LAUSR

Abstract A comprehensive study on the sources of groundwater contamination in the Triassic carbonate aquifer, southern Poland, was conducted. The Gliwice aquifer is an important source of potable water in the Silesia region, the most industrialized part of Poland. Groundwater quality has been deteriorating over the last decades, which encouraged researchers to undertake comprehensive study to identify the sources and fates of the observed pollution. The presented study comprised analyses of major and minor ions, trichloroethylene (TCE) and tetrachloroethylene (PCE), CFC-11, CFC-12, SF6, Ne and Ar in groundwater. The results showed that shallow groundwater within the Tarnowskie Gory town, located in the recharge zone of the aquifer, was more contaminated than groundwater abstracted from deeper part of the aquifer within the town, as well as groundwater located downgradient. A contamination plume of boron indicated an impact of the closed chemical plant, operating in the 20th century. Groundwater in the vicinity of the chemical plant was significantly altered, which was manifested by elevated concentrations of Cl−, SO42-, Na+, total Fe and Mn. The study revealed groundwater contamination with CFC-11 and CFC-12. Comparison of concentrations obtained in two field campaigns (in 2010 and 2015) showed an increase in the extent of pollution plumes. The third analysed gaseous tracer, SF6, did not appear to come from non-atmospheric sources, therefore, it was possible to calculate groundwater age using lumped parameter models. The results showed relatively young ages of the analysed groundwater samples, from 4 to 5 to 30–50 years. The youngest groundwater were found close to the Drama River, suggesting infiltration of the surface water into the carbonate aquifer. This feature of the river was confirmed by the observation of TCE and PCE concentrations in groundwater. Central part of the Tarnowskie Gory town was a source area for TCE and PCE contamination. Two directions of pollutants migration were observed, one of them was induced by the drainage of the historic ore mine and subsequently the Drama River – recipient of water coming from the mine drainage.