Sparkling mineral water at Western rim of the Doupovské hory mountains (Czech Republic): Genesis by water-rock interaction and deep-seated CO₂

Mineral water with dissolved CO₂ is discharged from the Variscian granite of the Karlovy Vary massif and from Tertiary basalts and pyroclastics of the stratovolcano of the Doupovské hory Mountains in the vicinity of Kyselka and Velichov. The sparkling mineral water is produced from numerous drill holes in the valley of the Lomnice creek, the Pstružný creek and the Petrovský creek. The mineral water with the high content of CO₂ is bottled as Mattoni sparkling mineral water. Atmospheric precipitation infiltrates either in outcrops of the granite or the basalt and the basaltic pyroclastics. Judged on the tritium content, the water is less than 50 years old. Where the ground water meets the ascending CO₂ of post-volcanic origin, it interacts more aggressively with the rocks of the aquifer. The total dissolved solids of the mineral water increase to more than 1 g/l. The mineral water from the granite is characterized by the mass ratio of (Na+K)/(Ca+Mg) higher than 1 and increased concentration of fluoride ions. Mineral water from basaltic rocks has the ratio lower than 1 and the concentration of fluoride ions is low. Isotopic composition of traces of He in CO₂ gas indicates that about 35% of the He component probably originates from a mantle source. Carbon dioxide is probably derived from a residual magmatic source and not from deep-seated marine carbonates or organic matter undergoing thermal decomposition. Sulphate ions in the Kyselka and Velichov mineral waters differ isotopically from the sulphates in the thermal springs of Karlovy Vary. The sulphates are not derived from fossil salts of a Miocene playa lake but they dissolve from oxidised sulphide minerals in bedrocks and are also derived from atmospheric SO₂. Isotopic composition of the dissolved lead indicates that this metal is probably derived from anthropogenic aerosols deposited in local soils and not from dissolution of isomorphic lead in rock-forming minerals. Patterns of rare earth elements and ytterbium (REY) show, that REY are derived from local rocks. The main cause of the formation of the sparkling mineral water is an input of CO₂ from a deep-seated magmatic source to an aquifer of meteoric ground water that percolates through pores, joints and fracture zones in local granite, basalt and pyroclastics.