Influence of sediment redox conditions on uranium mobilisation during saline intrusion

摘要: Abstract In the UK, several coastal nuclear sites have been identified as vulnerable to future sea level rise. Legacy contamination at these has accumulated in sub-surface sediments risk of seawater inundation and intrusion. Porewater salinization, changes pH influx oxygen into may impact stability sediment associated uranium (U). this study, saturated column experiments were performed compare mobilisation U from oxic reduced under environmentally relevant flow conditions. Uranium release profiles independent initial geochemistry sediments. was kinetically controlled, showing relatively slow desorption kinetics, with initially limited by on seawater. Significant only occurred when sufficiently high for formation U-carbonate complexes (pHoxic 6.3; pHreduced 7.5). more strongly bound after 400 pore volumes flow, extensive (46%) compared nitrate reducing (27%) iron (18%) The products cycling appeared act a buffer limiting mobilisation, but on-going dissolution Fe-phases suggests that they did not form permanent protective layer.