ABSTRACT
Since the early Pleistocene, artesian springs located in the valley of the river Neckar near Stuttgart have been discharged mineralized water enriched with carbonic acid. From the 19th century the confined mineral water, rising up along faults, has been drawn from 19 wells which were drilled into the Lower Keuper and karstified Upper Muschelkalk (Trias). Alltogether they discharge 275 l/s. Due to geothermic and hydro-chemical investigations in the river Neckar and the quaternary gravel deposits, additional natural outflows of mineral water could be located so that the total discharge increased to approximately 500 l/s. Whereas the karstwater in the Upper Muschelkalk generally shows low concentrations in the upstream of the mineral wells, different states of mineralization have been found in the discharge area. The geochemical evolution of the mineral water can be explained sufficiently by means of 34S-isotope determinations of evaporite sulfate and dissolved sulfate in water. It can be shown that the hydrochemical character of the mineral water must be understood as the result of mixing processes between low mineralized karstwater, tempered brines from the Buntsandstein and Middle Muschelkalk and water from the Gipskeuper. The δ18O and δ2H-signature of the karstwater is determined by the altitude effect. In the discharge area the signature is superimposed by rising brines which are strongly depleted in 18O.
