The application of selected hydrochemical indicators in the interpretation of hydrogeochemical data – A case study from Busko-Zdrój and Solec-Zdrój (Poland)

Abstract

Abstract The processes affecting the formation of the chemical composition of the waters take place in specific hydrochemical zones. The knowledge of such phenomena allows to draw conclusions regarding the origin and conditions prevailing in the regions of their occurrence, e.g. indicate a zone of active water exchange, i.e. an inflow of infiltration waters, or a zone of isolated geological structures, where diagenesis processes take place. The aim of the study was to assess the hydrochemical conditions which affect the formation of chemical composition and genesis of origin of sulfide waters from the Busko-Zdroj and Solec-Zdroj region (Poland) using selected hydrochemical indices (rNa+/rCl−, rNa+/rK+, rNa+/(rNa++rCl−), rSO42− × 100/rCl−, rCl−/rBr−, rHCO3−/rCl− and the weight index: Cl−/Br−). A detailed analysis was carried out for sulfide waters from fifteen intakes and five springs. Several aquifer systems are found in the study area. Investigated intakes and springs differ in terms of stratigraphy and lithology. The analysis of changes in the values of selected hydrochemical indices confirms that waters of the Busko-Zdroj and Solec-Zdroj region belong to two systems of circulation — “shallow” and “deep”. The formation of the chemical composition of analysed waters occurs mainly in the aquifer. The values of rNa+/rCl−, rCl−/rBr−, rNa+/(rNa++rCl−), and Cl−/Br− indices suggest that the salinity of sulfide waters may result from leaching of salt interburdens and inclusions. In the area of occurrence of sulfide springs, tectonic cracking zones enable the inflow of highly mineralized waters and thus contribute to the mixing of waters of different aquifers. High content of Cl− and Na+ ions as well as mineralization higher than in sea waters indicate the formation of waters from the upper Cretaceous level together with deposits in a sedimentary basin.