Polycyclic aromatic hydrocarbons (PAHs) were detected in different types of PAH-containing samples collected in Lake Baikal during wildfires in the adjacent areas. The set of studied samples included the following: (i) water from the upper layer (5 m); (ii) water from the surface microlayer; (iii) water from the lake tributaries; (iv) water from deep layers (400 m); and (v) aerosol from the near-water layer. Ten PAHs were detected in the water samples: naphthalene, 1-methylnaphthalene, 2-methylnaphthalene acenaphthylene, acenaphthene, fluorene, phenanthrene, fluoranthene, pyrene, and chrysene. The total PAH concentrations (ƩPAHs) were detected in a wide range from 9.3 to 160 ng/L, characterizing by seasonal, intersessional, and spatial variability. In September 2016, the ƩPAH concentration in the southern basin of the lake reached 610 ng/L in the upper water layer due to an increase in fluorene, phenanthrene, fluoranthene, and pyrene in the composition of the PAHs. In June 2019, ƩPAHs in the water from the northern basin of the lake reached 290 ng/L, with the naphthalene and phenanthrene concentrations up to 170 ng/L and 92 ng/L, respectively. The calculation of back trajectories of the atmospheric transport near Lake Baikal, satellite images, and ƩPAH concentrations in the surface water microlayer of 150 to 960 ng/L confirm the impact of wildfires on Lake Baikal, with which the seasonal increase in the ƩPAH concentrations was associated in 2016 and 2019. The toxicity of PAHs detected in the water of the lake in extreme situations was characterized by the total value of the toxic equivalent for PAHs ranging from 0.17 to 0.22 ng/L, and a possible ecological risk of the impact on biota was assessed as moderate.

The article analyzes the chemical composition (ions, elements, and polycyclic aromatic hydrocarbons) of the atmospheric aerosol in the near-water layer of the atmosphere above Lake Baikal during wildfires in Siberia. Aerosol deposition affects the aquatic environment of the watershed basin and the lake itself. The current law on Lake Baikal limits the activity of the permanent stationary anthropogenic sources of the aerosol in the central ecological zone, and they do not have a significant negative impact. Wildfires can have a much greater impact on the environment. Smoke emissions entering the area of Lake Baikal due to wildfires change the chemical properties of the atmospheric aerosol and increase its mass and number concentration. The concentrations of NH₄⁺, K⁺, NO₃⁻, and SO₄²⁻, which enter with submicron aerosol fraction, increase in the ionic composition of the aerosol. The composition of polyaromatic compounds changes, and their concentrations increase. Elevated concentrations of B, Mn, Zn, As, Sr, Cd, and Pb in the composition of aerosol indicate the influx of air masses from the areas prone to wildfires. Despite the sporadic effects of these natural factors, they affect the pollution of various Baikal ecosystems, especially small tributaries of the lake, whose main supply is atmospheric.

The aim of this study was the systematization and generalization of data obtained by authors during the last decade and the comparison of these data with those obtained by other authors. Gas chromatography (GC-MS) was used for the determination of PAHs and the positive matrix factorization (PMF) model and principal component analysis (PCA) were used for source apportionment of PAHs. It was found that the total concentration of 16 priority PAHs in surface waters varied from 5 to 200 ng/L, whereas the concentration of 16 PAHs in bottom sediments varied from 50 to 700 ng/g. The 2–3-ring PAHs were dominant in water, whereas the 4–6-ring PAHs were dominant in sediments. That was due to PAHs fractionation in the soil–water system. The source apportionment results showed that the PAHs in both water and sediments mostly originated from the combustion of biomass and fossil fuels. In contrast to sediments, there was a PAH fraction in water that did not originate from a single source. The pollution of freshwater ecosystems manifested itself in the lack of correlation between values of octanol/water partitioning coefficients and sediment/water partitioning coefficients of PAHs.

On the basis of hydrochemical investigations from 2010–2012 and with due regard for earlier data, we assess the present status of water quality for the main tributary streams of Lake Baikal. An analysis is made of the observed changes in the chemical composition of water induced by natural and anthropogenic factors. It is shown that the deterioration of the water quality in the Selenga river and in the small tributaries of South Baikal, respectively, is caused by wastewater discharges and by pollution of atmospheric precipitation, respectively.

This article presents the results of the long-term studies at two stations located in the city of Irkutsk and the Listvyanka settlement of the southern Baikal region (East Siberia) concerning the concentration of polycyclic aromatic hydrocarbons (PAHs) in atmospheric aerosol. The studies revealed the seasonal and interannual dynamics in the distribution of PAHs in aerosols from urban (source) and rural (receptor) areas. We carried out a comprehensive analysis of weather conditions such as wind direction, relative humidity, air temperature, and atmospheric pressure. The analysis determined high correlations between air temperature, atmospheric pressure, temperature inversions, and PAHs at the monitoring stations. The average annual concentrations of PAHs in the abnormally warm 2020 were three times lower than the average values obtained in the cold 2016. The toxic equivalent concentrations (BaPeq) increased from summer to winter with an increase in the contribution from benzo(a)pyrene, one of the most toxic and hazardous compounds of this class of organic substances. Four-, five- and six-ring PAHs mainly predominated in aerosol; the proportion of two- and three-ring PAHs increased from the warm season to the cold season. Diagnostic ratios of PAHs identified the main sources of air pollution by this class of compounds: combustion of coal, liquid fuel and firewood, vehicle emissions, and wildfires. The percentage of the transport of anthropogenic aerosol containing PAHs from industrial sources of the Southern Baikal region towards Lake Baikal was 65 to 71%.

Polyciclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants in urban atmosphere. Several PAHs are known carcinogens or are the precursors to carcinogenic daughter compounds. Understanding the contributions of various PAH emission sources is critical to appropriately managing PAH levels in the environment. The sources of PAHs to urban snowpack in Shelekhov city, Eastern Siberia, characterized by extremely high levels of PAH accumulation in snow were determined by using end-member mixing approach. The best potential to distinguish PAH emission sources is exhibited by ratios of PAH pairs of the principal mass 228, 252, and 276. The ratios of PAH pairs were used as tracers of end-member PAH sources. The contributions of sources were calculated using systems of linear equations. The results obtained using ratios of PAH pairs were compared with those obtained using molecular diagnostic ratios. It was shown that the results obtained using diagnostic ratios as tracers are less reliable than the results obtained using the ratios of the sums of PAHs.