Chemical composition of lake sediments along a pollution gradient in a Subarctic watercourse

Abstract

Sediment cores were collected from seven lakes in the Subarctic Pasvik watercourse, polluted by sewage waters and air emissions from the Pechenganickel Metallurgical Company, in order to study chemical composition and estimate the intensity of pollution by taking into account background concentration of elements and the vertical and spatial distribution of their contents in cores and surficial layers of sediments. Sediment samples were analysed by atomic-absorption spectrophotometry for 18 elements (Ni, Cu, Co, Zn, Cd, Pb, Hg, As, Cr, Sr, Mn, Fe, Ca, Mg, Na, K, Al, P). Maximum concentrations of all investigated heavy metals (Ni, Cu, Co, Zn, Cd, Pb, Hg, As) were found in the surficial sediment layers of Lake Kuetsjarvi situated directly below the metallurgic smelters. Decreased contents of heavy metals were observed in surficial sediment layers further downstream in the Pasvik watercourse, although pollution remained rather high. Considerable increase in the contents of the heavy metals emitted into the atmosphere in significant amounts by the Pechenganickel Company (Ni, Cu, Co, Zn), was not observed in surficial sediment layers of lakes upstream in the watercourse polluted only by air contamination and household sewage, but substantial increase of the concentrations of chalcophile elements (Pb, Cd, Hg, As) was revealed. The increase in P contents towards the sediment surface in some lakes may suggest a development of eutrophication processes. Our studies reveal that the metallurgic processing of the Pechenganickel Company has resulted in comprehensive heavy metal pollution and contaminations of lakes sediments in the Inari-Pasvik watercourse. The pollution impact on the sediments is most severe in Lake Kuetsjarvi in the vicinity of the smelters, intermediate in lake localities in the main watercourse downstream the metallurgic enterprises and least in lake localities in the upstream part of the watercourse.

The Impact of a Nickel-Copper Smelter on Concentrations of Toxic Elements in Local Wild Food from the Norwegian, Finnish, and Russian Border Regions

“…We observed no spatial trend for Hg concentrations in fish, which is in agreement with previous studies from this area [10,13]. Still, concentrations in sediments have indicated Hg emission from the Ni-Cu smelter in addition to other local anthropogenic activities and long-range transport [3,5]. …”

“…The Ni-Cu smelters on the Kola Peninsula use different technologies and process different ores, which can lead to the emission of different elements [7]; therefore, emission trends cannot be directly compared. Previous studies on sediments, surface soil, terrestrial moss, and vegetation in the area support the hypothesis that the Ni-Cu smelter in the city of Nikel is a source of Ni, Co, and as in the surrounding area [3,4,5,7,9]. …”

“…The Pechenganickel complex, located in the Russian city of Nikel, close to the Norwegian border, along with the briquetting facility in the city of Zapolyarny, located approximately 25 km from the smelter, comprises one of the largest nickel (Ni)–copper (Cu) smelters in the world [1,2,3,4]. The complex as a whole has been emitting large amounts of Ni, Cu, cobalt (Co), sulphur dioxide (SO 2 ), and dust particles into the atmosphere and local waters since Ni-Cu smelting began in the 1930s [1,3,4,5,6,7,8,9,10,11]. Although trace amounts of Cu are essential to humans, larger amounts can be hazardous [12].…”

“…Other toxic elements, such as arsenic (As), lead (Pb), cadmium (Cd), and mercury (Hg) are also emitted by the complex, but studies disagree on the magnitude of these emissions [1,3,4,5,6,7,10,13,14]. It is also likely that As, Pb, Cd, and Hg emissions are camouflaged by deposition from long-range transport and other local anthropogenic or geogenic sources [3,4,5]. According to the latest estimates, the Pechenganickel complex emitted 330 tons of Ni and 158 tons of Cu into the atmosphere in 2009, and these numbers have remained unchanged since the 1990s [1].…”

“…Elevated environmental concentrations of toxic elements such as Ni, Cu, and several others in these border regions, as well as several air pollution events [1,2,3,4,5,6,9,10,13,14,18,22,23,24,25,26,27], have given rise to concern among these residents [27], some of whom frequently use foods that grow wild in these regions. Therefore, knowledge of the concentrations of toxic elements in local wild foods is important, both to protect nature and to protect humans that consume local wild food.…”