Skip to main content
U.S. flag

An official website of the United States government

Oxidative dissolution of biogenic uraninite in groundwater at Old Rifle, CO

December 18, 2011

Reductive bioremediation is currently being explored as a possible strategy for uranium-contaminated aquifers such as the Old Rifle site (Colorado). The stability of U(IV) phases under oxidizing conditions is key to the performance of this procedure. An in situ method was developed to study oxidative dissolution of biogenic uraninite (UO2), a desirable U(VI) bioreduction product, in the Old Rifle, CO, aquifer under different variable oxygen conditions. Overall uranium loss rates were 50–100 times slower than laboratory rates. After accounting for molecular diffusion through the sample holders, a reactive transport model using laboratory dissolution rates was able to predict overall uranium loss. The presence of biomass further retarded diffusion and oxidation rates. These results confirm the importance of diffusion in controlling in-aquifer U(IV) oxidation rates. Upon retrieval, uraninite was found to be free of U(VI), indicating dissolution occurred via oxidation and removal of surface atoms. Interaction of groundwater solutes such as Ca2+ or silicate with uraninite surfaces also may retard in-aquifer U loss rates. These results indicate that the prolonged stability of U(IV) species in aquifers is strongly influenced by permeability, the presence of bacterial cells and cell exudates, and groundwater geochemistry.

Citation Information

Publication Year 2011
Title Oxidative dissolution of biogenic uraninite in groundwater at Old Rifle, CO
DOI 10.1021/es200482f
Authors Kate M. Campbell, Harish Veeramani, Kai-Uwe Ulrich, Lisa Y. Blue, Dianiel E. Giammar, Rizlan Bernier-Latmani, Joanne E. Stubbs, Elena Suvorova, Steve Yabusaki, Juan S. Lezama-Pacheco, Apurva Mehta, Philip E. Long, John R. Bargar
Publication Type Article
Publication Subtype Journal Article
Series Title Environmental Science & Technology
Series Number
Index ID 70006304
Record Source USGS Publications Warehouse
USGS Organization Branch of Regional Research-Central Region