Comparison of Experimental and Calculated Data on Ion Composition of Precipitation in the South of East Siberia

摘要

Permanent observations of the chemical composition of precipitation carried out by the Limnological Institute of SB, RAS, at the monitoring stations in the south of East Siberia (Irkutsk, Listvyanka, Mondy) make it possible to estimate the specific features of the ion composition of the precipitation in the region and to determine to some extent the anthropogenic impact on the chemical composition of the precipitation. However, based on the observational data alone it is difficult to separate the respective contributions of natural and anthropogenic sources of aerosols to the concentration of ions in the drops. In addition, in the process of fog and precipitation formation gaseous impurities are absorbed from the air (Stepanov, et al., 1997). Absorption of gaseous impurities by the drops of precipitation and fogs need to be estimated to evaluate the impact of abnormal weather conditions on the pollution level in the cities (Bezuglaya, 1985). The object of the paper was to compare experimental data with the results of numerical thermodynamic modeling of the equilibrium composition of precipitation in clean and polluted atmospheres. Thermodynamic models are suggested for the description of the complex processes in the atmosphere including phase changes and chemical inter-relations with incompletely studied reaction mechanisms. An undeniable advantage of the approach is that there are practically no constraints on the number of the substances that can be considered. Unlike the methods of chemical kinetics that are traditionally used when modeling transformations of substances in the polluted atmosphere the thermodynamic statement does not require information on a concrete mechanism of reactions, their speed and intermediate products.