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.

The long-term human impact on drainage basins o f lakes resulted in changes in the environ­ mental conditions that control the chemical composition o f sediments. Therefore, background concentrations o f heavy metals are important information for determination o f the effect o f an­ thropogenic activity on aquatic ecosystems. 4.2. Vertical Distribution of Heavy Metals in Bottom Sediments The vertical distribution o f concentrations o f Ni, Cu and Zn in the sediment cores o f the Norwe­ gian lakes o f the Paz River basin varies only slightly (Fig.8). The maximal increase o f the Ni concentration was fixed in the upper part o f the sediment core o f the Sametivatn. This lake is one o f the closer situated lakes from the smelters o f the Pechenganickel Company. Vertical dis­ tribution o f Co in sediment core o f the investigated lakes has very interesting pattern - maximal contents o f this heavy metal were noticed on the depth 2 - 5 cm (Fig. 8). The decreasing concen­ trations o f Co in the sediment cores may be connected with the reduction o f the Co emissions o f the Pechenganickel Company. In the investigated Norwegian lakes o f the Paz River basin, the concentrations o f Cd and Pb in the top layers o f the sediments is substantially higher than the background contents. It is unlikely for this elevated concentration to be due to the Pechengani- kel Company operation, since this part o f the drainage basin o f the Paz River is only slightly af­ fected by emissions o f heavy metals from the plant, particularly, south-west from the Pechen- ganikel Company (Lakes Isalombola and Gjekvatn). Obvious increasing o f the Pb concentra­ tions in the upper part on the sediment cores were noticed in the Sametivatn and Gardsjoen Lakes (Fig. 8). These abovementioned lakes (Lakes Isalombola, Gjekvatn, Sametivatn and Gardsjoen) showed also the increasing concentrations o f As and Hg in the upper layers o f the sediment cores. It should also be stated that Cd, Pb, As and Hg become the main polluting ele­ ments on the Norwegian site o f the Paz River watershed, in contrast o f Russian site, where Ni, Cu, Zn and Co are the main polluting heavy metals. 4.3. Distribution of heavy metals in the top layers of lake sediments Increased concentrations o f Cd, Pb, As and Hg were recorded in the upper layers o f the sedi­ ments in almost all investigated Norwegian lakes o f the Paz River watershed (Table 8). This in­ dicates that these elements now received the status o f global pollutants. The Pb contents o f the environment are controlled by tetraethyl lead, an antiknock component o f gasoline. Another, rather small (several t/year) source o f Pb (as well as Cd and As) pollution is the emissions o f melting furnaces. Since the melting point o f Pb, Cd and As is lower than that o f other heavy metals (including Ni and Cu), these elements virtually completely go into aerosol, which, on emission by melting furnaces, spreads (similar to SO2) over greater distances than any other heavy metal. Therefore, close to the Pechenganickel Company, elevated concentrations o f Pb, Cd, As and Hg in the top sediment layers o f the investigated Norwegian lakes can be absent (Fig. 9). Metals, emitted to the atmosphere by smelters o f the Pechenganickel Compony in ele­ vated concentrations (Cu, Ni, Co, Zn), show the highest contents in the top layers o f lake sedi­ ments close to the smelters that is confirmed by relatively high values o f the correlation coeffi­ cient in regression equation (Fig. 9). Other elements either have no reliable values o f the corre­ lation coefficient (Cd, Pb), or show the reverse dependence - the elevated concentrations (As, Hg) with distance increasing from the smelters (Fig. 9). This fact suggests about insignificant influence o f the smelter emission on concentrations o f these latter fore elements in sediment o f the investigated Norwegian lake o f the Paz system. 4.4. The Factor and Degree of Contamination of Lake Sediments The Norwegian lakes o f the Paz River watershed, situated more distant from the Pechenganickel smelters, have maximum values o f contamination factor (Cf) for heavy metals (mainly Cd, Pb, 28