skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Reduction of TcO4- by sediment-associated biogenic Fe(II)

Abstract

The potential for reduction of {sup 99}TcO{sub 4}{sup -}{sub aq} to poorly soluble {sup 99}TcO{sub 2} {center_dot} nH{sub 2}O{sub (s)} by biogenic sediment-associated Fe(II) was investigated with three Fe(III)-oxide containing subsurface materials and the dissimilatory metal-reducing subsurface bacterium Shewanella putrefaciens CN32. Two of the subsurface materials from the U.S. Department of Energy's Hanford and Oak Ridge sites contained significant amounts of Mn(III,IV) oxides and net bioreduction of Fe(III) to Fe(II) was not observed until essentially all of the hydroxylamine HCl-extractable Mn was reduced. In anoxic, unreduced sediment or where Mn oxide bioreduction was incomplete, exogenous biogenic TcO{sub 2} {center_dot} nH{sub 2}O{sub (s)} was slowly oxidized over a period of weeks. Subsurface materials that were bioreduced to varying degrees and then pasteurized to eliminate biological activity, reduced TcO{sub 4}{sup -}{sub (aq)} at rates that generally increased with increasing concentrations of 0.5 N HCl-extractable Fe(II). Two of the sediments showed a common relationship between extractable Fe(II) concentration (in mM) and the first-order reduction rate (in h{sup -1}), whereas the third demonstrated a markedly different trend. A combination of chemical extractions and {sup 57}Fe Moessbauer spectroscopy were used to characterize the Fe(III) and Fe(II) phases. There was little evidence of the formation ofmore » secondary Fe(II) biominerals as a result of bioreduction, suggesting that the reactive forms of Fe(II) were predominantly surface complexes of different forms. The reduction rates of Tc(VII)O{sub 4}{sup -} were slowest in the sediment that contained plentiful layer silicates (illite, vermiculite, and smectite), suggesting that Fe(II) sorption complexes on these phases were least reactive toward pertechnetate. These results suggest that the in situ microbial reduction of sediment-associated Fe(III), either naturally or via redox manipulation, may be effective at immobilizing TcO{sub 4}{sup -}{sub aq} associated with groundwater contaminant plumes.« less

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab., Richland, WA (US)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
15008808
Report Number(s):
PNNL-SA-42096
KP1301010; TRN: US0403876
DOE Contract Number:  
AC06-76RL01830
Resource Type:
Journal Article
Journal Name:
Geochimica et Cosmochimica Acta
Additional Journal Information:
Journal Volume: 68; Journal Issue: 15; Other Information: PBD: 1 Aug 2004
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; TECHNETIUM OXIDES; REDUCTION; GEOCHEMISTRY; IRON OXIDES; CATALYTIC EFFECTS; BACTERIA; ILLITE; MOESSBAUER EFFECT; SMECTITE; SORPTION; VERMICULITE; BIODEGRADATION

Citation Formats

Fredrickson, Jim K, Zachara, John M, Kennedy, David W, Kukkadapu, Ravi K, McKinley, James P, Heald, Steve M, Liu, Chongxuan, and Plymale, Andrew E. Reduction of TcO4- by sediment-associated biogenic Fe(II). United States: N. p., 2004. Web. doi:10.1016/j.gca.2003.10.024.
Fredrickson, Jim K, Zachara, John M, Kennedy, David W, Kukkadapu, Ravi K, McKinley, James P, Heald, Steve M, Liu, Chongxuan, & Plymale, Andrew E. Reduction of TcO4- by sediment-associated biogenic Fe(II). United States. https://doi.org/10.1016/j.gca.2003.10.024
Fredrickson, Jim K, Zachara, John M, Kennedy, David W, Kukkadapu, Ravi K, McKinley, James P, Heald, Steve M, Liu, Chongxuan, and Plymale, Andrew E. Sun . "Reduction of TcO4- by sediment-associated biogenic Fe(II)". United States. https://doi.org/10.1016/j.gca.2003.10.024.
@article{osti_15008808,
title = {Reduction of TcO4- by sediment-associated biogenic Fe(II)},
author = {Fredrickson, Jim K and Zachara, John M and Kennedy, David W and Kukkadapu, Ravi K and McKinley, James P and Heald, Steve M and Liu, Chongxuan and Plymale, Andrew E},
abstractNote = {The potential for reduction of {sup 99}TcO{sub 4}{sup -}{sub aq} to poorly soluble {sup 99}TcO{sub 2} {center_dot} nH{sub 2}O{sub (s)} by biogenic sediment-associated Fe(II) was investigated with three Fe(III)-oxide containing subsurface materials and the dissimilatory metal-reducing subsurface bacterium Shewanella putrefaciens CN32. Two of the subsurface materials from the U.S. Department of Energy's Hanford and Oak Ridge sites contained significant amounts of Mn(III,IV) oxides and net bioreduction of Fe(III) to Fe(II) was not observed until essentially all of the hydroxylamine HCl-extractable Mn was reduced. In anoxic, unreduced sediment or where Mn oxide bioreduction was incomplete, exogenous biogenic TcO{sub 2} {center_dot} nH{sub 2}O{sub (s)} was slowly oxidized over a period of weeks. Subsurface materials that were bioreduced to varying degrees and then pasteurized to eliminate biological activity, reduced TcO{sub 4}{sup -}{sub (aq)} at rates that generally increased with increasing concentrations of 0.5 N HCl-extractable Fe(II). Two of the sediments showed a common relationship between extractable Fe(II) concentration (in mM) and the first-order reduction rate (in h{sup -1}), whereas the third demonstrated a markedly different trend. A combination of chemical extractions and {sup 57}Fe Moessbauer spectroscopy were used to characterize the Fe(III) and Fe(II) phases. There was little evidence of the formation of secondary Fe(II) biominerals as a result of bioreduction, suggesting that the reactive forms of Fe(II) were predominantly surface complexes of different forms. The reduction rates of Tc(VII)O{sub 4}{sup -} were slowest in the sediment that contained plentiful layer silicates (illite, vermiculite, and smectite), suggesting that Fe(II) sorption complexes on these phases were least reactive toward pertechnetate. These results suggest that the in situ microbial reduction of sediment-associated Fe(III), either naturally or via redox manipulation, may be effective at immobilizing TcO{sub 4}{sup -}{sub aq} associated with groundwater contaminant plumes.},
doi = {10.1016/j.gca.2003.10.024},
url = {https://www.osti.gov/biblio/15008808}, journal = {Geochimica et Cosmochimica Acta},
number = 15,
volume = 68,
place = {United States},
year = {2004},
month = {8}
}