Bacterial influence on uranium oxidation reduction reactions : implications for environmental remediation and isotopic composition

The bacterial influence on the chemistry and speciation of uranium has some important impacts on the environment, and can be exploited usefully for the purposes of environmental remediation of uranium waste contamination. It is important to understand both from a scientific and environmental perspective how different types of bacteria can affect the chemistry and speciation of uranium. Analysis of the kinetics of uranium reduction, to determine the influence of external governing factors, can help us to understand the mechanisms of uranium reduction in vitro and aid in the design of more effective uranium remediation schemes in the environment. Bacterial reduction kinetics are found to fit well to a first order exponential decay model. Using this model we have determined the dependence of the rate of bacterial uranium reduction on several parameters, including bacterial density and pH. Understanding the reduction kinetics is also an important step in the determination of the extent of isotopic separation that occurs as a result of the bacterial reduction process. Here, we demonstrate that isotopes of uranium, the heaviest naturally occurring element, are subject to fractionation when uranium serves as a terminal electron acceptor during anaerobic bacterial respiration, resulting in an enrichment of 235U in the reaction product, UO2. The manganese oxidizing bacterium Leptothrix discophora produces manganese oxides with can both adsorb uranyl and partially oxidize UO2. Determination of if and how bacteria can influence the oxidation of uranium is important because oxidation will increase the solubility and mobility of uranium in the environment.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Nuclear Science and Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2007

Author dc:creator

• Mullen, Lisa Maureen

Advisor dc:contributor.advisor

• K. Czerwinski.

• Nuclear Science and Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/41293
• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Identifier URI

http://dspace.mit.edu/handle/1721.1/41293

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/41293