Climate change and anthropogenic activity in the Republic of Buryatia aggravate the processes of desertification and land degradation. The territory of Buryatia was zoned according to the aridity index based on ENVIREM climate data with a high spatial resolution. Long-term changes in the vegetation cover in arid and humid zones are quantitatively assessed based on a combined study of the time series of the normalized-difference vegetation index (NDVI) with the Advanced Very High Radiation Radiometer (AVHRR), meteorological series of the NCEP/NCAR Reanalysis data set, and field studies. Maps of the spatial distribution of NDVI linear trends and precipitation for 1982–2015 (with the differentiation of the wet (1982–1999) and dry periods (2000–2015)) have been constructed. During the wet period, positive NDVI trends are observed for almost the entire republic, while the dry period is characterized by a significant increase in negative trends of the vegetation index. A positive correlation between the Selyaninov hydrothermal coefficient and NDVI is observed for intermountain steppe basins, while it is negative for forest landscapes. The dynamics of the NDVI for steppe vegetation is more dependent on precipitation, while the dynamics of the NDVI for forests is more significantly correlated with temperature. Reforestation, postpyrogenic succession, the bushing of fallow lands, and other factors determine the growth in the NDVI. Negative NDVI trends are characteristic of steppe ecosystems with low precipitation and forest ecosystems exposed to felling and fires.

For the first time in the territory of the Russian Far East, a study related to the establishment of correlations between air quality and public health in Ulan-Ude (Buryatia, Russia) was carried out. This study is based on the analysis of official medical statistics on morbidity over several years, the data on the composition and volume of emissions of harmful substances into the air from various stationary sources, and laboratory measurements of air pollutants in different locations in Ulan-Ude. This study confirmed that the morbidity of the population in Ulan-Ude has been increasing every year and it is largely influenced by air pollutants, the main of which are benzo(a)pyrene, suspended solids, PM_2.5, PM₁₀, and nitrogen dioxide. It was found that the greatest contribution to the unfavorable environmental situation is made by three types of stationary sources: large heating networks, autonomous sources (enterprises and small businesses), and individual households. The main air pollutants whose concentrations exceed the limits are benzo(a)pyrene, formaldehyde, suspended particles PM_2.5, PM₁₀, and nitrogen dioxide. A comprehensive assessment of the content of various pollutants in the atmospheric air showed that levels of carcinogenic and non-carcinogenic risks to public health exceeded allowable levels. Priority pollutants in the atmosphere of Ulan-Ude whose concentrations create unacceptable levels of risk to public health are benzo(a)pyrene, suspended solids, nitrogen dioxide, PM_2.5, PM₁₀, formaldehyde, and black carbon. The levels of morbidity in Ulan-Ude were higher than the average for Buryatia by the main disease classes: respiratory organs—by 1.19 times, endocrine system—by 1.25 times, circulatory system—by 1.11 times, eye diseases—by 1.06 times, neoplasms—by 1.47 times, congenital anomalies, and deformations and chromosomal aberrations—by 1.63 times. There is an increase in the incidence of risk-related diseases of respiratory organs and the circulatory system. A strong correlation was found between this growth of morbidity and atmospheric air pollution in Ulan-Ude.

The Selenga River provides about half of the water and chemical runoff into Lake Baikal and plays an important role in the sustainability of the ecosystem of this large natural freshwater lake. Phthalate esters (PAEs) are organic compounds that can disrupt reproductive and endocrine systems. This study focused on investigating the distribution of six priority phthalates in the Selenga River and its delta utilizing SPE-GC/MS. The study found that the highest levels of Σ6PAE were observed during the high-water years, 2021 and 2023, and were evenly distributed along the river from the sampling sites upstream of Ulan-Ude to the delta channels. In contrast, the mean annual Σ6PAE content was relatively low in the low water period of 2022. Dibutyl phthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP) are the two dominant phthalates found in the surface waters of the Selenga River and delta channels. In 2021, the average total concentration of six phthalates (Σ6PAE) ranged from 8.84 to 25.19 µg/L, while in 2022 it ranged from 0.45 to 4.01 µg/L, and in 2023 it ranged from 5.40 to 21.08 µg/L. The maximum level for the sum of phthalates was 61.64 µg/L in 2021, 13.57 µg/L in 2022, and 30.19 µg/L in 2023. The wastewater treatment facilities in Ulan-Ude were identified as a stable local source of phthalates. In some cases, PAE concentrations exceeded maximum allowable concentrations, particularly for DEHP. This could have adverse effects on aquatic organisms.

The basin of the transboundary Chikoy River is the largest in terms of area among the catchment areas of the main tributaries of the Selenga River. The Selenga basin as a whole is characterized by a wide distribution of icing. The paper presents the results of mapping icings and their distribution according to various physical and geographical characteristics. Based on the Landsat-8 satellite imagery for 2019, a cartographic database of icings was compiled for the first time for this territory. The database includes 6,319 objects on a total area of 140 km2. The largest icing is 671.13 thousand m2 in area. The mean value, median, and mode are 22.16, 12.86, and 10.24 thousand m2, respectively. Most of the icings are located at altitudes of 900–1,200 m and on the slopes of the eastern exposure. Icings were not found in the western part of the Chikoy River basin and in the near-top belt of the ridges. Fissure rocks are predominant in the study area, which indicates the leading role of groundwater in the formation of icing. The greatest icing coverage is found in areas with annual precipitation in the range of 350–460 mm and with an average annual temperature of –2.5 ... –3℃. In the landscape structure, icing is common in low- and mid-mountain taiga larch-dark coniferous landscapes. About 80% of the icings are located on the complexes of soddy podburs, podburs, soddy podzols, and other associated soils. The level of icing coverage was found to be not proportional to the natural resources of groundwater, which can be caused by both the imperfection of the original groundwater map and the uncharacteristic manifestation of icing in 2019. The resulting database will become the basis for retrospective and predictive assessments of the icing dynamics in the Chikoy and Selenga River basins.

The advantages of a quantitative assessment of the spatial and temporal variability of the boundaries and volumes of ravines using modern means and methods of aerial photography from an unmanned aerial vehicle (UAV) are substantiated, in contrast to traditional survey methods (linear method of benchmarks, tacheometric, aerial and space photography, laser scanning). The erosion zoning and mapping of linear and gully formations on the territory of the Kuitunka, Tarbagataika, and Kunaleika river basins (Selenga middle mountains) are carried out. The reanalysis data were used to assess extreme meteorological events leading to the acceleration of erosion processes. Paleontological material confirms the long duration of erosive-accumulative processes in the Nizhnyaya Bulanka depression. High-accuracy multi-temporal orthophotomaps and digital elevation models of Bulanka gully using unmanned aerial vehicles were produced. The method of quantitative estimation of gully formation rates is offered, which allows estimating with high accuracy the change of area and volume characteristics of erosive forms.