The main hydrogeochemical processes affecting the composition of certain naturally carbonated waters of southwestern Poland

Kłodzko region is a historical region in southwestern Poland, cutting into the territory of the Czech Republic. In geological terms, it contains (within the Polish borders) the Upper Nysa Kłodzka Graben and the Orlica-Śnieżnik Metamorphic Unit. The region abounds in naturally carbonated waters, whose composition is dominated by HCO-3, Na+, Ca2+ and Mg2+ ions. This study concerns the chemical composition of waters from particular intakes situated in Kudowa-Zdrój, Jeleniów, Duszniki-Zdrój, Polanica-Zdrój and Gorzanów. Chemical data were analysed mathematically and by hydrochemical modelling performed with the help of the AquaChem5.1 and PhreeqC codes. The chemical composition of the waters studied is shaped chiefly by hydrolysis of aluminosilicates. The major ion composition is also influenced by ion exchange (adsorption and desorption) with and dissolution of carbonate minerals. Analysis of saturation indexes showed that these waters are in equilibrium with kaolinite. Generally speaking, the chemical composition of waters in this region is determined by dissolution and precipitation of carbonates (mostly secondary) and aluminosilicates in the presence of carbon dioxide, as well as by ion exchange.