DOI: 10.7256/2453-8922.2018.4.28527

Abstract: The subject of this study is the peatlands of the Seymchan-Buyunda depression, in particular the composition of gases contained in the permafrost peatlands and ice-wedge ice. Special attention is paid to conditions of the peat formation, features of the Seymchan-Buyunda depression climate and the Magadan region in general, the characteristics of the main types of vegetation, soil cover and landscape. The trend of changes in the average annual air temperature in the area of Seymchan town is considered. To estimate the time of formation of ice-wedge ice, the composition of spring pollen rain during the accumulation of the ice wedges was reconstructed. The composition of trapped gases in peatlands is established. Determination of gas composition was carried out using the chromato-mass-spectrometer Hitachi M-80. There are high methane content in frozen peat bog Chokachi and lake water on the surface of the peat bog; it was discovered that the lake on the surface of the peatland is both, a trap for gases released from the thawing peat and a depositing medium, in which the processes of reduction of hydrocarbons take place intensively; in the composition of gases trapped in the frozen peatland there is a high content of hydrogen, which is one of the mandatory conditions for the life of methane-forming bacteria.

DOI: 10.7256/2453-8922.2018.4.28583

Abstract: The object of this research is the organic-mineral deposits of the Late Pleistocene polygonal ice-wedge complex. They are studied in the outcrop of the second terrace, located on the left bank of the Mongatalyangyakha River, 3 km west of the estuary (71 ° 58'60 "N, 75 ° 16'0" E), on the Yavay Peninsula in the north of the Gydan Peninsula. The botanical composition of allochthonous peat in the upper part of the section is dominated by the remnants of Ledum palustre, and in the organic-mineral sediment the remains of Drepanoladus fluitans, Calliergonella cuspidata (or Calliergon cordifolium) are prevalent. A field outcrop study was performed; three wells were drilled. Palynological and hydrochemical diagrams were constructed and the radiocarbon age of the Late Pleistocene polygonal massif was determined. The main conclusions of the study are: 1. The age of the organic-mineral deposits varies from 30,200 to 21,900 years BP. 2. The rate of accumulation of organic-mineral deposits in the Karginsky time at the mouth of the Mongatalyangyakha River is about 0.25mm/year. 3. According to the palynological analysis, three local pollen zones are distinguished.

DOI: 10.7256/2453-8922.2018.4.28528

Abstract: The article presents preliminary results of field studies of the outcrops of the eastern coast of the Chukchi Peninsula, containing massive ice beds. The expeditions were conducted in 2014–2018. Descriptions and photographs of ice and enclosing sediments are given. Four outcrops of ice up to 4.7 m thick and up to 45 m long are described within the Saint Lawrence Bay and Mechigmensky Bay. The morphology of the massive ice bodies, a variety of ice structures and host sediments allow suggesting their polygenetic origin. The results of long-term active layer thickness monitoring indicated that the intensification of thaw slump events in the past four years is associated with the increase in the depth of thawing, which in 2018 reached highest values in over two decades. The formation of thaw slumps and associated thermocirques is cyclic. As the active layer thickness increases, their number increases, forming nested thermocirques, and as the thaw depth decreases, cryogenic creep slows down.

DOI: 10.7256/2453-8922.2018.4.28619

Abstract: The processes of isotope fractionation inside the snow cover during the formation of infiltration ice (ice interlayers, crusts) are considered. On the temperate glacier zones of infiltration, ice formations are very common, and an understanding of the processes of isotopic transformation during snow-ice transition is important for distinguishing the type of ice formation. In addition to recrystallization transformation of snow into ice on the glaciers, the formation of infiltration and superimposed ice occurs, which should be accompanied by isotopic fractionation due to the difference in the fractionation coefficients between vapor and liquid/ice (precipitation) and liquid and ice (congelation ice formation). A field experiment was performed on the formation of infiltration ice inside a snow column with artificial stimulation of snow melting from the surface. The main method was the study of the isotopic composition of oxygen and hydrogen of snow and ice. Primary snow was homogenized, after a 14-day experiment inside the snow columns, a differentiation of snow by the isotopic composition of oxygen and hydrogen occurred. The values of δ18О and δD are described by a regression equation with a slope 5. Such slope indicates water vapor diffusion processes. Infiltration ice on the isotopic composition of oxygen and hydrogen is slightly different from the original snow.

DOI: 10.7256/2453-8922.2018.4.28173

Abstract:   The increase of temperatures of permafrost and the corresponding increase in the depth of seasonal thawing leads to activation of thermokarst. To estimate the intensity of thermokarst process development on the Sentsa River (East Sayan), the index of the eccentricity of the radial increment in the Siberian larch (Larix sibirica) was used. It allowed gaining understanding about the compression processes over the last centuries, and forecast their strengthening in the future at increase in average air temperature of the warm period. This methodological approach is fairly universal and is not tied to any particular conditions of the locale. It can be applied in future research of the thermokarst processes, as well as other phenomena accompanying the landscape changes.  

DOI: 10.7256/2453-8922.2018.4.28589

Abstract: In this article the influence of drying temperature and dispersion of sandy soils on isotopic composition of water evaporated from soils is investigated. These studies are relevant for those permafrost areas, where sharply continental conditions with very warm summers and active evaporation. During evaporation water molecules with the lightest isotopes evaporate first, after then the molecules with more heavy isotopes evaporate. At high drying temperatures (180, 200, 220 °C) the isotopic composition of moisture categories in soils becomes heavier in the series: free water< transitional water < bound water. The effect of soil grain size on the isotopic composition of water evaporated from sands is more noticeable at lower temperatures, wherein the water vaporized from silty sand at the same temperature is isotopically heavier than water evaporated from medium-grained sand. For medium-grained sand portions of the condensate evaporated at a higher temperature have a heavier isotopic composition in δ18O and δ2H values, the same relationship is observed for silty sand in deuterium values, but the effect of temperature is less pronounced for silty sand in oxygen values.