V. A. Obolkin

Dynamics of sulfur-containing admixtures in the atmosphere around a point source—the Baikal Pulp and Paper Plant on the southeast coast of Lake Baikal

A complex of organic and inorganic sulfur compounds have been measured for the first time in the vicinity of a point anthropogenic source—the Baikal Pulp and Paper Plant (BPPP) on the southeast coast of Lake Baikal; their spatial distribution and possible chemical transformation depending on the meteorological conditions and the time of day have been estimated. It is shown that the different heights of the emission of the sulfur compounds by departments of the plant and the coal thermal power station are responsible the different behavior of the corresponding admixtures in the plant’s surrounding.

Low-level atmospheric jets as main mechanism of long-range transport of power plant plumes in the Lake Baikal Region

This paper considers some peculiarities of anthropogenic admixtures propagation from large regional Coal Power Plants towards the South Baikal using experimental data and model estimates. Results of observations show that the main mechanism for transfer of atmospheric admixtures towards the South Baikal is low-level atmospheric jets having high velocity and a weak turbulent mixing. A weak mixing of emitted plume with the surrounding air (within a jet flow) results in deficiency of oxidants in it and in slowing of chemical transformation of some admixtures during the transfer.This paper considers some peculiarities of anthropogenic admixtures propagation from large regional Coal Power Plants towards the South Baikal using experimental data and model estimates. Results of observations show that the main mechanism for transfer of atmospheric admixtures towards the South Baikal is low-level atmospheric jets having high velocity and a weak turbulent mixing. A weak mixing of emitted plume with the surrounding air (within a jet flow) results in deficiency of oxidants in it and in slowing of chemical transformation of some admixtures during the transfer.

Results of long-term investigations on acid deposition in the area of South Baikal

We examine the acid deposition monitoring results (2000–2010) for the southern territory of East Siberia (the Irkutsk-Angarsk industrial center). It is established that acid deposition events are most frequently recorded in the area of South Baikal (70–100 km south-east of the Irkutsk-Angarsk industrial center), with the acidity of precipitation continuing to increase. Atmospheric precipitation acidity data are compared with long-term monitoring results for Europe.

Long-range transport of plumes of atmospheric emissions from regional coal power plants to the South Baikal water basin

We compare cases of actually observed regional transport of atmospheric pollutants to Lake Baikal against calculations according to a mathematical model. The observational data suggest that the most severe atmospheric pollution over the Lake is associated with atmospheric transport of sulfur and nitrogen dioxides from large coal-fired power plants both from the direction of Irkutsk and Angarsk, and from the direction of Buryatia (Ulan-Ude and Gusinoozersk). Transport of sulfur and nitrogen oxides to the Baikal atmosphere is especially strong at nighttime, under inversion-type meteorological conditions, in the form of weakly dispersed plumes from tall stacks of power plants. Data of automatic measurements of sulfur and nitrogen oxides demonstrate that actual mechanisms of anthropogenic pollutant transport to Lake Baikal are more complex and multiform as compared to model results. Model estimates of SO2 concentrations over the Lake are close to monthly average measurements; however, they fail to explain certain specific cases of increased pollutant concentrations in the Baikal atmosphere.

Peculiarities of spatial distribution of sulfur dioxide in Cisbaikalia from the data of shipboard measurements and numerical experiments

Presented are some results of sulfur dioxide measurements over South Baikal and Irkutsk Reservoir performed with the research vessel I.D. Papanin. It is obtained that sulfur dioxide concentration over the whole South Baikal did not exceed 1–2 μg/m3 at the absence of northwestern air mass transport in the region. On one of the days, two maxima of sulfur dioxide concentration were registered at the west-northwestern wind: over Irkutsk Reservoir (>80 μg/m3) and over Lake Baikal, between Listvyanka and Bol’shie Koty settlements (>40 μg/m3). It is supposed that the revealed maxima are the traces of sulfur dioxide plume from the sources in Irkutsk city. Numerical experiments with the mathematical model and the analysis of air mass trajectories corroborate this idea.

Comparison of formation conditions of secondary aerosol particles in boreal forests of Southern Finland and Siberia

Complex measurements of size distributions and chemical content of aerosols, trace gases SO2, NH3, ozone, and meteorological parameters were performed in boreal forests of Central Siberia during 03.2005–05.2006 at the rural station of Listvyanka. The data from Listvyanka are then analyzed from the point of view of their similarities and differences with respective data at Hyytiala background station (Southern Finland). The goal of this paper is to compare the conditions of formation of secondary aerosol particles in boreal forests in two different regions: in Southern Finland (Hyytiala station) and Siberia (Listvyanka station). Our main conclusion is that the particle formation–growth processes in Listvyanka occur in presence of high (compared to Hyytiala) concentrations of sulfur dioxide and ammonia. We show that their concentrations are enough for providing the particle growth up to 3.5 nm h−1 with much higher concentration of the nucleation mode particles in contrast to Hyytiala, where the sulfuric compounds are much less concentrated and the nucleation mode particles grow by consuming low volatile organic vapors that result from photochemical processing of highly volatile organic plant emissions. On the other hand, the nucleation bursts in Siberia occur more seldom than in Hyytiala. The difference in UVB irradiation regimes at Siberian stations and in Hyytiala can lead to different seasonal patterns of the particle formation–growth rates and the concentrations of nucleation mode in Siberia.

Aerosol Particle Formation Events at Two Siberian Stations

We present one-year data on atmospheric aerosol particle size distributions covering the ultrafine size range from two measurement stations situated in central Siberia: Tomsk and Listvyanka. The size distributions were measured using Diffusion Aerosol Spectrometers (DAS), which are able to detect particles as small as 3 nm in diameter. The analysis of the size distribution time series revealed about 30 new-particle formation and growth events at both stations. The events occurred predominantly during the springtime. The average particle formation rates were 0.4 cm -3 s -1 at both stations, whereas the particle growth rates were on average 5.5 nm h -1 at Tomsk and 1.8 nm h -1 at Listvyanka. The formation and growth rates were comparable with those observed in the western part of the Eurasian boreal forest.

Effect of long-range transport of sulphur and nitrogen oxides from large coal power plants on acidification of river waters in the Baikal region, East Siberia

Research has focused on the effect of sulphate and nitrate atmospheric deposition on river water chemistry in the Baikal region. During long-term monitoring it was ascertained that anthropogenic SO2 and NOx in the plumes emitted from regional coal Power Plants (PPs) cause extra nitrate and sulphate deposition in the Pereemnaya River basin that is located 100–150 km away from the emission sources. As a result, average concentrations of sulphate and nitrate in the water of the Pereemnaya River are 2–3 times higher than those in Lake Baikal, whilst total mineralisation of the river water is approximately 3 times lower. Because of the acidity of atmospheric deposition in the Pereemnaya river basin, pH value of the snow cover and precipitation is about 4.7. That makes the river water pH significantly lower (=6.8) than that in the lake and other tributaries (=7.8). It is recommended to strengthen monitoring of the natural environment in the southern basin of Lake Baikal and to apply measures to reduce pollutant emissions from PPs.

Experimental and theoretical research of wet deposition of sulfates and nitrates in the Lake Baikal region

The results on monitoring of chemical structure of atmospheric precipitation at Lake Baikal region are presented. The factors influencing on acidity and mineralization of wet deposition at different sites of the region (background, rural and urban) are considered. The special attention is given to dynamics of pH value, contents sulfates and nitrates. It is shown, that an acidity of precipitation is influenced not by absolute amount of strong acids anions, but by ratios of anions and cations in wet deposition. The fluxes of acidifying ions on an underlying surface of considered region are evaluated. With the help of mathematical simulation the possible contribution of regional anthropogeneous sources to acid loads (sulfuric and nitric acids) on water area of Southern Baikal with wet deposition is estimated.

Results of experimental observations and mathematical simulation of distribution of acidic atmospheric impurities in the region of Southern Baikal

In an outcome of two-years observations in the region of Southern Baikal, experimental data about inter-annual variability of 7-10 days average concentrations of some acid gases, as well as main ions in soluble faction of atmospheric aerosols and in rains. The evaluations of a dry deposition amount are represented, in comparision with the measured wet deposition. In the summer period the dry and wet deposition in considered region are close on magnitude, but in an annual sum the dry deposition essentially predominates because of their highest contribution in the winter period. As a whole, the results are satisfactorily agreed with obtained earlier observations in different parts of the Baikal region. In addition to experimental studies, the accounts with the help of the mathematical model based on numerical solution of the spatial non-linear non-stationary semi-empirical equation of a turbulent diffusion of impurity were made. In an outcome of conducted numerical experiments with the model the spatial fields of monthly average concentration of both sulphur and nitrogen compounds and a small gas components of the atmosphere over considered region were obtained.