Effects of Organic Carbon Supply Rates on Uranium Mobility in a Previously Bioreduced Contaminated Sediment

Abstract

Bioreduction-based strategies for remediating uranium (U)-contaminated sediments face the challenge of maintaining the reduced status of U for long times. Because groundwater influxes continuously bring in oxidizing terminal electron acceptors (O 2 , NO 3 -

Microbial Community Succession during Lactate Amendment and Electron Acceptor Limitation Reveals a Predominance of Metal-Reducing Pelosinus spp

“…and Geobacter spp. (16,55) decreased from their initial 1.51% and 0.33%, respectively, to an average of 0.13% and 0.14%, respectively. It was instead the less-studied Pelosinus spp.…”

A Post-Genomic View of the Ecophysiology, Catabolism and Biotechnological Relevance of Sulphate-Reducing Prokaryotes

“…Great efforts were made to determine the feasibility and robustness of this technology in the ensuing years (Wall & Krumholz, 2006). However, data began to accumulate showing that exhaustion of electron donors used to stimulate microbes capable of U(IV) production would often result in resolubilization of uranium as U(VI) (Anderson Senko, Istok, Suflita, & Krumholz, 2002;Wan et al, 2008;Zhong et al, 2005). Two possible explanations, not mutually exclusive, were given: exhaustion of the electron donor could allow dissolved oxygen access to the reduced uranium and abiotic oxidation could occur or, second, the microbes responsible for the reduction would now be limited for electron donor sources and turn to U(IV) for electrons.…”

Radioactivity, Geochemistry, and Health

“…Biologically precipitated nanocrystals UO 2 are especially vulnerable to reoxidation (Singer et al, 2007), and can be oxidized by ferrihydrite, with concomitant production of uranyl and Fe(II) (Ginder-Vogel et al, 2010). Reoxidation could be limited by long-term injection of organic carbon; however, even under these conditions, uranium mobilization has been shown to increase with time, owing to enhanced microbial respiration and increasing carbonate/bicarbonate concentrations (Wan et al, 2008). Finally, Senko et al (2002) showed that the biogenic intermediates of dissimilatory nitrate reduction, including nitrite, nitrous oxide, and nitric oxide, can reoxidize and mobilize U(IV), raising questions about the long-term effectiveness of bioremediation even if the system remains anaerobic.…”