Home – Home – Jornals – Atmospheric and Oceanic Optics 2025 number 6

The propagation and accumulation of impurities in the near-surface atmospheric layer largely depend on layer stability, which can be quantitatively characterized by the mixing layer height (MLH). For the first time, using a single methodology, the average values for 2001-2021 were estimated for different territories of Russia in the central months of seasons separately for daytime and nighttime. The analysis is based on MLH (or atmospheric mixing depht) values from the website [www.arl.noaa.gov] obtained during long-term studies of the long-range air mass transport to the various Russian regions. The MLH values averaged through the area over individual mainland quasi-homogeneous climatic territories or over Russian Arctic seas are given, as well as the spatial distribution of MLH over the Russian territory on a geographical grid of 1° × 1°. The results of the study can be used in environmental assessments of, for example, the atmospheric pollution potential, fluxes of aerosol impurities onto the underlying surface, sources of air pollution and the degree of their impact on the environment and humans, as well as in comparative analysis of climate of various Russian regions.

The Russian Federation participates in the international programme of Acid Deposition Monitoring Network in East Asia (EANET). Two regions in the Asian Russia were selected for monitoring research: South-Eastern Siberia (three sites) and the Far East (one site). A database on the chemical composition of atmospheric aerosol was compiled. The spatial and temporal variability of the ionic composition of aerosol over five-year periods from 2001 to 2024 was studied using the ratio of the total concentration of the main ions. Based on data of other projects, some relevant trace elements in atmospheric aerosol were analysed: Li, Al, Ti, V, Mn, Fe, Sr, Th, U, Ba, Co (of terrigenous origin) and Cr, Cu, Ni (of non-terrigenous origin). Their contribution to the total level of atmospheric air pollution at the monitoring sites was assessed. The monitoring results of can be used for practical assessment of the environmental conditions, scientific research, and public information.

Atmospheric aerosol affects astronomical observations performed in the visible spectral range (400-700 nm). Therefore, information on the dynamics of the optical properties of the medium in the area of an astrophysical experiment is necessary for the correct interpretation of the results. Due to the lack of local measurements, data on the state of the atmosphere can be obtained, for example, from numerical simulation. The paper discusses the results of AOD simulation using the GEOS-CHEM chemical transport model and CAMS chemical reanalysis for the TAIGA gamma-ray observatory area, where EAS Cherenkov radiation is recorded at night. It is shown that the average AOD value (550 nm) for the period from September to April in 2019-2022 according to GEOS-CHEM and CAMS data are ~ 0.08 and ~ 0.05, respectively. The AOD maximum is observed in April and can attain 0.6. Verification of the simulation results using AERONET data showed their satisfactory agreement: the correlation coefficient is 0.92 for GEOS-CHEM and 0.91 for CAMS. Thus, the results of GEOS-CHEM and CAMS can be used at the stage of processing the experimental data of the TAIGA gamma-ray observatory, as well as similar astrophysical projects.

The morphology and composition of aerosol particles determine aerosol activity in atmospheric heterogenic processes affecting the optical, radiation, and chemical properties of the atmosphere. In addition, the structure and mineral composition of the particles serve indicators of anthropogenic and natural sources of pollutants into the environment. However, there is still insufficient information about the morphological characteristics of atmospheric aerosols. In this work, the mineral and matter characteristics of dust aerosol particles were studied, which made it possible to identify natural and man-made formations in aerosol composition in the surface air layer in Moscow metropolis in wintertime. Micro-particles containing a lot of potentially toxic elements, such as heavy metals and metalloids of man-made or mixed origin, were found. Several groups of metal-containing micro-particles in near-surface aerosol have been identified, among which the most common are: 1) sulfates (mainly Ba, Sr); 2) sulfides (Fe, Sb, Pb); 3) oxides (Fe, W, Cu, As, Cd, Pb); 4) intermetallides (Pb-Sn-Zn, Pb-Zn, Cu-Zn, Cu-Pb, Te-Sb-Al-Bi, Fe-Ni-Cu-Sn Fe-Cr-Ni); 5) native metals (Pb, Zn, Ni, Te, Fe, Zr, W). The distributions of various elements over the surface of filters with aerosol samples were evaluated, and it was found that most of the micro-minerals in dust particles are in the calcium phase and to a lesser extent, in silicate and aluminosilicate phases. The results complement information on the morphology and micro-mineral composition of aerosols in the near-surface air of a megalopolis and can be useful both for clarifying the role of aerosol particles in atmospheric heterogeneous processes leading to climate change and for solving applied environmental problems.

Thermophoresis of aerosols traditionally has been studied both theoretically and experimentally for spherical or, more generally, compact isometric particles. This paper compares the theory of thermophoretic motion of fractal-like particles developed by the authors with experimental data for carbon aggregates obtained in the gas phase under the DLCA formation scenario. It is shown that the theoretical results for the thermophoretic velocity qualitatively and quantitatively agree well with experiment. Possible limitations of the proposed theory and fundamental issues related to the estimation of the determining structural and thermophysical parameters for fractal-like aggregates are discussed. The results can be useful for the physics of atmospheric aerosols in modeling the processes of carbonaceous particles motion with fractal properties.

The results of studies of atmospheric aerosol in the 95th and 96th cruises of RV Akademik Mstislav Keldysh in the waters of the Barents and Kara Seas are presented. It is shown that the average values of aerosol characteristics over the Barents Sea are 1.1-1.9 times greater than over the Kara Sea. Taking into account the new data, the long-term average values of aerosol characteristics over these seas have been clarified: the volume concentrations of submicron aerosol were 0.47 and 0.44 μm³/cm³, respectively; concentrations of coarse aerosol were 2.17 and 1.65 μm³/cm³; mass concentrations of the absorbing substance (black carbon) were 67 and 36 ng/m³; aerosol optical depths of the atmosphere (0.5 microns) were 0.078 and 0.038.

Based on numerical simulation, we have estimated the thickness and spatial distribution of the methane hydrate stability zone (MHSZ) associated with submarine permafrost. Using CMIP6 ensemble model results under a scenario of high anthropogenic greenhouse gas emissions (SSP5-8.5), we find that the shrinkage of the MHSZ weakly depends on ongoing warming and occurs mainly on the lower boundary side. This process is mainly a consequence of the Holocene marine transgression and depends on the intensity of the geothermal flux. The spatial distribution of the methane fluxes from the bottom sediments as a consequence of the degradation of gas hydrates under the violation of their conditions of existence has been obtained. The estimated intensity of methane emission from the seafloor to the water was 15 Tg per year for the modern period and 16-17 Tg per year up to 2300 (similar estimates for the intensity of emission from the water to the atmosphere were not made in this work). Significant changes in the intensity of methane emissions from the seafloor to the water are not likely for at least several thousand years. The resulting fields of methane fluxes from bottom sediments can be used in numerical ocean models to estimate methane emissions to the atmosphere.

In environmental studies of atmospheric pollution, information is needed on the physical processes that determine the spatiotemporal distribution of aerosol fields. The article presents the results of lidar studies of the troposphere in the summer period from 2015 to 2023 on Lake Baikal, at the Boyarsky research station of Institute of Physical Material Science SB RAS, the Republic of Buryatia. Observations were carried out using LOSA lidars. Three main types of meteorological situations typical for the coastal zone of southern Baikal in the summer period, which determine generation and transport of aerosol in the atmosphere, are considered: breeze circulation, southwesterly transfer, and change of air masses. The features of the daily dynamics of the spatial distribution of aerosol in the atmosphere are given for the three specified types of situations. In the first case, the main changes are observed in the lower 2-3 km layer of the troposphere. During the day, due to the wind from the lake, the aerosol in the lower part of the atmosphere (below 1 km) begins to “press to the ground” and does not rise to the overlying layers. A distinctive feature of the second type of situations is that aerosol layers were detected at fairly high altitudes of up to 5-7 km. The third type is characterized by a smooth decrease of the observed aerosol layers throughout the range of altitudes down to the ground layer during the day. The results of two-position synchronous lidar observations of the transport of atmospheric heterogeneities at different altitudes above the coastal zone of Lake Baikal are also presented; it was revealed that the transport velocity can greatly vary, reaching several tens of meters per second.

It is currently relevant to study the composition and optical characteristics of aerosols in the atmosphere of Lake Baikal, a unique natural object. Results of the studies of the microstructural and physicochemical properties of near-water and near-ground aerosol in the atmosphere of the Lake Baikal basin in summer 2024 onboard the research vessel Akademik V.A. Koptyug and at the Boyarsky research station on the southeastern coast of the lake are analyzed. It is confirmed that in the absence of smoke plumes from forest wildfires, the aerosol spatial distribution over the lake and the black carbon concentration in particles are determined by the location of anthropogenic sources. The characteristics of hygroscopicity and volatility of the aerosol matter in the atmosphere of Lake Baikal depending on the particle size are studied for the first time. It is revealed that the aerosol condensation activity over the coastal zone is greater than over the lake. The results can be useful in developing regional models of atmospheric aerosol.

Cocrystals are commonly obtained using solid-phase or liquid-phase methods, though in the case if these methods are employed to develop cocrystalline pharmaceutical dosage forms, difficulties related to the control of mixture compositions and dosing accuracy arise. In the present work, we describe condensation-based method for generating aerosol particles of cocrystals formed by isoniazid, a known antituberculous remedy, and succininc acid. This method allows obtaining a pharmaceutical dosage form for delivery through inhalation with the high accuracy of dosage control. Inhalation delivery of isoniazid in the form of cocrystal can overcome the drug resistance of the mycobacteria by making high local concentration of the drug directly in the affected organ. The binary nucleation of the vapors of isoniazid and succinic acid in a horizontal flow thermal condensation reactor is investigated. The nucleation zone was determined using the method of supersaturated vapor shutoff. The composition of thus obtained cocrystals was determined by the full-profile X-ray diffraction. The conditions for generating cocrystals in a high yield have been selected, and nucleation rate was measured. The dose for inhalation delivery to laboratory animals under optimal conditions of binary nucleation is assessed. The results allow developing pharmaceutical dosage forms for delivery through inhalation with high accuracy of dosage control to treat pulmonary tuberculosis, including its drug-resistant forms.

The quality of atmospheric air in many cities of Siberia is unsatisfactory, which requires research to identify the cause-and-effect relationships between natural factors and the degree of anthropogenic impacts. The article studies long-term air pollution processes in Chita and the influence of calm conditions on them. Linear correlations between the measurements of monthly average concentrations of benzo(a)pyrene at Roshydromet stationary monitoring posts winters 2020/21 and 2023/24 are analyzed. It is shown that the paired measurements at posts, in general, are proportional to each other. The relationships between benz(a)pyrene concentrations and calm conditions are investigated. A dependence of its high concentrations on the frequency of calm periods in winter has been revealed. The established statistical relationships create opportunities for external control of observation results at stationary monitoring posts in the city and for assessing the effectiveness of measures taken to improve the quality of atmospheric air. The derived dependencies also allow numerically filling gaps in observation data and identifying additional emissions from benz(a)pyrene sources.

The study proposes a mathematical model for assessing the impact of crown forest fires on buildings. Based on this model, numerical calculations were performed to determine safe distances between forested areas and construction sites taking into account such factors as wind speed, building size, and other parameters. The model considers the type and properties of vegetation, geometric characteristics of forested areas, their moisture content, and fuel load. The finite volume method was used to obtain a discrete analogue of the model. As a result of the calculations, the maximal distances at which ignition of structures from wildfire sources is possible were determined. It was found that the distance between forest and building, at which ignition can occur, increases with the wind speed. Additionally, the calculations showed that an increase in building height also increases the safe distance. The proposed model can be used for numerical simulations aimed at ensuring fire safety during the design and construction of buildings near forested areas taking into account their specific characteristics.

The atmospheric transformations of vegetation-emitted organic compounds are initiated by their interaction with photolytically generated short-lived free radicals. The chain process, which is a sequence of radical stages, leads to the formation of condensable products as the nuclei of aerosol phase. The free radicals generated during the photolysis of benzaldehyde and biogenic aldehydes, including aromatic ones (salicylic, ortho- and para-anisic), were identified under laboratory conditions. Chromatographic analysis of the products formed after the introduction of additional free radicals shows that the composition and amount of condensable products change. The field measurements of the concentrations of aldehydes and the products of their photochemical decomposition under sunlight were carried out, and the compounds formed in the interaction of initial aldehydes with free radicals were detected. These products can be employed to estimate the concentrations of free radicals even below the limit of detection by physicochemical methods. The rates of free radical generation and sink were shown to change with altitude in the troposphere. The approach taking into account the vertical transport of air masses and the corresponding changes in photolysis rate constants has been developed. The formation of condensable products is the chain termination stage in the whole process of atmospheric photonucleation of biogenic aldehydes. The new data on the altitudinal variation in the concentrations of short-lived free radicals allow calculating photonucleation rates for biogenic aldehydes at different altitudes. The developed kinetic schemes can be used to simulate the formation of organic atmospheric aerosol in the troposphere taking into account the vertical transport of air masses.