Abstract: Studies of the dependence of the accumulation of stable carbon isotopes on the growing conditions in modern plant species of tundra are very relevant. It was discovered that the same plant species accumulate the stable 13C isotope in different ways. The goal of this work is to reveal the relationship between the content of the stable 13C isotope in modern plants and the natural conditions of typical terrains of the tundra of the Western Yamal. At the geocryological station Marre-Sale, modern plant species were selected that grow under conditions of different moisture and remoteness from the sea. Modern plant species were determined using determinant atlases, carbon isotope contents using a DELTA V Advantage isotope mass spectrometer in the laboratory of LBIT (IMCES SB RAS). In different tracts, for identical plants the distribution of carbon isotopes depending on moisture was confirmed: the heavier 13С accumulates in dry ones, and lighter in humid and moist ones. It was determined that near the sea, the same plants of dry and wet tracts accumulate heavier 13С due to the influence of marine aerosols.

Keywords: marine influence, 13С plants, carbon, moisture, tundra, growing conditions, modern plants, bioforms, isotopic composition, analysis of variance

Abstract: This paper presents the results of a study of the Kamenka-1 section. This unique exposure is located 1,712 m asl in the upper reaches of the Kamenka River, on the northeastern slope of the mountains surrounding Mountain Mus-Khaya (2,959 m, Suntar-Khayata Range). A sample was taken from the stump horizon to determine the absolute age. A soil horizon was identified, the upper part of which contained numerous larch stumps in a natural (upright) position. The stump horizon is partially buried by a 1.5-m layer of fine rubble and silt. It has been dated to 5.37±0.05 ka BP (MPI-41), suggesting the position of treeline in the study region by the end of the Holocene climatic optimum. It is analyzed in the radiocarbon laboratory of the Melnikov Permafrost Institute of the Siberian Branch of the Russian Academy of Sciences using contemporary equipment – ultra low level liquid scintillation spectrometer Quantulus 1220 (made in U. S.), and chemical installation for benzene synthesis (Institute of Environmental Geochemistry of National Academy of Sciences of Ukraine).

Keywords: glaciers, history of climate, tree-stump horizon, Suntar-Khayata Range, altitudinal zonality, radiocarbon dating, Holocene Optimum, upper tree line, permafrost, climate change

Abstract: The article discusses variations in the values of δ18O, δ2H, dexc of snow on Krasnaya Polyana, the southern slope of Elbrus and on the transect from Konosha to the Polar Urals. In each of the described snowfalls, the deuterium excess is a unique isotope mark of the prevailing process involved in the formation of the isotope composition of the snow cover. To interpret the values of obtained isotopes, we used the method of back trajectories by the HYSPLIY model. The main goal of the work is to demarcate the main processes responsible for the formation of the isotope composition of snow. On the Aibga slope in Caucasus, there is addition of a continental water vapor on the southern slope of Elbrus – wind erosion, and isotope fractionation during condensation in a single snowfall from Konosha to the Polar Urals. The back trajectories of air mass movement help considering in more detail the formation of the isotope composition of individual snowfalls.

Keywords: precipitation, Polar Ural, Caucaus, snowfall, deuterium excess, hydrogen isotopes, oxygen isotopes, air mass, trajectories, HYSPLIT model

Abstract: This article considers the migration frost mounds (palsa) in the settlement of Yeletsky in the northeast of Bolshezemelskaya tundra. The new radiocarbon dating on the frost mounds of various size and different stages of development within the boundaries of massif explored by the authors in 2000 and 2015. The work meticulously examines the representative 3m high frost mound with no signs of destruction, covered with peat having capacity over 1m. The object of the research is defined by the goal to characterize the conditions of peat accumulation and identify the moisture sources that form the upper part of the ice core. For the radiocarbon dating was selected the thawed peat on the top or shoulder of the mound. In the shafts was minutely (at intervals of 5-10cm) selected the peat for identifying the concentration of carbon and nitrogen and isotopic composition of carbon and nitrogen. From the bottom of the shaft using the electric ice auger MORA-ICE was drilled the wellbore in frozen peat and the underlying frozen loam, as well as selected the ice lenses. The determination of isotopic composition of oxygen and hydrogen of ice were conducted using the mass spectometer Delta-V; radiocarbon dating of the peat carried out in laboratory of archeological technology of the Institute of Material Culture of the Russian Academy of Sciences. The scientific novelty consists in the comprehensive approach towards exploring the peat deposit covering the frost mound.

Keywords: hydrogen, oxygen, segregated ice, nitrogen, carbon, isotopes, radiocarbon age, peat, palsa, deuterium excess

Abstract: The object of the study is the isotopic composition of the January snow on the slopes of the Aibga and Psekhako mountains in Krasnaya Polyana in 2010 (29 snow samples) and 2017 (58 snow samples). In 2010, the snow cover was sampled on the Aibga ridges and the Psekhako Ridge. In 2017, on the slope of the Aibga ridge, fresh snow was sampled. Along the ski run Rosa Khutor, surface snow was also sampled. Isotopic composition measurements were performed using the Delta-V (Finnigan) mass spectrometer in the isotope-geochemical laboratory of the Faculty of Geography of Lomonosov Moscow State University. The authors of the study conclude that high values of the deuterium excess can be caused by three reasons: 1) the air mass itself, which had been above the inland areas for a long time, has changed its isotope characteristics due to re-evaporation and moisture condensation, 2) the conditions of condensation, when adiabatic cooling of the air mass leads to isotope depletion in the precipitation, more prominent for δ18O than for δ2H and 3) post-sedimentation processes on the snow surface. Perhaps the isotopic composition of the snow cover in Krasnaya Polyana is formed under the influence of all these three factors.

Keywords: altitude isotopic effect, fresh snow, snow cover, hydrogen isotopes, oxygen isotopes, isotopic composition, Krasnaya Polyana, Aibga Ridge, Psekharo Ridge, Western Caucasus

Abstract: The subject of the study is the subfossil pollen spectrum from polygonal tundra of different succession stages: the formation of a framework of vegetation and overgrowing patches of polygons. It is established that local components of the pollen spectrum are basic information on the stages of succession. Determination of the sequence of changes in the dominant pollen taxon in the process of typical succession enables the allocation of such sequences for pollen plots, allowing to more objectively assessing the changes in biocenoses. We also analyze the pollen spectrum features during the development of waterlogging and pyrogenic succession reflected in the palynologic signal. The main research method is the palynologic analysis of surface samples and interpret the results in relative stages of succession. The main conclusions of the study is allocation of the standard sequence of dominants on pollen plots, which correspond to the stages of succession. Pollen dominants sequences are detected migration of woody vegetation to the North by open ground, eutrophication of lakes, overgrowing of polygons in the Arctic tundra, as well as for pyrogenic succession

Keywords: biocenosis, subfossil pollen spectra, pollen analysis, stages of succession, vegetation, polygonal tundra, spores, pollen, Arctic, polar desert