In Situ Community Control of the Stability of Bioreduced Uranium
The overall objective of this research is to understand the mechanisms for maintenance of bio-reduced uranium in an aerobic to microaerophylic aquifer under actual field conditions after electron donor addition for biostimulation has ended. Primary Objectives: (1) Determine the relative importance of microbial communities and/or chemical and physical environments mediating uranium reduction/oxidation after cessation of donor addition in an aerobic aquifer. (2) Determine, after cessation of donor addition, the linkages between microbial functions and abiotic processes mediating. Initial Hypotheses: (1) The typical bio-reduced subsurface environments that maintain U(VI) reduction rates after biostimulation contain limited amounts of oxidized iron on mineral surfaces. Therefore, the non sulfate-reducing dissimilatory iron reducing bacteria will move to more conducive areas or be out-competed by more versatile microbes. (2) Microbes capable of sulfate reduction play an important role in the post-treatment maintenance of bio-reduced uranium because these bacteria either directly reduce U(VI) or generate H2S, and/or FeS0.9 which act as oxygen sinks maintaining U(IV) in a reduced state. (3) The presence of bioprecipitated amorphous FeS0.9 in sediments will maintain low U(IV) reoxidation rates under conditions of low biomass, but FeS0.9 by itself is not sufficient to remove U(VI) from groundwater by abiotic reduction. FIELD SCALE EXPERIMENTS: Field-scale electron donor amendment experiments were conducted in 2002, 2003, and 2004 at the Old Rifle Uranium Mill Tailings Remedial Action (UMTRA) site in Rifle, Colorado.
- Research Organization:
- University of Tennessee, Knoxville, TN
- Sponsoring Organization:
- USDOE - Office of Science (SC)
- OSTI ID:
- 896792
- Report Number(s):
- ERSD-1024777-2006
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
54 ENVIRONMENTAL SCIENCES
59 BASIC BIOLOGICAL SCIENCES
AQUIFERS
BACTERIA
BINDING ENERGY
BIOMASS
COMMUNITIES
ELECTRONS
FEED MATERIALS PLANTS
IRON
MAINTENANCE
OXYGEN
REMEDIAL ACTION
SEDIMENTS
STABILITY
SULFATES
TAILINGS
URANIUM
VALENCE