Estimation of groundwater residence time using environmental radioisotopes (14C,T) in carbonate aquifers, southern Poland

Triassic carbonate aquifers in the Upper Silesia region, affected by intense withdrawal, have been investigated by means of isotopic analyses of 14C, δ13C, δ2H, δ18O and 3H. The isotopic examinations were carried out in the 1970s and in the early 1980s, and it was the first application of tracers to estimate age and vulnerability for the contamination of groundwater in this region. Similar isotopic analyses were conducted in 2007 and 2008 with the same Triassic carbonate formation. The isotopic examinations were performed within the confined part of the carbonate formation, wherein aquifers are covered by semi-permeable deposits. The direct recharge of the aquifer occurs in the outcrop areas, but it mainly takes place due to percolation of the water through aquitards and erosional windows. The Triassic aquifer has been intensively drained by wells and by lead–zinc mines. Nowadays, the declining water demand and closure of some mines have induced a significant increase in the water table level. The detaile...