Uranium content and uranium isotopic disequilibria as a tool to identify hydrogeochemical processes

Elevated uranium concentration and low activity ratio (234U/238U) in the Œuf river as the result of groundwater–surface water interaction (Essonne river valley, South of Paris Basin, France)

“…Groundwater with AR nearby or below 0.5 was documented in a variety of hydrogeological settings (Abdul-Hadi et al, 2001;El-Aassy et al, 2015;Kaufman et al, 1969). To explain 234 U deficit in groundwater, several factors were pointed out based on field settings or laboratory experiments (Andersen, Erel, & Bourdon, 2009;Bonotto & Andrews, 2000): a change in the redox conditions (Osmond & Cowart, 1976;Osmond et al, 1983), an increasing rate of weathering in karstic limestones (Kaufman et al, 1969), a lack of U renewal during rock weathering (Kumar et al, 2016) and a leaching of surface and subsurface horizons that already have experienced 234 U loss (Israelson et al, 1997;Milena-Pérez et al, 2021;Riotte & Chabaux, 1999).…”

“…This could explain the observation of low AR (< 0.4) founded in Orléanais and Pithiviers limestone aquifers. Also it can be interpreted in terms of lack of U renewal in U accumulation in ground material (Milena-Pérez et al, 2021;Osmond & Cowart, 1976;Osmond et al, 1974): ground material that experienced a loss in 234 U is not compensated by the arrival of undepleted material. That could explain the difference in 234 U observed upstream and downstream the OEuf river.…”

A critical review on the occurrence and distribution of the uranium- and thorium-decay nuclides and their effect on the quality of groundwater

“…as an indicator of U ore deposits, and the decay of the excess 234 U as the groundwater continues downgradient has been used as a groundwater age indicator (Osmond and Cowart, 2000). The distinction between weathering and dissolution with 234 U/ 238 U ~1 and recoil process with 234 U/ 238 U >1 have been also used to delineate between external uranium sources such as uranium-rich fertilizers; (Liesch et al, 2015;Lyons et al, 2020) or uranium-mill effluent (Zielinski et al, 1996) versus naturally occurring uranium mobilization for tracing groundwater contamination (Coyte et al, 2018;Milena-Pérez et al, 2021;Zielinski et al, 2000;Zielinski et al, 1996).…”

Uranyl Photocatalyzed Polystyrene Oxidative Degradation under Visible Light in a Green Solvent

“…It is also present in drinking water and food . As uranium has very low alpha specific activity, the effect of its radioactivity on living things can almost be neglected compared to its chemical effects. In other words, external exposure to uranium is not dangerous unless there is direct ingestion or inhalation of high concentrations of uranium .…”