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Role of nitrate in conditioning aquifer sediments for technetium bioreduction
- Source :
- Law, G T W, Geissler, A, Boothman, C, Burke, I T, Livens, F R, Lloyd, J R & Morris, K 2010, ' Role of nitrate in conditioning aquifer sediments for technetium bioreduction ', Environmental Science and Technology, vol. 44, no. 1, pp. 150-155 . https://doi.org/10.1021/es9010866
- Publication Year :
- 2009
-
Abstract
- Here we examine the bioreduction of technetium-99 in sediment microcosm experiments with varying nitrate and carbonate concentrations added to synthetic groundwater to assess the influence ofpHand nitrate on bioreduction processes. The systems studied include unamended-, carbonate buffered-, low nitrate-, and high nitrate-groundwaters. During anaerobic incubation, terminal electron accepting processes (TEAPs) in the circumneutral pH, carbonate buffered system progressed to sulfate reduction, and Tc(VII) was removed from solution during Fe(III) reduction. In the high-nitrate system, pH increased during denitrification (pH 5.5 to 7.2), then TEAPs progressed to sulfate reduction. Again, Tc(VII) removal was associated with Fe(III) reduction. In both systems, XAS confirmed reduction to hydrous Tc(IV)O2 like phases on Tc removal from solution. In the unamended and low-nitrate systems, the pH remained low, Fe(III) reduction was inhibited, and Tc(VII) remained in solution. Thus, nitrate can have complex influences on the development of the metal reducing conditions required for radionuclide treatment. High nitrate concentrations stimulated denitrification and caused pH neutralization facilitating Fe(III) reduction and Tc(VII) removal; acidic, low nitrate systemsshowed no Fe(III)-reduction. These results have implications for Tc-cycling in contaminated environments where nitrate has been considered undesirable, but where it may enhance Fe(III)-reduction via a novel pH "conditioning" step. © 2010 American Chemical Society.
- Subjects :
- Geologic Sediments
Water Pollutants, Radioactive
Denitrification
Nitrates
Technetium
General Chemistry
Human decontamination
Polymerase Chain Reaction
chemistry.chemical_compound
Bioremediation
Nitrate
chemistry
X-Ray Diffraction
Nitric acid
RNA, Ribosomal, 16S
Environmental Chemistry
Carbonate
Sulfate
Microcosm
Oxidation-Reduction
Nuclear chemistry
Subjects
Details
- ISSN :
- 0013936X
- Volume :
- 44
- Issue :
- 1
- Database :
- OpenAIRE
- Journal :
- Environmental sciencetechnology
- Accession number :
- edsair.doi.dedup.....c1518a567857c81d3526d98b66b61689