfjord area but, since 1987, the mean pH has increased from below 5 to 5.4 in 2004. Similar signs of recovery from acidification have been reported in the Vatsari lakes. However, the lakes in Vatsari are in the early stage of recovery, and the increase in the buffering capacity is not yet very strongly reflected in the pH. The low alkalinity and low pH values in some lakes in the Raja-Jooseppi area, as well as in the reference area in Pallas, are caused by the naturally higher concentrations of organic acids in the lakes. Water quality is a basic element in monitoring and assessing the impacts of the Pechenganikel smelter on aquatic ecosystems. It represents the chemical environment in which aquatic organisms live. Water quality more directly reflects changes in the deposition of acidifying compounds than the deposition of metals, because the metal concentrations are more strongly dependent on bedrock geology, pH and the amount of organic material (TOC) in the soil and surface water. Lake bottom sediments Lake sediment samples provide an excellent tool for assessing the ecological state of lakes and the impact of pollution from both local and global sources. Analysis of the distribution of heavy metals in the bottom sediments clearly demonstrates that lakes with high concentrations of highly correlated elements (e.g. Ni, Cu, Co and Hg) are located within a 50 km radius around the smelter complex. The increase in Pb con­ centrations follows a gradient running from east to west, and is related to the long­ distance, trans-boundary transport of pollutants from central Europe. Cadmium, As and Hg are, in addition to Pb, also so-called global pollutants. The maximum Ni and Cu concentrations, which exceeded the background (pre-industrial) values by a factor of 10 to 130, occur within a distance of 10 km from the Pechenganikel smelter. At dis­ tances of 10 to 30 km from the emission source the concentrations are only 3-7 times higher than the corresponding background values. The concentrations of Co are 4-10 times higher than the background values within a distance of 15 km from the smelter, and up to 3 times higher at distances of more than 15 km. Lakes Kuetsjarvi, LN-2, LN-3, LN-4 receive the highest pollutant loads from the Pechenganikel smelter, and this is reflected in the fact that the maximum concentrations of Ni, Cu, Co, Zn, Cd, Hg and As occur in the uppermost sediment layers. Some lakes located at greater distances from the smelter have relatively high Cd, Pb, Hg and As concentrations in their sediments, and this is related to global pollution by these elements during the past few decades. 136 Catalogue o f Lakes in the Russian, Finnish and Norwegian BorderArea