Home – Home – Jornals – Combustion, Explosion and Shock Waves 2025 number 6

This paper deals with new geological, mineralogical, geochemical (major, trace, and rare earth elements) and Sm-Nd isotopic data for the unique Kalevian (1923-1926 Ma) komatiite-tholeiite association for the first time identified in the supracrustal Kaskama Formation from the Inari Terrane of the Kola-Norwegian region Fennoscandian shield.

In the massive and porphyritic komatiites, the primary (magmatic) mineral paragenesis represented by olivine 20-40%, orthopyroxene up to 5%, hornblende up to 10%, clinopyroxene 20-40% and plagioclase 20-30% was identified.

Relic igneous minerals (olivine, pyroxene) make it possible to estimate (COMAGMAT3.73 program) their liquidus temperatures in the range of 1500-1200 °С.

The komatiites of the Kaskama Formation belong to the Al-nondepleted type and are characterized by a low level of REE_N content (1-2 relative to C1 chondrite), their total concentration (∑REE = 0.15-0.36 ppm) and an unfractionated distribution of REEs, which is a consequence of the generation and evolution of their primary melts outside the field of thermodynamic conditions of garnet stability.

The Zr–Y–Nb and Sm-Nd isotopic systematics of the rocks of the komatiite-tholeiitic association indicates the origin of their high-temperature primary melts from the plume source in depleted mantle (εNdT=+3.2±0.3), which is different from the mantle sources of the Jatulian-Ludicovian picrite-komatiite association of the Central-Lapland greenstone belt of Finland and the Pechenga intracratonic structure.

Considering the amphibolite facies metamorphic conditions of the Kaskama formation, it can be assumed that the komatiite-tholeiitic association is a deeply eroded (at least 10 km) section of the upper crustal volcanic apparatus.

Undertaked analysis of composition of the monzonite-sienite intrusive rocks, is abundant in the area of Bilikano-Khulamrinskaya magmatic zone of Central segment of the Yana-Kolyma orogenic belt. That rocks compose of small intrusions, which cut of terrigenous strata of Inyali-Debin turbidite terrane. That contained medium quantity of silica and Al₂O₃, relatively high – K₂O, Na₂O, MgO and chemically similar with latite. By chemistry that very close to alkaline felsic intrusive rocks of Aldan magmatic province. Balance concentrations of chemical elements, pointed out to belonging this rocks, to granitoids of convergent continental margin, include syncollision volcanic arcs. Age of that, by U‒Pb zircone dating (SIMS) 84 Ma, coincide with secondary impulse of magmatic activity of the Okhotsk-Chukotka Volcanic belt. Specific chemical composition of monzonite rocks of the Bilikano-Khulamrinskaya magmatic zone, close to shoshonite and latite, determined by location far in rear volcanic belt, at 200 km from axis zone of that, on the sialic basement, presented by turbidite sedimentary rocks.

Due to degradation of laser beam properties on atmospheric paths, the maximum length of communication lines is limited. In this regard, it is of interest to evaluate the possibility of detecting the topological charge of a vortex beam disturbed by atmospheric fluctuations using wave front sensors. The problem of measuring the wavefront tilts of a vortex laser beam propagating along a path in a turbulent atmosphere by a Shack-Hartmann sensor is considered. Estimates are obtained for the change in the angles of local tilts of wavefront associated with the solenoidal component of the Poynting vector and the influence of turbulent fluctuations of the refractive index of the atmosphere. Using several specific models of the Shack-Hartmann sensor as an example, the possibility of calculating the value of the topological charge of a vortex Laguerre-Gaussian beam from the measured angles of local wavefront tilts is investigated.

Based on the representation of the solution of the stochastic Helmholtz equation in the form of a path integral (Samelsohn G., Mazar R. Phys. Rev. E. 1996. V. 54, N 5) for the Kolmogorov model of the turbulence spectrum, an expression for the spatial coherence function of a spherical wave propagating in a turbulent atmosphere is derived under the assumption that the geometric-optical approximation is valid for a random phase incursion in the path integral. Estimates of the corrections to this approximation by order of magnitude are found. The obtained formula has no restrictions on the wavelength and the angle between the observation points that arise when using the parabolic and Markov approximations. The error in estimating the radius of spatial coherence in the parabolic approximation, arising from the sphericity of the wave front with an increase in the angular separation of the observation points, is calculated. It is shown that the error increases with the wavelength, and for millimeter and longer waves it can lead to an overestimation of the scale of spatial coherence of a spherical wave by few times.

Water vapor is a significant component of the Earth's atmosphere. Assessing the contribution of water vapor to the Earth's radiation balance has remained a topical issue for decades. In this work, the water vapor self- and foreign-continuum spectra have been retrieved at temperatures of 310, 325, and 340 K in the 1600 cm^-1 absorption band for the first time based on earlier Fourier-measurements of water vapor absorption under self-broadening and broadening by air at 296-340 K within this absorption band with the use of HITRAN2020 spectroscopic database. The retrieved spectra show characteristic for self- and foreign-continuum spectral and temperature dependences. The spectra we retrieved are compared with the MT_CKD semi-empirical continuum model and the semi-empirical dimer-based continuum model ( Simonova A.A., Ptashnik I.V., Shine K.P. Semi-empirical water dimer model of the water vapour self-continuum within the IR absorption bands // J. Quant. Spectrosc. Radiat. Transfer. 2024. V. 329. P. 109198-1-19. DOI: 10.1016/j.jqsrt.2024.109198). The results are important from both fundamental, within the molecular spectroscopy, and practical point of view, in problems of atmospheric modeling and remote sensing.

Ergodic theorems are important when comparing measurement results with theoretical conclusions. Compilation of a “statistical ensemble" requires numerous experiments under similar conditions, which is practically impossible. Therefore, average values are necessarily derived from the measurement data of a single experiment by averaging the empirical data over a certain time range or spatial region. The question of how close such empirical averages are to probability averages is answered by so-called ergodic theorems. An ergodic theorem for stationary processes was proved by G. Taylor in 1922. In this work, we have proved an ergodic theorem for the case of non-stationary random processes. The proof confirms the ideas of O. Reynolds (1894), according to which the time averaging interval should be large compared to the characteristic periods of a pulsation field, but small compared to the periods of the averaged field. The cause of the drift of the mean value, which consists in the dependence of the average values of hydrodynamic fields on averaging interval length and significantly complicates the determination of empirical average values, is found. An approximate measure for quantitative assessments of this phenomenon is suggested; the existence of an averaging time at which the influence of this phenomenon is minimal is shown. The results are important for studies of atmospheric turbulence, where all hydrodynamic elements are non-stationary and show pronounced daily and annual variations.

Aerosol turbidity of the atmosphere over Antarctica is the lowest on the planet. However, it shows regional peculiarities in the temporal variability. In this paper, the main features of the interannual and seasonal variations in the aerosol optical depth (AOD) are revealed on the basis of the analysis of its long-term measurements at Mirny Station. Pronounced variations with a period of 5-6 years and amplitude of 0.005 relative to the average level of 0.023 in the interannual variability of AOD (0,5 mm) are shown. The annual variation in AOD of fine aerosol is characterized by spring and summer maxima (October and February), and that of coarse aerosol is characterized by one summer maximum. Approximation formulas are proposed that make it possible to estimate the monthly average values of spectral AOD in the wavelength range 0.34-2.14 mm.

Bio-optical parameters of seas of the Far East region obtained from the MODIS/AQUA radiometer data are analyzed. The results of two main atmospheric correction algorithms based on the following assumptions are compared: the absence of water-leaving radiance in the near-infrared spectral bands and the stability of the sea water spectral shape in this range (MUMM). Verification was carried out using data of Japanese and Korean AERONET-OC stations. An approach to improving the results of MUMM atmospheric correction by using a regional adjustment of the color indices is considered. The MUMM correction after adjustment is not inferior to NIR correction in terms of the calculation accuracy of chlorophyll- a concentration. It was found that the recommended NIR correction leads to negative reflectivity coefficients Rrs at a wavelength of 412 nm in 10% of cases. These cases correspond to highly trophic waters and are accompanied by an overestimation of the chlorophyll-a concentration by an average of 1.8 times. The proposed correction of the color indices does not lead to negative values of Rrs; the color indices in the blue spectral range have significantly lower errors than those of the NIR algorithm. The proposed approach ensures more reliable estimates of bio-optical parameters of the sea based on satellite data.

Wind Doppler lidars have proven themselves as an effective means of evaluating wind turbulence in aircraft measurements. However, existing methods of sounding from aboard an aircraft assume the presence of a complex scanning system. In this work, we test possibility of evaluating turbulence parameters and wind convective flows using the second version of the lidar created in the Laboratory of Wave Propagation of IAO SB RAS during nadir sounding from aboard a flying aircraft. Based on the analysis of experimental data, we retrieved vertical profiles of estimates of vertical wind velocity (VWV) dispersion and turbulent kinetic energy dissipation rate up to altitudes of 1250-1600 m. During the analysis of sounding data near clouds, we recorded VWV shear according to one lidar signal spectrum, which contained two Doppler peaks. The results of this work can be useful in creating new methods for evaluating turbulence and wind shear.

Characteristics of a convective cloud with heavy rainfall over Saint-Petersburg and Leningrad region on 1st of July, 2023, are considered. The analysis was based on data of the weather radar DMRL-C, weighing precipitation gauges Pluvio² 200, and two lightning detection networks. The appearance and development of Cb under study was a result of merging two convective clouds. During their development the clouds slowly converged moving towards Saint-Petersburg from the southwest. Measurements have shown that the cloud merging led to explosive growth of the cloud top, which reached an altitude of 13.4 km; significant increase in the maximal reflectivity up to 69 dBZ, in volume of the cloud supercooled part with high reflectivity, volumes of the cloud with graupel and hail, precipitation intensity up to 140 mm/h, and lightning rate. The appearance of “the cloud bridge” was recorded. It has been shown that it consisted of graupel and wet snow particles.

Correct assessments of greenhouse gas fluxes and the global carbon cycle require well-provided data on greenhouse gas sources and sinks in the surface - atmosphere system at various natural sites. The article summarizes the results of shipboard measurements of carbon dioxide concentration in surface water throughout the water area of Lake Baikal received in eight spring campaigns of Limnological Institute, Siberian Branch, Russian Academy of Sciences. Spring period is of particular interest for research, since due to the large geographical extent of the lake from south to north, after the opening of the ice cover, the water gradually warms up. This makes it possible to take measurements in relatively different “seasons" during a time-limited expedition. Against the background of a noticeable interannual variability in the spatial distribution of CO₂ concentration in surface water in spring, its decrease from the Southern to the Northern basins of the lake is pronounced. While moving away from the coastal zone to the central part of the water area (to depths of more than 200 m), the concentration of dissolved carbon dioxide increases. The results of the study are of interest to specialists in climate issues and biologists, since carbon dioxide is one of the integral components of the carbon cycle during photosynthesis of aquatic plankton in the Baikal water.

The work is devoted to the study of the effect of aerosols on various processes in the atmosphere, in particular, the formation of convective clouds and their electrification. The special cases of thunderstorms in the Krasnoyarsk Territory during wildfires are considered. This region is characterized by the highest risk of increased wildfires due to the climate change among Russian regions. The thunderstorm events were selected based on the analysis of lightning activity in the selected area from 2015 to 2022 in comparison with wildfire data. A series of numerical experiments on simulating thunderstorms in the WRF model with different aerosol concentrations in the atmosphere have been performed. Based on the simulation results, electrical parameters of clouds have been calculated. To find correlations between the density of lightning discharges and the parameters of convective systems we suggest methods for estimating lightning activity based on the volume of thunderstorm cells with a certain radar reflectivity and the area of high electrical potential. We have revealed that an increase in the aerosol load in the atmosphere increases the time of convection development, as well as a significant effect of aerosol concentration on electric potential maximum at near constant radar reflectivity maximum. The results can be used to develop fundamental ideas about the relationship between lightning activity and wildfires and to improve methods for predicting lightning activity.

The problem of atmospheric emission source identification using remote sensing data is considered. An algorithm is proposed for a three-dimensional model of atmospheric pollutant transport and a nonlinear measurement model represented as a “differentiable black box". The algorithm is based on sensitivity operators and ensembles of adjoint equations solutions. It was tested on a realistic scenario for identifying soot sources for the Baikal region with synthetic satellite measurements of the Terra/MODIS platform, which showed its applicability. Additionally, the measurement data decomposition modification of the algorithm is proposed, which made it possible to reduce the relative error of retrieving the source function by 12% compared to the version without decomposition. The results can be used in the development of remote sensing data processing systems.

In atmospheric remote sensing, particularly in the interpretation of lidar signals from cirrus clouds, the accuracy of light scattering modeling on non-spherical randomly oriented ice particles plays a crucial role. Although the physical optics approximation is commonly used due to its computational efficiency, it does not always provide sufficient accuracy, especially when particle sizes are comparable to the wavelength of incident radiation. This introduces systematic errors into scattering matrix databases used for solving inverse problems. This study employs the discrete dipole approximation to verify the validity of the physical optics approximation. The primary focus is on comparing results obtained at wavelengths of 0.532 and 1.064 mm for particles of various shapes and sizes from 2 to 8 wavelengths. It is shown that in this size range, the physical optics approximation leads to relative errors of up to 20% in the linear depolarization ratio and reduces the backscattering intensity by half. The findings enable a more precise estimation of the applicability limits of the physical optics approximation and provide corrections for existing scattering matrix databases. This, in turn, will improve the accuracy of lidar data interpretation and enhance the quality of microphysical retrievals for cirrus clouds.

Highly directional supercontinuum (HDSC) is a unique source of broadband coherent radiation. To create such a source, it is necessary to know the parameters and conditions of its occurrence. The article presents the results of experimental study of the conditions for HDSC generation in gaseous nitrogen pumped by a radiation pulse with wavelength of 950 nm, duration of 70 fs, and energy of 3-6 mJ. The pump radiation was focused into a gas chamber by a spherical mirror with F = 75 cm under aberration conditions (the angle of incidence of the radiation on the mirror was 15°). It is shown that there is optimal pump energy of 4.5 mJ and gas pressure of 3-4 atm. The spectral composition of the HDSC covers the range from 350 to 1000 nm. The divergence of HDSC radiation is diffraction-limited and its greatest value (the diameter of the white spot in the far zone) corresponds to a wavelength of 780 nm. The maximal HDSC energy was 17 μJ. The results are useful for understanding the physical mechanisms underlying the emergence of HDSC, as well as for developing broadband coherent radiation sources.

A study of hydrogen oxidation in the presence of sulfur dioxide was conducted in an oscillatory mode. It was found that this process occurs via a degenerate chain mechanism, with sulfur oxide (SO), the primary product of sulfur dioxide conversion, playing a significant role. It was shown that the hydrogen oxidation reaction in the presence of sulfur dioxide in the autoignition region under certain conditions (pressure, temperature, gas mixture composition, contact time) proceeds explosively and is accompanied by light emission. A comparison of experimental data on hydrogen oxidation in the presence of sulfur dioxide with the results of calculations using the proposed model of the process under study revealed good agreement. Based on the calculation results, the effective activation energy of the reaction was determined to be 9 200 J/mol.

The paper presents the results of experimental determination of the flammability concentration limits of methane--air--water vapor, methane--hydrogen--air--water vapor mixtures with a methane to hydrogen volume ratio of 1:2 and 2:1, and carbon monoxide--hydrogen--air--water vapor mixtures with a hydrogen to carbon monoxide volume ratio of 4:1 at an initial temperature of 150 °C and a pressure of 101 kPa. The water vapor content varied in the range of 0 ÷ 60 vol. %. The experiments were conducted in a spherical chamber with a volume of 100 dm3. The presence of mixture ignition and flame propagation were recorded using infrared imaging. The flammability limits of the methane--air--water vapor mixture obtained in the experiments are in agreement with the data available in the literature. The flame propagation mode in hydrogen-containing mixtures near the lower concentration limit was recorded in the form of a spherical flame turning into a toroidal vortex.

The effect of chemical nonequilibrium in the combustion process of a diffusion methane-air flame at moderate pressures and temperatures of the initial reactants on the reduction of nitrogen oxide in reactions known as NO reburn was studied. Based on the detailed mechanism of chemical kinetics of methane oxidation GRI-Mech 3.0, an analysis was performed of the distribution of the main NO-reducing substances (CH, CH₂, CH₃, HCCO) in reburn reactions, as well as the initial substances forming NO in Zeldovich reactions, across the thickness of a diffusion laminar flame based on a numerical solution of the Peters-Kuznetsov system of equations using the thin flame front model (flamlet model). In the flame representation as a chain of isolated ideally mixed reactors distributed across the flame thickness, the NO concentration was estimated using a precise analytical formula representing the rates of reburn reactions in accordance with three detailed kinetic mechanisms: GRI-Mech 3.0, Glarborg, and Miller---Bowman. A comparative assessment of the efficiency of these mechanisms for reducing NO concentration was performed; the maximum reduction was 13.3, 23, and 30.4%, respectively. An assessment of the influence of diffusion showed a change in the relative concentration of NO profiles by no more than 0.06%. It was also shown that, as the chemical equilibrium deviates, reburn reactions gradually begin to occur on the "lean" side of the flame (as fuel radicals diffuse across the stoichiometric boundary), and the region of reburn reactions in terms of the composition of the gas mixture expands more than twofold. The contribution of reburn reactions on the lean side of the flame increases steadily and can reach 56% of the total reburn efficiency, which is of practical significance in systems with a high degree of combustion nonequilibrium. The main contributions to NO reduction on the lean side of the flame are reactions with CH (up to 75% via the GRI-Mech 3.0 mechanism) and reactions with HCCO (up to 80% via the Glarborg mechanism).

The results of a study examining the effect of a weak electric field on a Bunsen burner flame are presented, including the combustion of an aerosol consisting of water microdroplets in an air-methane mixture. Analysis of velocity fields obtained using a PIV system revealed changes in the laminar flame front propagation velocity when exposed to a weak electric field. Moreover, over a significant portion of the combustion front, the laminar front propagation velocity can be considered constant. The existence of an ion wind caused by the drift of negative charge carriers is confirmed. The introduction of water microdroplets into the fuel reduces the charge carrier concentration, indirectly evidenced by the fact that the effect of an electric field on combustion in this case leads to smaller changes in the flow structure ahead of the flame front.

The lower temperature limits for flame propagation of mixtures of oil vapor with oxygen and nitrogen in the presence of liquid oil were determined. Experiments showed that the lower temperature limit differs significantly from that expected for oxygen. One reason for this discrepancy is that, in the presence of an ignition source and a large amount of oxygen in the gas phase, diffusion combustion of the liquid oil film present on the inner surfaces of the vessel can initiate. The flame propagates along this film to the bulk of the oil. As the oil continues to diffuse, a pressure increase significantly exceeds that expected for flame propagation through the gas phase.

The gas-dynamic, kinetic, and energy parameters of detonation in dual-fuel methane-hydrogen systems are presented: a) stoichiometric methane-oxygen and hydrogen-oxygen mixtures in various ratios; b) stoichiometric methane-oxygen mixture with added hydrogen in various ratios; c) stoichiometric hydrogen-oxygen mixture with added methane in various ratios; d) lean hydrogen-oxygen mixture with added methane in various ratios; e) enriched hydrogen-oxygen mixture with added methane in various ratios. The main behavioral patterns of such systems are discussed.

A study was conducted to determine the effect of sample length fixation and mechanical activation of the mixture on the combustion rate and elongation of the samples during synthesis, as well as on the phase composition and morphology of the combustion products in the Ti + C system. After activation for 9 min in an AGO-2 mill with an acceleration of 90g using 9 mm diameter steel balls in air, partial mechanochemical synthesis occurred in the mixture, with the TiC product present in addition to the initial Ti and C components. With activation lasting 9 min, the mixture became pyrophoric and, in some cases, ignited upon removal from the activator drum. After mechanical activation lasting less than 9 min, the combustion rate of the mixture increased and the particle size decreased compared to the combustion rate and particle size of the original mixture. With an increase in activation time in the range of up to 9 min, the amount of impurity gases in the mixture increased, which led to an increase in elongation, and at longer times, to the dispersion of the product samples during synthesis. Fixing the sample length significantly increased their combustion rate, but, like mechanical activation of the mixture, did not affect the phase composition of the synthesis products.

A study was conducted on the macrokinetic combustion of a granulated Zr + 0.5C mixture under nitrogen flow conditions. It was shown that the combustion rate increases nonlinearly with increasing gas flow rate, with the combustion process accompanied by sample shrinkage of up to 26%. Experimental data were analyzed using conductive and convective combustion models. Calculations showed that combustion in a nitrogen flow at gas flow rates exceeding 500 l/h occurs via the convective mechanism. It was established that longitudinal sample shrinkage is due to the presence of a significant amount of zirconium melt during combustion. According to X-ray diffraction analysis, the synthesis products are a mixture of zirconium carbonitrides ZrC_xN_y of variable composition. Chemical analysis of the synthesis products revealed that the degree of nitridation of the granulated mixtures is higher than that of the powder mixtures and increases with increasing nitrogen flow through the sample.

To improve inherent safety and reduce energy consumption in industrial explosives production, the water-soluble compound hexamethylenetetramine is being used to replace the traditionally used insoluble fuel oil in ammonium nitrate-based explosives. This oxidizer and fuel, combined in water, create an intermolecular explosive called an ammonium amine explosive. The effect of pH in the range of 4.0 to 5.8 on the density of this explosive, crosslinking time, microbubble formation, detonation velocity, and water resistance was determined. The studies were conducted using density measurements, a digital viscometer, an optical microscope, detonation velocity tests, and a conductivity meter. The results show that ammonium amine-based explosives prepared at various pH levels form numerous chemically sensitized microbubbles, the average diameter of which decreases as the pH decreases. Lower pH values are associated with higher foaming rates and shorter crosslinking and foaming times. The detonation velocity of ammonium amine-based explosives is 3,500-4,200 m/s, slightly lower than that of conventional emulsion explosives. Furthermore, a comparison of the water resistance of ammonium amine-based explosives with crosslinking times of 1 and 24 hours yields contrasting results. A pH of approximately 5.2 sets the boundary between in-situ mixed and packaged ammonium amine-based explosives. Packaged explosives show significant advantages at pH values above 5.2, while in-situ mixed explosives are more advantageous at lower pH values. These results provide a theoretical basis for improving the performance of this new water-resistant nitrated substance and simplify its industrial application.

Aluminum diboride (AlB₂) microcapsules coated with polyvinylidene difluoride (PVDF), fabricated by a simple rotary evaporation method, were studied. According to the morphology study, PVDF forms an intact outer shell on the surface of each individual AlB₂ particle. Compared with uncoated AlB₂, the AlB₂@PVDF microcapsule has a shorter ignition time, more intense combustion, and faster pressure build-up. At an appropriate PVDF content, the measured heat of combustion is higher than that of the composition with unencapsulated AlB₂, due to a higher heat release efficiency during combustion --- 92.3% (the efficiency of the composition with unencapsulated AlB₂ is 85.2%). Mechanistic study shows that the PVDF decomposition product likely accelerates the oxidation of AlB₂ at several reaction stages, providing higher reactivity of the AlB₂@PVDF microcapsules. The use of AlB₂@PVDF in explosives increases density, detonation velocity, and heat release with good component compatibility, while maintaining acceptable mechanical sensitivity. Therefore, AlB₂@PVDF microcapsules are a promising metallic fuel in composite energetic materials.

Using the molecular dynamics method, numerical experiments were conducted to study the dependence of the melting temperature of various materials (copper, silver, titanium, and silicon carbide) on the nanostructure size. Analysis of the obtained data showed that for all materials, starting from a certain nanostructure size, the melting temperature decreases with decreasing nanostructure size.

The problem of measuring particle size distribution in shock-induced flows is discussed. The design of a mobile holographic system developed by the authors, which implements the method of axial pulse holography, is presented. The system enables the acquisition of holograms with a field of view of approximately 20 mm in diameter and a depth of over 20 mm, and the recording of flows of lead particles ≥3-5 μm in size, moving at velocities up to approximately 2 km/s. Examples of shock-induced flows moving in a vacuum, recorded using the mobile holographic system, are presented. These flows consist of both individual particles 5-100 μm in size and, predominantly, filamentary formations 3-10 μm thick. Methods of analog and digital recording and reconstruction of holograms are discussed, as well as the problem of identifying particles in images reconstructed from recorded holograms.

A new type of ammonium nitrate-based explosive is presented, prepared by replacing diesel fuel with liquid coal fuel (coal atomized in water). Experimental results show that the higher the calorific value of the raw coal, the higher the detonation velocity of the new liquid explosive. For example, with a liquid coal fuel content of approximately 9-12% and a calorific value of 5,500 kcal/kg, the efficiency of the new explosive is relatively stable and achieves improved parameters: velocity equals 2,800-3,000 m/s, brisance increased by approximately 7-10%, and the work performed increased by approximately 8-24% compared to an explosive made from ammonium nitrate and diesel fuel. Minimal changes in the physical and chemical properties were observed during 30-day storage. At the same time, the blast efficiency of this explosive was significantly improved by adding composite additives consisting of a new coal-based fuel, diesel fuel, and an emulsifier. Blast tests under industrial production conditions were conducted at the Heidaigou open pit mine. The test results showed that the new explosive exhibits significantly improved brisance and greater work-producing capacity compared to ammonium nitrate- and diesel-based explosives.

Using the electric contact method, the influence of sample porosity, dispersion, and diameter on the detonation velocity of the individual low-sensitivity explosive triaminotrinitrobenzene (TATB) was studied. Data on the detonation wave front curvature were obtained. The results show that, under identical initiation conditions, the detonation process of TATB is complete after the detonation wave travels a distance equal to 3.5 times the explosive sample diameter and is independent of the porosity, dispersion, and diameter of the samples.

To study the effect of initial ambient pressure on the explosion parameters of thermobaric explosives (HE), static explosion experiments were conducted using trinitrotoluene (TNT) as a reference at both low and high initial ambient pressures. Various grades of thermobaric explosives were tested, and a correlation model was proposed for analyzing the overpressure and momentum of the blast shock wave in different initial environments, taking into account atmospheric pressure. Analysis of the pressure data showed that the general propagation and attenuation characteristics of blast shock waves from TNT and thermobaric explosives are essentially the same at different initial ambient pressures. As the initial ambient pressure decreases, both the shock wave overpressure and momentum decrease. The explosion propagation velocity also decreases with decreasing initial ambient pressure. Furthermore, as the explosive mass increases, the reduction in overpressure and momentum decreases for both thermobaric explosives and TNT, and the difference in the shock wave propagation velocities from these two types of explosives also decreases. A comparison of the correlation model results with experimental data yielded average maximum relative errors of 12.3% for TNT and 8.8% for thermobaric explosives in low-pressure environments relative to the shock wave overpressure. Momentum errors were 12% for TNT and 13.7% for thermobaric explosives. These results demonstrate the high accuracy of the correlation model. This correlation model allows one to determine the shock wave overpressure and momentum of an explosion at various initial ambient pressures, and to estimate the shock wave power generated by thermobaric explosives.

The question of how solid rocket propellants react to fragment impacts remains relevant. Identifying potential mechanisms for propellant propellant reaction to fragment damage is crucial for assessing the safety of solid rocket motors and developing high-energy, low-sensitivity propellants. In this study, a fragment impact experiment on a propellant propellant consisting of glycidyl azide polymer, hexogen, and triethylene glycol dinitrate (GRT) was conducted using a 14.5-mm ballistic gun and a high-speed camera to obtain images of the propellant reaction time history under various ballistic behaviors. Based on the obtained images and measured ballistic data, the relationship between propellant reaction characteristics, the primary reaction mechanisms, and two ballistic limits was analyzed. The results of a 10.0 mm diameter tungsten ball impact on a GRT charge contained in a 3 mm thick cylindrical steel shell show that the threshold reaction velocity corresponds to the ballistic limit of fragment penetration into the shell. Below this ballistic limit, no propellant reaction occurs. In the case of a significant reaction delay caused by the ignition of RDX crystal hot spots rather than ammonium perchlorate particles, the propellant reaction upon complete penetration is combustion. Only when a large number of ammonium perchlorate particles and RDX crystals simultaneously ignite hot spots, and the fragment's initial velocity exceeds the charge's ballistic limit by 2.2 times, can the charge undergo reactions more intense than combustion.

The Arctic is one of the most climate-vulnerable regions of the planet, where the rate of temperature increase is twice as high as the global average. The rapid increase in temperature is largely due to the increasing concentration of greenhouse gases in the atmosphere. Forecasts indicate that the continuation of this trend may lead to a large-scale release of carbon accumulated in permafrost. The scale and duration of the expected effect are not obvious due to the poorly developed monitoring of greenhouse gases in the Russian Arctic: sporadic estimates of their atmospheric variations and exchange with ecosystems. The paper presents the results of studies of the dynamics of atmospheric greenhouse gases in the estuarine zone of the Yenisei River, indicating a stable annual increase in CO₂ (~1.9 million^-1/year) and CH₄ (~12.6 milliard^-1/year). The values of soil emissions of these gases for different types of tundra and vegetation on the western coast of the Taimyr Peninsula are presented, where it is shown that the highest values are typical for areas with vascular plant forms. Disturbances of the living ground cover by all-terrain vehicles lead, on average, to a threefold increase in methane emissions into the atmosphere.

The current state of the grass-shrub cover and soils of the forest area «Birch Grove», which belongs to the urban forests of the city of Krasnoyarsk and has been subjected to a strong anthropogenic impact over the past 30 years, is investigated. The main forms of recreation are walking, picnic, and physical culture. A detailed description of the vegetation of three types of forest is given: large-grass birch, forb birch with Scots pine ( Pinus sylvestris L.) and forb-sedge pine forest and their recreational characteristics. It was found that in the forb-sedge pine forest, which is most subject to recreation, there was a decrease in the degree of projective cover of the grass cover and the introduction of ruderal grass species under the forest canopy. It is shown that the largest stock of forest litter is characterized by less trampled large-grass birch, the smallest - forb-sedge pine forest. It was established that trampling led to the complete degradation of the forest litter and grass cover on the trails. A significant increase in the density of the composition and a decrease in the moisture content of the top layer of the trail soil was also noted. Water-physical and chemical analysis of dark gray and gray forest soils did not reveal a significant change in their parameters and deterioration of forest vegetation properties under the influence of recreation in forest types with stage 1 of digression. In sod-carbonate soil (a type of forest with the 2nd stage of digression), a significant increase in the density of composition, a decrease in the porosity of the root layer, alkalinization of the soil solution, as well as a weak accumulation of humus and biophilic elements were noted. A further increase in the recreational load on the Birch Grove forest area will lead to a more significant deterioration in the forest vegetation properties of soils, a decrease in the productivity of grass and tree layers.

The results of 18-year observations of cone production in clones from latitudinal and longitudinal ecotypes of the Siberian stone pine ( Pinus sibirica Du Tour) on geographical crops in the south of Tomsk Oblast are presented. With age, the number of female cones increased in trees of all ecotypes, and the pattern of differences between ecotypes changed. At the age of 10 years, the northern ecotypes and one of the eastern ecotypes formed the greatest number of cones. After 8-10 years, the central ecotypes from both transects had the most abundant cone production. By the age of 28 years, the southern ecotype became the leader in the cone number among the latitudinal ones, and among the longitudinal ecotypes, the western, local, and one of the eastern ones differed insignificantly. This trend remained unchanged until the end of the observation period for the longitudinal ecotypes, and among the latitudinal ecotypes, by the same time, the southern ecotype became the leader. The Siberian stone pine ecotypes were characterized by periodicity of cone crops. The degree of cone retention in all Siberian pine ecotypes was closely related to the date of the last spring frost and the sum of effective temperatures accumulated by this date; no significant correlations were found with other weather factors. Dangerous late frost led to a complete or partial loss of cone crop in all ecotypes. The later the frost and the higher the accumulated sum of effective temperatures, the greater the damage to the cone crop. At this time, cones were preserved more often in northern ecotypes than in others.

City parks are an integral part of the green infrastructure of Yekaterinburg, maintaining and regulating various ecosystem services. More than half of the city’s parks are created on the basis of natural plantings integrated into the urban environment during the construction of new districts. The purpose of the study is to identify the degree of Scots pine ( Pinus silvestris L.) participation in the formation of phytomass reserves of plantings of large parks in Yekaterinburg that arose during urbanization. The applied approach will reflect the level of anthropogenic transformation of the planting through the change in the stock of stem mass of Scots pine. The plantings of ten parks located in different parts of the city and created in different periods were studied: «Sem klyuchey» (Seven springs), «Zelenaya Roshcha» (Green grove), im. Chkalova (named after Chkalov), along the street of Chkalov, im. Agafonova (named after Agafonov), Kamvolny Kombinat (Worsted mill), Letniy «Uralmash» (Summer), Kompressorny Microrayon (Compressor microdistrict), plantings within the boundaries of the regional hospital and Park-stadion «Khimmash» (Park-stadium of chemical engineering plant). To assess the ecological efficiency of tree species, the indicator of the stem wood stock was chosen as the most accessible for working with growing trees. It is known that the stock closely correlates with the mass of the tree, which acts as an integrated indicator reflecting the participation of certain plant species in ecosystem services, primarily in carbon-depositing and oxygen-producing activities. In the course of the study, based on the tree inventory, the species composition, indicators of the sanitary condition of trees were determined, and the stock of stem mass was calculated. As a result of the study, it was established that there is a negative relationship between the share of introduced species in the massifs of large parks in Yekaterinburg, the stock of stem mass and the health condition of Scots pine.

It has been established that in the highlands of the Southern Urals, spruce trees are represented by single- and multi-stemmed forms of growth. Over the past two decades, the total number of spruce ( Picea A. Dietr.) trees in the upper tree-line ecotone has increased significantly, which indicates the continued colonization of relatively open spaces of the ecotone with woody vegetation. The nature of the dependence of the mass of the crowns as a whole and the mass of the needles on the diameter of the trunks is determined by the form of tree growth. Therefore, when evaluating these fractions of aboveground phytomass, the corresponding equations should be developed separately for single- and multi-stemmed trees. The form of the growth does not affect the dependence of the mass of trunks on their diameter. The total aboveground phytomass of spruce stands, and, consequently, the reserves of carbon deposited in them, increase significantly as the altitude above sea level decreases. During the period from 2002 to 2024, the aboveground phytomass of sparse tree stands and open forests increased at a higher rate than in the lower closed forest. In particular, it increased 2.2 times in sparse tree stands, 1.9 times in open forests, and only 1.2 times in closed forests. This situation is explained by the continued expansion of arboreal vegetation in the upper tree-line ecotone and the lower age of the stands formed there. The data we have obtained on the reserves of aboveground phytomass of spruce stands and carbon deposited in them can be used to assess and forecast the biosphere role (in particular, the carbon budget) of forests formed in previously treeless territories of highlands as a result of modern climate change.

The climate change observed on our planet recent decades most scientists explain by the increase in the atmosphere the share of greenhouse gases. One of them is carbon dioxide, which is released during volcanic eruptions, burning of coal, peat and oil products. Among the ways to minimize carbon dioxide in the atmospheric air it is possible to single out its deposition by plants during the growth process. We succeeded in analyzing the possibility of creating carbon farms on disturbed lands. These farms are created in the process of reclamation biological stage by planting the most productive in a given region forest crops of various species and forms of woody plants. Based on the materials of the trial plots, the accumulation of wood and carbon deposited in was analyzed on the example of disturbed in the process of mining and processing of resources these lands mineral as well as on gold dump. In particular, it was established that at the golden dump, the stock of only stem wood Scots pine ( Pinus sylvestris L.) in artificial plantations of 30-years age is 290 m³/ha, which corresponds 107.3 t/ha deposited carbon. The creation of carbon farms on chrysotile asbestos waste dumps ensures the deposition of 145 t/ha of carbon in the wood by the age of 42 years, which corresponds to 3.45 t/ha annually. When creating carbon farms on exhausted clay quarries, by the age of 40 years, the amount of carbon deposited in the wood is 142.67 t/ha, which corresponds to the annual deposition of only 3.57 t/ha of carbon from atmospheric air by the forest stand. The obtained data indicate the effectiveness of creating carbon farms on disturbed lands in the Middle Ural taiga forest region by planting Scots pine forest crops.

Toxic waste from tailings dumps, as a result of erosion processes, can cause significant environmental damage through the migration of pollutants. This leads to the degradation of forest ecosystems, since heavy metal and arsenic compounds are absorbed by plants and soil. The purpose of the work is to assess the state of natural forest vegetation near a man-made source and determine the resistance of forest species in the stand and undergrowth to heavy metal pollution. To assess the state of natural vegetation, 4 test plots were laid taking into account the vegetation on strip counts. According to chemical analysis data, migration of heavy metals from the soil and litter to tree needles is noted. According to the assessment of the state of forest stands, 55 % of all studied species can be classified as weakened and drying out. The article provides an inventory characteristic of tree species and undergrowth near the Vysokogorskiy tailings dump on the territory of the Kavalerovskiy forestry of Primorskiy Krai. The obtained data on the state of the forest stand and the chemical composition of the components of the forest ecosystem made it possible to determine the resistance of various forest species to the impact of unfavorable factors.

Scots pine ( Pinus sylvestris L.) sawdust is highly promising as a raw material for wood carbon sorbents. However, the prospect of using pine sawdust as adsorption materials to extract toxic metals from aqueous solutions depends heavily on the composition of active surface functional groups. The purpose of the study is to assess the sorption properties and the degree of change in the composition of oxygen-containing functional groups of carbon sorbents. The modification was made with solutions of one-, two- and polybasic carboxylic acids to promote large-scale woodworking waste as real alternative sorption materials. 1 % carboxylic acids of different basicity (acetic, succinic, tartaric, citric) were used as chemical modifiers for both initial sawdust and sawdust thermally treated at 300 ± 10 °C. Chemical modification was carried out at a temperature of 80 °C for 5 hours. To quantify functional groups in the composition of modified carbon sorbents, the Boehm titrimetric method was used. Impregnation of carboxylic acids of different basicity has increased the total acidity of the resulting carbon sorbents due to increasing in the number of hydroxyl groups in their composition, which were not previously present in initial pine sawdust. The sorption behavior of chemically and thermochemically modified carbon sorbents was investigated in relation to Cu (II) and Zn (II) ions and a positive effect of the modification has been established only in the case of copper extraction from aqueous solutions. The calculated thermodynamic parameters indicate the spontaneous physical sorption occurs without the formation of stable chemical bonds, and the sorption of Cu (II) ions on the original sawdust proceeds in accordance with the Dubinin-Radushkevich model, and extraction by modified samples occurs according to the Langmuir model. Pine sawdust sorbents modified chemically and thermochemically with 1 % citric acid (sorption capacity 16.96 and 12.20 mg/g, respectively) has shown good potential for effective extraction of copper iones.

First registered in Perm Krai in 2022, the invasive four-eyed fir bark beetle Polygraphus proximus has expanded its secondary range to almost 8,000 ha on the territory of 10 forestry districts of the region by the beginning of 2025. At the same time, the phytosanitary quarantine zone has grown to 1 million hectares. For dendrochronologic dating of tree mortality on the sites where initial foci was documented, the samples from five sites were analyzed: in Dobryanskoe forestry (2 sites) and in urban forests of the city of Perm (3 sites). In total, 131 tree-ring rows for 118 trees killed by the bark beetle and 60 rows for 40 live trees were used to construct a master chronology. Dating the dieback of the trees which appeared to have the earliest infestation signs of the beetle allowed us to define time when four-eyed fir bark beetle could first occur in Perm Krai. The earliest tree dieback was observed on the two sites in Dobryanskoe forestry (in 2011 and 2014 respectively). The invader penetrated the city of Perm significantly later: fir trees started to die in 2018, 2021, and 2022 on the studied city sites. Bearing in mind that the beetle requires at least 2-3 years to settle down in a new region, it can be assumed that four-eyed fir bark beetle arrived to Perm Krai no later than 2009.