Hydrochemical Characteristics of Thermal Water Reservoir in Lądek-Zdrój in Light of Research into the Borehole LZT-1—The Deepest Borehole in the Sudetes (SW Poland)

• Main Authors: Barbara Kiełczawa, Wojciech Ciężkowski, Mirosław Wąsik, Marek Rasała
• Format: Article
• Language: English
• Published: MDPI AG 2021-02-01
• Series: Energies
• Subjects: geothermal water; medicinal water; hydrochemistry; geothermometers; crystalline massif; Lądek-Zdrój
• Online Access: https://www.mdpi.com/1996-1073/14/4/1009

Lądek-Zdrój is situated within the tectonic unit of the Lądek-Śnieżnik metamorphic complex. Thermal water is captured by five springs and borehole L-2. These waters are characterized by TDS content in the range of 160–230 mg/L and predominance of HCO₃⁻ (15–100% meq), SO₄²⁺ (10–36% meq), and Na⁺ (57–91% meq) ions. Increased concentrations of radon, hydrogen sulfide, and fluoride ions (7 mg/L–13 mg/L) determine the medicinal properties of these waters, classified as thermal waters of Na-HCO₃-(SO₄), F⁻, H₂S, Rn type, with temperatures of 18 to 30 °C and 41 to 45 °C in springs and in the L-2 borehole, respectively. At the turn of 2018 and 2019, a new borehole LZT-1 was drilled in the area of Lądek-Zdrój. It captured thermal waters with a temperature of 37.4 °C at the outflow. The water temperature at the bottom of the heated borehole reached about 59 °C. The lithology of rocks found in the recharged areas implied that the Ca²⁺ ions present in the studied waters originated from pyroxenes, amphiboles, calcite, calcium plagioclases, and fluorite. As for Na⁺ and K⁺ ions, they originate from sodium plagioclases, microcline, and orthoclase. The probable deposit temperature of waters from this borehole was estimated with the use of chemical geothermometers, as ranging from about 87 °C to 97 °C.