ARSENIC IN THE THERMAL WATERS OF SOTHERN BULGARIA
Published: 1 Aug 2019
Abstract: The research is based on water samples from thermal mineral waters and individual water sources associated with confined fractured aquifers in Southern Bulgaria. The analysis indicated that more than 65% of them contain arsenic below the drinking water standard of 0.01 mg/l, as defined in Regulation No. 9 from 2001 for the drinking water quality. In 3.5% of the samples (11 water sources), the arsenic concentration exceeds 0.05mg/l, which was the quality standard before the adoption of Regulation No. 9. Some of the thermal waters with highest arsenic concentration come from Triassic limestones and dolomites (Kazichene, Starozagorski Bani, Slivesnki Bani, Ovcha Kupel), individual sources are associated to gneiss (Kozhuh, Gotsedelchevski Bani), granites (Yakoruda), andesites (Merichleri). In some cases, thermal water of elevated arsenic concentration from fractured hydrothermal systems discharge in younger unconsolidated deposits, where they come into contact with freshwater (Ravno Pole, Sandanski, Merichleri). In such environments, if drinking water abstractions are overexploited, it is possible to compromise them by drawing in mineral water of naturally elevated arsenic concentration. Such risk depends on the hydrodynamic conditions, the physicochemical conditions, and the forms of arsenic in the water.
Keywords: thermal waters, arsenic, geothermal contaminant, hydrochemistry, south bulgaria
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