No abstract

The protected area "Bohemian Switzerland National Park" with its characteristic sandstone landscape was influenced by the long-term air pollution and acidic deposition within the area known as Black Triangle (located where Germany, Poland, and the Czech Republic meet, is one of the Europe's most polluted areas). The local Upper Cretaceous sandstone is subhorizontally stratified, fine-to coarse-grained, quartz dominated, with low content of clay minerals. One of the significant negative effects of the intensive acidic deposition on sandstone outcrops has been identified as chemical (salt) weathering, i.e., a process when the porous sandstone rock is except of chemical influence attacked also by force of crystallization of growing salts crystals. Anions NO 3 − together with SO 4 2− and cation NH 4 + were the most abundant solutes in bulk precipitation samples. Current (2002 to 2009) bulk deposition fluxes of SO 4 2− determined at three sites directly in the National Park indicate decline from 23 to 16 kg −1 ha −1 year −1 . Infiltration of bulk precipitation solutes into the sandstone mediates the weathering processes. Natural outflow of sandstone pore-water (sandstone percolates) can be sampled only during certain days of year when the sandstone becomes saturated with water and percolates drip out on small number of sites from roofs of overhangs. Under usual conditions percolation water evaporates at the sandstone surface producing salt efflorescences-the typical example is Pravčická brána Arch locality. The average pH of the dripping sandstone percolates was 3.76. Concentration of SO 4 2− and Al in sandstone percolates reached up to 46 and 10 mg L −1 . The concentration of Al in percolates has been 160-fold greater the one in the precipitation samples suggesting the sandstone as a source. The water O and H isotopic composition of percolates has been virtually identical to precipitation samples, indicating thus relatively short residence time of the solutions within the sandstone pore-spaces. Evaporation experiments with bulk precipitation and percolate samples proved possible origin of some Ca in bulk precipitation and the sandstone rock as the source of Al and possibly of K for the salt efflorescence identified on Rock Arch body.

No abstract

Atmospheric inputs of elements/ions into the soil through bulk precipitation and throughfall (precipitation below tree canopies) were monitored monthly at two forested catchments (Lesni Potok and Liz) in central and southwestern Bohemia, respectively. The annual deposition fluxes (expressed in µg/mg m −2 yr −1 ) of Al, As, Ba, Be, Ca, Cd, Cl It is declared that high fluxes of these elements/ions in TH significantly affect the forest soil water chemistry and that the forest vegetation significantly contributes to the mobilization of several elements in soil and to their redistribution throughout the soil profile.