FACTORS AFFECTING THE CONTENT OF HEAVY-METALS IN BULK ATMOSPHERIC PRECIPITATION, THROUGHFALL AND STEMFLOW IN CENTRAL BOHEMIA, CZECH-REPUBLIC

Content of coppers, manganese, lead, and zinc in samples of bulk preci pitation, throughfall and stem-flow has been studied in a forest area in central Bohemia. The sampling localities are situated on two types of bedrock granite and cenomanian sandstones. The content in bulk prec ipitation reflects the impact of fossil fuel emission sources and the vehicular sources of lead. The deposition rate of elements in throughf all, in comparison with that of the deposition on an open land, exhibi ts increased values in essential microelements (in Mn approx. 45 times , Zn-5 times, Cu and Cd - 2 times), with significant seasonal fluctuat ions. The value of the same ratio for ecotoxic lead is 0.23. The enhan ced flux of elements in throughfall is ascribed mainly to the metaboli c processes of the trees. Differences in the chemical composition of t hroughfall and stemflow collected on stands with different kind of bed rock are ascribed to various degree of accessibility of the micronutri ents and various intensity of their vegetation uptake.