Modelling of the dissolution and reprecipitation of uranium under oxidising conditions in the zone of shallow groundwater circulation

Generic hydrochemical modelling of a grantoid-groundwater system, using the Russian software “HydroGeo”, has been carried out with an emphasis on simulating the accumulation of uranium in the aqueous phase. The baseline model run simulates shallow granitoid aquifers (U content 5 ppm) under conditions broadly representative of southern Norway and southwestern Siberia: i.e. temperature 10°C, equilibrated with a soil gas partial CO2 pressure (PCO2, open system) of 10-2.5 atm. and a mixture of geochemical parameters that enhance the understanding of uranium behavior in shallow groundwater systems. This study evaluates various scenarios of dissolution and reprecipitation processes, providing insights into the geochemical interactions that govern uranium dynamics in the environment. The results indicate that under oxidizing conditions, uranium tends to remain dissolved, suggesting significant implications for groundwater quality and uranium mobility. This research contributes to the understanding of uranium behavior in natural water systems, with potential applications in environmental monitoring and management strategies.