Physicochemical properties and chemism of atmospheric precipitation, influenced by atmospheric air pollution, are a major element affecting contemporary degradation of the natural environment. It is known that water, apart from its function as a partner in physical reactions, is also the carrier of anthropogenic transformation of the natural environment. Acid rain is all the rain, snow, and mist that contain an unnatural acid. The major sources of acid rain are sulfur dioxide (SO₂) and nitrogen oxides (NO_x) in the atmosphere. Rainwater in equilibrium with carbon dioxide in air is slightly acidic (pH>5.6). However, rainwater is often more acidic due to the natural emissions of SO₂, NO_x, or organic acids. The typical pH values of acid rain resulting from anthropogenic emissions are in the range of 3.5-5.0 [1].
In the literature [2, 3], much discussion is devoted to the problem of acid rain and its adverse influence on forest ecosystems. The combustion of fossil fuels, carbon in particular, has caused a noticeable increase of sulphur emissions to the atmosphere, which has consequently led to higher deposition of sulphur in ecosystems. Atmospheric deposition occurs both in the vicinity of the combustion source and in extensive areas adjacent to industrial and urban centres. As early as the 1970s and 1980s, several attempts were made to Oden [4]. It is known that forest ecosystems are among the most sensitive to atmospheric deposition of acid components. In the more sensitive ecosystems of temperate regions, this accelerated supply of sulphur has caused dramatic changes to chemical composition of soil solutions, and is partly responsible for spreading forest dieback, especially in the mountains [5, 6]. Another consequence of increasing acidification of the soil environment is the increasing mobility and availability of heavy metals [7-9] and an increase of panning of lifegiving elements [10].