Isotope study of therapeutic waters from Horyniec Spa, SE Poland.

The curative waters of HCO3-SO4-Mg-Na+H2S chemical type and 0.6-0.8 g/dm3 total dissolved solids are exploited in Horyniec Spa located at the northern boundary of the Carpathian Foredeep, near the Polish-Ukrainian border. Although these waters occur at relatively shallow depths (their aquifer is encountered about 30 m below the ground surface), they are quite well protected from surface pollutants by a cover of clayey sands. This paper revises and discusses the origin of specific chemical components of these waters based on the following analyses of stable isotopes: (a) δ34S in [image omitted] , H2S, and CaSO4·2H2O, (b) δ18O in [image omitted] , H2O, and CaSO4·2H2O, and (c) δ2H in H2O and CaSO4·2H2O. The most important process which takes place in the aquifer is the dissolution of gypsum present in the Miocene formation and subsequent bacterial reduction of sulphate ion to hydrogen sulphide in the presence of an organic matter. This process shifts both δ34S and δ18O of sulfate ions towards higher concentration of heavy isotopes by several per mil in comparison to that in the original Miocene gypsum. The hydrogen sulphide generated this way (up to a concentration of 45 mg/dm3) is highly depleted in a heavy isotope by about 41 ‰ with respect to a sulphate ion. [ABSTRACT FROM AUTHOR]