(tass.ru) – The researchers from the Institute of Geochemistry and Analytical Chemistry (GEOKHI) RAS found that the main source of mercury in the bottom sediments of lakes in the Russian Arctic is atmospheric fallout. It appears as a result of the transboundary transfer of elemental mercury vapor from industrial areas, the press service of the Russian Ministry of Education and Science reported on Tuesday.
The researchers studied bottom sediment cores of two Arctic thermokarst lakes - Longtibeito on the Yamal Peninsula and Goltsovoye on the Gydan Peninsula. Both lakes are thermokarst, i. e. they were formed as a result of thawing and subsidence of permafrost. Bottom sediments of arctic lakes not subject to direct anthropogenic impacts are a kind of archives containing information on inputs from the lithosphere and atmosphere, biogeochemical processes in the watershed and in the reservoir itself, and informatively reflecting changes in climate and the environment.
"During the studies of the columns, we determined that the lowest layers belong to the pre-industrial period (before 1850). The mercury content in the near-surface layers, unlike other elements, showed an excess of 7.5-8 times relative to the background values. However, even these concentrations are only slightly higher than the average content of mercury in the earth's crust (0.045 μg/kg) and are far from critical values. In our opinion, the flow of mercury from the earth's crust, which determines the background, is fairly constant. It is much less than the input into the upper layers of sediments from the atmosphere," Yury Tatsiy, Senior Researcher at the Laboratory of Evolutionary Biogeochemistry and Geoecology of the GEOKHI RAS, quoted the press service as saying.
Scientists also assessed the possible threat of mercury release accumulated in permafrost because of climate warming. The researchers drew attention to a short-term sharp increase in the flow of mercury in Lake Goltsovoe at the beginning of the 20th century with an increase in the concentrations of other elements. A possible explanation could be the warming that affected this region at the beginning of the century, when the permafrost boundary receded to the north, and the temperature of frozen soils increased by 1.5-2 degrees. According to the institute, sustainable climate warming can lead to an increase in the average annual temperatures of lake waters and temporarily change the trophic status of the lake. This leads to an increase in the sediments of organic matter and the proportion of micron-sized particles - the main collectors of mercury, and, as a result, to an increase in its concentration due to inputs from the watershed.
The research was supported by the Russian Ministry of Education and Science.
The researchers studied bottom sediment cores of two Arctic thermokarst lakes - Longtibeito on the Yamal Peninsula and Goltsovoye on the Gydan Peninsula. Both lakes are thermokarst, i. e. they were formed as a result of thawing and subsidence of permafrost. Bottom sediments of arctic lakes not subject to direct anthropogenic impacts are a kind of archives containing information on inputs from the lithosphere and atmosphere, biogeochemical processes in the watershed and in the reservoir itself, and informatively reflecting changes in climate and the environment.
"During the studies of the columns, we determined that the lowest layers belong to the pre-industrial period (before 1850). The mercury content in the near-surface layers, unlike other elements, showed an excess of 7.5-8 times relative to the background values. However, even these concentrations are only slightly higher than the average content of mercury in the earth's crust (0.045 μg/kg) and are far from critical values. In our opinion, the flow of mercury from the earth's crust, which determines the background, is fairly constant. It is much less than the input into the upper layers of sediments from the atmosphere," Yury Tatsiy, Senior Researcher at the Laboratory of Evolutionary Biogeochemistry and Geoecology of the GEOKHI RAS, quoted the press service as saying.
Scientists also assessed the possible threat of mercury release accumulated in permafrost because of climate warming. The researchers drew attention to a short-term sharp increase in the flow of mercury in Lake Goltsovoe at the beginning of the 20th century with an increase in the concentrations of other elements. A possible explanation could be the warming that affected this region at the beginning of the century, when the permafrost boundary receded to the north, and the temperature of frozen soils increased by 1.5-2 degrees. According to the institute, sustainable climate warming can lead to an increase in the average annual temperatures of lake waters and temporarily change the trophic status of the lake. This leads to an increase in the sediments of organic matter and the proportion of micron-sized particles - the main collectors of mercury, and, as a result, to an increase in its concentration due to inputs from the watershed.
The research was supported by the Russian Ministry of Education and Science.
