Groundwater investigations with environmental isotopes

The development of measuring techniques for environmental isotopes at the Institute of Radiohydrometry, Munich, is described together with hydrological applications and details of three investigations at present in progress. The preparation times of samples for deuterium and 18O analyses have been shortened by new preparation systems. The mass-spectrometric 18O analyses are now conducted in an on-line procedure. For gas counting tritium from 20 cm3 water samples a propane synthesis method has been developed with a detection limit of 3 TU. In a hydrological application the mean seepage velocity of surface water in a massif in the Austrian Central Alps was estimated to be about 20 to 55 m/yr by determining the tritium and deuterium content of seepage water taken from a mountain tunnel. Tritium and deuterium analyses are again mainly used for investigating the hydrological interrelation between a drinking water spring in Bad Kissingen (Bavaria) and some nearby drinking-water wells. Finally, initial results are given for the measurement of 14C, 13C, tritium, deuterium and 18O in brines from springs and deep wells at Bad Reichenhall (Bavaria). (author)