Aerosol in the atmosphere of the Baikal region: history and contemporary researches

Abstract

The results of long-term studies (1995-2017) of the physical properties and chemical composition of atmospheric aerosol in the Baikal region are considered. These studies are important for understanding the role of the atmosphere in the formation of the chemical composition and quality of the waters of Baikal and its inflows. Over the past two decades, Limnological Institute SB RAS (Irkutsk, Russia) have conducted various joint studies of the characteristics of atmospheric aerosol with Russian and foreign groups. The chemical composition, biological component, size distribution, spatial distribution and aerosol sources over the lake were investigated. The interannual variability of the main chemical compounds in the aerosol was estimated. So, over the period studied, there was a gradual decrease observed in the concentrations of the main ions in the aerosol composition: in Irkutsk by 2.1 times, Listvyanka - by 4.0 times, at the background site of Mondy - by 3.5 times. In addition to quantitative changes, there is a change in the ratio of the main ions in the aerosol at Listvyanka site (south-west coast of Lake Baikal) and at the background site of Mondy. Upon condition of no external influences the content of the main ions in the aerosol on the surface layer of Lake Baikal is signifcantly lower (0.33-5.2 μg·m^-3) than during of extreme conditions (2.2-5.2 μg·m^-3). Forest fres near Baikal causean increase of the concentrations of Na⁺, K⁺, NH₄⁺, Cl^-, and NO₃^- ions in Baikal aerosols. Componentsof soil-erosion origin (Al, Fe, Zn, Cr, Ba) dominate in the elemental composition of the aerosol. Theirconcentration increases during forest fres up to 1.4 - 6 times at average. The flows of sulfur and nitrogen, the main acidifying components, differ in different years of observations both at the monitoring sites and over the surface of Lake Baikal.