Investigation of uranium geochemistry along groundwaterflow path in the Continental Intercalaire aquifer (Southern Tunisia)

This study aims to investigate the uranium geochemistry and hydrodynamics within the groundwater of the Continental Intercalaire aquifer in Southern Tunisia. Environmental tracers, including stable isotopes of deuterium (2H), oxygen (18O), and Uranium, were utilized to elucidate the recharge conditions and chemical dynamics of the aquifer's groundwater. The research involved analyzing the chemical and isotopic composition of groundwater samples, revealing predominant cation and anion ratios that characterized the water types throughout the basin. Results indicated that total dissolved solids increased from the margins of the Saharan Platform towards the Chotts region, with significant groundwater flow paths identified in that direction. The isotopic analyses exhibited a range of stable isotope compositions, suggesting varying contributions from geological formations to the current recharge under arid conditions. Furthermore, the study documented a range of uranium concentrations and activity ratios using alpha spectrometry, identifying critical controls on the geochemistry of uranium isotopes in groundwater. These include water-rock interactions and varying contributions from different water sources, indicating complex hydrological and geochemical processes at play within the aquifer. This research provides crucial insights into the groundwater dynamics and uranium behavior in a context of limited freshwater resources.