SREL Reprint #3568

Bacterial-facilitated uranium transport in the presence of phytate at Savannah River Site

Runwei Li1, Victor Ibeanusi2, Jada Hoyle-Gardner2, Christy Crandall2, Charles Jagoe2, John Seaman3,
Aavudai Anandhi4, and Gang Chen1

1Department of Civil and Environmental Engineering, FAMU-FSU College of Engineering,
Tallahassee, FL, 32310, United States
2School of the Environment, Florida A&M University, Tallahassee, FL, 32307, United States
3Savannah River Ecology Laboratory, University of Georgia, Aiken, SC, 29802, United States
4Department of Biological System Engineering, Florida A&M University,
Tallahassee, FL, 32307, United States

Abstract: At the Department of Energy (DOE) managed Savannah River Site (SRS), uranium and other heavy metals continue to pose threats to the ecosystem health and processes. In the oxic soil of this site, uranium is present primarily as soluble salts of the uranyl ion (i.e., U(VI) or UO22+). Although UO22+ has a strong sorption to the soil, the mobile indigenous bacteria may facilitate its transport. On the contrary, precipitation of UO22+ with phosphate has been found to be an alternative remediation strategy. This research investigated the effects of mobile bacteria and phytate on UO22+ transport at SRS in column experiments. It was discovered that UO22+ can barely be mobilized by de-ionized water but can be significantly transported with the aid of mobile indigenous bacteria. UO22+ had the most facilitated transport observation when it reached equilibrium with the bacteria before the transport. When UO22+ and bacterial were introduced to the soil at the same time or UO22+ was pre-deposited in the soil, the facilitated transport was less pronounced. In the presence of phytate, bacterial-facilitated UO22+ transport was hindered. pH was found to play the key role for UO22+ immobilization in the presence of phytate. The immobilization of UO22+ with the addition of phytate increased with the increase of pH within the pH range of this study because of the impact of pH on the solubility of UO2(OH)2. Phytate promoted UO2--PO43- complex and/or [Ca(UO2)2(PO4)2] formation, leading to enhanced UO22+ immobilization in the SRS soil.

Keywords: UO22+; Transport; Phytate; Facilitated; MRS-1 Bacillus cereus

SREL Reprint #3568

Li, R., V. Ibeanusi, J. Hoyle-Gardner, C. Crandall, C. H. Jagoe, J. C. Seaman, A. Anandhi, and G. Chen. 2019. Bacterial-facilitated uranium transport in the presence of phytate at Savannah River Site. Chemosphere 223(2019): 351-357.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).