Micro-Scale Heterogeneity in Biogeochemical Uranium Cycling

One method for the in situ remediation of uranium contaminated subsurface environments is the removal of highly soluble U(VI) from groundwater by microbial reduction to the sparingly soluble U(IV) mineral uraninite. Success of this remediation strategy will, in part, be determined by the extent and products of microbial reduction. In heterogeneous subsurface environments, microbial processes will likely yield a combination of U(IV) and U(VI) phases distributed throughout the soil matrix. Here, we use a combination of bulk X‐ray absorption spectroscopy (XAS) and micro‐focused XAS and X‐ray diffraction to determine uranium speciation and distribution with sediment from a pilot‐scale uranium remediation project located in Oak Ridge, TN.