Home – Home – Jornals – Earth’s Cryosphere 2023 number 6

The results of studies carried out at the tundra-woodland interface in the Anabar region of the Republic of Sakha (Yakutia) in order to trace the dynamics of permafrost landscapes and identify the influence of vegetation on the soil temperature regime and seasonal thawing depth are presented. The overgrowing of tundra with larch trees took place during the second period of long-term warming in the Arctic (1979-2011). The displacement of tundra communities by woodland communities has changed permafrost conditions in the region. Thus, according to our data, the maximum depth of seasonal thawing is reached in the tundra area; the depth of seasonal thawing decreases with an increase in the woodland density. On the contrary, permafrost temperature has minimum values in the tundra area and increases under woodland. In this paper, the results of the first - stage of the study are presented. Further monitoring studies are planned in the area under consideration.

An overview geocryological map (1:1 M scale) for an area of 136 700 km² covering a significant part of the Bolshezemelskaya tundra was compiled on the basis of large-scale field permafrost-landscape surveys and interpretation of medium-resolution Landsat-7 satellite images. The method of landscape indication implemented in relation to geocryological subzones was used. Spatial variability of geocryological characteristics was analyzed at the levels of natural subzones and groups of dominant landscape units.

Data on the actual maximum area of 71 largest aufeis-taryn in the North-East of Russia (with an area of at least 10 km²) based on the results of interpretation of Landsat satellite images in 2013-2018 (661 km²) and Sentinel-2 in 2020-2021 (838 km²) is presented. The total area of aufeis fields turned out to be at least 2 times lower than the total area of aufeis glades indicated in the Cadaster of aufeis of the North-East (1958) (1680 km²). For 42 objects the area for 1973-1975 were also obtained according to Landsat/MSS data (before the beginning of the warming period). The total value was 555 km², which is close to modern estimates for 2020-2021 (581 km²), and on average. 1.9 times lower than their total area according to the Cadastre (1958) (1083 km²). Despite the fact that individual giant aufeis show very high interannual variability, their area can change up to two times from year to year (100 %), on average for most aufeis fields this value is about 20 %. On numerous examples, a discrepancy between the contours of aufeis glades and the boundaries of aufeis fields was established. The total area of aufeis glades, both indicated in the Cadaster (1958) and identified on the basis of modern space images, significantly exceeds the actual area of aufeis. Estimating the area of aufeis (even the maximum in a long-term period) by the size of aufeis glades can lead to significant errors in the calculation of the dynamic reserves of aufeis groundwater and other characteristics. In the period after 1973-1975 significant change of total aufeis area in the North-East were not identified. Further field studies of giant aufeis are important to identify the causes of their variability, including the establishment of long-term regime observations at special aufeis research plots.

This study is devoted to experimental modeling of the interaction of frozen hydrate-saturated sandy sediments with salt solutions at subzero temperatures. It is shown that the migration of salt ions in frozen hydrate-containing sands is more active than in frozen hydrate-free sands. Gas pressure proves to be one of the main factors controlling the intensity of migration of salt ions in frozen sands containing gas hydrates in contrast to frozen hydrate-free sands. With an increase in gas pressure and a decrease in temperature, the intensity of salt transfer in frozen hydrate-containing sands decreases, while the preservation of pore hydrates increases. Based on experimental data, the parameters of salt transfer in frozen hydrate-containing sand (salt flux density, diffusion coefficient) depending on gas pressure and ambient temperature have been obtained for the first time.

New data on the species diversity and metabolic potential of insufficiently studied microbial communities in cryopegs of the Yamal Peninsula are presented. The total number of microorganisms inhabiting cryopegs is high and reaches 10⁶-10⁸ cells/mL. At the same time, sulfate-reducing bacteria have only been found in two out of three studied cryopegs in numbers not exceeding 10³ cells/mL. Representatives of the bacterial genera Acetobacterium (strains K1/0, K1/6 =VKM B-3638, K1/7, K1/8), Labilibaculum (K2S^T, =VKM B-3650^T), and Trichococcus (K1Tr^T, =VKM B-3651^Т) have been isolated from cryopegs for the first time. All isolates are psychroactive and are able to grow at 6°C.

Synthetic aperture radar (SAR) images Sentinel-1 were used to detail the structure of aufeis and characteristic features of aufeis landscapes in the valleys of Verkhnyaya Neyungri and Samokit rivers (southern Yakutia). Based on the results of preliminary image analysis, the ranges of typical backscatter signals within the ice glade were established, and representative points characterizing various components of the ice landscape were chosen. The type of surface of the aufeis landscape (ice, open water, snow cover, rock, etc.) was preliminarily diagnosed using Sentinel-2 images. During fieldwork, the vertical structure of the aufeis landscape and its surface were studied at the chosen test plots. As a result, the ranges of backscattering of the radio signal for co-polarization (VV) and cross-polarization (VH) modes characteristic of the four types of the aufeis landscape were determined. Based on SAR images, the structure of the aufeis body could be detailed: areas of river flow under the ice and places of groundwater discharge were identified. At the final stage, aufeis areas at the end of winter in the Samokit and Verkhnyaya Neryungri river valleys were determined based on Sentinel-1 SAR images and the normalized difference snow index (NDSI) calculated from Sentinel-2 images; the discrepancy between the obtained estimates was assessed.

The article reflects the main milestones of the scientific activity of D.S. Drozdov, Doctor of Geological and Mineralogical Sciences, Chief Researcher, Deputy Director for Scientific Work of the Earth Cryosphere Institute, Tyumen Scientific Centre SB RAS, Deputy Editor-in-Chief of the journal “Earth’s Cryosphere”. Dmitry Stepanovich is a well-known specialist in the field of structuring and forecasting the state of cryolithozone geosystems. The main focus of his activities is on the study of permafrost areas, monitoring of the cryolithozone, and technogenesis of the geological environment.

On February 13, 2023, Georgii Petrovich Kuzmin, an outstanding permafrost researcher, Doctor of Technical Sciences, Corresponding Member of the Russian Academy of Engineering, Honored Scientist of the Republic of Sakha (Yakutia), and Chief Researcher at the Melnikov Permafrost Institute celebrated his 90th birthday. In this paper, the milestones of his biography and the main areas of his versatile scientific activity are elucidated. His great role in mastering natural resources of cold in permafrost areas for practical purposes is emphasized.

On August 31, 2023, the famous geocryologist, candidate of geological and mineralogical sciences, leading researcher at the Faculty of Geology of Moscow State University, Alexander Borisovich Chizhov, died. He will be remembered as a wonderful scientist and wise person with a subtle sense of humor.