Hydrogeochemical processes in sulphurous waters used in balneotherapy

Sulphurous water is used for balneotherapeutic purposes throughout the world. Its therapeutic properties are affected by the forms and concentrations of S(II) occurring in the solution. The processes that occur along the flow of water can affect the speciation of sulphur and influence on the installation. This article concerns an investigation of hydrogeochemical processes in five different sulphurous water distribution systems. Speciation modelling indicated that, in cold water, the concentration of H₂S equals or even exceeds that of HS⁻. In hot water, bisulfides become the predominant form and constitute 60–70 %. Natural waters usually achieve equilibrium with carbonate minerals, while upon heating, the water tends to become supersaturated with respect to these minerals. The calculated LSI values exceed 0.5 indicating a propensity for scale formation. Also, RSI values suggest that a scale formation is possible in the systems. No significant differences in the concentration of S(II) compounds are observed at various points.