Laboratory of Geochemistry of Radioactive Elements and Ecogeochemistry (216)

For suspended matter (> 0.45 µm) of snow waters, collected near large settlements (Group 1) with increased anthropogenic load, higher 7Be/210Pb ratios of 1.8-1.9 are characteristic. For conditionally background areas, these ratios vary in the range of 0.5-0.8.

Studies of the accumulation of a wide range of micro and macroelements in mosses, lichens, cedar, and larch needles in the Novy Urengoy District of the Yamalo-Nenets Autonomous Okrug were conducted. Based on measurements of the specific activities of 7Be and 210Pb, atmospheric fallout markers, it was shown that dust particle concentrations increase in the following order: cedar needles, larch needles, mosses, and lichens. Concentrations of Zr, Hf, Ti, Th, Fe, V, Li, Na, Si, Be, Y, ΣREE, and Sc also increase in this order in this area. The enrichment factors (EF) for these elements relative to clay shale are close to unity, confirming their terrigenous origin. The terrigenous origin of these elements in the studied biological samples is also confirmed by their high correlation coefficients with Sc. This indicates that their concentrations in the studied samples are the result of solid background atmospheric fallout.

For the first time, a large-scale study of the artificial radionuclide 137Cs in mosses, lichens, and cedar and pine needles was conducted along a north-south transect in Western Siberia from 67.5 to 55 N latitude. The presence of 137Cs here is associated with nuclear weapons testing on Novaya Zemlya. Measurements showed that at all sampling points south of 59.6 N latitude, there is a very sharp decrease in the specific activity of 137Cs in all ecosystem components (approximately 20-fold in mosses and lichens, and 100-fold in needles). This fact is explained by the presence of global atmospheric circulation, consisting of three circulation cells in the Northern Hemisphere. The boundary between the polar and temperate circulation cells occurs precisely at 60 N latitude. At this boundary, the opposing surface air currents of these cells (in our case, a polluted flow from the north and a clean flow from the south) collide, generating ascending air currents that carry away 137Cs. Water vapor condenses in these ascending currents, leading to snowfall, rain, and thunderstorms. During the Novaya Zemlya test, this precipitation contributed to the large amount of 137Cs deposited north of the polar cell boundary. Meanwhile, areas south of 60°N should remain clear, which is what was observed.

The distribution of natural (238U, 226Ra, 210Pb, 40K) and technogenic (137Cs) radioisotopes in the vertical profile of the Sherstobitovsky peat bog and indicator bioobjects of the biogeocenosis was studied for the first time. Reliable dating of the Sherstobitovsky peat bog to the 30 cm horizon (≈140 years) was carried out using the model of a constant flux of nonequilibrium 210Pb (Pbex) from the atmosphere. The accuracy of the dating was verified by the distribution of technogenic 137Cs across the depth of the peat section. For the studied Sherstobitovsky peat bog deposit, a violation of the radioactive equilibrium between 238U and 226Ra in favor of the latter is observed. For the depth of the studied section and for the main components of the biogeocenosis, the 226Ra/238U ratio has values ​​​​greater than unity. The first data were obtained to estimate the deposition density of natural (7Be, 210Pb) and man-made (137Cs) radioisotopes in suspended snowmelt on the surface of raised bogs in the Baraba forest-steppe. It was established that the main concentrator of the 7Be radioisotope is the fine colloidal fraction (3 μm).