Chemical composition of lake sediments along a pollution gradient in a Subarctic watercourse / Dauvalter V., Kashulin N., Sandimiriv S. [et al.] // Journal of Environmental Science and Health. Part A. - 2011. - Vol. 46.

Downloaded by [Vladimir Dauvalter] at 21:54 24 November 2013 1022 Dauvalter et al. Russia and Norway and consists o f lakes and reservoirs adjoined by small river stretches. Seven hydroelectric power stations are located along the watercourse from Lake Inari to the ocean, including Kaitakoski, Janiskoski, Rajakoski, Hevoskoski, Boris Gleb, Skogfoss and Melkefoss. The first five belong to Russia and the last two to Norway. The largest lakes are the Vaggatem reservoir (35 km2), Langvatn (10 km2), Svanvatn and Skrukkebukta (6.9 km2). Lake Kuetsjarvi is located 4.5 km below the Nikel smelters o f the Pechenganickel Company (Fig. 1). The length o f the lake from the South to the N o rth is 11.5 km, the width varies from 1 up to 2 km, the maximal depth is 32 m, and the lake area is 18 km2. The largest tributaries o f the Lake are the River Shuonijoki (50 % o f all flow into the Lake) and the River Kolosjoki (30%) which drains the industrial area o f the smelters. Lake Kuetsjarvi is connected to the main stem o f the Pasvik watercourse by a channel close to Lake Svanvatn. The channel length is 2.7 km, the width up to 600 m, and the water flow 7-11 m3/s. The an nual flow volume entering into Lake Kuetsjarvi varies from 218 up to 350 million m 3. The industrial settlement Nikel, which is an administrative centre o f the Pechenga district o f the Murmansk Region, is located near the lake. Lake Kuetsjarvi has big recreational importance with recreation places, small summer houses and kitchen gardens o f Nikel inhabitants being placed along its shores. The contents and behaviour o f metals in sediments o f the Inari-Pasvik watercourse was investigated in the frame o f the Inerreg IIIA Kolarctic project “Development and implementation o f an environment monitoring o f assess ment programme in the jo in t Finnish, Norwegian and Russian area” . Sediment cores were sampled during 2002-2004 from seven lakes: two stations in Lake Inari at depths o f 15 and 42 m (stations 1 and 2), single stations in five lakes o f the lacustrine parts o f the Pasvik watercourse: Hestefoss (station 3, depth 10.5 m), Ruskebukta (station 4, 15 m), Vaggatem (station 5, 19 m), Bjornevatn (station 10, 23 m) Skrukkebukta (station 11, 37 m), and four stations in Lake Kuetsjarvi: G u lf Stream (station 6, 23 m), Kolosjoki (station 7, 12 m), Salmijarvi (station 8, 10 m), White Stone (station 9, 32 m) (Fig. 1). Sediment samples were collected by a gravitational corer and vertically sliced into 1-cm layers for the analysis.[12] Loss on ignition (LOI) (an indirect index o f the contents o f organic substance) was determined and concentrations o f Ni, Cu, Co, Zn, Cd, Pb, Hg, As, Sr, Mn, Fe, Ca, Mg, Na, K, Al, extracted by the concentrated nitric acid, were analyzed by atomic absorption spectrophotometry o f the sediment samples. Techniques for the chemical analysis are described in detail by Dauvalter.[8,11] Anthropogenous influence on water ecosystems was as sessed by calculating the factor o f contam ination (Cf) for each investigated heavy metal (Ni, Cu, Co, Zn, Pb, Cd, Hg, As). Values o f Cf were determined as the ratio o f heavy metal concentration in surficial 1-cm layer divided by the background concentration in the deepest layer o f the sed iment core.[325] The overall degree o f contam ination (Cd) was determined as the sum o f all values o f Cf for eight heavy metals for each given lake or lake station. Results and discussion Background concentration o f heavy metals Definition o f natural background concentrations o f heavy metals is a basis for all research on lake sediments. Sedi ment samples collected from the deepest core layers (usual between 20 and 30 cm) allow the determ ination o f these background concentrations. The age o f these layers is some hundreds years as sedimentation rates in reservoirs o f No rthern Fennoscandia as a rule are less than 1mm /years, i.e., they were formed before the industrial development of the No rthern part o f Fennoscandia.[26] These layers reflect natural geochemical features o f the catchment and allow an estimation o f the pollution degree o f water objects, and also provide a possibility to reveal anomalies o f concentra tions o f metals with the purpose o f searching for deposits o f minerals.[27] Background concentrations ofelements and loss on igni tion (LOI) in sediments from the Inari-Pasvik watercourse are summarized in Table 1. Statistical parameters are cal culated without taking into account data from station 7 in Lake Kuetsjarvi as long-term and strongly polluted mate rial from the Pechenganickel Company were collected in this part o f the lake, which is highly influenced by the River Kolosjoki, which directly drains the smelter area. Highly insignificant values o f organic material contents (LOI val ues in the layer o f 12-13 cm is less than 1%) in the sediment core at station 7 also reflect the presence o f strongly pol luted mineralized material. The maximum background concentrations o f the m ajo r ity o f heavy metals (Ni, Zn, Co, Cd, Hg, As) were found in lake Kuetsjarvi, and mainly at station 8. This is caused by geochemical and morphometric features o f the catch ment area o f the lake where there are extensive copper- nickel sulphidic deposits present including minerals such as pentlandite (Fe,Ni) 9 S 8 , chalcopyrite CuFeS 2 , cobaltite (Co,Ni)AsS, nickeline NiAs and others.[16] The background concentrations o f the abovementioned elements in the sed iments o f Lake Kuetsjarvi are 2-10 times higher than in the other investigated lakes. It should also be noted that the background concentra tions o f heavy metals (except for Hg) were minimal (or among the smallest) in sediments o f the most no rthern and deepest water area o f the Lake Kuetsjarvi; the Pitkaloukko Bay, where the sediment core from station 9 was collected. This is related to geochemical features o f the lake catch ment, as the river Kuvernerinjoki entering into this bay, has no deposits o f copper-nickel ores in its catchment area. The highest background concentrations o f Cu and Pb were found in the deepest layers o f the sediment cores from

Chemical composition of lake sediments along a pollution gradient in a Subarctic watercourse / Dauvalter V., Kashulin N., Sandimiriv S. [et al.] // Journal of Environmental Science and Health. Part A. - 2011. - Vol. 46. - P. 1020-1033.