Past mining of uranium for use as an energy source and from enrichment and weapons production activities at sites managed by the U.S. Department of Energy has resulted in groundwater contamination. Developing appropriate remediation strategies is paramount in protecting public safety and in the continued use of uranium in a balanced energy production portfolio.

Groundwater travels in the subsurface through a complex mixture of soils and sediments containing a magnetic iron oxide mineral, known as magnetite, that can significantly slow down uranium migration and act like a ​“rechargeable battery” for continued removal of uranium by sequestering it as nanoparticles of uranium dioxide within the sediments.

Using Argonne’s Advanced Photon Source, new information was discovered on how uranium interacts with magnetite and behaves within the complex chemical environment of the subsurface. In a collaborative effort, researchers at Argonne and Pacific Northwest National Laboratory have found that titanium, a common impurity in these natural magnetic iron minerals, obstructs the formation of the uraninite nanoparticles which results in the formation of novel molecular-sized uranium-titanium structures.

Incorporation of this new knowledge into ongoing modeling efforts will improve scientists’ ability to predict future migration of contaminant plumes in the subsurface and will help to provide the detailed information necessary for the long-term stewardship of DOE legacy sites.

Reference: Latta, D.E., Pearce, C.I., Rosso K.M., Kemner, K.M., Boyanov, M.I., ​“Reaction of UVI with titanium-substituted magnetite: Influence of Ti on UIV speciation,” Environ Sci Technol. 2013 May 7;47(9):4121-30.