Introduction. The territory located within the Steppe Don (Rostov region) is relatively well studied in relation to the flea fauna of small mammals, with the exception of its northern part. The bulk of research was conducted in the first half - mid-twentieth century. However, during the time that separates this period and the present day, the natural environment and the animal population of the region have undergone a transformation, and there have been noticeable changes in the taxonomy of both fleas and their mammalian hosts. Our work covered a signiicant part of small mammal species and the territory of the Steppe Don region; it allowed us to clarify information about the specificity of parasite-host relationships and distribution for a number of species. Materials and methods of the research. Small mammals were caught in semi-desert, steppe, meadow and forest biotopes in all seasons 1997-1998, 2006-2008, and 2014-2020. The work covered a signiicant part of the species of small mammals and the territory of the Steppe Don region. The results of the study and their discussion. The data on 29 species of leas known from small rodents, insectivores and their nests are presented. In terms of distribution, the species form three groups: inhabiting the entire territory of the Steppe Don region; inhabitants of the wormwood-fescue steppe subzone; species limited to the subzone of the forb-cereal steppe. Conclusions. The study made it possible to clarify for a number of flea species information on the speciicity of host-parasite connections and distribution within the Steppe Don region. The lea list of small mammals includes 29 species. Megabothris turbidus, Ceratophyllus sciurorum, Ctenophthalmus proximus, Palaeopsylla soricis and Hystrichopsylla talpae were found here for the irst time.

Introduction: The paper considers the world experience of using CO₂ as a displacing agent in oil fields. An analytical assessment of determining the minimum mixing pressure for the conditions of Western Siberia has been carried out. Materials and methods of the research: The world experience of using CO₂ as an agent for displacement of residual recoverable reserves is described. The possibility of application based on empirical dependencies is estimated. The results of the study and their discussion: The results of the analysis of the development of enhanced oil recovery methods, in particular gas methods with the use of CO2, are presented. The results on additional oil production from the use of gas methods and the geography of distribution of these methods are presented. The main empirical relationships have been determined and a preliminary assessment of the applicability of CO₂ as a displacing agent has been carried out to increase oil recovery. Potential gas suppliers have been identified based on large CO2 sources in Russia. Conclusions: Recently, in connection with global warming, technologies for reducing CO₂ emissions, based on capturing industrial emissions and further using this gas as a displacing agent, have been developing in the world. The use of gas methods to enhance oil recovery on the territory of the Russian Federation is relatively small compared to other methods, and we can expect the emergence of new projects for CO₂ injection into the reservoir, using industrial emissions as a source of this gas.

Introduction. Experimental PVT studies of a multicomponent gas-condensate mixture to determine the loss of hydrocarbons in the presence of condensation water in the reservoir were carried out on recombined samples of separation gas, condensation water and saturated condensate. Materials and methods of the research. During the exploitation of an oil and gas condensate reservoir for depletion, the component composition (mixture of hydrocarbons and water vapor) of the produced gas condensate system changes, which affects the formation losses of hydrocarbons, as well as the properties of fluids and the dynamics of their phase behavior during field development. Experimental modeling of operating conditions under various thermodynamic states was carried out in order to determine the effect of condensation water on the amount of condensate recovery during development. The results of the study and their discussion. In the process of deposit formation, condensation waters are formed during geological time during the inversion of traps with gas and gas condensate deposits. In reservoirs at high pressures and temperatures, the amount of water vapor increases, which has a negative effect on the amount of formation losses of hydrocarbons. As a result of modeling on the experimental PVT installation, the influence of water vapor as a component of the hydrocarbon system on the phase behavior of condensate in the reservoir and on the value of the current reservoir losses in the reservoir was determined. Take into account that multicomponent hydrocarbon systems consist of a mixture of gas, condensate and water vapor, which signii-cantly changes the properties of the system and the dynamics of its phase state during development. Conclusions. Conducting multiple PVT - experiments determined the pressure of the beginning of condensation. From the obtained graphical dependence it can be seen that with the contact and differential research method, the beginning of condensate dropout is equal to the reservoir pressure, in the presence of water in the gas condensate system, the condensation process increases. In this case, the maximum condensation pressure is shifted towards the initial reservoir pressure. The nature of the "formation loss" curve indicates an intensification of the condensation process in the presence of condensation water in the well production. In the presence of water, condensate losses in the reservoir increased up to 5 %, respectively, the CFC value decreased.

Introduction. Underground gas storage plays an important role in changing gas consumption. The main factors in the creation of UGS facilities are the presence of large gas consumers and the availability of the necessary reservoirs. The total volume of gas in UGS facilities is necessary to cover the needs of industrial enterprises and social needs both for short time periods (day, week) and for a longer period. Materials and methods of the research. Using the method of numerical modeling of the operation of underground gas storage, it becomes possible to substantiate the optimal parameters of its operation and control gas leaks from the storage. The results of the study and their discussion. Mathematical modeling of the cyclic operation of UGS facilities allows using the known pressure in the gas cavity to calculate the mass of gas in the underground storage, and thereby control gas leaks. Conclusions. The presented mathematical model of the operation of a linear underground gas storage in an aquifer, its numerical and software implementation makes it possible to construct hysteresis diagrams (P / Z, M) of UGS facilities for analyzing the operation of a gas storage facility, which are convenient for analyzing the operation of a storage facility and monitoring the parameters of its operation.

Introduction. The subject of the research is the climatic conditions of the Western Elbrus region, as one of the leading factors in the recreational activity of this unique region of the North Caucasus. Already at present, more than 100 thousand organized and unorganized vacationers come here, mainly in the summer season. Moreover, the climatic features of this region have not yet been sufficiently studied. This is due to the lack of meteorological data (there is only one meteorological station in the region) and the lack of modern recreational studies of the climate of this region. Materials and methods of the research. This research was carried out on the basis of the author's field microclimatic data, available meteorological statistics, fund materials and literature data. During the recreational assessment of the region, special attention is paid to the radiation characteristics of the climate and the seasonal characteristics of meteorological elements. The results of the study and their discussion. The climatic conditions of the region are very diverse, which is determined by its complex orography, which forms a complex system of air circulation with the effect of windward and leeward slopes and determining the features of thermal fields, moisture fields, as well as changes in other climatic elements. Another important factor affecting the climate of the region is the absolute and relative altitude above sea level, which significantly affects the formation of high-altitude climatic, geobotanical and landscape zones. The variety and complexity of the relief, significant fluctuations in altitude, the originality of the regime of radiation and heat balances in combination with seasonal features of atmospheric circulation determine a wide variety of temperature fields, a complex distribution of precipitation, significant differences between the warm, growing season and cold and other climatic indicators important for tourism. Conclusions. The western Elbrus region has extremely diverse climatic conditions in comparison with other high-mountain regions on the northern slope of the Greater Caucasus, which is associated with its position on the border of the more humid western and more continental - central sectors. The combination of unique climatic characteristics and their diversity makes this region one of the most promising in the North Caucasus for the development of tourism, for the design of a balanced recreational model for the functioning of mountain areas.

Introduction: Considering all the growing trends associated with the deterioration of the natural environment, the priorities, inherent in the sustainable development model, are shifting towards the long-term preservation of the biosphere and natural potential. The key direction for this task implementation should be processes aimed at the development of resource conservation of natural assets. Materials and methods of the research: To assess the conjugation of production and degradation processes, it is proposed to use the contingency coefficient, which takes into account the multidirectional nature of these processes. The peculiarity of the connection between production processes with environmental and resource-saving parameters has been identified and presented in a graphical form. The results of the study and their discussion: The generalized research results show that the most accurate and effective for assessing the innate quality of natural resources is a multi-stage approach with elements of the predicted productivity of the i-th natural resource. The model of the productivity balance proposed by the authors allows to determine the change in the level of land productivity in order to prevent degradation processes. Conclusions: The calculations carried out in the research using the balance of nutrients showed a deficiency of nutritional chemicals in the soils of the Stavropol Territory. The authors concluded that to determine the type of nature management existing in a territorial entity, it is advisable to use the coefficient of environmental threat, applying it taking into account the peculiarities of ecological zoning.

Introduction: in the modern world, cities have become a place of concentration of the main part of the world's population. Under these conditions, urbanized territories act as capacious territories of tourist value. In this regard, it is important to study urbanized territories as areas of concentration of tourist and recreational activities. Materials and methods of the research: the problems of urbanization and the definition of urbanized territories are studied by many Russian and foreign scientists. Most of the works are devoted to the problems of cities and urbanized territories, agglomerations as centers and areas of population concentration, industrial and social spheres. In the field of tourism, the main attention in scien-tiic works is paid to the deinitions of tourist territories and recreation, as well as recreational zoning. There are also studies of the attractiveness of a tourist area, which usually use sociological and geographical approaches. The results of the study and their discussion: the article studies the concepts of urbanized and non-urbanized territories in Russia and in the world, as well as their differences. In addition, the definitions of "urbanized agglomeration", "tourist territories", "urbanized recreational zones" are given, and the definition of "urbanized tourist territories" is derived from the result. Conclusions: urbanized tourist areas are of great interest for research and at the present stage, researchers distinguish tourist areas, tourist recreational areas and urbanized tourist areas.

Introduction. Socio-economic transformations of living conditions of the population of Russia led to a change in the adolescents health indicators. There was an increase in the incidence of diseases determined by environmental quality. This article is analyzed the regional characteristics of the adolescent health status of Smolensk region (western part of Russia), including analysis of the current adolescent health status by incidence rates. Materials and methods of the research. The study is based on age-standardized incidence rates (agestandardized to the 2000 Russian population) among adolescents in Smolensk region between 1999-2016 years. For analysis, we took the indicators of the general incidence of adolescents in the most significant classes of diseases. We analyzed data using two algorithms - typological algorithm and integral ranking calculations. The results of the study and their discussion. As a result of mathematical cartographic modeling clusters were obtained that give an objective idea of adolescent health status. Integral ranking calculations determine districts with negative trends in health indicators associated with the environment. The use of multidimensional classifications allows, avoiding subjectivity in assessments, to analyze long-term data. Conclusions. The use of multidimensional classifications allows, avoiding subjectivity in assessments, to analyze long-term data. Cartographic visualization based on mathematical modeling makes it possible to effectively interpret the situation, opens up mechanisms for practical application in managerial decision-making in the healthcare sector. The results will be transferred to the Department of Health of the Smolensk region. Negative trends in changes in health indicators of adolescents associated with the state of the environment indicate an increase in environmental risks for the population of the Smolensk region.

Introduction. The subject matter of this study is an analysis of approaches for researching of metropolitan area’s development processes. The special attention is given to the problem of in-metropolitan and cross-metropolitan area’s development. The primary research goal is the original concept development of integrated multiscale study of transformable metropolitan area’s demographic space Materials and methods of the research. The study is based on traditional soviet-designed urban geography approaches for defining the basic terms and delimitation of metropolitan areas: As a first main criteria of area’s demarcation the hour and a half or two hours transport accessibility is used. It is suggested to use selectively the second common criteria - the presence of a big city core The results of the study and their discussion. The concept presents main idea, approaches and principles of spatialtemporal analysis of demographic and migration processes in metropolitan areas based on modern research tools. The authors believe that the proposed methodology allows to systematize disembodied data on Russian metropolitan area’s demographic development and reveals the major trends linked with a special and human resources synergy. It is substantiated the idea that metropolitan areas should be classified based on demographic process’s patterns in city cores, suburban and outlying areas. A multiscale mode of analysis allows to reveal not only the common patterns of demographic development, but also determine local and regional factors which are implicitly making impact on a complex picture. Conclusions. Despite the well-understood metropolitan area’s subject-matter there is no integrated studies in Russian scholarly traditions which are aimed to have an integrated analysis of metropolitan area’s demographic development based on spacial features. It is proposed the view that the demographic development is a leading factor of metropolitan area’s development. The proposed concept has revealed the key methodological aspects of subject studies.

Introduction. To investigate dangerous weather phenomena associated with convection in the atmosphere, actual upper-air sounding data are required. However, the network of upper-air radio sounding of the atmosphere in our country cannot provide information consumers with a sufficient frequency of measurements in time and the required density of points in the country. In this work, it is proposed to use the output of the global atmospheric model GFS NCEP instead of the upper-air sounding data, which is especially important for predicting convective phenomena. The possibility of such a replacement is assessed by the methods of correlation analysis. Materials and methods of the research. The research materials are the output of the global atmospheric model GFS NCEP, which includes stratified fields of meteorological elements: air temperature, dew point temperature, wind speed and direction, with an increasing lead time of 24, 48, 60, 84 and 132 hours. The actual data were obtained from the aerological sounding at the meteostation «Mineralnye Vody» in the Central part of the North Caucasus. The degree of their coincidences was estimated by correlation analysis methods. The results of the study and their discussion. In the course of the study, the correlation coefficients were obtained between the predictive (model) and actual data of air temperature, dew point temperature, wind direction and speed. It was found that a consistent increase in the lead time of forecasting meteorological fields up to 132 hours did not lead to a noticeable decrease in the correlation coefficients between them. This indicate to the preservation of the predictive potential of the data of the global atmospheric model up to average term meteorological forecasts. Conclusions. The results obtained show the possibility of using the data of the fields of meteorological elements from the global model of the atmosphere with increasing lead time when predicting dangerous weather phenomena, modeling thunderstorm-hail clouds for operational use with an active impact on dangerous phenomena.

Introduction. The article is devoted to calculation and analysis dynamics and modern temperature regime of calendar summer of over Stavropol height, which is one the main ground features of the Central Pre-Caucasus. At the end of the last and the beginning of this century, there was almost unanimous opinion on the unique and universal «global» warming. Later, with the expansion of thematic integrated approach, the understanding of the problem has significantly enhanced and changed. To the present day the most common is an idea that the main contribution into increasing of average year air temperature gives the winter season. Within the period of 1970-2019, every year the mean annual temperature in Stavropol region showed a considerable positive anomaly, which in certain years exceeded 2°C above the climatic normal on the average across the territory of the region. The main focus of the present article is focused on the study result of the summer air temperature change and its effects on the increasing of average year air temperature. Materials and methods of the research. Some characteristic features of air temperature variations according to the observation data of the weather station Stavropol for the period of 1921 -2020 are analyzed. The characteristic of prevailing tendency of long-term air temperature variations are given. The trend of the average air temperature are estimated by the regression analysis. The results of the study and their discussion. It was made the detail analysis temperature regime for all summer months, including of average and extreme air temperature, the frequency of days with air temperature higher/lower of certain degree, variations of months and season air temperature and temperature gradients across the absolute maximum and absolute minimum for all summer months over the last 20 years. Conclusions. The increasing of summer air temperature and its large contribution into the increasing of average year air temperature are shown. For practical purposes it is proposed to use the wide range of modern air temperature characteristics of summer season.

Ntroduction: Long-term monitoring of the quality of surface waters in a specific area reveals regional features of the formation of the chemical composition of natural waters and the ranges of quantitative characteristics of the studied compounds of pollutants. Materials and methods of the research: The work studies the long-term variability (2005 - 2019) of the content of dissolved forms of manganese and molybdenum compounds in the water of four rivers: Terek, Malka, Baksan, Cherek. The choice of these metal compounds is due to the assumption of their signiicant content in the rocks that make up the drainage basin of the Terek River and their active participation in geochemical processes. Determination of the content level of the dissolved forms of these compounds was carried out by the atomic absorption method using a spectrometer with electrothermal atomization "MGA-915M". Excel was used for mathematical and statistical data processing. The results of the study and their discussion: The results of the analysis presented in Table 1 show that the range of fluctuations in the concentrations of the compounds of these metals in the studied objects and in the middle and lower reaches are different. This indicator is an important characteristic of the series and provides the irst general idea of the difference in indicators within the population. The revealed levels of the content of heavy metal compounds (HM) in the water of rivers for the studied long-term period are illustrated by histograms. Conclusions: In the water of the Baksan, Terek, Malka, Cherek rivers for the period 2013- 2019, there is a tendency towards an increase in the level for the content of manganese compounds, both in the middle and in the lower reaches. Exceeding the maximum permissible concentrations of dissolved forms of manganese and molybdenum compounds is mainly associated with the peculiarities of the lithological structure of the catchment basins. Increased values of the content of molybdenum are observed in the water of the Baksan river in the middle course, which is explained by the location of the tailing dump of the mining and processing plant in the catchment area of the river.

Introduction: Long-term monitoring of the quality of surface waters in a specific area reveals regional features of the formation of the chemical composition of natural waters and the ranges of quantitative characteristics of the studied compounds of pollutants. Materials and methods of the research: The work studies the long-term variability (2005 - 2019) of the content of dissolved forms of manganese and molybdenum compounds in the water of four rivers: Terek, Malka, Baksan, Cherek. The choice of these metal compounds is due to the assumption of their significant content in the rocks that make up the drainage basin of the Terek River and their active participation in geochemical processes. Determination of the content level of the dissolved forms of these compounds was carried out by the atomic absorption method using a spectrometer with electrothermal atomization “MGA-915M”. Excel was used for mathematical and statistical data processing. The results of the study and their discussion: The results of the analysis presented in Table 1 show that the range of fluctuations in the concentrations of the compounds of these metals in the studied objects and in the middle and lower reaches are different. This indicator is an important characteristic of the series and provides the first general idea of the difference in indicators within the population. The revealed levels of the content of heavy metal compounds (HM) in the water of rivers for the studied long-term period are illustrated by histograms. Conclusions: In the water of the Baksan, Terek, Malka, Cherek rivers for the period 2013- 2019, there is a tendency towards an increase in the level for the content of manganese compounds, both in the middle and in the lower reaches. Exceeding the maximum permissible concentrations of dissolved forms of manganese and molybdenum compounds is mainly associated with the peculiarities of the lithological structure of the catchment basins. Increased values of the content of molybdenum are observed in the water of the Baksan river in the middle course, which is explained by the location of the tailing dump of the mining and processing plant in the catchment area of the river.