Home – Home – Jornals – Combustion, Explosion and Shock Waves 2024 number 1

This issue of the journal is dedicated to the 90th birthday of Academician of the RAS A.E. Kontorovich. This introductory article reviews the included materials. The topics of the articles are closely connected to the scientific interests of Aleksei Emilievich, even though they are not fully represented. This anniversary issue includes articles concerning topical questions of geology, tectonics, stratigraphy, petroleum potential, as well as various aspects and characteristics of oil and organic matter geochemistry in oil-and-gas source formations of sedimentary basins of Siberia and the Arctic. Among the many lines of research A.E. Kontorovich pursued was the geology and geochemistry of concentrated forms of subsoil organic matter - coal. Therefore, this issue logically ends with an article on the study of the most ancient Devonian coals.

The estimation results of the initial total unconventional resources of hydrocarbon in Domanik type sediments, the Khadum and Bazhenov formations are provided. The reasonability of estimating hydrocarbon resources in these deposits by the volumetric method is substantiated. The stratigraphic interval of their distribution is given. The technique of oil and gas geological zoning based on the mapping of structural and facies zones, the degree of catagenetic transformation of organic matter, and the boundary values of the thickness of carbonaceous rocks in the section is described. The criteria for the allocation of pay intervals that make up the effective part of the section are determined. The choice of parameters such as porosity coefficient, oil recovery coefficient, oil saturation coefficient, correction factor and oil density is justified. For each complex of deposits, adjustments related to the features of the geological structure of the estimation targets, the conditions of their occurrence and the degree of geological and geophysical study have been introduced into the estimation of total geological resources. The volumes of total geological and recoverable resources of unconventional hydrocarbon sources for the Volga-Ural, Timan-Pechora, Black Sea-North Caucasus, West Siberian and Lena-Tunguska oil and gas provinces are given. The conducted research has rationalized extensive resources, the recovery of which can compensate for the decrease in oil volumes from traditional deposits.

This article presents the latest state of exploration and development of shale oil of continental lacustrine formations in the main basins of China, summarizes the main theoretical considerations and key technologies for exploration and development, and suggests prospects for exploration and development of shale oil in China. It is believed that the exploration and development of oil in shale formations rich in organic matter of types I and II of medium and high maturity are key to the breakthrough of production of 10 million tons in China. This will play an important role in China’s stable oil production at the level of 200 million tons per year in the future. The efficient development of medium- and low- maturity shale oil resources can be significantly improved and lead to serious changes in oil production only after new breakthroughs in the theory and technology of shale deposits.

The results of regional geological exploration over the past 18 years within the Aldan-Maya potential petroleum area were used as the basis for the refinement of the geological structure of the study area. The study considers the key structural features of the sedimentary cover of the Aldan-Maya region and major tectonic events that affected its structure. The generalization and interpretation of regional seismic survey data provided the basis for building a series of geoseismic sections and structure maps, which, in turn, were used in structural tectonic zoning of the study area. The map showing outcrops of Riphean formations and groups on the pre-Vendian erosion surface was complied. Tectonic schemes for three structural levels (upper Karelian-Lower Riphean, Middle-Upper Riphean and Vendian-Cambrian) confirmed their fundamental difference. In particular, the large Maya inclined swell was detected only in the topography of the Lower Riphean and is absent in the overlying structures of Middle Riphean-Vendian age, which are represented by weakly differentiated monoclines. The parameters of the major tectonic elements were determined.

The Vendian oil and gas complex (OGC) consists of the Vilyuchan, Nepa, and Tira stratigraphic horizons. The horizons are divided into correlation layers, stratigraphic charts are refined, cyclometric stratigraphic charts of oil and gas-bearing areas of the southern part of the Lena-Tunguska province are constructed. The lower boundary of the Vendian oil and gas complex and the base of the Vendian system are established in the Nuj zone of the Nepa-Botuoba and Irkutsk zones of the Angara-Lena oil and gas region (OGR) at the end of the pre-Vendian break in sedimentation. In the Angara-Lena OGR, the Typta Formation lies after a break both on different formations of the Baikalian system, and on the basement, and it is covered by sandstones of the Vendian Nepa horizon. The Typta Formation is assigned to the Vendian system, to the Vilyuchan horizon. In the Nepa-Botuoba OGR, a long pre-Vendian break divided the Talakan Formation into an upper Vendian and a lower Riphean parts. The name Talakan is left for the Vendian strata, the lower part is divided into three strata of the Baikalian system. The cyclometric stratigraphic scale is based on repetitions of cyclically constructed sections of horizons and their parts. Repetitions are considered as the result of oscillatory movements of the Earth, which take place at different intervals of time. The ranks of movements are planetary (40 Myr), long-period (20 Myr), and regional. In these ranks of time, nexacylites, horizons and regocyclites were formed. The horizons linked the regional and cyclometric stratigraphic scales. Breaks in the sedimentation of the Vendian OGC are divided by duration into short-term separating regocyclites, long-term separating horizons and two breaks - pre-Vendian and pre-Danilovo, the duration of which reaches 10-20 Myr.

In this paper we analyze the geological structure and prospects of hydrocarbon potential of the Paleozoic deposits in southeastern regions of West Siberia, including the Tomsk, Novosibirsk, Omsk regions and the southwest of the Krasnoyarsk Territory in the left-bank part of the Yenisei River. In the process of our studies, we analyzed the tectonic structure of the basement and made a conclusion that most of the studied area is occupied by the Central West Siberian zone of Late Hercynides. In the northeast of the Tomsk region and the adjacent area of the Krasnoyarsk Territory, the cis-Yenisei Upper Protezoic-Paleozoic sedimentary subbasin, lying on the pre-Baikal basement, developed. We constructed regional-zonal models of the Riphean-Cambrian deposits of the cis-Yenisei subprovince and Paleozoic deposits in the area of distribution of Hercynides and analyzed the material composition and age of the rocks of the pre-Jurassic basement. We assessed hydrocarbon potential of the Upper Proterozoic-Paleozoic deposits, identified prospective blocks and objects, developed seismogeological criteria to identify and map in detail the Paleozoic oil and gas prospective reservoirs and constructed seismogeological models of reference fields.

The Bazhenov horizon is the main source rock stratum of the West Siberian petroleum province, which possesses significant resources of hard-to-recover hydrocarbons, making it a unique exploration target. The study summarizes geochemical data on crude oils (39 samples) collected from pools within the Bazhenov and Tutleima formations. A comparative analysis of the carbon isotope composition and geochemical parameters calculated from the composition of the identified saturated and aromatic compounds (pristane/phytane, C₂₉/C₂₇ steranes, C₃₅/C₃₄ homohopanes, tricyclane index, relative concentrations of dibenzothiophenes) confirm a common aquatic genotype of the studied oils and their genetic affinity to the organic matter of the same age. At the same time, significant variations in the main physical and chemical characteristics of the studied Bazhenov oils may be caused their fractionation during migration processes.

A complex of laboratory studies of Riphean rocks and oils was carried out by the organic-geochemistry methods to construct a basin model for the Kamo arch of the Baikit anteclise of the Siberian craton. We compared the parameters of the organic matter (OM) and oils of the Upper Riphean Iremeken carbonaceous member by biomarker hydrocarbons. Analysis of the obtained chromatography-mass spectrometry data showed an unordinary group hydrocarbon composition of extracts from the OM and oils and low contents of cheilanthanes and steranes in them. Within the Kamo arch, the Upper Riphean Iremeken OM-enriched deposits with a high petroleum potential might have reached the peak of petroleum generation only in the deepest part of the Madra trough; thus, the traps could not be completely filled with oil. The distribution of tricyclic terpanes in the rock bitumens from the studied wells testifies to immature OM in the Iremeken Formation. However, in the most submerged zones of the Kamo arch and in the adjacent areas, oil was generated from the OM of the Iremeken Formation. This is evidenced by the oils of the Upper Iremeken Subformation in the Kuyumbinskoe field and the Ter’-Kamo license area.

The kinetic characteristics of kerogen (activation energy and frequency factor distributions of the initial generative potential) determine the dynamics of naphthide generation during catagenesis. In the previous studies on quantitative modeling of naphthidogenesis in the Kuonamka source rocks, the kinetic characteristics were taken by analogy with the known kerogens from other complexes and provinces. It seems relevant to determine the effective kinetic characteristics of the kerogen from the Kuonamka source rocks from experimental data. To estimate the kinetic parameters, specialized multi-rate pyrolysis studies were performed. The variations in pyrolysis data was reported to be presumably associated with the conditions of kerogen and source rock formation during accumulation and diagenesis of organic matter. The effect of carbonate and organic carbon contents on the temperature range of the second pyrolysis peak is recorded. Reconstruction of the average (effective) kinetic characteristics of kerogens from the Kuonamka source rock, was conducted using data on kerogens from Serkinsky-5 and 10 and Tit-Ebya-6 wells, which are less degraded than kerogens from Ust’-Maiskaya-366 well and probably attained the early mesocatagenesis grades. The current average effective kinetic characteristics of kerogen were estimated and corrected for the possible partial degradation of reference samples. The obtained effective kinetic models of kerogen are compared with models of kerogens of various genetic types known from the literature. The estimated effective kinetic characteristics of kerogens or Menil-1 and Type B kerogens with similar characteristics are to be taken, as a first approximation, in regional historical-genetic (basin) modeling of naphthide generation in the Kuonamka source rock.

We have studied biostratigraphy, lithology and geochemistry of drill cores from the Kyulenke River basin. The study of fossil remains and rock compositions, the analysis of trilobite distributions and changes in the lithological and geochemical characteristics of the sediments made it possible to identify structural features of the marker horizons, to correlate borehole sections and outcrops, to compare individual Cambrian intervals and the regional zones of the Yudoma-Olenek facies region of the Siberian Platform. The study has shown rocks of the Kuonamka Fomation to be enriched in uranium (U) and revealed a direct relationship between the contents of U and organic carbon (C_org) in the analyzed rocks, typical for the lower and middle Cambrian black shale deposits sampled from the outcrops in the eastern parts of the Siberian Platform. For the first time, a relationship of rock radioactivity by gamma-ray logging with the contents of U and C_org in Cambrian rocks was established.

The composition of the oldest coals of the Timan-northern Urals region has been studied comprehensively, and their hydrocarbon and microcomponent characteristics are given. The relationship between different types of coals and Late Devonian plant communities of the North Timan is revealed. It is also determined that some samples contain microspores, megaspores, and plant remains belonging mainly to the lycopod Helenia . The most probable source of jet coals is identified as the wood of the progymnosperm Callixylon . The values of vitrinite reflectance and T_max and the data on the distribution of polycyclic biomarkers and methylphenanthrenes indicate the low maturation of the coal organic matter. The coal bitumen investigated here is characterized by the dominance of steranes and diaster-13(17)-enes of compositions С₂₈ and С₂₉. The following diterpanes are identified: beyerane, 16α(H)-kaurane, 16β(H)-kaurane, and 16α(H)-atisane. At the same time, phyllocladane is absent.

The initial part of a hydrogen jet exhausting upward from a 2 × 20 mm slot and burning in air is studied. The profiles of the streamwise and transverse velocity are determined by means of particle image velocimetry; the local temperature distribution and the composition of stable substances are obtained by the Raman scattering method with the use of a focusing resonator system. Based on experimental data, the contributions of molecular and convective transfer mechanisms to the heat release intensity is determined. It is shown that the maximum intensity of heat release depends mainly on gas-dynamic and thermophysical characteristics of the gas flow during its macroscopic motion.

The combustion of rich mixtures of methanol and hydrogen with air has been studied by experimental and numerical methods. It has been shown that the deviation from the Le Chatelier rule for the rich flammability limits is due to two factors: inhibition of flame propagation by methanol in rich mixtures of hydrogen and the presence of superadiabatic temperatures in rich mixtures of methanol. It has been found that the effect of adding small amounts of hydrogen to rich mixtures of methanol is the same as the effect of adding inert nitrogen and carbon dioxide. Numerical simulation has shown that adding small amounts of hydrogen to rich mixtures methanol leads only to physical effects on the normal flame speed. Additives of H₂ affect the implementation of above-adiabatic temperatures in a methanol flame in the same way as Inert additives of CO₂ and N₂.

A mathematical method is developed for solving the problem of detonation initiation in a hydrogen-air mixture by a small-diameter sphere flying with a velocity greater than the Chapman-Jouguet detonation velocity. The mathematical model verification is performed against experimental data on the detonation cell size in hydrogen-oxygen and hydrogen-air mixtures. Depending on the pressure in the mixture, which is varied from 100 to 250 kPa, three regimes of oblique detonation waves are obtained: (1) stabilized oblique detonation wave at 250 kPa; (2) stabilized oblique detonation wave of the “straw hat” type at 200 kPa; (3) periodic regime with a detached oblique detonation wave, which was not observed in previous experiments, at 125 kPa. At 100 kPa, a regime of shock-initiation combustion is observed. Based on an analytical dependence, the energy of detonation initiation by a high-velocity body is estimated, and the analytical and numerical data are found to be in good agreement.

Organometallic complexes of transition metals with inorganic anions are considered as promising precursors for the synthesis of nanoscale materials used in various fields, including chemical catalysis. In this work, organometallic complexes of nickel, iron, and copper with an organic ligand (imidazole) and with an inorganic ligand (nitrate anion) were synthesized and characterized. The kinetic parameters of thermal decomposition of the synthesized organometallic complexes were determined by low heating rate thermogravimetric analysis and high-speed dynamic mass spectrometric thermal analysis. The main gaseous products of thermal decomposition of the complexes under high-speed heating were identified. The chemical and phase composition of condensed combustion products of organometallic complexes in air was studied.

There are various methods for synthesizing composites from mixtures of powders of metals forming intermetallic phases, as well as from mixtures of powders of metals and non-metals (for example, carbon or boron). In the 1970s, an approach was proposed to describe combustion and explosion processes with identification of reaction cells, which from modern positions can be classified with two-level synthesis models. The approach has been actively developed for binary systems, but remained rather conditional. This paper presents an overview of similar models; it is suggested that they can be developed by taking into account accompanying processes (not only diffusion, but also the evolution of the stress-strain state), and modified in relation to synthesis controlled by a laser or electron beam.

Mathematical modeling was used to study the modes of electrothermal explosion of a gasless system surrounded by a dielectric medium. The influence of the intensity of conductive heat transfer and Joule heating power on the formation of dimensionless temperature and concentration profiles, the integral depth of transformation and the speed of propagation of the reaction front is considered. To separate the stages of ignition and propagation of the reaction, the criterion was to achieve a conversion depth of 0.99 at any point in the sample. The amount of product formed at the ignition stage was determined. It is shown that near critical conditions during ignition on the axis of the sample, a large depth of transformation is achieved, leading to a displacement of the ignition zone from the axis to the surface of the sample.

This paper presents the results of thermodynamic calculation of adiabatic temperature and the equilibrium composition of products of HfO₂ reduction with calcium depending on carbon and calcium content at different pressures. The calculations are based on the possibility that solid HfN-HfC solutions could be formed, and their formation is identified with that of hafnium carbonitride. It is shown that adiabatic temperatures lie in a range of 2000 ÷ 2900 K, and its elevation is limited by the melting of CaO at 2900 K. The introduction of carbon often reduces the adiabatic temperature, and a pressure rise leads to its increase. A connection is revealed between the composition of products and the type of temperature curves. The main reason why adiabatic temperature rises along with pressure is a displacement of equilibrium toward the formation of condensed phases and an increase in the HfN proportion in the products.

Targeted synthesis of oxynitride composites is implemented by means of organizing coupled processes. Interaction of ferrosilicon with nitrogen in the combustion regime is considered as the main (inducing) process. The phase composition of the products of the coupled processes is determined by the chemical and phase compositions of the components added to ferrosilicon before performing self-propagating high-temperature synthesis. The influence of the basic products of the synthesis on the burning rate, fraction of nitrogen, phase composition, and morphology of synthesis products is considered. Chemical stages of ferrosilicon interaction with additives of natural minerals (zircon, ilmenite, and shungite) and aluminum in a nitrogen medium are demonstrated. The phase composition is determined by chemical transformations in the combustion wave. It is found that addition of aluminum leads to reduction or elimination of the Si₂N₂O phase in synthesis products with an increase in the aluminum fraction and obtaining composites based on the Si₃N₄ (SiAlON) solid solution. The microstructure of combustion products is presented by aggregates (5-10 μm) composed of small faceted crystals, shapeless structures, and crystal flakes. Oxynitride composites with an open porosity value of 51.0÷68.8% are obtained.

The authors propose a sequence of acquisition and interpretation of geospatial data obtained using different methods and means during mineral mining toward the accuracy increase in evaluation of industrially disturbed land. This approach uses the concept of stage-wise transition from the areas of industrial facilities to their individual points. The integration of data of satellite surveys, ground-based laser scanning and unmanned aerial surveillance in the digital models of land areas is described. It is highlighted that the rational combination of different methods of geospatial data acquisition and interpretation produces a high-accurate geoinformation system of digital twins of various subsoil use facilities.

The features and trends of coal mining in the east of Russia are examined. The current and planned managerial decisions connected with coal production and supplies to competitive markets are analyzed. The coal products are ROM fuel, concentrate and middlings. The authors discuss approaches to effective mining and processing management within the chains of supplies, and to provision of the required quality of solid fuel produced and delivered to customers.

The present study analyzes the fatal accident occurrences of seventy years from 1951 to 2020 in Indian coal mines. The autoregressive integrated moving average (ARIMA) model, Brown’s double exponential smoothing method, Holt’s double exponential smoothing method, and neural network time series forecasting are used in this research to analyze fatal accidents and forecast future accident incidents. By analyzing various parameters of the applied models, the neural network model was found to be the most appropriate model for the collected data to forecast Indian coal mine accidents as it provides the least root mean squared error (RMSE) (17.62), and mean absolute error (MAE) (13.33) among all models. According to this study, the Neural Network model is the most suitable one to predict Indian coal mine fatality.

This article is devoted to the generalization of the world experience of research on communication geography in order to define future directions of studying the spatial and temporal deployment and functioning of telecommunications networks. The author’s semantic search algorithm for publications in bibliographic databases is used to reveal about 400 articles on communication geography published during 1981-2020 in scientific journals of all countries. An analysis of these publications showed that six types of communication (fiber-optic, mobile, telephone, postal, telegraph and satellite communications) were studied within the framework of infrastructural, statistical, impact, streaming and optimization directions of communication the geography. The methods of moving average and bi-proportional indices were used to identify trends. Linear extrapolation of trends in the number of publications by type of communication and scientific directions suggested that in the future preference will be given to the geographical study of fiber-optic and mobile networks within the framework of infrastructural and statistical approaches in an effort to optimize the line-nodal structure. Based on a comparative analysis of unsolved problems, it is established that in the future, first of all, it is necessary to solve the following meta-tasks: transferring the experience of geographical study of one type of communication to other types; using «big data» of telecom operators for geographical analysis of the functioning of networks; the transition from descriptive to constructive communication geography; identification of geographical patterns for deployment of telecommunication networks, and the development of a territorial telecommunications complex concept. A network of machine-to-machine information exchange, a 6G mobile communication network and a multifunctional network are identified as promising objects of research.

The concept of “system” is analyzed. The basic properties of systems are established. It was revealed that all its elements must be interconnected and be in interaction, the system interacts with the external environment as a whole, and the division in it occurs from the whole to the parts. It is concluded that in relation to geographical objects these requirements are too stringent, because then there arises a need for mandatory implementation of all the conditions inherent in the systems. And this is not always possible, because the realization of the goals, in accordance with which the object is formed, may require consideration of independent factors. It is shown that not all geographical and related objects - socio-geographical and geo-ecological - meet the requirements for classical systems, because some (and sometimes all) of their components (or influencing factors) are not mutually dependent. A virtual example of a problem is given, namely the selection of the optimal location of an object out of several alternatives, consisting of several groups of factors, illustrating the absence of direct links between some of the components of the object. It is proposed to call such objects “non-system” objects. In contrast to systems, for them it is possible to form the structure from the bottom up, from private to general, combining, if necessary, the components of the object into groups, which makes it possible to consistently complicate the object of research as necessary. At the same time, a number of factors, such as seasonal factors, can change their importance over time, which leads to the transition of objects from the “system” state to the “non-system” state, and vice versa. Factors, the influence of which is limited in space, can lead to similar consequences. A graphical interpretation of the concepts of “system” and “non-system object” in the form of oriented graphs, the edges of which represent groups of components (influencing factors) is provided. With such an approach, systems can be considered as a special case of objects in which all components are interrelated. At the same time, systems can be components of complex non-system objects.

We present results form a ten-year-long study into local features of mountain glacier dynamics in the central part of Asia - from the latitudes of the middle taiga of Cisbaikalia and Transbaikalia, through the mountains of the steppe zone of Mongolian Altai and the desert zone of China to the cold deserts of the Himalayas. Interpretation of multi-temporal satellite images was carried out, thereby making it possible to obtain quantitative information on changes in the area and length of glaciers in the key areas of the mountain territories under study. These data are linked to climatic parameters, absolute altitude, permafrost, morphology and tectonics of the mountain ridges, and to anthropogenic impact. The study revealed a general trend, namely a retreat of the glaciers starting in the 1970s, with an increase in the average annual air temperature in the northern hemisphere by 1,4-1,6 °С. Accelerated glacier melting and a reduction in glacier length were observed from 1990 to 2020 when there occurred the most significant warming. The following years with above-average temperatures are highlighted: 1990, 1995, 1997, 2002, 2005, 2005, 2007, 2008, 2011, 2012, 2016, 2019, and 2020. During this period also showed an increase in the area and length of some of the glaciers studied during 2013-2015 and in 2021 associated with abnormal winter precipitation in 2012, 2013 and 2020. It was found that in the mountains of the south of Eastern Siberia the aforementioned years showed a slowdown in the reduction of the area of glaciers, an increase of the number of perennial snow patches, and an increase in the frequency of snow avalanches. It has been revealed that the glaciers in Siberia, Mongolian Altai, and the Altyn-Tag Range retreated from the terminal moraines of the Little Ice Age retreated an average of 500 m, on the Karlyktag Range 800-900 m, and in the Himalayas (Langtang area) from 1 to 4,5 km.

The issues related to soil degradation, and the possibility of preserving and restoring soil fertility in the southern regions of Siberia are considered. On the basis of synthesizing long-term observational data from fixed stations, the mechanism of erosion processes was revealed and quantitative data were obtained for soil losses depending on the main factors of water and wind erosion. Particular attention is paid to the periodically extreme behavior of processes that cause catastrophic soil degradation. The patterns of changes in the structure of processes that require the use of soil-protective methods of agriculture are shown. The mechanism of soil erosion and of soil degradation rate changes from west to east along the belt of steppes and forest-steppes in southern Siberia. It is necessary to protect soils from thawed soil loss in the south of Western Siberia. Soil deflation poses a particular danger in Khakassia. Soil degradation in Cisbaikalia and Transbaikalia is enhanced by the combined effect of storm runoff and deflation. Based on a case study of the Irkutsk-Cheremkhovo plain, and the Nazarovskaya and South-Minusinsk depressions, results of a quantitative cartographic assessment of the erosion hazard to lands in terms of empirical models of potential soil loss and deflation are presented. A decrease in soil losses from erosion as a result of socio-economic reforms of agriculture and a significant reduction in the area of arable land in the early 1990s and in the post-reform period (2010-2017) were noted. In connection with the restoration of arable land occurring in recent years, the need for large-scale inventory mapping of erosion processes in southern Siberia is emphasized. It will be the basis for choosing a nature management policy that promotes the conservation of soil resources.

This article is devoted to the analysis of the results from investigating the soil geochemistry in the south of Russia, and assessing atmospheric pollution and the status of public health in some of the cities of Krasnodar krai and Rostov oblast. The research has been made for more than 30 years, including repeated tests of the soils (more than 10 000 samples) and settlements (about 3000 samples), and comprehensive assessments of the state environment of a large biosphere structure where almost 20 % of the population of Russia lives. The study revealed an increase in atmospheric pollution, concentrations of chemical elements in soils, and the negative impact of pollution on public health. The geochemistry of air pollution has a particularly strong effect on the increase in diseases of the upper respiratory tract. The highest degree of air pollution by aerosols in the south of Russia is noted in Novorossiisk. A three-dimensional analysis shows that the maximum percentage of diseases and increased mortality of newborns was detected in areas with old 1-2-storey buildings, and the minimum percentage of diseases in areas of multi-storey buildings. It is shown that the sickness rate in the population decreases with an increase in the storey of residence. Such a distribution of morbidity indicates a high level of atmospheric aerosol pollution. To confirm the toxicity of air pollution in cities, an ecological-geochemical assessment of the solid part of aerosols was made in comparison with natural deflationary aerosols. Geochemical features of various sources of aerosols in the atmospheric surface layer are revealed. It has been established that technogenic aerosols are enriched with a number of chemical elements, but especially intensively with Ag, Pb, Cu and Zn elements, polymetals that are not characteristic for the local geological situation and industrial specifics.

We present the principles of landscape analysis of a territory and demonstrate the experience of implementing these principles on a step-by-step basis (functional, complex, dynamic, classification-hierarchical, and discrete) was demonstrated for assessing the fire resistance of forest geosystems in the south of the Selenga middle mountains. The practical expression of the step-by-step implementation of these principles involves analyzing the landscape-forming factors and conditions, selecting complex indicators of the functioning of geosystems, creating a landscape-information basis for assessment, and carrying out a correlated analysis of the resulting complex indicators and the landscape-typological map, followed by an assessment of fire resistance of different types of forest geosystems. Within the framework of this research program, intra-landscape conditions and features of forest geosystems (relief, nature of underlying rocks and soils, and vegetation) were analyzed, determining their fire resistance, and a landscape-information basis (landscape-typological map) of forest geosystems was built. The value of the near-surface temperature that characterizes the level of moisture exchange between the components of geosystems, which determines the micro- and mesoclimatic features of landscapes, is used as a complex indicator. To determine the moisture exchange potential, a correlative analysis of index images characterizing land surface temperatures (LST) and moisture (normalized difference moisture index, NDMI) was carried out, which were calculated on the basis of infrared channels of Landsat 8 OLI and TIRS satellite images. Forest geosystems with high fire resistance are characterized by a higher level of moisture exchange and by minimum values of LST. Further, a correlative analysis of results obtained by the data overlay method was carried out: a grid of landscape map selections was superimposed on the LST and NDMI index images to identify modal values of the land surface temperature characteristic of each type of geosystems. It was found that the minimum level of fire resistance is characteristic of pine forests of steppizated, sometimes dead-cover, forests on plains and foothill elevations, composed of aeolian and deluvial-proluvial deposits on soils of light mechanical composition. The reliability of the results from assessing the fire resistance of geosystems is confirmed by the analysis of the actual fire frequency index of forests conducted on the basis of a time series of Landsat satellite images over the past 50 years when fires affected approximately 51 % of the area of all forests of the study area.

The tendencies of forest formation on fallow lands of different years, currently acting as rangelands, in post-agrarian areas of Western Transbaikalia have been established. When assessing the nature of the restorative dynamics of forests on fallow lands, the typological and species composition of phytocenoses of the surrounding areas, not previously used for plowing, was taken into account as much as possible. In the forming herbaceous communities on fallow lands and steppe plots, the presence of woody species such as Scots pine (Pinus sylvestris L.), more rarely Siberian larch (Larix sibirica Ledeb.), and sometimes dwarf elm (Ulmus pumila L.) was established. It was determined that in plant communities removed from intensive pasture turnover, there occur a gradual restoration of layering, and an increase in species diversity of plants and in their abundance in communities. At the same time, an active introduction of pine to herbaceous (steppe) communities, consisting of plant species characteristic of the forest-steppe and steppe, was noted. It was found that the age composition of pine varies from 2-5-year-old individuals to 20-25-year-old trees represented by separate groups everywhere on fallow lands. It was noted that in the plots of fallows adjacent to a closed forest stand, there is a fairly closed undergrowth, regardless of the orographic features of the territory. A significant presence of plant species characteristic of zonal light coniferous forests was detected in the ground cover of such groupings. This is probably due to the early stage of formation of light coniferous taiga of zonal type. A restraining factor in the development of forests on fallow and steppe plots in the study area should be attributed to a possible increase in anthropogenic influences, mainly grazing regimes, due to the formation of farms. There are often periodic human-induced fires (“deliberate fires”) in order to preserve rangelands. Simple felling of pine undergrowth has also been noted, both in fallow lands and in adjacent territories. In many respects, this is of decisive importance for the possibility of formation and development of forests on post-agrarian territories in the near future.

The content of 14 polycyclic aromatic hydrocarbons (PAHs) in the soils of the city of Severobaikalsk (Republic of Buryatia) was studied for the first time and an ecological and geochemical assessment of their pollution in different land-use zones of the city was made. The main sources of PAHs were determined, namely the emissions from the heat and power complex operating on Kansk-Achinsk brown coal, railway and motor transport, and from oil depots, which form extensive high-contrast PAH anomalies in the soils in the north-east, north-west, and south of the city. Fluoranthene, benzo(b)fluoranthene, and phenanthrene predominate in the composition of brown coals used; the amount of PAHs in them is 5.44 mg/kg; in the ash of the thermal power plant it is 20 times less than in the brown coals. In the upper (0-10 cm) soil horizons of Severobaikalsk, the total content of PAHs averages 0.441 mg/kg, which is 4 times higher than the background level. The composition of PAHs in urban soils does not differ from their natural analogs with the predominance of fluoranthene, pyrene, and benzo(b)fluoranthene. The sum of 2-4-ringed PAHs is 1.5-2.9 times higher than the sum of 5-6-ringed ones. The degree of soil pollution with PAHs is caused by the level of technogenic load, which depends on the functional status of the territory. It is concluded that the soils of residential manor and industrial zones are most heavily polluted with PAHs whereas the least polluted are those of the residential multi-storey zone. The content of BaP in the soils of the industrial zone exceeds the MPC on average by a factor of 1.5, and in the residential manor zone by a factor of 1.3. The maximum exceedances reach 31 MPC in the northeastern anomaly. When taking into account the contribution of other PAHs, expressed in terms of the equivalent amount of BaP in soils, the average frequency of exceeding the MPC for BaP increases to a factor of 2.3, and in the industrial and residential manor zones, to factors of 3.4 and 3.6, respectively. 34 % of the city’s soils are characterized by an acceptable pollution level, and 23.4 % by a dangerous and very dangerous levels of PAH pollution, which threatens public health and can cause deterioration of the water composition in Lake Baikal.

A study was made of the gross content of rare-earth elements (scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, tulium, ytterbium and lutetium) in the peat deposit of the high bog in the Dubches River valley (Krasnoyarsk krai). It was revealed that the age of the bottom peat layer is 13 617 ± 190 cal BP. The main sources of rare-earth elements entering the peat deposit of the bog are considered. They are underlying rocks, atmospheric aerosols, regional and local forest fires, and peat geochemistry. It was noted that atmospheric aerosols and regional forest fires had little effect on the concentration of elements in the peat studied. The main sources of input of rare-earth elements into the peat deposit were the underlying rocks and the oxide-recovery environment at the initial period of the formation of the bog. During the study it was found that the content of rare-earth elements in the upper, transitional and lowland peats is below the clarke number and all the elements are dispersed. Cerium, terbium, and holmium are most dispersed in the upper and transitional types of peat, and cerium and terbium in the lowland ones. The concentrations of scandium and ytterbium in the lowland peat types are close to the soil clarke. It is concluded that the concentration of rare-earth elements in different types of highland and transitional peats down the profile not almost change. Their insignificant accumulation is noted only in the near-surface layers of 0.30-0.35 m. In pyrogenic interlayers at the depths of 2.65, 2.90, 3.15, and 3.25 m, increased content of almost all rare-earth elements relative to the overlying layer of peat was recorded. In the lowland types of peat in the depth interval of 4.0-3.75 m, the highest concentration of all elements was noted. It is suggested that the main source of rare-earth elements in the initial stage of bog development could be the bedrock of ancient glacial origin.

Based on daily data on isobaric surface altitude 700 hPa (lower troposphere) of NCEP/NCAR reanalysis we made an objective classification of synoptic types over the Kodar Range (Transbaikalia) for the period 1970-2020 and investigated seasonal and interannual variability of cyclonic and anticyclonic weather types frequency. It was found that the advective atmospheric circulation regime dominates at the level of the lower troposphere over the Kodar, and cyclonic types prevail over anticyclonic types in all seasons except summer (June-August). It was further found that the frequency of occurrence of anticyclonic types has a tendency to increase in summer and decrease in autumn over the last 50 years, and the frequency of cyclonic types to decrease in spring and, on the contrary, to increase in autumn. It is concluded that the atmospheric circulation over the Kodar may influence changes in the mass balance of mountain glaciers. According to the ratio of cyclones and anticyclones in different seasons of the year, three main modes of atmospheric circulation, determining possible changes in the mass balance of glaciers, were established. Until the mid-1980s, the increased frequency of winter and spring cyclones contributed to a stabilization of the glacier mass balance. From the mid-1980s to the early 2000s, the frequency of winter, spring, and summer cyclones decreased and the number of summer anticyclones increased. It is concluded that such conditions contributed to a decrease in winter precipitation and summer cloudiness, an increase in the net radiation and accelerated ablation of glaciers in the 1990s. Since the early 2000s the atmospheric circulation has contributed to a partial restoring of the glacier mass balance.

The dynamics of the total population of Siberia and changes in age groups by working capacity are considered. Attention is focused on a significant reduction in the working-age population and an increase in the number in the group older than working age. The dynamics of coefficients of three types of demographic load is analyzed: potential (children), pension and general - over a twenty-year period. It is shown that since 2000, the coefficients of the potential load on the territory of Siberia have increased by 16 %, and the pension load by 23 %. Significant territorial disproportions in the coefficients of general demographic load were revealed, and the difference between the minimum and maximum values in the context of regions is 1,5 times. It has been established that the minimum loads are typical for the Khanty-Mansi Autonomous Okrug-Yugra (KhMAO-Yugra) and Yamalo-Nenets Autonomous Okrug (YaNAO) as centers of attraction for the young able-bodied population; the maximum values of the demographic load are recorded in regions with a high proportion of children in the population structure: in the Republics of Tyva and Altai as well as in regions characterized by population aging, namely in Altai krai, Kemerovo oblast, and Omsk oblast. The problem of the demographic potential of the regions is considered through the indicator of the value of the potential demographic load. The maximum exceedance of the load of children over the load of pensioners (by 67 %) was revealed in the Republic of Tyva. The maximum exceedance of the load of pensioners over the load of children (by 43 %) was noted in Altai krai. The influence of regional socio-economic factors on the formation of the demographic load indicator is emphasized: the level of fertility and mortality, migration activity, the influx of able-bodied population, and population aging.

A case study was made of the municipalities of Irkutsk oblast for 2000-2019 with a diagnostics of social security which is considered within the framework of economic security. At the first stage of the study, key indicators of the standard of living of the population were identified. The method of indicative analysis was used to assess destructive processes in the sphere of living standards. At the second stage, integral indices of social security were calculated in dynamics for the periods of administration by the oblast governors. To determine the degree of compliance of the city/municipal district with social security, a gradation of risk zones was used, on the basis of which a territorial ranking was carried out. In each risk zone, characteristic destructive processes in the sphere of living standards were identified. They are especially pronounced in the crisis zone. The lowest index of social security during the period under review is characterized by rural areas that are part of the crisis zone of catastrophic and critical risk. A “game of statistics” was noted, namely an automatic increase indicators of the standard of living in the rural population living in the areas of oil and gas production. It has been established that in the municipalities of the pre-crisis zone of moderate risk and the zone of stability, there is a tendency to equalize the level of wages relative to the average for the Russian Federation. The population of the entire region belongs to the categories of “low-income” and “below average”. It is shown that the imbalance of demand and supply of labor force in the professional and territorial sections remains, especially in cities and districts with a single-industry structure of the economy and oil and gas production areas. It is concluded that the greatest response of all the measures taken at the regional and federal levels fell on the policy to improve the investment and business climate. This is reflected in the dynamic transition of oil and gas production areas and the timber industry complex from the crisis zone to the zone of stability.

This paper presents for the first time the results of practice-oriented investigations for determining the magnitude of socio-economic damage to coastal areas of Lake Baikal as a result of the highest rise of its level (457,85 m according to the Pacific Reference Frame). The study area includes the coastal areas of Baikal, and some areas of the Irkutsk reservoir of Irkutsk oblast within the Slyudyanskii, Irkutskii and Olkhonskii administrative districts. When compiling the list of sites falling within the zone of potential submergence, use was made of the open public database of the Unified State Register of Immovable Property, and a package of working large-scale cartographic products and images. Expeditions made it possible to update, correct and complement the working register. The list of economic facilities and infrastructure (about 200), falling within the zone of potential submergence, includes line structures, enterprises of social services, and households. A calculation of economic damage to facilities of socio-economic activity is presented within the framework of the recommended technique of assessing the probable damage from the harmful effect of water, and assessing the effectiveness of preventive hydroeconomic measures (as of the year 2006). The amount of damage (for facilities and main sectoral groups) is corrected by using the deflator index (as of 2022 in the “construction” position on the territory of Irkutsk oblast)). Potential losses (lost profit) are illustrated by an example of recreational activity on the coast of Baikal within the boundaries of Irkutsk oblast. The possible considerable losses have been revealed in the recreational sphere as a result of direct damage to the facilities and infrastructure as well as lost profits due to a loss of attractiveness of coastal areas, including beach zones. A preliminary quantitative assessment of socio-economic damage to coastal administrative districts of Irkutsk oblast as a result of water level fluctuations in Lake Baikal and in the Irkutsk reservoir may well provide a basis for developing program-strategic directions and measures and for seeking managerial decisions of a preventive nature for minimizing negative impacts.

The purpose of the study is to analyze the transformation of the sectoral and territorial structure of international labor migrants in the Far East in the post-Soviet period. The subject for study is represented by international labor migration in the Far Eastern regions. Unlike earlier studies on similar topics, this paper analyzes the change in the structure of migration both at the district level and at the level of individual regions of the Far East. It is shown that changes in the structure of labor migration in the Russian Far East correspond to the all-Russian trends with a time lag of 10 years. While in general throughout Russia a steady excess of labor migrants from neighboring countries with visa-free regime has been observed since the mid-2000s, in general throughout the Far East - since the mid-2010s. It was found that by the beginning of the 2020s, a sectoral specialization of labor migrants from the non-CIS and CIS countries has been formed in the labor market of the Far Eastern regions. It was established that the ratio of migrants’ categories differs in individual regions. It was determined that a list of source countries and the sectoral structure of foreign workers’ employment for countries with visa regime has formed from countries with visa regime in structure of labor migration of the Far East; however, the ratio of the countries is changed. China remains the leader, and citizens of Turkey, Vietnam, and Serbia also occupy a stable position in the Far East labor market. In the labor market of the Far East, among citizens of the CIS countries, citizens of Uzbekistan, Kyrgyzstan, and Tajikistan are in the lead. It is shown that the regions of the Far East are characterized by the process of deconcentration of skilled and highly skilled labor migrants and their distribution in a larger number of regions than before.

A technique is suggested for assessing the attractiveness of beaches as a tool for monitoring their state in controlling the coastal areas. This approach was developed and is being used for assessing the beaches of seas and oceans in popular tourist destinations, such as Spain, Malta, Cuba, Turkey, and others. A calculation of attractiveness is based on an expert assessment of 26 beach parameters (18 natural and 8 anthropogenic). This technique for assessing the aesthetic attractiveness of the beaches along the Lake Baikal coast has been applied for the first time. It was tested in popular recreation areas of local residents and tourists; the assessment was carried out for 21 beaches. According to the assessment results, the beaches were divided into five attractiveness classes. It was revealed that protected areas (national parks) have a positive impact on the attractiveness assessment; most of the first class beaches are located in national parks. Anthropogenic load, on the contrary, has a negative impact; beaches of classes 4 and 5, for example, are located within urban areas. Urban development, car traffic and noise reduce the beach attractiveness. Anthropogenic parameters, unlike natural parameters, are the most easily changed; their monitoring makes it possible to control the beach attractiveness. The results of the assessment showed a high potential of natural landscapes of Lake Baikal which is associated with natural environment features, such as the mountains surrounding the lake, mature woody vegetation, transparent water, existence of geological monuments, dune complexes, sandy beaches as well as low anthropogenic pressure.

Changes in land use and land cover (LULC) resulting from human activities have significant impacts on the surrounding environment and ecosystems. Detecting and mapping changes in LULC in the Ba Ria-Vung Tau province, Vietnam, is critical for sustainable development, planning, and management. This study applied the maximum likelihood classifier algorithm of supervised classification in ArcGIS 10.8 software to detect observed LULC changes in the study area during the period of 2000-2020 using multi-temporal satellite images. For each satellite image, the study applied spectral indices (NDVI - Normalized Difference Vegetation Index, and NDWI - Normalized Difference Water Index) and a supervised classification to classify and assess LULC changes. The study performed an accuracy assessment of the classification maps derived from Landsat 5-TM for 2000 and 2010 and Landsat 8-OLI for 2020 using kappa coefficients of 0,882, 0,891, and 0,915, respectively. The area was classified into five main LULC classes including agriculture, water bodies, forest, settlement, and bare soil/rock. The LULC status and change maps created in ArcGIS 10.8 show a significant change in LULC. The settlement class has increased continuously over 20 years from 128,09 km² (2000) to 300,30 km² (2020); the agricultural land class has increased by 124,96 km² in the period 2000-2020. The remaining three classes, forest, water bodies, and bare soil/rock, all decreased in area during this period. These LULC changes pose a serious threat, impacting and disturbing the environment. The results of this study can be used in the management and planning of future land use in the area.

The landscape structure of the equatorial Merkele Ridge composed of limestones, on which the highest peak of the Maluku Islands, Mount Binaya, is located, has been studied. As a result, landscapes taxa spectrum, which is not characteristic in extratropical-latitude mountains, has been identified. The main factors determining the modern landscape structure of the Merkele Ridge are the formation of limestone by coral polyps, which was subsequently raised up to three thousand meters above the level of the World Ocean by tectonic movements, and also the hypsometric factor and the humid equatorial climate. The influence of the relief-substrate basis on the landscapes taxa differentiation is shown. Seven landscape taxa were identified. An analysis of the spatial distribution of soil types and plant formations made it possible to single out, among them, 15 smaller landscape taxa. Their vertical differentiation was caused by a decrease in temperatures and a change in moisture with increasing height. The taxonomic composition of vegetation becomes simpler in this case. Representatives of the flora of higher latitudes appear in it. The anthropogenic factor has had a strong impact on landscape taxa in the lower belt of the ridge. Below the isohypse of 300 m there emerged landscape taxa with a predominance of plant communities of cultivated plants, as well as those devoid of natural vegetation and soil cover, as a result of cutting down low-mountain rain forests on gentle and moderately steep slopes. Landscape taxa above the isohypse of 300 m have mostly preserved their natural state.

It is suggested that a new term “singularity” should be introduced into geography and biology implying the final and transforming process of states of natural systems equal in importance to the concept of “equifinality”. An analysis of interdependence of the equipotential and singular states in a single cycle of natural and natural-economic processes of local, regional and global scales was carried out. The term “singularity” is widely used in astrophysics, where it denotes the formation of the limiting, final state of cosmos systems, which provides the transition to a different, subsequent state (kind) during a mass-energy burst. In this connection, it is necessary to specify from geographical positions the definition and the relation of the singularity concept with equifinality, and to substantiate the connection and consistency of its interpretation with the provisions of the geosystem theory. The place of singularity in the organization of geosystems was revealed. The significance of interdependence of equifinal and singular states of processes and phenomena in the spatial and temporal scales of the landscape geosphere was established. The equifinal-singular model of geosystems is substantiated as a single form of integral natural systems of geography and biology, based on the concept of optimum physical-geographical process and the Shelford-Liebig universal law. A minor geosystem cycle which forms the subsequent sections, blocks, and a major cycle of matter and energy of the planet as a whole are revealed.