Sandimirov S.S. Chemical Composition of Bottom Sedimentary Deposits in Lakes in the Zone Impacted by Atmospheric Emissions from Severonickel Plant. Geochemistry International. 2010, Vol. 48, №11, p. 1148-1153.

CHEMICAL COMPOSITION OF BOTTOM SEDIMENTARY DEPOSITS IN LAKES 1151 The highest values of the contamination coefficient of Cd (table, figure), which is regarded as high, was detected in the BD of Pagel’ Lake. The water of Malevoe Lake had the highest Cd concentrations (0.20—0.32 ag/l) during the monitoring of the Monchegorsk area [3] and 30 ag/l on the daywhen the BD were sampled. These concentrations are much lower than the MPCf for Cd (5mkg/l). The waters of the other lakes have Cd concentrations below the detection limit (<0.05 ag/l). The Cd concentrations in the surface layers of the BD of twenty lakes in the influence zone of atmospheric emissions from Pech- enganickel were determined to be 0.09—3.14 ppm (at an average of 0.84 ppm) [11]. Cd concentrations higher than 0.5 ppm were detected in the surface layer of BD in lakes within 10 km from the smelters of Pech- enganickel and in the influence zone of atmospheric emissions from SNP. The surface layer (0—1 cm) of BD in Siritkul’ Lake contains 0.50 ppm Cd, and the background layers at depths of >1 m contain 0.04 ppm Cd [12]. Similar to Cu and Zn, the maximum Cd con­ centrations (0.75 ppm) were found in the depth range of 10—14 cm in the b D of Siritkul’ Lake. The highest (according to the classification [8]) values of the contamination coefficient were detected in the BD of Pagel’ Lake (table, figure). High and sig­ nificant values of the Pb contamination coefficient were encountered in the waters of Moncheozero and Malevoe lakes. Malevoe Lake had maximum Pb con­ centrations in the water during the monitoring from 0.5—40 ag/l (average of 3.6 ag/l) [3] and 1.1 ag/l on the sampling day of the BD. These values are lower than the MPCf for Pb (100 ag/l). The Pb concentra­ tions in the surface layers of the BD of twenty lakes in the influence zone of atmospheric emissions from Pecehnganickel were determined to be 3—46 ppm (at an average of18 ppm) [11]. The maximum Pb concen­ trations were found in the surface layer of BD of lakes in the vicinity of smelters of Pechenganickel, but high Pb concentrations were also detected at significant distances from the plant (>100 km). It was established [11] that the Pb concentration in the surface layer of BD in lakes is prone to increase from east to west due to the general contamination flux from Central Europe in the northeast to the Arctic. The surface layer (0—1cm) of BD of Siritkul’ Lake has Pb concen­ trations of 154 ppm and occur, similar to the maxi­ mum concentrations of Cu, Zn, and Cd, not in the surface layer but at depths of 10—14 cm in the BD of Siritkul’ Lake. An increase in the Hg concentration toward the surface of BD were encountered in Pagel’ and Malevoe lakes (table, figure). The Hg concentration in the waters of these lakes are below the detection limits (0.01 ag/l). The Hg concentrations in the surface lay­ ers of the BD of twenty lakes in the influence zone of atmospheric emissions from Pechenganickel are 0.016—2.89 ppm (at an average of 0.26 ppm) [11]. Hg concentrations higher than 0.2 ppm were detected in the surface layer of the BD of the lakes at distances less than 20 km from the smelters of Pechenganickel. The maximum values of the contamination coeffi­ cient for As were detected in Malevoe Lake (table, fig­ ure). During the monitoring, the highest As concen­ trations in waters were also determined in this lake (0.25—2.7 ag/l at an average of 1.5 ag/l) [3]; the As concentrations on the sampling day of the BD was 2.5 jag/l. These values are lower than the MPCf for As (50 ppm). The rest of the examined lakes have As con­ centrations below the detection limit (0.25 ppm). The As concentrations in the surface layers of the BD of twenty lakes in the influence zone of atmospheric emissions from Pechenganickel are 2—87 ppm (at an average of 18.5 ppm) [11]. As concentrations higher than 40 ppm were determined in the surface layer of BD in lakes within 20 km from Pechenganickel smelt­ ers. The surface layer of BD in Macfarlane Lake has a higher As concentration than those in Mancheozero and Malevoe (approximately 80 ppm) [23]. The Fe and Mn concentrations also increase toward the surface of the BD of the lakes (table). The Fe and Mn contamination coefficient values and con­ centrations are at a maximum in the largest and deep­ est of the lakes (Moncheozero Lake). Elevated Fe and Mn concentrations in the surface layer of BD are likely explained by the availability of oxygen and the trans­ formation of the metals into oxide (poorly soluble) modes of occurrence. The oxygen concentrations rap­ idly decrease in deeper BD layers, because this ele­ ment is spent on the decomposition of organic mate­ rial. Under these conditions, Fe and Mn occur in sol­ uble lower-oxide modes and migrate toward the surface, near which the metals are oxidized and replenish the stored Fe and Mn amounts. This process is responsible for the lowest Fe and Mn concentrations in the surface layers of BD in many oligotrophic lakes in the north [6, 14, 15]. Because ofthis, increase in the Fe and Mn concentrations can not be directly related to the pollution of the drainage basins of the lakes. This conclusion is also corroborated by the occurrence of brown oozes and marsh ore in the form of crusts in the DB of Pagel’ and Moncheozero lakes [10] (these oozes and crusts were found in 1933, i.e., before the commissioning of SNK in 1938). The oozes contain as much as 8.9% Fe (in dry residue) in Pagel’ Lake and up to 31.6% Fe (obviously, Fe ore) in Mocheozero Lake, and the Mn concentrations were up to 7.2% in Pagel’ Lake and up to 11.6% in Mocheozero Lake [10]. Sim­ ilar concentrations of Fe (30.5%) and Mn (8.17%) were found in Imandra Lake, in an Fe—Mn ore crust of brown color, 10 mm thick, which was localized at a depth of 0—4 mm from the surface of BD and at a water depth of 14.5 m in the lake [15]. It was men­ tioned in [10] that ore crusts cover 22.7% of the area of GEOCHEMISTRY INTERNATIONAL Vol. 48 No. 11 2010