Investigation of Technetium Redox Cycling in FRC Background Sediments using EXAFS and Gamma Camera Imaging
Technetium-99 is a priority pollutant at numerous DOE sites, due to its long half-life (2.1 x 105 years), high mobility as Tc(VII) in oxic waters, and bioavailability as a sulfate analogue. {sup 99}Tc is far less mobile under anaerobic conditions, forming insoluble Tc(IV) precipitates. As anaerobic microorganisms can reduce soluble Tc(VII) to insoluble Tc(IV), microbial metabolism may have the potential to treat sediments and waters contaminated with Tc. Baseline studies of fundamental mechanisms of Tc(VII) bioreduction and precipitation (reviewed by Lloyd et al., 2005, in press) have generally used pure cultures of metal-reducing bacteria, in order to develop conceptual models for the biogeochemical cycling of {sup 99}Tc. There is, however, comparatively little known about interactions of metal-reducing bacteria with environmentally relevant trace concentrations of {sup 99}Tc, against a more complex biogeochemical background provided by mixed microbial communities in aquifer sediments. The objective of this project is to probe the site specific biogeochemical conditions that control the mobility of {sup 99}Tc at the US DOE Field Research Center Site (FRC; Oak Ridge, Tennessee). This information is required for the rational design of in situ bioremediation strategies for technetium-contaminated subsurface environments. We are using a combination of geochemical, mineralogical, microbiological and spectroscopic techniques to determine the solubility and phase associations of {sup 99}Tc in FRC sediments, and characterize the underpinning biogeochemical controls.
- Research Organization:
- University of Manchester, UK; University of Leeds, UK; Manchester Royal Infirmary, Manchester, UK
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- FG02-04ER63743
- OSTI ID:
- 894940
- Report Number(s):
- CONF-ERSP2006-71; TRN: US200702%%469
- Resource Relation:
- Conference: Annual Environmental Remediation Sciences Program PI Meeting, April 3-5, 2006, Warrenton, VA
- Country of Publication:
- United States
- Language:
- English
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