Bottom sediments are an integral part of any water body and a key to the current state of a hydrosystem, particularly the upper layers of lake sediments. The chemical composition of bottom sediments from small Ukonlampi Lake (Lahdenpohja District, Republic of Karelia, Russia) is discussed. Evidence for considerable historical heavy metal pollution of the lake and its surroundings was obtained, based on an analysis of a 30-centimeter-long bottom sediment core. Concentrations of elements in the bottom sediment samples were estimated using the mass-spectral method on a ХSeries-2 ICP-MS. The influence of the long-range transport of pollutants on the formation of the geochemical features of current bottom sediments from the study area was assessed. It should be noted that the main sources of heavy metals are industrial emissions from St. Petersburg, some other cities of the Leningrad Region and from Finland. The heavy metal behaviour of bottom sediments from other small and large lakes of the Republic of Karelia and the Murmansk Region was shown to display a distinctive pattern. All the lakes contain similar heavy metals, which are accumulated most actively in the surface layers of current lake sediments. Lake sediment pollution in the present study was assessed using a geoaccumulation index (Igeo) of the determined elements. It was shown that Ukonlampi Lake sediments have uncontaminated and moderately contaminated P, Cu, Zn, W, and Tl levels. Other elements (Cd, Sn, Sb, Pb, and Bi) displayed Igeo from the uncontaminated and moderately contaminated level to the moderately contaminated level.  

25.1.2020