Environmental and artificial tracers for investigating leakages into salt mines

The paper presents the results of five years of experience in investigating the origin of waters in the Wapno mine, where salt is exploited in a Zechstein dome, in northwestern Poland. Tritium and 14C measurements showed young infiltration waters in leakages at the third level of the mine. Stable isotope determinations showed a considerable shift of values from the precipitation line, both on activity and on concentration scales. Despite this shift, it was possible to distinguish infiltration waters from connate ones appearing at deeper mine levels. In 1976 and 1977 leakage flow-rates increased and the mineralization decreased. Tritium and 14C contents did not then change, showing that, at the initial stages of flooding, the origin of water in the leakages was not changed. The first results of isotope investigations in the Klodawa mine, situated in another Zechstein salt dome in central Poland, showed connate waters. Observations performed in the Wieliczka salt mine, situated in Miocene formations in southern Poland, showed old waters originating from the surrounding formations. Their stable isotope composition shows that recharge took place in a cooler climate. The 14C content of these waters is 1 to 2% of recent carbon. The experimental procedure used to determine the isotopic composition of highly mineralized brines is also described. (author)