Home – Home – Jornals – Siberian Journal of Forest Science 2021 number 2

We present the time series of the total ozone content and integrated aerosol backscattering coefficient in the stratosphere obtained at Siberian Lidar Station in Tomsk. Annual harmonics are distinctly manifested in the frequency spectra of energies of these time series, as well as the semiannual component in ozone time series. Representation of the frequency spectra of both stratospheric constituents on a logarithmic scale made it possible to identify in these spectra the intervals, characteristic for turbulent motion and, hence, cascade energy transfer from larger to smaller eddies and, in particular, in the energy spectrum of the total ozone content. However, the slope of the linear interval is not -1.67, as it would in obedience to the Kolmogorov-Obukhov law, but smaller (-1.22), indicating the presence of an additional energy source which contributes to the frequency variations in the total ozone content.

A broadband model for simulation of the transfer of shortwave solar radiation in the Earth’s atmosphere for spectral channels of radiometers placed in Sentinel-2A satellites is developed. This model is based on line - by - line calculations of absorption spectra with use of modern spectroscopic information and following parameterization of the transmission functions of radiation in the form of short exponent series, which allows one to apply standard method of discrete ordinates to solution of the radiative transfer equation for each exponential component. The errors in the spectral brightness coefficients of the surface due to uncertainties of aerosol extinction in Sentinel-2A channels are estimated for typical optical-meteorological conditions of the lower Volga region.

The review provides information on ozone concentration in the surface air layer in the second half of 2020. Data were obtained at 13 stations located in different regions of Russia. An assessment was made of the excess of hygienic standards established in the Russian Federation, both in the second half of the year and in the whole 2020. It is shown that the daily average maximum permissible concentration of ozone is regularly exceeded at all stations. There are cases of exceeding the one-time maximal maximum permissible concentration.

The vibrational and rotational terms of the X²Π and A²∑⁺ electronic states of the PO molecule have been calculated, as well as the absorption spectrum corresponding to the transition A²∑⁺(ν'=0;J')-X²Π(ν"=0;J") is calculated. The efficiency of laser excitation of PO molecules is estimated as a function of the spectral parameters of the radiation.

Fractal interpolation provides an efficient way to describe the smooth or non-smooth structure associated with nature and scientific data. The aim of this paper is to introduce a bivariate Hermite fractal interpolation formula which generalizes the classical Hermite interpolation formula for two variables. It is shown here that the proposed Hermite fractal interpolation function and its derivatives of all orders are good approximations of the original function even if the partial derivatives of the original functions are non-smooth in nature.

The error caused by the inaccuracy of the equation system solution by iterative methods has been investigated. The upper error estimate for the axially symmetric heat equation is found in the accumulation process in several time steps. The upper estimate shows the linear dependence of the error on the threshold value of the limiting criterion for the iterations number, the quadratic error growth from the range partitions number, and its independence of the time partitions number. The computing experiment shows a good correspondence of the obtained estimate to real errors with boundary and initial conditions of various types. The quadratic error growth for the Laplace equation, caused by the accuracy limitation for applying the iteration method, on the number of range partitions n, is empirically found. A similar error growth for the biharmonic equation is found in proportion to n⁴.

The paper discusses a computational 3D double porosity model of a two-phase incompressible fluid filtration in a fractured-porous medium. Conservation laws are formulated in the integral form, and for their spatial approximation, a combination of the mixed finite element method to determine the total flow and pressure velocities is used and the finite volume method to determine the saturations in porous blocks and in fractures. The approximation of equations for saturations according to an explicit scheme with upwinding to eliminate unphysical oscillations is carried out. The model under consideration includes the injection and production wells with total flow rates. For the total velocities and pressures, the Neumann problem is formulated, for which the condition of unique solvability is indicated and a method for solving it without additional conditions is proposed. For an explicit upwind scheme for solving equations for saturations, a weak maximum principle is established, illustrated by computational experiments.

A matrix is said to be unitoid if it can be brought to diagonal form by a congruence transformation. We say that an algorithm is rational if it is finite and uses the arithmetic operations only. There exist rational methods designed for checking congruence of particular classes of unitoid matrices, for example, Hermitian, accretive, or dissipative matrices. We propose a rational algorithm for checking congruence of general unitoid matrices. The algorithm is heuristic in the sense that the user is required to set the values of two integral parameters M and N. The choice of these values depends on the available a priori information about the proximity of neighboring canonical angles of the matrices under checking.

This paper concerns the development of fundamental theoretical foundations and the creation of algorithms and software for pulsed electromagnetic soundings in relation to studying an unconventional source of hydrocarbons with hard-to-recover reserves - the Bazhenov formation. We carry out the mathematical substantiation of a new geophysical technology for the localization of oil-prospective zones, using a spatially distributed system of highly deviated wells. For the fast mathematical simulation, we obtained a solution to the problem of pulsed electromagnetic soundings in layered homogeneous models of media for an arbitrary current pulse in the electromagnetic source, which allows deep parallelization. Based on the created computational algorithm, a parallel one was developed, as well as a fast computer program for numerical simulation of the signals of the new system on multiprocessor devices of the Siberian Supercomputer Center, SB RAS. We carried out a large-scale numerical simulation and analysis of the signals in realistic geoelectric models of the Bazhenov formation to estimate an applicable scope of the new pulsed electromagnetic sounding installation. The calculations show that determining spatial locations of the formation boundaries is possible when logging the wells over a wide range of the sonde spacings. We analyzed the applicability of the diagonal and off-diagonal field components to ensure high sensitivity for mapping the reservoir boundaries and evaluating its internal heterogeneities. The results obtained form a basis for the further design of the optimal configuration of the new electromagnetic sounding system.

Let X and Y be Banach spaces. Let f: Ω → Y be a Frèchet differentiable function on an open subset Ω of X and F be a set-valued mapping with closed graph. Consider the following generalized equation problem: 0 in f(x)+ F(x). In the present paper, we study a variant of Newton's method for solving generalized equation (1) and analyze semilocal and local convergence of this method under weaker conditions than those considered by Jean-Alexis and Piètrus [13]. In fact, we show that the variant of Newton's method is superlinearly convergent when the Frèchet derivative of f is (L,p)-Hölder continuous and (f+F)^-1 is Lipzchitz-like at a reference point. Moreover, applications of this method to a nonlinear programming problem and a variational inequality are given. Numerical experiments are provided which illustrate the theoretical results.

We present a family of fifth order iterative methods for finding multiple roots of nonlinear equations. Numerical examples are considered to check the validity of theoretical results. The results show that the new methods are competitive to other methods for multiple roots. Basins of attraction for new methods and some existing methods are drawn to observe the dynamics in the complex plane.

In connection with the existing problem of permafrost soil thawing in the Arctic zone of Russia, it seems relevant to use space images to decipher thermal objects at the fields of the Yamalo-Nenets Autonomous District to identify soil deformation zones. Spatial and statistical analysis of satellite temperature data, hydrocarbon output and the number of operating flare units was carried out by the example of 16 fields in the Purovsky administrative region of the Yamalo-Nenets Autonomous District. A correlation has been established between hydrocarbon output and the calculated area of thermal zones. The spatial analysis of the location of thermal installations reflects their possible adverse impact on the environment in the form of thawing and deformation of permafrost landscapes.

The effect of the nature of silicon source on the physicochemical properties of synthesized Zn-aluminosilicates is studied, along with their catalytic activity in the course of propane conversion into aromatic hydrocarbons. It is shown that the source of silicon plays an important role in the hydrothermal synthesis of Zn-aluminosilicate since it affects the crystallization rate, physicochemical and catalytic properties of the final product. The tests of the catalysts indicate that they are highly active in propane aromatization. The selectivity of the formation of aromatic hydrocarbons over the prepared samples reaches more than 40% with almost complete conversion of the feedstock. The highest aromatization activity is exhibited by the Zn-aluminosilicate synthesized using carbon white. The yield of aromatic hydrocarbons over this catalyst reaches 42.9 % at a temperature of 600 °C, while the conversion is 99 %. The properties of the synthesized zinc aluminosilicates are investigated by means of X-ray phase analysis, temperature-programmed desorption of ammonia, and low-temperature adsorption of nitrogen. As a result, distinguishing features of the synthesized zinc aluminosilicates affecting their catalytic properties in propane conversion into aromatic hydrocarbons were established.

A composite material is manufactured on the basis of multiwalled carbon nanotubes (MWCNT) activated with nickel and cobalt. Its physicochemical and catalytic properties are investigated in the oxidation of sulphur-containing compounds (SC) of fuel oil with hydrogen peroxide. It is demonstrated by means of X-ray phase analysis and transmission electron microscopy that the material is composed of MWCNT phase and the phases of introduced metals (Ni and Со), with nanostructure represented by thin sheets 20 × 30 nm in size. The optimal conditions for the oxidation of sulphur-containing compounds of fuel oil were revealed: temperature, 50-60 °C; process duration, 90 min; catalyst content, 1.0-1.3 mass %; the ratio of sulphur in the raw material to the oxidizer was equal to 1 : 4. It was established that the most efficient system for the extraction of oxidized sulphur-containing compounds from fuel oil is dimethylformamide - water (10 vol. %) system. Under these conditions, it is possible to achieve a degree of sulphur removal of more than 75 %.

Laboratory set-up was developed on the basis of Reokinetika stand for the static and dynamic determination of the elastic modulus. Static and dynamic tests of polyvinyl alcohol cryogels were carried out, and the dependences of the output signals of force sensors on sample deformation were obtained. Dynamic measurements were made using a device with piezoceramic force sensor and an electromechanical source of mechanical oscillations. Laboratory balance was used as a force sensor in static measurements. Sample deformation was set with a micrometer. The absolute values of the static elastic modulus are obtained. A linear correlation of the results of static and dynamic measurements is demonstrated. The ratio of the slopes of the considered dependences is equal to the ratio of the absolute values of static and dynamic elasticity modules of the samples.

Results of the laboratory tests of acid chemical oil-substituting GBK composition developed at the Institute of Petroleum Chemistry SB RAS are presented. The composition is based on a surfactant, an adduct of inorganic salt, polyatomic alcohol, and carbamide. The technology is aimed at increasing the oil recovery due to the action on reservoir rock, with the restoration of well injectivity for the wells at the late stage of development, and oil-washing capacity of surfactant components, within a broad temperature range (23-150 °C). A strong acid is formed directly in the reservoir under the effect of formation conditions. The acid is able to interact with the reservoir rock, with an increase in the injectivity of the bottomhole zone for water and hot steam. It is established that the action of the acid composition leads to the equalization of filtration flows and a significant increase in the oil displacement coefficient.

The data on the special aspects of the composition of oils located in four areas of the Nenets Autonomous District on the coast of the Barents Sea are presented. Normal and isoprenoid alkanes, naphthalenes, phenanthrenes, fluorenes, biphenyls, sesquiterpanes, steranes, hopanes, dibenzothiophenes, dibenzofurans, retene, and cadalene are identified among petroleum hydrocarbons by means of gas chromatography-mass spectrometry. The concentrations of metalloporphyrins and perylene were determined spectrophotometrically. It is demonstrated that cyclohexane content is much higher than the fraction of acyclic compounds only in oil from the Toboyskoye oil field. The composition of this oil is also characterized by the maximal content of bicyclic terpanes (nordrimans, drimans, and homodrimans). For oils from the Perevoznoye and Toraveyskoye oil fields, the co-presence of vanadyl- and nickel-porphyrins suggests marine conditions of the accumulation of initial organic matter in the absence of bottom water contamination with hydrogen sulphide. Dibenzofurans were identified only in oil from the Toraveyskoye oil field, while the presence of dibenzothiophenes is observed in all the studied oil samples.

This article presents the analysis of the results of 57 cyclic steam stimulation (CSS) treatments of the wells in the Permian-Carboniferous reservoir of high-viscosity oil of the Usinsk oil field, Komi Republic, Russia. All wells were subjected to the first cycle of steam stimulation. Among them, 46 wells were treated without additional reagents, and 11 wells were treated using the GALKA^® thermotropic composition developed at the Institute of Petroleum Chemistry SB RAS. The use of gel-forming compositions was validated, starting from the first cycle of CSS, in the case of the high initial water cut. An assumption was made concerning the optimal amount of steam during CSS for a specific type of wells, as well as an increase in this parameter when using a gel-forming composition.

Changes in the structural parameters of resin and asphaltene molecules were studied depending on the composition of the dispersion medium in the process of low-temperature dewaxing of oil. Liquefied hydrocarbon gases (propane, propane/butane, and propane/pentane) were used as a dewaxing agent. Sediments formed during dewaxing are composed of hard paraffins, resins and asphaltenes. Resins and asphaltenes were investigated by means of structural group analysis (SGA) based on PMR spectroscopy data, elemental composition and molecular weight. It is shown that variations of the oil dispersion medium due to dilution with liquefied gases lead to changes in the structural parameters (molecular weight, the number of aromatic and naphthenic rings, alkyl substituents, and the number of structural blocks in the molecule) of the average molecules of resins and asphaltenes.

The effect of steam isolation with GALKA^® gel-forming composition in steam-assisted gravity drainage during the development of a horizontal well at the Lyael area of the Yaregskoye field on oil production and its composition was investigated. The effect of treatment was 2 - 4 t of additionally produced oil per day, with a decrease in water cut by 8 - 10 %. The effect was accompanied by an increase in oil viscosity and the proportion of heavy polar components in it, followed by a decrease to the initial values. Ammonium and hydrocarbonate ions were detected to appear in the produced water after treatment with the thermotropic composition GALKA^®. An increase in the content of carbonate and chloride ions, an increase in mineralization by a factor of 2, and pH of the produced water from 7.1 to 9.7 were also detected.

The possibilities of using long-term satellite data to monitor the environmental situation in the area of oil and gas enterprises are considered. The studies were carried out for the territory of Tomskneftepererabotka oil refinery as an example. The data of the MODIS spectroradiometer (Moderate Resolution Imaging Spectroradiometer) for the years 2015-2019 were used as the initial information. To assess the state of the vegetation cover in the study area, the values of enhanced vegetation index (EVI) were included in the analysis. The minimum and maximum values of EVI index for the study area were determined, and a trend of an increase in the index values since 2018 was revealed, which is evidence of vegetation cover restoration.

The effect of K-210 additive, developed on the basis of the ordered amphiphilic nitrogen-containing polymer, on the structural-rheological characteristics of water-oil emulsions is investigated. The presence of water in oil-containing dispersed systems (ODS) as 10 % oil emulsions is characterized by a primary increase in the degree of additive inhibition for all emulsions under study. An increase in the degree of inhibition may be a consequence of the fact that the additive contains an amphiphilic polymer, which is soluble both in the organic phase and in water. The studies showed that the group composition of the precipitates depends on the degree of additive inhibition. Changes in the group composition may be explained by the structural-phase transitions of the fractions of resinous-asphaltenic components. Differences in the composition of resins and asphaltenes of ODS were studied by means of IR spectroscopy. It was established that an increase in the fraction of water in the resins of asphaltene-resin-paraffin deposits (ARPD) in emulsions causes an increase in the condensed aromatic oxygen- and sulphur-containing fragments. Investigation of the surface tension of resin and asphaltene fractions revealed that the maximal surface activity is characteristic of the resinous-asphaltenic components of ARPD oil emulsions with a minimal degree of additive inhibition.

Propylene oxidation by oxygen in the presence of water in the barrier discharge (BD) reactor is investigated. Data obtained previously in the investigation of propylene oxidation in the presence of n -octane in the BD reactor are presented. Product composition remains the same if n -octane is replaced by water. The major products of propylene oxidation by oxygen in the presence of water are propylene oxide, propanal, and other hydroxyl- and carbonyl-containing compounds. The content of propylene oxide in the product mixture decreases from 45 to ~30 mass %. Propylene conversion values both in the presence of octane and in the presence of water are comparable: 12.9 and 15.4 %, respectively. Ignition of the discharge was determined to occur earlier in the presence of water than in the presence of n -octane. The volt-coulomb characteristics of BD during propylene oxidation in the presence of water and in the presence of octane differ from each other only slightly. The capacity of discharge cell (plasmachemical reactor) in the case of propylene oxidation in the presence of water is larger than in the presence of octane, while the transitive charge per one high-voltage pulse is smaller in the case of water. The active discharge power and propylene conversion are similar in both cases. Electron energy losses in the BD reactor were calculated for propylene-oxygen mixtures with water and without it. The addition of water was determined to have almost no effect on energy distribution in the mixture of oxygen with propylene, and the major losses of electron energy are related to the excitation of electronic states in oxygen and propylene molecules. The major direction of propylene oxidation in the BD reactor in the presence of water may be predicted relying on the analysis of calculation results.

The physicochemical and catalytic properties of Mo/ZSM-5 catalysts for methane dehydroaromatization prepared using different (NН₄- and H-) zeolite forms and nanosized Mo powder are studied. It is shown that the properties of the samples under study depend on the initial form of the zeolite used for their preparation. According to the data of electron microscopy and EDS analysis, the morphology and elemental composition of particles in the Mo/H-ZSM-5 and Mo/NH₄-ZSM-5 samples are practically similar, and molybdenum is stabilized in the zeolite matrix in the form of the aggregates of atoms. The distribution profiles of silicon and molybdenum in the catalysts indicate that a more uniform distribution of molybdenum in the zeolite is observed for the Mo/NH₄-ZSM-5 sample. Changes in molybdenum localization after methane dehydroaromatization were revealed. Molybdenum migration to the zeolite surface was observed, with the formation of MoC _x particles up to 100 nm in size, coated with a carbon layer about 3 nm thick. It was established by means of the thermal desorption of ammonia that the concentration of strong acid sites in the catalyst prepared using the hydrogen form of the zeolite was lower than that for the catalyst prepared on the basis of the ammonium form of the zeolite. This difference in the acidic characteristics of the obtained Mo/ZSM-5 catalysts depends on the conditions of their preparation. The number of thermal treatments increased in the course of catalyst preparation using the hydrogen form of the zeolite, which resulted in the partial destruction of the zeolite crystal lattice with the formation of the Al₂(MoO₄)₃ phase. Studies of the catalytic properties of the samples showed that the Mo/ZSM-5 catalyst prepared on the basis of ammonium zeolite exhibited the highest activity in the course of the nonoxidative conversion of methane to aromatic hydrocarbons.

Regularities of the geographical distribution of world resources of high-resin oil as an essential source of hydrocarbon raw material in the future are considered. It is demonstrated, relying on the analysis of information from the database on physicochemical characteristics of the world’s oils, that one third of all oil and gas-bearing basins contain reserves of highly resinous oils. The features of the distribution of these oils over countries are studied. It is demonstrated that about 90 % of the world resources are located in Canada and in Russia. About 94 % of the resources of highly resinous oil are located in three oil and gas bearing basins - Timan-Pechora, West Siberian, and Volga-Ural. Statistical analysis of the physicochemical properties of highly resinous oil was carried out. It was established that oil with high resin content is characterized by high density and viscosity, high content of sulphur, nitrogen and oxygen, as well as vanadium and nickel.

Original structural changes of the surface of a coal sample under the action of pulsed mode laser radiation were studied. It was found that original quasiperiodic columnar structures were formed on the sample surface as a result of the laser action of 10⁴ s duration with the frequency of 6 Hz and the single pulse energy density of 1.95 J/cm². The diameter of single fragments reached 100 mm with the distance between them attaining 50 mm. On the top of the fragments, there were spherical shapes composed of silicon compounds with a size reaching 10 mm. A scheme of the formation of columnar structure was proposed.

The efficiency of the dissolution of bituminous coal at moderate temperature to produce quinoline-soluble substances was studied using commercially available coal tar (CT), its anthracene fraction (AFCT), heavy coal semicoking tar (HCST), heavy gas oil from catalytic cracking of petroleum (HGOCC), their binary blends, as well as tetralin (for comparison) as solvents. The chemical and molecular compositions of the coal, solvents, and the extracts obtained were characterized in detail by chemical and group analyses, FTIR spectroscopy, liquid chromatography, analysis by means of gas chromatography-mass spectrometry. The highly aromatic CT, AFCT, low aromatic HGOCC solvents, binary blends of these solvents and hydrogen donor tetralin showed high performance for coal dissolution at 380 °C in the quinoline-soluble substances, the yields of gases being no more than 0.6 %. The extracts obtained with CT and AFCT solvents represented highly aromatic pitch-like matter with rarely substituted aromatic rings. The extract obtained with the HGOCC solvent was characterized by lower aromaticity, the aromatic nuclei being highly substituted with fairly large alkyl fragments. The blended solvents yielded more extracts whose structural parameters were intermediate between those obtained with each solvent separately. Heavy semi-coking HCST tar showed no dissolving ability because of the high content of phenolic hydroxyls. The concentration of benzo(a)pyrene (BaP) in the toluene-soluble fractions of the extracts obtained was much lower than that in the solvents used, and decreased as the coal dissolution time increased, thus indicating BaP conversion.

Pharmacokinetics of the aerosol and oral forms of the delivery of the antituberculous drug pyrazinamide was investigated. The pharmacokinetic parameters for both forms of the medicinal preparation were demonstrated to be comparable. The advantages of aerosol delivery of pyrazinamide for therapeutic application are considered.

The article highlights the results of a paleobotanical study of peat deposits in different forest zones and types of habitats in the Western Sayan, where the Siberian stone pine Pinus sibirica Du Tour is currently the dominant species. Based on paleocarpological and radiocarbon analyzes, changes in vegetation, climate and landscapes from 8000 years ago to the present have been reconstructed. The material for the study was the macroremains of fossil plants. Changes in the species composition of macroremains of dominant plant species in each section made it possible to combine them into macrocomplexes, each of which characterizes a certain time and landscape-climatic regime. Carpograms were constructed for four sections, with a detailed characteristic of fossil macrocomplexes by species composition. When analyzing the morphological and anatomical physiognomy of each fossil object according to the degree of preservation, they were differentiated into two groups of plants - the local reflecting peculiarities of the habitat (facies) and the adjacent one characteristic of a larger territorial complex (paleolandscape). Their combination gives an idea of the change in the landscape situation in centuries of climate change. In each group, the edificator and dominants of past phytocenoses, fixed by macrocomplexes of fossils, were determined using the method of ecological-cenotic analysis. The dynamics of the composition and phytocenotic structure of plant communities, replacing each other in a thousand-year history, has been established. A quantitative assessment of the climatic situation is given, which determines their change in different climatic epochs. The repeated displacement of the upper forest boundary was established with conjugate changes in heat and atmospheric moisture, which manifested themselves simultaneously in the study areas. On the example of the Siberian stone pine formation, represented in different forest areas by three different climatic facies of the formation, it is shown that in each of them, with the trends of climate change common for the mountains (warming or cooling, as well as changes in atmospheric moisture), centuries-old changes of communities had their own specific features.

The article highlights the impact of ammunition at military ranges on the natural environment of disposal. The results of complex studies are presented (soil, vegetation, small mammals) for two sites: in the Krasnoyarsk forest-steppe (N. 1), where in 2013 the disposal of projectiles was completed and in Kansk subtaiga (N. 2), where the disposal of projectiles continue. The scientific novelty of the work lies in the interdisciplinary consideration of the issue using instrumental research methods and satellite data. It was found that under the influence of explosions, a belligerative landscape is formed, funnels are formed, which are filled with water. As a result of the removal of soil (soil and underlying parent rocks) during explosions, the structural organization and physical properties of soils change at a distance of up to 15 m from the edge of the funnel. The authors note that the formation of communities takes a long time and begins from the pioneer stage as result of shedding of the walls an erosional succession type occurs in the blast craters. The direct impact of explosions is manifested as internal hemorrhage and impaired kidney in small mammals. An indirect effect is manifested in a change in the biotope: loosening the soil and the formation of reservoirs at the bottom of the craters, contributes to the formation of local settlements of tundra voles Microtus oeconomus Pallas. According to the results of the research, the parameters and spatial confinedness of disturbed by the explosions habitats were determined, which is necessary for the organization and monitoring of this anthropogenic impact. This problem has been little studied and requires further research.

The magnetic susceptibility (MS) of three types of permafrost forest soils (pale-yellow, pale-brown, and podzolic) formed on permafrost soil-forming rocks in the cryoarid climate of Central Yakutia for the first time was studied. It is noted that the studied permafrost soils develop within various high-altitude geomorphological levels of the ancient alluvial Central Yakut plain and form a regular zonal series from bottom to top, that is, with an increase in the absolute height of the terrain: pale-yellow gray - pale-yellow typical and solodic - pale-yellow leached - pale-brown typical - pale-brown podzolized and podzolic soils. At the same time, in this series of zonal soils, the values of their volume (VMS) and specific (SMS) magnetic susceptibilities also naturally decrease, due to the increased intensity of eluvial soil processes, such as solodization and podzolization in the genesis of these soils. The weighted average values of the specific magnetic susceptibility calculated for 9 sections of the studied permafrost forest soils, taking into account individual values of SMS and the thickness of their genetic horizons, changed for pale-yellow soils in the range of 21.6-42.1, pale-brown - 3.9-12.4, podzolic - 1.8-5.7 × 10^-8 m³/kg. It is also established that based on certain values of the VMS of these soils, all the studied types of permafrost forest soils in Central Yakutia belong to the group of low-magnetic ones and differ in the values of volumetric magnetic susceptibility that do not exceed 100 × 10^-5 Si units. Among the studied pedons of zonal forest soils of Central Yakutia, various types of their magnetic profiles are noted, which are determined by the geographical and genetic features of these soils.

Studies of natural hybrid zones of Populus L. in Western Siberia have shown that the observed hybridization is asymmetric and introgressive. However, its phenotypic manifestation has not been sufficiently studied, which makes it difficult to create effective programs for the selection of valuable forms and subsequent selection work. The purpose of this study is to analyze the results of studying the populations of P. nigra L., P. laurifolia Ledeb. and P. irtyschensis Ch. Y. Yang in the Tom River basin, according to some qualitative anatomical and morphological characteristics, to show phenotypic manifestations of introgressive hybridization, to reveal its scale, direction and significance. Studies of a complex of qualitative morphological characters were carried out in 23 populations on 684 individuals. It was found that hybridization of P. laurifolia and P. nigra in the Tom River basin is not observed everywhere. Clusters of hybrids (foci of hybridization) stand out only in areas where the optimal combination of factors promoting hybridization develops. The morphological characters we selected allow us to reliably identify the parental taxa and P. irtyschensis . Additional use of the features of petiolar anatomy makes it possible to study the diversity of individuals within the identified taxa. The study of P. laurifolia in both mixed and pure (monospecific) plantations did not reveal any signs indicating the penetration of P. nigra genes into its gene pool. On the contrary, in the populations of P. nigra , phenotypic manifestations of introgression were found in both morphological and anatomical characteristics. It has been suggested that the asymmetric introgressive hybridization between two poplar species observed in the Tom River basin is apparently a fairly widespread phenomenon within the genus Populus . The studies performed demonstrate the adaptive role of introgression in the colonization of suboptimal habitats.

Deforestation and forest degradation in the forest-steppe zone is one of the most pressing issues in the world, involving territory of southern boreal forests in Northern Mongolia. The changes in forest cover between 1999 and 2016 and driving factors to deforestation and forest degradation in the Khustai nuruu mountains of the Northern Mongolia were analyzed. Forest monitoring was carried out in mature and over-mature flat-leaved birch Betula platyphilla Sukacz. forests with an admixture of aspen Populus tremula L. using the combined method of remote sensing and ground based field measurements. We found an accelerated deforestation trend between 2006 and 2009, which amounted to 463 ha (23.2 %) since deforestation in the Khustai nuruu mountains was started. Overall 17-year forest monitoring revealed that a total of 675 ha of forests were completely converted to non-forest area. As urgent measures to mitigate the effects and limit rapid deforestation in study area, it is recommended to improve the sustainable forest management via establishing optimum head of livestock and wild animals, strengthening prevention and control measures against pests, and reforestation on deforested areas using seedling of native tree species taken from forest nurseries in the region.

The study presents new data on the cryolithological structure of a ridge-shaped peat plateau typical for the north of Western Siberia, located in the lower reaches of the Nadym River. Two wells were drilled at the top of the ridge and in the inter-ridge depression, with subsequent core analysis. Grain size distribution, shape and surface structure of sand quartz grains, botanical composition and radiocarbon age of organogenic deposits were determined. The study revealed the presence of a three-layer peat-sand-loam ridge structure. The lower loam layer with a ~60 % volumetric ice content was affected by frost heaving. Layers of pure ice are identified below this loam layer. The ridge was formed as a result of water migration with the complementary influence of ice injection; it is of the peat-mineral type. In the ridge formation history, we identified the stages of loam and sand deposits accumulation at the end of the Late Pleistocene; bogging occurred at the beginning of the Holocene (10.6-9.8 ka BP), while active frost heaving was during the Subboreal stage (5.5-5.0 ka BP). Currently, there is a decrease in the upper organic horizon thickness and some erosion. It is proposed to consider peat-mineral and mineral frost heave landforms (mounds and ridges) as separate type of cryogenic landforms.

The work reports on new data on geochemistry of water of the Sytygan-Sylba Thermal Spring located in the permafrost zone in the northeast of Yakutia. Data on the content of rare and trace elements, elements of a rare-earth group, oxygen and hydrogen isotopes in the studied waters have been obtained for the first time. Groundwaters of the spring are classified as low-mineralized siliceous thermal waters of the deep origin, which are seasonally fed due to the inflow of more mineralized suprapermafrost waters. The year-round activity of the thermal spring in the zone of continuous permafrost 300-500 m thick is associated with the significant heat flow in the anomalous mantle uplift zone. Geochemical signs of the thermal water of the spring involve an increased concentration of sulfates, anomalous contents of Ge, Mo, W, As and other elements, which may be indicators of halo waters and proximity of ore accumulations.

The analysis of affectivity of frozen soils surface cooling methods based on the theoretical understanding of temperature shift formation with seasonal processes in the upper ground layers is provided. The surface cooling method for the building with aerated underfloor space is suggested on the base of this analysis. This method includes heat-insulation layer ground surface and free convection cooling system with its horizontal evaporator under insulation layer. Condenser of the cooling system is out of the building contour and it makes evaporator temperature near to winter air temperature. The results of mathematical modelling demonstrate that suggested method provides a significant and rapid decrease of the ground temperature as compared to other methods (up to 1.0-2.5 °С for not more than 1.5 year instead of 3-5 years). An additional temperature decrease by 1.5 °С may be obtained by connecting of the forced cooling device to the cooling system for one summer season. The calculation results allow us to propose the best sequence for connecting the cooling elements of the system at the initial stage of its operation.

A correlation analysis of long-term dynamics of sea ice extent in the Northern Hemisphere involving calculations of insolation characteristics with high spatial resolution was performed. The revealed close negative relationships between multi-year variations in sea ice extent, winter insolation and irradiance contrast were calculated in model cells with resolution of 1° x 1° for the period 1901-2018. The linkage density maps have been constructed to analyze relationships between multi-year changes in sea ice extent and insolation characteristics based on annual, semi-annual and monthly (March, September) means of sea ice extent. It is revealed that the correlation between multi-year variations in sea ice spatial distribution in the Northern Hemisphere and insolation contrast is interpreted as cause and effect relationship, while insolation contrast can be used as a predictor in statistical models for the sea ice extent dynamics. A close relationship between spatial distribution of sea ice and insolation contrast throughout the entire Northern Sea Route has been determined. This gives a perspective for long-term forecasting of the sea ice extent for the Northern Sea Route based on calculations of the intensity of insolation contrast for the Northern Hemisphere.

The features of the Late Pleistocene ice wedges in the outcrop of the Zelyony Mys Yedoma located on the right bank of the Lower Kolyma River are considered. The oxygen isotope composition of ice wedges, their radiocarbon age, hydrochemical features have been studied. Stable oxygen isotopes provide the main basis for reconstructing the mean January air temperature history of a site from ice wedges. Detailed quantitative assessments of paleogeocryological and paleoclimatic changes of the region in the Late Pleistocene 48-15 cal ka BP were performed.

It has been revealed that methodological techniques and formulas developed and widely used by Yu.K. Vasil’chuk for the reconstruction of average January temperatures (t_J = 1.5xδ¹⁸O), the sum of winter negative temperatures (∑t_w = 250xδ¹⁸O), as well as average winter temperatures (t_w = δ¹⁸O) based on the oxygen-isotopic composition of polygonal ice wedge are incorrect, and the paleoclimatic reconstructions obtained from these formulas are unreliable.

The main milestones of the history of the Earth Cryosphere Institute, Tyumen Scientific Centre SB RAS are reflected in the light of its thirtieth anniversary, celebrated in 2021.