Hlanganani Tutu Adrian Brown Linda Figueroa Christian Wolkersdorfer Raymond H. Johnson 2013 Geochemical changes that can occur down gradient from uranium <i>in situ</i> recovery (ISR) sites are important for various stakeholders to understand when evaluating potential effects on surrounding groundwater quality. If down gradient solid-phase material consists of sandstone with iron hydroxide coatings (no pyrite or organic carbon), sorption of uranium on iron hydroxides can control uranium mobility. Using one-dimensional reactive transport models with PHREEQC, two different geochemical databases, and various geochemical parameters, the uncertainties in uranium sorption on iron hydroxides are evaluated, because these oxidized zones create a greater risk for future uranium transport than fully reduced zones where uranium generally precipitates. application/pdf en International Mine Water Association Reactive transport modeling at uranium in situ recovery sites: uncertainties in uranium sorption on iron hydroxides text