Home – Home – Jornals – Chemistry for Sustainable Development 2023 number 1

A river seismic survey technology based on using pneumatic water sources and autonomous seismic recorders, which are installed on the shore and configured for continuous seismic recording, is developed at the Geophysical Survey of the Russian Academy of Sciences (GS RAS). In recent years, several thousand kilometers of profiles have been worked out by the CDP-2D method on the rivers of East Siberia: Lena, Nizhnyaya Tunguska, and Vitim. Previously, only 6- to 10-second seismograms were used to study the structure of the upper part of the Earth’s crust. At the same time, the deep structure of the Earth’s crust in the vast territories of East Siberia remains poorly understood due to the high cost of research. The river seismic survey data are used on a profile section worked out in the lower reaches of the Lena River to demonstrate the possibility of studying the structure of the Earth’s crust to the full depth, including the Moho discontinuity. For this purpose, the archival seismic records are reprocessed the construction of montages of seismograms of increased duration (up to 23 s). The low-amplitude oscillations of reflected waves from deep boundaries are distinguished due to multiple summation, which is much larger than in conventional seismic surveys. The equipment used in this study has a sufficient dynamic range, and a high magnification is achieved by increasing the binning area. Wind noise reduces the quality of time sections of the upper part of the Earth’s crust, but does not worsen the section at great depths, so this material should not be excluded from processing. The river seismic surveys carried out using the technology developed at the GS RAS on the rivers of East Siberia within about 2700 km contain data that make it possible to build deep sections up to the Moho discontinuity, and this work needs to be done.

We propose a technique for the extended processing of cross-well seismic data for reflection imaging. Based on the analysis of the wave field and synthetic modeling, a graph for processing cross-well data is developed to separate the reflections in the presence of the boundary of a sharp change in the velocity of elastic waves. The migration of the reflection waves from the time scale to the depth one is performed by solving a forward problem for each source-receiver pair. As a result, the position of the reflection points is calculated, after which all traces are stacked based on the binning grid. The input information for performing the migration and solving a forward problem is the velocity characteristic of the massif, which is calculated using traveltime tomography on direct body waves obtained from the same data set of cross-well survey and vertical seismic profiling. The resulted depth seismic section has a much higher resolution than that of vertical seismic profiling and ground-based shallow seismic studies. This opens up the possibility of identifying various small-sized natural or technogenic objects in the interwell space. Practical implementation was carried out at the Verkhnekamskoe potassium salt deposit.

Calculated carbon dioxide broadening coefficients of sulfur dioxide lines at a room temperature are presented. The calculations are performed for the ν₁ + ν₃ band, rotational quantum numbers vary in the ranges of J up to 100 and of K_a up to 20. Based on the experimental data the semi-empirical method parameters are determined; the computed broadening coefficients are in good agreement with the literature data.

Contributions of stable dimers to the water continuum in the 1600 and 8800 cm^-1 bands are examined. They are found as the difference between experimental data and the calculation data within the asymptotic line wing theory taking into account the violation of the longwave approximation for the molecular centers of mass. The stable dimer contribution is close in value to the contribution due to all other pair interactions and decreases with increasing temperature. The estimate of the equilibrium constant of the dimer formation reaction is derived proceeding from the temperature dependence of the classical interaction potential of water molecules describing the temperature behavior of the second virial coefficient.

In 2021, concentrations and elemental chemical composition of the inorganic part of solid snow impurities were studied on the territory of the Norilsk Industrial District. Based on the analysis of these data, a list of priority polluting chemical elements is compiled (Ni, Cu, Cd, Co, Sn, Pb, B, and Zn) and a method for quantifying the contribution of atmospheric emissions from Nadezhda Metallurgical Plant to aerosol pollution of the territory is suggested. In the sub-latitudinal direction, emissions from this plant predominate in dust pollution of the air at a distance of up to 7 km from the source.

In the Arctic, global warming is 2-3 times faster than over other regions of the globe. As a result, noticeable changes are already being recorded in all areas of the environment. However, there is very little data on such changes in the Russian Arctic. Therefore, to fill the gap in the data on the vertical distribution of the gas and aerosol composition of air in this region, an experiment was carried out on the Tu-134 Optical laboratory aircraft in September 2020 to sound the atmosphere and water surface over the water areas of all seas in the Russian Arctic. This paper analyzes the spatial distribution of methane. It is shown that during the experiment its concentration was the highest over the Kara Sea (2090 ppb), the lowest over the Chukchi Sea (2005 ppb). The East Siberian and Bering seas were slightly different from the Chukchi Sea in its content. Average values of CH₄ are characteristic of the Barents (2030 ppb) and the Laptev Seas (2040 ppb). The difference in the concentrations between the level of 200 meters and the free troposphere reached 150 ppb over the Kara Sea, decreased to 91 and 94 ppb over the Barents and Laptev Seas, and further decreased over the East Siberian, Chukchi and Bering Seas to 66, 63 and 74 ppb, respectively. Horizontal heterogeneity in the distribution of methane over the Arctic seas is the greatest over the Laptev Sea, where it reaches 73 ppb. It is 2 times higher than over the Barents and Kara Seas, and 5-7 times higher than over the East Siberian and Bering Seas.

In this work, we present the time series of regular observations of the total ozone content over Tomsk with three independent instruments over the period from 2006 to 2020. The main statistical characteristics of these time series are determined. We carried out the comparative analysis of these time series with each other and, in particular, the analysis of long-term annual average behaviors. The causes for the discrepancies of these measurements are discussed.

The results of numerical simulation of a scanning lidar return for the case of sounding a cloud containing quasi-horizontally oriented plate-like crystals are presented. It is shown that a vertically oriented lidar is "blinded" by the specular component of the scattered radiation, while the scanning lidar return is sensitive to the crystal shape. The results of the numerical calculation confirm a sharp increase in the depolarization ratio in the vicinity of scanning angles of 30°, which was earlier observed in experiments. It is found out that this depolarization ratio enhancement is a marker of the perfect shape of a plate-like crystal and can be used to interpret experimental data.

Forest are among the main places on Earth where carbon is collected and accumulated. However, quantitative instrumental assessment of carbon fluxes is possible only for small-scale areas. When solving the scaling problem, we use machine learning methods, which can transform the values of the intensity of the Earth’s surface reflectance in different spectral intervals into ground-based in situ observations. The assessments of carbon fluxes by a regression neural network model of the multilayer perceptron type trained on FLUXNET network data for a station located in a boreal coniferous forest (56.4615°N, 32.9221°E) are presented. Using vegetation indicies NDVI and EVI measured by MODIS Aqua, air temperature at an altitude of 2 m, and total precipitation as input data, the model estimates of gross primary production (GPP), net ecosystem exchange (NEE), ecosystem respiration (TER), and some other parameters describing water and energy fluxes are calculated. Statistical estimation provides high values of the correlation coefficient and Nash-Sutcliffe coefficient on test dataset: R ≥ 0.9 and NSE ≥ 0.87 for GPP and TER; R = 0.4 and NSE = 0.15 for NEE.

A computational technology for studying aerosol-radiation interactions and calculating regional estimates of the direct and semi-direct radiative effects of biomass burning (BB) aerosol based on calculations with the CHIMERE chemistry-transport model coupled to the WRF meteorological model is described. The technology was applied to the numerical study of the radiative effects of Siberian BB aerosol in the eastern Arctic in the period of July 16-31, 2016. The simulation results show that Siberian BB aerosol had a significant cooling effect on the atmosphere in the eastern Arctic in that period due to the direct radiative effect (DRE), the value of which at top of the atmosphere was, on average, -6.0 W × m^-2, being minimal over the snow-ice cover of the ocean (-1.2 W × m^-2). At the same time, it is found that the contribution of the Siberian BB aerosol DRE to the radiative balance of the Arctic atmosphere is compensated to a certain extent by the semi-direct radiative effect (SDRE), which is positive on average (2.0 W × m^-2). The SDRE is formed as a result of the aerosol feedback on meteorology during many hours of the evolution of the atmosphere and plays the most important role over the snow-ice cover, where it exceeds the DRE in absolute value. It has been shown that the SDRE of Siberian BB aerosol in the performed numerical experiments is mainly due to the process of scattering (rather than absorption) of radiation by aerosol particles.

The results of the analysis of atmospheric blockings in the regions of the Northern Hemisphere (NH) under general warming during recent decades are presented. In particular, estimates of the total increase in the duration of summer atmospheric blockings in the NH with an increase in the hemispheric surface air temperature for the period 1969-2022 are obtained using observations and reanalysis data. Significant coherence of the most long-term changes of the integral index of summer atmospheric blocking activity for the Russian regions and for the NH as a whole is noted. A statistically significant correlation of the duration of atmospheric blockings of the area of wildfires in the Russian regions with related gas and aerosol emissions into the atmosphere is estimated based on satellite and reanalysis data. Estimates of the correlation of the Siberian fires with anomalies in the content of atmospheric impurities, including black carbon, in the Arctic regions are presented.

We consider data from laboratory simulation of the dynamics of sulfate origination in atmospheric haze particles during oxidation of SO₂ captured from the gas phase in the presence of Mn/Fe ions. The rates of sulfate origination under dark conditions of these experiments (tens of micrograms m^-3 × h^-1) have been found to correspond to a previously unknown mode of catalytic reaction. Its key element is the branching of chains involving the intermediate HSO₅^- ( Caro’s acid) and Mn²⁺ ions. Estimates are given for the rate constant of this aqueous-phase reaction, and a criterion for separation the slow and degenerate-branched (fast) modes of SO₂ oxidation is considered. The observed rate constant of sulfate origination in particles k^*_obs = 1.4 L × mol^-1 × s^-1 ( T = 298 K). The calculations of the dynamics of sulfate origination agree with data of laboratory experiments (smog chamber data). Their results also do not contradict the monitoring data on sulfate content in the haze over Beijing (December 2016).

The experimental setup and the technique are suggested for sequential feeding of controlled doses of Hg, benzene, and toluene vapors into the measuring cell of a DOG-07 analyzer with a mercury capillary lamp based on the transverse Zeeman effect as a radiation source. It is shown that when benzene or toluene vapors with concentrations of up to 10 mg/m³ are added to the measuring cell with mercury vapors in a concentration of more than 30 ng/m³, there is no error in the measured Hg concentration. With the introduction of a higher concentration of benzene vapors, an increase in the measured concentration of Hg is observed. The introduction of a higher concentration of toluene vapor into the measuring cell leads to a decrease in the measured concentration of Hg.

This article is devoted to a study of the properties of an implicit method for Abel type integral algebraic equations. An Abel type integral equation with stiff components is used for examining the properties of these methods and the stability domains are constructed. Numerical calculations confirming the results obtained are performed. In this article, a fractional “stiff” problem is proposed to study the stability of the mathematical objects considered.

Numerical differentiation of functions with large gradients is investigated. It is assumed that a function contains a component known up to a factor and responsible for the large gradients of the function. Application of classical formulas for calculating derivatives to such functions may lead to significant errors. Special-purpose formulas are studied for numerical differentiation on a uniform grid which are exact for a boundary layer component. Conditions are formulated under which an error estimate of a difference formula for a derivative does not depend on the gradients of the boundary layer component. In the case of an exponential boundary layer, when calculating a derivative of an arbitrarily given order error estimates that are uniform with respect to a small parameter are obtained. The results of numerical experiments are presented.

For optimal estimation of quantities of interest from observational data and a model (optimal filtering problem) in the nonlinear case, a particle method based on a Bayesian approach can be used. A disadvantage of the classical particle filter is that the observations are used only to find the weight coefficients with which the sum of the particles is calculated when determining an estimate. The present article considers an approach to solving the problem of nonlinear filtering which uses a representation of the posterior distribution density of the quantity being estimated as a sum with weights of Gaussian distribution densities. It is well-known from filtration theory that if a distribution density is a sum with weights of Gaussian functions, the optimal estimate will be a sum with weights of estimates calculated by the Kalman filter formulas. The present article proposes a method for solving the problem of nonlinear filtering based on this approach. An ensemble π-algorithm proposed earlier by the author is used to implement the method. The ensemble π-algorithm in this new method is used to obtain an ensemble corresponding to the distribution density at the analysis step. This is a stochastic ensemble Kalman filter which is local as well. Therefore, it can be used in high-dimensional geophysical models.

The paper is devoted to the mixed finite element method for the equation ΔΔυ + κ²υ = ƒ, x ∈ Ω, with boundary conditions υ = ϑυ/ϑν = 0 on ϑΩ, where ν is the normal to the boundary and κ ≥ 0 is an arbitrary constant on each finite element. At κ ≡ 0 residual type a posteriori error bounds for the mixed Ciarlet-Raviart method were derived by several authors at the use of different error norms. The bounds, termed sometimes a posteriori functional error majorants, seem to be less dependent on the constants in the general approximation bounds and are more flexible and adaptable for attaining higher accuracy at practical implementation. In this paper, we present a posteriori functional error majorants for the mixed Ciarlet-Raviart method in the case of κ ≠ 0 and having large jumps. Robustness and sharpness of the bounds are approved by the lower bounds of local efficiency.

A construction of the original HLL method for solving problems of relativistic hydrodynamics by using a piecewise-parabolic reconstruction of the physical variables is described. The resulting numerical method makes it possible to reproduce the numerical solutions with small dissipation at the discontinuities. The method is verified in problems of discontinuity breakdown in one-dimensional and two-dimensional formulation. The accuracy of the numerical scheme is studied in one-dimensional discontinuity breakdown problems. The method is also tested in typical astrophysical problems: interaction of relativistic jets, collision of clouds at relativistic speeds, and supernova explosion.

A two-dimensional eikonal equation which describes the propagation of tsunami wave fronts is considered. The paper presents the spatial form of an initial source of waves which causes accumulation of wave energy along the coastline of a round island. The theoretical results are confirmed by numerical simulation with a shallow water model of tsunami wave dynamics.

A realization of an adaptation criterion in the technology of generation of three-dimensional structured grids designed for the numerical solution of differential equations modeling the vortex processes of multi-component hydrodynamics is described. Earlier the adaptation criterion was realized for volumes of revolution and volumes of revolution deformed by other volumes of revolution. The adaptation criterion is realized within a variational approach for the construction of optimal grids satisfying optimality criteria: closeness of the grid to a uniform and orthogonal one and adaptation to a given function. In the realization of the criterion, the technology is supplemented by a new way of boundary nodes computation and an algorithm for the construction of an admissible set for minimization of a discrete functional formalizing the optimality criteria. Examples of grids adapted to a given function and its first derivatives are given.

The article deals with a boundary value problem of mathematical physics describing the unsteady process of diffusion of a reacting gas to a spherical coal particle located in the atmosphere of a mine. The solution of the boundary value problem is based on self-similar transformations which are a special case of group analysis. Formulas for determining the concentrations of the reacting gas in the vicinity of the coal particle and on its surface are obtained. Graphs of the dependencies of the burn-out time of the coal particle on a number of its parameters are constructed, and the fields of the reacting gas concentration at various stages of combustion of the coal particle are revealed.

The unique ecosystem of Lake Baikal is made up of a diverse, mostly endemic fauna. The spongiofauna of the lake is represented by two families: endemic Lubomirskiidae and cosmopolitan Spongillidae. In recent years, the situation on Baikal has been characterized as catastrophic, especially when it comes to the littoral. There are numerous reports about the oppressed state of the Baikal sponges and the decrease in their numbers in many areas of the lake. The question is raised that not only nature protection, but also nature restoration measures are needed. The review discusses the basic techniques and methods of growing sponges. 4 main approaches to the cultivation of sponges ex situ and in situ are described in the most detail in world practice: 1) from larvae; 2) from primmorphs (sponge cell cultures); 3) from resting stages (gemmules and reduction bodies); 4) from explants (fragments of living tissue separated from the parent organism). The review discusses attempts to apply the described approaches used in world practice for growing Baikal sponges. Based on the analysis of the literature, it is assumed that the use of the most effective of the above approaches will make it possible to develop a technology for obtaining Baikal sponges.

In the last decade, mass death of endemic sponges has been observed in the coastal zone of Lake Baikal. This paper presents observations of the Baikal sponge fauna within the transects established throughout Baikal in 2015. Based on visual descriptions, the types of damage to Baikal sponges are characterized. A downward trend was revealed from 2015 to 2020 in the projective cover of the bottom with healthy sponges of various body shapes: encrusting - 3.6 times, branched - 2 times and globulous - 4 times. The reduction in the total area occupied by healthy and damaged sponges of various forms occurred more than 2 times, from 238 m² to 110 m².

Results of bird counts from 1880 to 2019 (intermittently, and mainly since 1960), averaged over the first half of the summer (16.05-15.07) were analyzed to identify the spatial-typological structure and organization of the corvid assemblage of Northern Eurasia. 352 researchers have been involved in collecting of this material over 110 years. Data processing was carried out using multivariate statistics methods, including cluster analysis and linear qualitative approximation of connection matrices, as well as gradient and expert approaches. As a result, the main territorial trends in corvid assemblage and the natural and anthropogenic regimes correlating with them have been identified, and the relationship between the spatial variability of the assemblage of these birds and the heterogeneity of habitats has been assessed. Quasifractal spatial differentiation of assemblage was shown. The analysis of corvid groups identified using factor classification gave an unsatisfactory result of approximating the spatial and typological variability of their assemblage in terms of abundance at the level of landscape tract type and a rather high information content of species classification by abundance in all 8144 habitats. A satisfactory explanation for the heterogeneity of corvid assemblage was achieved only after averaging the abundance indices over landscape groups. It was not possible to get an idea about them using cluster analysis, and only the use of gradient and expert (speculative) approaches, followed by an assessment of the information content of the representations, can be considered acceptable for obtaining such generalizations. The use of these techniques increased the assessment of the information content of representations by averaged abundance indicators by seven times in terms of explained variance and three times in terms of the multiple correlation coefficient. At the same time, structural classifications by species, and especially by territorial communities, acquire a two-dimensional reticular (network) form. The formalized classification of corvid species according to the similarity of distribution is seven, and the assemblage is almost twice as informative as expert-speculative representations.

Based on the results of winter bird surveys conducted in 70 habitats over 12 years, in the period from 1982 to 2002, a hierarchical classification and a structural graph of the similarity of ornithocomplexes of the southwestern plains of Western Siberia and Northern Kazakhstan were compiled. The hierarchical classification contains 3 types and 9 subtypes of the ornithocomplexes. The similarity graph (the spatial-typological structure of the ornithocomplexes) is constructed at the subtype level and is represented by three trends. The first, the most significant of these series is determined by the influence of urbanization, afforestation and partly by the development of the reed tier. The second series of territorial changes of ornithocomplexes is associated with changes in the built-up and anthropogenic feeding of residential habitats. The third row is formed under the influence of afforestation and overgrowth. The characteristics of ornithocomplexes subtypes are compared, which contain information on the three most numerous bird species (leaders in abundance), their share in the community, population density, as well as background species richness. Based on the assessment of the degree of coincidence of the similarity of ornithocomplexes and environmental factors, the hierarchy of the impact of the main anthropogenic and natural factors determining the formation of the winter bird population is established. Regional specifics and seasonal changes in the significance of environmental factors in the formation of winter ornithocomplexes of the Tobolo-Irtysh forest-steppe and steppe are established.

Climate changes entails an increase in the forests burning throughout the whole boreal zone. We have studied the long-term dynamics of fire rate and post-fire recovery of vegetation cover productivity in the pine forests of Central Siberia, and analyzed the dependences of the fire frequency and the burnt areas on climatic variables. Methodically, the work is based on a combined analysis of data from ground surveys, remote sensing (spectroradiometric and gravimetric surveys by Terra / MODIS and GRACE satellites), and coupled analysis of dendroecological data and environmental and climatic variables. The main impact on the fire frequency and burnt areas is due to the moistening conditions (total precipitation, soil moisture, aridity index scPDSI) in the period preceding the fire. The correlations of combustibility parameters with air temperature are lower than with humidification conditions. It is shown that soil moisture gravimetry data can be used in assessing the risk of forest fires. A decrease of fire Return intervals from 33 years to 20-25 years in the period from the 18th to the 20th century was revealed. In the second decade of the 21st century, both catastrophic (more than 1 million ha) forest fires and a significant increase in flammability were observed: the number of fires and the area of burnt areas increased, respectively, by 3.5 and 3.0 times. A high level of correlation has been determined between the growth index of pine trees and the vegetation cover productivity indices (gross (GPP) and net (NPP) productivity) generated from remote sensing data. The result obtained indicates the applicability of the indices in the studies of the forest stands productivity. Significant trends in flammability in the 21st century, both in terms of the frequency of fires and the areas covered by fire, have not been identified. The productivity of the vegetative cover on burnt areas, as well as the value of the index of radial increment of pine trees, quickly (within ~ a decade) recovers to pre-fire values, which indicates that northern pine forests retain their carbon-storing function under conditions of climate change and increased fire rate.

The results of the evaluation of the effect of experimentally dosed salinization and salinization with a simultaneous moderate increase in temperature on somatic indices, biochemical blood parameters and survival of perch Perca fluviatilis fingerlings are presented. The limit of salinity tolerance for perch fingerlings used in the experiment turned out to be a mineralization value of 8 g/l. An increase in temperature led to a decrease in the tolerance limit of perch fingerlings during salinization to 5.3 g/l. In conditions of elevated temperature and mineralization, maximum mortality was noted, the lowest values of the fatness coefficient and the hepatosomatic index of fish, indicating the depletion of experimental individuals, which was determined by the revealed violations of water homeostasis. An increase in energy costs with an increase in temperature is consistent with the data of an increase in the load on the excretory system of fish due to an increase in the permeability of fish tissues, which leads to a decrease in the content of basic inorganic ions in blood plasma. At background temperature, chronic exposure to increased mineralization also leads to depletion of the metabolic reserves of the fish body and the predominance of catabolic processes, which is confirmed by the low content of total protein and protein metabolism metabolites in blood plasma.

The results of studies of the dynamics of productivity, photosynthetically active radiation and evapotranspiration according to Terra Modis data for 5 test plots in the near-channel part of the floodplains of the Kargy river (a glycophyte, a swampy valley and a valley meadows), as well as willow thickets along the banks of the Mugur river, are presented. Analysis of long-term changes in meadow vegetation from 2000 to 2021 in the study area showed a general positive trend in gross productivity and differences between communities. Against the background of an increase in actual evapotranspiration (by 43 %), there is a decrease in potential (by 10 %), which indicated the drying up of the study area. Seasonal maxima of meadow productivity were observed in 2014, 2016 and 2020-2021. The years 2001, 2003-2004, and 2009 turned out to be critical for meadow vegetation. A weak positive correlation was found between the gross productivity of vegetation and the evapotranspiration of the territory, and a stronger one with photosynthetically active radiation. The seasonal dynamics of productivity corresponded to the meadow type of vegetation.

The reactions of leaves of balsam poplar (Populus balsamifera L.) on the impact of emissions of aluminum smelters were analyzed. The results of comparative analysis of mineral phase distribution on the surface of poplar leaves in the influence zone of Bratsk, Irkutsk, Sayanogorsk, Krasnoyarsk and Novokuznetsk aluminum smelters are presented. Newly formed minerals similar in composition to fluorite and gypsum were found in stomata of poplar leaves. Calcite crystals were found in large quantities in the conductive system of leaves. The formation of a biogeochemical calcium barrier in the stomata of poplar leaves, through which the neutralization of fluorine and sulfur compounds into inert minerals is assumed.

The article reports the geochemical characterization of soils, vegetation, and groundwater of the recultivated spoils of three coal deposits. Recultivation was carried out 30-40 years ago, and then the spoils were left for self-overgrowth without any additional measures. A common pattern for all sites is the presence of carbonaceous particles, their oxidation leads to an increase in temperature in the spoil rocks. The sum of biologically active temperatures exceeds the values for natural soils of undisturbed areas. Technogenic landscapes are characterized by a smaller share of moisture-loving forest and pratal species, compared to the reference areas. Hydrogeochemical anomalies practically do not go beyond the flooded borrow excavations of spoils. Reclamation by applying a fertile soil layer provides minimization of the negative effects associated with an increase in the temperature of spoil soils and accelerates the remediation of regional plant communities.

Results of the field studies of mercury emission from the cyanation waste dump in the oxidation zone of the Novo-Ursk pyrite polymetallic deposit (Ursk settlement, the Kemerovo Region) are presented. Mercury content in the surface atmospheric layer above the dump surface is determined to vary within the range of 20-3600 ng/m³, while the diurnal average maximum permissible concentration (MPC_d) is 300 ng/m³, thus this value is exceeded in some sites by a factor of 12. The regional background above the dump surface is exceeded by a factor of 570 on average. Comparison between the morning and evening measurement results shows that mercury concentration increases in the evening. This is due to the active emission of mercury under the action of solar radiation and heating of the dump surface. Numerical models of mercury propagation are constructed using the methods of mathematical modelling. According to the model built up on the basis of the maximal measured concentrations, the whole territory of Ursk settlement is within the zone of very high mercury vapour concentrations. Calculation over the averaged concentrations shows that the safe level is achieved at a distance of 600 m from the dump, but within the boundaries of the settlement. The obtained results provide evidence of the danger of mercury action on the population of the settlement and pose the goal of more detailed investigation of air composition over old gold mining waste storage facilities.

Currently there is no agreement among the researchers worldwide about the mechanism of MFI-type zeolites deactivation due to coke accumulation in the areas of coke localization. This problem does not allow answering the question about the stability of these zeolites and their resistance to the reversible deactivation by coke. Our research provides the solution to this problem using physical and chemical methods: the electron paramagnetic resonance, X-ray photoelectron spectroscopy, thermal analysis and catalytic method of methanol conversion into hydrocarbons. We show that the key mechanism of coke formation is carbenium mechanism. Deactivation of zeolites occurs mainly due to the coke accumulation on the external surface of crystals of MFI-type zeolites. The contribution of “hydrocarbon pool” mechanism is negligibly small compared to the contribution of the carbenium mechanism of olefin formation by the dehydration reaction. This understanding allows increasing the stability of MFI type zeolites to coke formation by removing the acidic centres from the external surface of the crystals.

The effect of high-temperature treatment (900 ^oC) of N339 carbon black in the presence of carbon dioxide, followed by low-temperature treatment (-5 ^oC) in a mixture of oxygen with ozone, on its properties was studied. As a result of complex oxidative action, a carbon material is formed with textural properties that are several times higher than the levels of values characteristic of the original carbon black. The oxygen content in the final material can vary from 19 to 35 wt. %, which suggests that it is promising for use as a high-performance pigment.

The conditions for the formation of Pickering emulsions in the crude oil-water system were studied using cellulose nanocrystals with partially acylated surface as a stabilizer. Biodegradation of the obtained emulsions by natural microorganisms was investigated depending on the ratio of components in the emulsion. The formation of stable emulsions was evaluated depending on the nanocellulose concentration. At a low content of cellulose nanocrystals, the stability of the emulsion is achieved only with an increase in the concentration of the background electrolyte. Oil dispersing in water allows conserving the contact between the air and water phases, which promotes efficient biodegradation of oil due to an increase in the area of contact between oil microdrops and water. According to chromatographic analysis, the residual content of hydrocarbons in the emulsion is 20-25 % after incubation with an inoculant of microorganisms for 30 days. This method enhances the stability of oil dispersion, which promotes an increase in the rate of its biodegradation on various water surfaces.

The morphology and age of cryogenic deformations (cryoturbations and ground wedges) in the Holocene floodplain sediments of river valleys in the Selenga River basin within the areas of seasonal, discontinuous, sporadic, and isolated permafrost were studied. Late Holocene ground wedges and cryoturbations were identified in the seasonally frozen layer of floodplain sections of the Itantsa, Il’ka, and Orkhon rivers. The time of formation of the cryogenic deformations was determined on the basis of detailed morphological descriptions and dating of low and high floodplain sediments of these rivers. The age of the alluvium with cryoturbation on the low floodplain is less than 2 kyr. Cryogenic deformations on the high floodplain formed in the Late Holocene (the last 4.2 kyr). It was determined that alluvium layers with cryoturbation are underlain by moderately wet to satiated wet loamy sands and loams. Cryogenic deformations are considered a paleoclimatic indicator of the Late Holocene in the Transbaikal region and northern and central Mongolia.

The article presents the results of physical modeling of soil freezing in laboratory. The samples of silty clay of kaolinite composition were used as model soil. The main characteristics of the component and phase composition of water, as well as the heat and mass transfer and deformation properties of the soil were experimentally determined. During the physical modeling, parameters of the freezing process, differential heaving of frozen and shrinkage of thawed zones, heat and moisture transfer, and pore pressure were monitored. The appearance of segregated ice in the freezing soil, layered axial and horizontal deformation, and the dynamics of density and water content of water-saturated soil samples over time were determined using position markers and time-lapse video.

The possibility of using the dielectric method to determine the unfrozen water content in the frozen natural mineral soil was proved by establishing the relationship between the contents of soil water forms measured by the dielectric, calorimetric, and contact methods. The unfrozen water content in the sample was measured by the calorimetric and contact methods. In the dielectric method, it was estimated by measuring the maximum content of bound water. The unfrozen water content measured by the calorimetric method in the soil samples with different initial water contents varied within 17 %. The unfrozen water content measured by the contact method and the bound water content determined by the dielectric method were within the ranges of values determined by the calorimetric method. The values of the bound water content obtained by the dielectric method and the unfrozen water content obtained by the contact method differed by no more than 17 %.

This paper reports on the hydrogeological conditions and groundwater regime in the Lena River floodplain near Yakutsk. The published and archive materials, including field data collected by the authors in 2013-2021, were analyzed. Data from more than 70 boreholes were examined to characterize permafrost and hydrogeological conditions in the area. Data on groundwater level monitoring in the reclaimed area of the floodplain were also used. Over 250 sample analyses were interpreted to characterize the chemical composition of surface and ground waters. The results suggest that suprapermafrost waters in the high floodplain are recharged both by infiltration of river water and by a transit water flow under the river channel hydraulically connected to floodplain taliks. The seasonal and spatial variability of the chemical composition of waters was revealed in the Lena River and in the studied taliks. The surface and ground waters of the Quaternary aquifer on the east bank of the Lena River are characterized by the lowest total dissolved solids (TDS) concentration (0.1-0.3 mg/L) and by the magnesium-calcium chloride-bicarbonate composition. These waters are recharged by fresh water of the supra- and interpermafrost taliks of the Bestyakh terrace and by the riverbed taliks under small rivers. In the vicinity of Yakutsk, TDS concentrations in the Lena River and in the Quaternary aquifer increase to 0.5-1.3 g/L due to high mobility of chloride and sulfate ions migrating with the surface and suprapermafrost runoff from the low terrace, where the city is located.

High rates of degradation of the Bolshoy Azau Glacier on Elbrus make it necessary to assess the development of lakes on the ice-free land and on the glacier itself. For this purpose, aerospace data for the period of 1957-2021, as well as information from visual observations, Internet sources, and tourist photographs were analyzed. The existence of 15 lakes with an area of 0.14-20.25 thousand m² on the Bolshoy Azau Glacier and the adjacent territory was recorded at various times. The long-term existence of the lake in contact with the glacier on the Echo of the War mountain passage covering with an area of up to 4.5 thousand m² was revealed for the period of 1971-2009. The maximum area (20.25 thousand m²) was detected on a satellite image from June 25, 2009 for a lake on the dead ice part of the median moraine between left and right ice streams of the Bolshoy Azau Glacier. In the hollows on the glacier surface, up to three lakes with a maximum total area of 7.86 thousand m² were observed in different times. Lakes on the Bolshoy Azau Glacier appeared mainly during the snow cover melting, while masses of drifted snow served as dams in the drainage area of hollows. These lakes disappeared after melting of drifted snow dams and/or in the course of drainage through subglacial and underground runoff channels.

The probabilistic-statistical method is applied to study the causes of the thermokarst distribution heterogeneity along the long linear constructions. A list of natural conditions affecting the development of thermokarst along an oil pipeline is discussed. The methodology for zoning buffer area of long-distance linear constructions (e.g., oil pipeline) according to the conditions of thermokarst development is substantiated. We have delineated thermokarst-susceptible and thermokarst-tolerant areas along the oil pipeline buffer zone according to the environmental conditions.