The behavior of the rare earth elements and yttrium in groundwaters of the Holy Cross Mountains, SE Poland

In areas of contrasting geology, local but significant spatial changes in environmental conditions can occur suddenly and unexpectedly within aquifers, hampering accurate assessment of groundwater chemistry. Recently, the rare earth elements (REEs) have become extensively used in identifying geochemical processes in aqueous systems, due to their unique sensitivity to environmental changes. In this study, the REEs and Y (yttrium), combined with the chemical parameters of the main, minor and trace water components, and with the isotopic signatures of δ18O-H2O, δ2H-H2O, 3H-H2O, δ34S-SO4, δ18O-SO4, were investigated in order to gain a better understanding of the geochemistry of the groundwaters in the Holy Cross Mountains, which possesses a diverse hydrogeological system. The waters studied are ‘young’, meteoric-derived, of acidic to slightly alkaline pH (4.95–7.75) and TDS values of 38.97–2713.91 mg/L. They represent predominantly the HCO3-Ca-Mg and less often the HCO3-Ca-SO4-(Mg) or SO4-Ca-(Mg) types. The dissolved (