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Experimental studies of phase transformations in frozen hydrate-containing fine sand samples during their interaction with frozen saline solutions have been conducted using low-field NMR relaxometry. The obtained results confirm that the amount of liquid water in the investigated samples increases over time as a result of salt transfer and dissociation of pore hydrate. In addition to the pore hydrate dissociation and supercooled water content increase, a reverse process occurs, which is associated with the freezing of the pore solution as a result of a decrease in the salt ions concentration. The performed studies enable identifying the boundary of the area with the high liquid water content in soil systems in the direction of salt migration. In this case, the velocity of this front in the target samples was determined not only by the concentration of the contacting solution but also by the initial content of the liquid water phase and the conditions of the pore hydrate existence. Thus, the movement of the liquid water front in frozen sands containing metastable hydrates occurs approximately 30-40 % faster than in similar soils containing stable hydrates, which is in good agreement with the results of previous studies. As a result, the developed NMR technique opens up a great potential for permafrost and gas hydrate studies in general and, in particular, for understanding the contribution of nonequilibrium and equilibrium liquid water to the salt ions migration mechanism in frozen and hydrate-containing soils.

An analysis of samples of cryoconite and moraine material collected on the surface of the Eastern Mugur Glacier (Mongun-Taiga Ridge, southeastern Altai) was carried out. The results of metagenomic analysis indicate significant differences in the microbiota of cryoconites at different altitudes of the glacier: at the maximum altitude, the absolute dominance of actinobacteria from the Kineosporiaceae family was noted; closer to the edge, actinobacteria from the Microbacteriaceae family predominated. Representatives with a wide ecological amplitude, as well as psychrophilic and extremophilic bacteria (representatives of the Kineosporiaceae and Geodermatophilaceae families) were found in the cryoconites, which probably indicates different pathways for the microorganisms to enter the cryoconites and possible differences in the time of their presence in these habitats. Actinobacteria are most adapted to the extreme conditions that develop in the cryoconites of the Eastern Mugur Glacier, which contributes to the accumulation of primary biomass and the formation of organomineral substances in cryoconite holes. As one approaches the edge of the glacier, the taxonomic diversity and proportion of microorganisms with a wide ecological amplitude increase, which is probably explained by the airborne transport of particles of moraine material settling in the cryoconites. In the surface moraine material at the edge of the glacier, proteobacteria (representatives of the Sphingomonadaceae family) turned out to be superdominants, which may be associated with the processes of initial soil formation.

Calculation for examples of frozen soils with temperatures of -3 and -6 °C using both numerical and analytical methods demonstrated that for an analytical description of the frozen soil thawing during the well operation period, the problem statement in the Leibenson form can be used with the assignment of an exact solution for the temperature in an unlimited part of space. The solution for the thawing radius in such a problem is written in a form close to self-similar. An exact analytical solution is obtained for the equation describing the change in the talik size upon its refreezing. It is shown that the time of refreezing of the talik depends not only on its size but also on the history of its formation. It is established that there is a boundary soil temperature value, below which the talik refreezing time is less than the time of its formation. At a soil temperature above the boundary value, the relationship between these times is inverse. At the final stages of well support design, it is recommended to rely on the results of numerical calculations of the parameters of thawing and refreezing processes using high-quality software products. The accuracy of the analytical method does not fully meet the requirements for the accuracy of the forecast during design, but it allows for fairly reliable tracking of trends in the evolution of process parameters, preserves the order of the calculated values, and ensures a high speed of their assessment. This allows us to recommend the use of the analytical method for operational assessments of thawing and refreezing processes at the preparatory stages of surveys for construction and in the design of well support structures, in monitoring studies, as well as at the stages of debugging standard computing programs for a specific task.

The variability of average and extreme seasonal snow depth values on the East European Plains has been assessed taking into account regional characteristics of the meteorological regime. The regional distribution of average and extreme (5th and 95th percentiles, minimum and maximum extremes) snow depth values has been clarified. A tendency for a long-term decrease in the average and extreme snow depth values with an increase in air temperature and precipitation has been revealed. According to the results of regression analysis, the dependence of long-term dynamics of snow depth on meteorological characteristics is more pronounced for maximum extremes. The most significant contribution to changes in the snow cover depth belongs to the variability in precipitation. The difference integral curves indicate the presence of two negative phases of snow depth characteristics in 1985-1995 and 2005-2015, which corresponds to the long-term features of atmospheric circulation. Based on data from reference weather stations, the accuracy of snow depth calculations using ERA 5-Land reanalysis has been estimated: the relative error reaches 45-50 %, and linear trend coefficients differ by 1.5-3 times, which should be taken into account when using the calculated values.

The thickness and thermal properties of snow cover play a significant role in the formation of the thermal regime of the ground surface and an urban heat island in regions with cold or temperate climate. This article describes the results of laboratory and field studies of the snow thermal properties in Yekaterinburg carried out in 2023/24. The thermal conductivity vs density dependence for different types of snow, including snow contaminated with pollutants typical of Yekaterinburg, was investigated in laboratory using the needle probe method. A regional dependence of thermal conductivity of the snow on its density was plotted. The snow cover depth and the vertical distribution of snow density were measured in situ at the geothermal test site of the Institute of Geophysics, Ural Branch of the Russian Academy of Sciences. Based on these data and taking into account the obtained density vs thermal conductivity dependence, time sections of changes in the density, thermal conductivity, thermal diffusivity, and thermal effusivity of the snow cover in the 2023/24 season were constructed.

On March 7, 2025, at the age of nearly 80, just a few months before his jubilee, Stanislav Victorovich Gubin, Doctor of Biological Sciences, leading researcher of the Department of Soil Cryology of the Institute of Physicochemical and Biological Problems of Soil Science of the Russian Academy of Sciences (Moscow Region, Pushchino), suddenly passed away. Stanislav Viсtorovich will be remembered as a remarkable permafrost soil scientist and experienced field worker.

The research was carried out within the framework of the “Flora of Uzbekistan” project. In connection with the critical revision of the species of the families Heliotropiaceae and Boraginaceae of the flora of Uzbekistan, the herbarium materials stored in the Herbariums LE, MW, TASH, AA, TAD, NS, NSK, TK, P were studied. Heliotropiaceae is represented by 2 genera and 15 species and the family Boraginaceae by 31 genera and 118 species distributed in 10 tribes. The largest number of species is represented by genera from the tribes Eritrichieae (31) and Cynoglosseae (25). The tribe Lithospermeae (21) is distinguished by the specificity of the species composition. Species of family Heliotropiaceae and small tribes Trichodesmeae (3), Heterocaryinae (6), Myosotideae (9) emphasize the ancient nature of the flora of the republic. Representatives of the tribes Boragineae (8) and Echieae (3) were either introduced in ancient times, naturalized and occupy vast areas, or occupy weedy habitats. When comparing the taxonomic composition of borage in Uzbekistan with the composition of genera and species of the neighboring republics of Central Asia, it was found that the borage flora of Turkmenistan and Tadjikistan is characterized by the closest composition. When analyzing the ranges of all species found on the territory of Uzbekistan, three chorological groups with 14 types of ranges were identified. It is shown that the Iranian-Turanian chorological group determines the specifics of the species composition of borage in Uzbekistan, and the Holarctic chorological group emphasizes the diversity and diversity of both autochthonous and allochthonous representatives of the flora. Ecological analysis shows that landscapes are widely represented in Uzbekistan, found in deserted mountain steppes in black forest, juniper, semi-savannah and shilyak belts at altitudes up to 2500 m. 39 species of borage grow in these communities. On the territory of Uzbekistan, xerophytic and cryoxerophytic lines of evolution were noted in families - 119 species, with a slight participation of mesophytic and cryomesophytic - 14 species. The flora is dominated by biennial monocarpics and ephemera - 70 species and herbaceous polycarpics - 63 species.

The article presents new data on the distribution of two associations of the class Epilobietea angustifolii Tx. et Preising ex von Rochow 1951 in the South Urals (Torilidetum japonicae Lohmeyer ex Görs et Müller 1969, Urtico dioicae-Chamaenerietum angustifolii Likhanova et Zheleznova 2021) and the association Artemisio nitrosae- Puccinellietum tenuissimae Korolyuk 1993 Korolyuk 1993 class Festuco-Puccinellietea Soó ex Vicherek 1973) in Western Siberia.

Intermountain basins in Khakassia and southern part of the Krasnoyarsky Krai represent an interesting steppe region of Russia. This territory extends in the latitudinal direction for more than 350 km - from the Arga ridge in the north to the piedmonts of the Western Sayan in the south. As in many mountainous steppe and forest-steppe regions, four environmental gradients are responsible for vegetation patterns: moisture, stoniness, salinity, and sand content in soils. The high diversity of habitats is the reason for the high diversity of plant communities and species, among which there are many endemics. In numerous publications, since 1998, 22 associations have been given for the studied territory. Ecological analysis of these associations using plant indicator values (Korolyuk, 2006) showed that some of them do not differ in position on the main gradients. This requires an explanation and analysis of differences in floristic composition of syntaxa. The purpose of the work is to revise current syntaxonomical scheme of Nazarovsko-Minusinskaya intermountain depression using formalized methods or relevés analysis.

The main floristic differences of meadows of West Siberia plain, and of Altai-Sayan mountain region were revealed to be geomorphologically determined. The concept of syntaxa-“cores” uniting moderately disturbed meadows has been formulated. Their areas correspond to 5 geomorphological regions: the forest zone of West Siberian Plain, the northwestern foothills of Altai-Sayan mountain region, hyperhumid low mountains, hyperhumid middle mountains, and humid middle mountains. Dissimilarities of meadows in one region are caused by edaphic and anthropogenic factors, i.e. the recent fallow past, long-term overgrazing, relatively poor soils, periodically over wetted habitats, slightly salinized habitats. Taking into account the above ideas, the scheme of floristic classification has been corrected. The phytocoenotic diversity of studied area meadows is represented by 21 syntaxa belonging to 16 associations and 9 subassociations of 2 alliances from 2 orders of the Molinio-Arrhenatheretea class. Short descriptions of these syntaxa have been carried out. 15 syntaxa have been described for the first time or validated.