Abstract: The subject of the study is the cryostructures of Pleistocene sediments uncovered by a 30-m borehole in the Churapcha village and the distribution of stable oxygen and hydrogen isotopes in the schlieren ice and thin ice lenses. The research was located in the area of continuous permafrost distribution, the vertical thickness of which reaches 400–500 m here. The average annual temperature of rocks ranges from -4.6 to -6.2 °C, in river valleys the temperatures are increased to about –2 to –1°C. Permafrost sediments in the Churapcha area are characterized by relatively high iciness, from 26 to 47%. Ice is found in deposits as interlayers that form a layered (as well as lenticular and braided) cryostructure. During the fieldwork, frozen cores opened by a drilling hole at a depth of 30 meters were studied. Drilling was carried out using a large-sized drilling rig (PBU-2) based on a Kamaz truck. A core drilling pipe with a diameter of 146 mm was used. Sampling was carried out from the frozen core. The well-uncovered permafrost deposits, which have mainly dark brown and gray colors, especially bluish-gray shades characteristic of heavy loams and clays. The seasonally active layer has a sandy loam composition, and below, at depths from 1.5 to 6.0 m, the deposits are loamy. At depths of 6.0–20.0 m, alternating layers of loams and clays of different thickness are observed, and below there is a sharp change in the lithological composition to medium and fine sand (20.75–24.0 m), including a large number of layers of organic matter. The distribution of δ18O and δ2H values was examined in structured ice up to a depth of 17.7 meters. In the upper 12 m, the isotopic composition is significantly more negative: δ18O values vary from –29.44 to –34.35‰, while δ2H values range from –213.5 to –253.6‰. In the 12-17.7 m range, δ18O oscillates between –25.94 and –28‰, whereas δ2H ranges from –195.3 to –214.3‰. Analysis of data on the isotopic composition of structure ice in the yedoma deposits of Yakutia showed a close range of values with the ice of unit 1 from the borehole in Churapcha that we studied. The heavier isotopic composition of ice of unit 2 is probably explained by another source of water and the influence of isotopic fractionation during the interaction of clay particles with water. As for the contrast of the isotopic characteristics of unit 1 and unit 2, we note that such a ratio, when the isotopic composition in the upper unit is on average consistently 3-5‰ lower than in the lower unit, is quite rare in permafrost.
The water for the formation of segregation ice from the borehole could have been formed to a greater extent from melted winter snow and was less subject to evaporation. Contrasting values in the ice of the two studied units may indicate different water sources; for the ice in unit 1, the water source could have been, to a greater extent, winter precipitation (surface water formed from melted snow); the presence of a negative peak in the vertical distribution of isotopic values may indicate two-sided freezing (from above and below) and isotopic fractionation during freezing.
The deposits of unit 2 are represented by heavy loams, probably lacustrine. It can be assumed that the saturation of these deposits under these conditions occurred with lake water, which consisted of a mixture of precipitation from both winter and summer seasons and was characterized by higher values of the isotopic composition. Freezing of these loams could have begun already when the lake became shallow. In any case, for now the probable explanation for the heavier isotopic composition of unit 2 is isotopic fractionation in water during interaction with clay particles and a different water source than in unit 1.

Abstract: The subject of the study are soils on the territory of the Khanovey educational field training site in the Vorkuta district of Komi Republic. Morphological descriptions of soil profiles and diagnostics and classification of soils in the modern Russian system were carried out. Laboratory analysis was carried out to determine soil properties: moisture content, acidity and total content of soluble salines. The study area is located in the southeastern part of the Bolshezemelskaya tundra, it is represented by inclined surface of the right side of the valley of the Vorkuta River valley, composed of alluvial and ancient alluvial sands, overlain by loamy and sandy-loam deposits. Holocene peatlands up to 4–5 m thick are the youngest deposits within the studied territory. Small and large dwarf birch tundras with shrub-green moss and grass-shrub-sphagnum cover are common here. The studied soils belong to the division of organogenic, postlitogenic and synlitogenic soil formation. The first includes oligotrophic peaty soils within a thick peatland (Histosols), the second includes cryogenic and cryometamorphic soils (Cryosols), as well as peaty gleyzems (Histic Cryosols). The third includes alluvial humic soils (Fluvisols). The moisture content of soils varies widely from 2 to 900 %. Soils acidity is from acidic to neutral (pH 4.5 to 7.5). The content of soluble salts in soils varies from about 0 to 300 mg/l.

Abstract: The subject of this research is the soils and soil-geochemical catenae in the area of Yeletsky settlement, located in the northeast of the Komi Republic. Catena were deposited on the mound covered with moss-shrub tundra transect from the interfluve of Usa and Yelets Rivers to a lacustrine depression, complicated by arching permafrost mounds. Within the district of research, the authors laid five soil incisions (EL20-P1, EL20-P2, EL20-P3, EL20-P4 and EL20-P5) that formed a soil-geochemical catena along the slope. Complex land cover found at the periphery. The explored soils were formed on silty loams with permafrost horizon at a depth of 0.5-0.7 m and belong to Cryosols, Turbic Cryosols and Histic Gleysols. Cryosols in the upper part of catena show specific cryogenic granular structure due to lack of soil moisture content. The soils on the slope and in the depression are more saturated with water; therefore, structureless Turbic Cryosols and Histic Gleysols are formed. In the soil horizons, the values of pH and electrical conductivity were measured, the content of organic carbon and soil texture were studied. An increase in soil acidity on organogenic zones by 4.3 - 5.7 was noticed; in underlying horizons the pH values reach 6.9.