The St. Moritz Mauritius mineral spring (Upper Engadine Valley, SE Switzerland): review of its importance by the joint facts of geological occurrence, archeology, health effects, chemical properties, and long-term chemical stability

Abstract

The St. Mauritius mineral spring has been used since the late Bronze Age times (1410/1411 BC), as dated on the wooden headworks using radiocarbon and tree ring (dendrochronology) methods. It became eminent during the late Middle Ages epoch of curative treatments. The water is renowned for its high iron content and high amounts of dissolved and gaseous CO2. This special character of the Mauritius spring made it attractive to be analyzed by esteemed chemists over more than two centuries. By these analyses transferred in coherent units, a comparison of the chemical composition of this Mauritius mineral spring during the entire interval from 1788 to 2022 became possible. It reveals that the chemical composition of the Mauritius mineral spring water has largely remained stable and apart from some minor changes in water quality caused by alterations to the spring capture headworks since that time. These capture remediation actions were aimed to maintain the original composition of the Mauritius mineral spring water, which since its first utilization is threatened by the prevailing mixing processes with the shallow, low mineralized groundwater. The mineral water can be characterized as being an acidic calcium–sodium–magnesium–bicarbonate-type water, rich in iron, with a total mineralization of about 1.8 g/l. The spring discharge with a temperature of about 4–6 °C and contains about 2500 mg/l of free gaseous carbon dioxide. This high concentration of free outgassing of CO2 is due to the emission of this gas from a great depth from the Engadine Fault Line which crosses the spring discharge area.