Integrating Hydrogeochemical and Isotope Data in Studying Regional Groundwater flow Systems in the Great Hungarian Plain

Environmental isotopes (δ 18O, δD, δ 13C, 14C, 87Sr/86Sr) combined with hydrogeochemical data have been used in studying regional groundwater flow systems in the Great Hungarian Plain part of the Pannonian Basin. Oxygen and deuterium isotope data show groundwater is of meteoric origin, with isotopic signatures indicative of petroleum producing units in the deeper part of the basin. Based on the carbon isotopes analysed on dissolved inorganic carbon, the groundwater residence times vary from a few thousand to tens of thousands of years. Strontium isotopic signatures show enrichment where carbonate dissolution is indicated by increasing bicarbonate values in Upper Miocene aquifers.