Lake Baikal—a unique ecosystem on a global scale—is undoubtedly of great interest for a comprehensive study of its ecosystem. In recent years, one of the most significant sources of atmospheric pollution in the Baikal region was the emission of smoke aerosol and trace gases from forest fires, the number of which is increasing in the region. The transport and accumulation of aerosol and small gas impurities over water area of Lake Baikal is observed every summer due to forest fires occurring in the boreal forests of Siberia. The atmosphere above the lake covers a huge area (31,500 km²) and is still a little-studied object. This article presents the results of experimental studies of ground-level ozone, sulfur dioxide, and nitrogen oxides in the atmosphere over Lake Baikal, carried out on a research vessel during the boreal forest fires in Siberia in the summer of 2019.

The paper analyzes the interannual, seasonal variations of the optical and microphysical characteristics of aerosol in the Baikal region atmosphere according to measurements using the CIMEL sun photometer of the AERONET network at Tory station and according to the data of expedition measurements using the SP-9 sun photometer on the southeastern coast of Lake Baikal from 2010 to 2020. It is shown that in recent years, there has been an increase of the average monthly aerosol optical depth (AOD) values in the summer months, which is consistent with an increase in smoke emission due to annual large-scale wildfires in the boreal forests of Siberia and Yakutia in summer. Aerosol classification was carried out based on filtration and selection of the prevailing types of aerosols by analysis of aerosol optical depth and Angstrom exponent. It was revealed that in summer, the proportion of the smoke component of the aerosol optical depth increases to 30% compared to the spring. In the presence of smoke advection, the close relationship of AOD with the concentrations of the microdispersed aerosol fraction PM₁₀ and PM_2.5 was revealed. The correlation coefficients between the concentration of particulate matter (PM₁₀ and PM_2.5) and AOD were 0.87 and 0.86, respectively.

Forest ecosystems play an important role in the process of removing trace gases from the atmosphere. The purpose of this work is the experimental study of the flux and rate of the dry deposition of ozone on different types of vegetation in the Baikal region. Based on the eddy covariance method and the flux gradient methods (including the aerodynamic gradient method (AGM), the modified Bowen method (MBR) and modified gradient method (MGM)) and with experimental data, the quantitative estimates of the fluxes and dry deposition velocity of ozone on the underlying surface were obtained for different environments (grasslands, forest). The average values of the dry deposition velocity of ozone (V_d) were equal to 0.37 cm/s at night (0–3 h) and 0.91 cm/s during daytime hours (12–18 h). The ozone flux (F) was 0.24 μg m^–2 s^–1 at night and 0.72 μg m^–2 s^–1 in the afternoon. The quantitative estimates of V_d and F on vegetation and in the forest show a higher absorptive capacity of forests compared to soil vegetation.

The results of experimental studies of the daily variability of surface ozone concentration (O₃) in the atmosphere of the arid territory of Mongolia, obtained during scientific expeditions for the period 2005-2014 at the Sainshand station, are presented. Variations of hourly average concentrations of the O₃ changed from 70 to 126 μg m^-3.The daily variation of surface ozone concentration has minimal values in the morning during sunrise, and then there is an increase in ozone concentration in the daytime. The average amplitude of diurnal variations of O₃ was 56 μg m^-3.The maximum values of O₃ in the daily dynamic were observed in 2014, and the minimum values in 2007.The factors leading to increased surface ozone content and their relationship to meteorological and turbulent characteristics of the atmosphere are analyzed. A special mode of behavior of surface ozone, characterized by its day and night increase in daily changes, was revealed.

Comprehensive studies of aerosol pollution in the atmosphere were conducted at “Boyarsky” scientific station from spring to autumn 2024. The results of expeditionary work revealed the impact of smoke aerosol on the air quality at “Boyarsky” station, transported from both western and eastern directions. The highest concentrations of aerosols PM2.5 up to 42 µg/m³ and PM10 up to 104.4 µg/m³ were recorded from July 31 to August 1, as well as on August 16 and 20, 2024, due to the transport of smoke aerosols from wildfire areas in the Irkutsk region, the Republic of Buryatia, and Yakutia. During the same study, measurements of the number concentration of submicron aerosol (SMA) were conducted. The measurement results showed that from August 16 to 24, 2024, the temporal variation in the number concentration of SMA mirrored the variation in the mass concentration of PM2.5 and PM10 aerosols at “Boyarsky” station. A sharp increase in the number concentration of submicron aerosol up to 150 cm⁻³ and the mass concentration of PM10 up to 95 µg/m³ during daytime hours indicates the transport of smoke aerosol.