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A comparison of two methods of radiocarbon age determination of groundwater is presented. The simplest Pearson model and the "user-defined" option of the NETPATH program were considered. Both methods were used to determine the age of water from a PZ-2 piezometer that is situated in the foreground of chamber Z-32 in Wieliczka Salt Mine. Results of these calculations clearly demonstrate that 14C ages obtained by the Pearson model can be significantly overestimated in comparison with those determined by the NETPATH code. Without additional data, such as the stable isotope composition of the water, conclusions on the age of the groundwater based solely on the Pearson model may be highly inadequate. [ABSTRACT FROM AUTHOR]

Identification of the conditions of circulation, mixing, origin and age of groundwater in the area of underground mining plants is necessary for the correct design of drainage systems, directions of mining exploitation and intensity of mining works. For this purpose, isotopic studies were carried out in the mines of the Legnica-Głogów Copper District (LGCD) in Poland, characterized by complex hydrogeological conditions. The observed values of δ2H, δ18O and concentrations of tritium, as well as chlorides, sulfates and main cations in 29 water samples taken from different lithostratigraphic levels (and a few historical results) were used to explain the spatial variability of the origin of groundwater flowing into the mines. A model of groundwater mixing in the mining area of the LGCD was developed. The results of the research indicate that, depending on the region, the LGCD mines contain Holocene and/or interglacial waters, pre-Quaternary waters as well as older waters, recharged in period of very warm climate - flowing into the mining workings from deeper geological strata. Isotopic studies together with the chloride content measurements confirmed the correctness of the conceptual model of groundwater circulation within the mines. Their results will be useful in further elaboration of the strategy related to dewatering and designing further mining activities. • Groundwater in underground mines with complex hydrogeological conditions was studied. • Stable isotopes enable the determination of the age, origin and mixing of mine waters. • A model of groundwaters mixing in the mines and surrounding area was created. • Isotopic studies confirmed the correctness of the conceptual hydrogeological model. [ABSTRACT FROM AUTHOR]