Hydrogeochemistry and aragonite scaling in the Sijarinska spa (Serbia)

• Autores: B.Z. Todorovic, Dragan T. Stojiljkovic, Tanja Petrovic Pantic, Nebojsa C. Mitic, Ljubisa S. Nikolic, Suzana M. Cakic
• Localización: Carbonates and Evaporites, ISSN 0891-2556, Vol. 31, Nº. 4, 2016, págs. 367-374
• Idioma: inglés
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• Resumen

  • This paper presents the results of the inorganic carbon species hydrogeochemistry in order to explain aragonite precipitation in the mineral geothermal waters of Sijarinska spa, where the deep B-4 borehole represents the most important geothermal water discharge. Hydrogeochemistry of ions in B-4 water showed domination of Na-HCO3-type. The detailed hydrogeochemical analysis of the major carbon species gave reasons for CaCO3 precipitation. The main reason is CO2 partial pressure reduction, which led to the increase of the pH value from the aquifer value of 5.88–6.39 to 7.1–7.8, measured in surface discharge. These changes led to the increase of the concentration of CO2−3CO32− ions which with Ca2+ ions form poorly soluble aragonite. The Ryznar’s index of solubility values, 4.2-4.7, indicates that the examined water has the prominent tendency to carbonate scaling. This tendency was confirmed by the mineralogical analysis of precipitated solids, which are dominated by aragonite (>95 %) accompanied by small amounts of calcite (<5 %) with minor amount vaterite. Monitoring saturation index values for the examining period (1995–2015) exhibited that B-4 geothermal water showed constant tendency toward CaCO3 deposit formation.