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

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

doi:10.1021/es200482f

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

Environmental Science & Technology

By: 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, and John R. Bargar

https://doi.org/10.1021/es200482f

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Abstract

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.

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Additional publication details
Publication type	Article
Publication Subtype	Journal Article
Title	Oxidative dissolution of biogenic uraninite in groundwater at Old Rifle, CO
Series title	Environmental Science & Technology
DOI	10.1021/es200482f
Volume	45
Issue	20
Year Published	2011
Language	English
Publisher	ACS Publications
Publisher location	Washington, D.C.
Contributing office(s)	Branch of Regional Research-Central Region
Description	7 p.
First page	8748
Last page	8754
Country	United States
State	Colorado
Other Geospatial	Old Rifle Site
Google Analytic Metrics	Metrics page