Image courtesy of Pacific Northwest National Laboratory
Research on uranium transformation and mobility in the subsurface is providing insights that can aid remediation efforts at contaminated sites such as the Hanford 300 area in Washington.
A magnetic iron oxide mineral, magnetite, in soil sediments can significantly slow down uranium migration by reducing it to a less mobile form. Researchers at Argonne National Laboratory and Pacific Northwest National Laboratory now have found that titanium, a common impurity in magnetite, obstructs the formation of less-mobile uraninite nanoparticles, resulting in the formation of novel molecular-sized uranium-titanium structures.
This previously unknown association of uranium with titanium affects the mobility of uranium in subsurface groundwater. Incorporating this knowledge into ongoing modeling efforts will improve scientists’ ability to predict future migration of contaminant plumes in the subsurface and help provide detailed information needed for the long-term stewardship of U.S. Department of Energy (DOE) legacy sites.
Uranium contamination of groundwater has resulted from mining the element for use as an energy source and from past enrichment and weapons production activities at DOE sites. Understanding the impact of uranium contamination on water sources and developing appropriate remediation strategies are needed to protect public safety and to continue using uranium as part of a balanced energy portfolio. Water traveling underground through a complex mixture of soils and sediments acts as a “rechargeable battery” that continually removes uranium from groundwater by sequestering it as nanoparticles of uranium dioxide within these underground sediments. Researchers used the Advanced Photon Source at Argonne National Laboratory to study how uranium interacts with titanium-containing magnetite within the complex subsurface chemical environment.
Drew E. Latta
Biosciences Division, Argonne National Laboratory
Argonne, IL 60439
Research under the Subsurface Scientific Focus Area (SFA) program at Argonne National Laboratory (ANL) and under the Pacific Northwest National Laboratory SFA was supported by the DOE Subsurface Biogeochemical Research program of the Office of Biological and Environmental Research within DOE’s Office of Science. MRCAT/EnviroCAT operations are supported by DOE and member institutions. Use of the Advanced Photon Source, an Office of Science user facility operated by ANL for the DOE Office of Science, was supported by DOE. Use of the Electron Microscopy Center at ANL was supported by the University of Chicago Argonne, LLC operated under contract DE-AC02-06CH11357.
Latta, D.E., Pearce, C.I., Rosso, K.M., Kemner, K.M., and Boyanov, M.I. “Reaction of UVI with titanium-substituted magnetite: Influence of Ti on UIV speciation,” Environ. Sci. & Tech. 47(9), 4121–4130(2013). [DOI: 10.1021/es303383n]
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