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

Fredrickson, James K.; Zachara, John M.; Kennedy, David W.; Kukkadapu, Ravi; McKinley, James P.; Heald, Steve M.; Liu, Chongxuan; Plymale, Andrew E.

doi:10.1016/j.gca.2003.10.024

Cited by 189 publications

(214 citation statements)

References 46 publications

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“…Contrary to Se, microbially-mediated reduction of Tc(VII) was proved only in anaerobic condition [7,8]. But abiotic reduction of Tc(VII) should not be excluded [4]. …”

Section: Batch Experimentsmentioning

confidence: 92%

“…Several studies have shown that reduction of Se(IV) and Tc(VII) to insoluble forms, as Se(0) or Tc(IV), are efficient in their immobilisation. These reduction reactions can be achieved abiotically by heterogeneous reactions with FeII-containing minerals for example [3,4]. But they have also been proved to be microbially mediated, resulting either from direct interaction between Se / Tc and some microorganisms [5,6,7,8] or from physico-chemical changes due to the microbial activity [4,9].…”

Section: Introductionmentioning

confidence: 99%

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Biogeochemical behaviour of anionic radionuclides in soil: Evidence for biotic interactions

Février

Martin-Garin

2005

Radioprotection

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Abstract. 99Tc and 79 Se, two long-lived radionuclides, are supposed to be highly mobile in soils, because of their anionic forms. Their behaviours in the soil are often considered only from a physico-chemical point of view, although the microorganisms can affect either directly or indirectly their speciation. This study demonstrates the role of the microbial compartment in the retention of Se and Tc in soil by comparing experiments with soils constrained to different microbiological status (sterile / raw / amended). Kd coefficients for Se and Tc were determined in batch experiments, whereas transport of Se and Tc was investigated through column leaching experiments. Kd for Se was enhanced for the raw soil without amendment compared to the value obtained for the sterilised soil. The retention of Se was higher again in the amended soil. Besides, a biofilm, which can directly retain Se, was obtained at the entrance of the amended soil column. This effect was less obvious for Tc in batch experiments, but was revealed by leaching experiments where a high quantity of Tc was retained in the amended soil columns. These results give strong evidence that microorganisms are responsible for a greater retention of Se and Tc in soil.

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“…Contrary to Se, microbially-mediated reduction of Tc(VII) was proved only in anaerobic condition [7,8]. But abiotic reduction of Tc(VII) should not be excluded [4]. …”

Section: Batch Experimentsmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Biogeochemical behaviour of anionic radionuclides in soil: Evidence for biotic interactions

Février

Martin-Garin

2005

Radioprotection

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“…A number of experiments that examined the reduction and retention of 99 Tc in natural sediments whose oxidation states have been artificially altered (Burke et al 2006, Burke et al 2005, Fredrickson et al 2004, Morris et al 2008, Zachara et al 2007) yielded some interesting and useful results for secondary 99 Tc sequestration. Reduction of Tc(VII) to Tc(IV) by ferrous iron (Fe(II)) in solution is sluggish (homogeneous kinetics), even though the reaction…”

Section: Goethitementioning

confidence: 99%

“…is thermodynamically feasible (log K 298 = -21.8) (Fredrickson et al 2004). However, when Fe(II) is adsorbed or surface precipitated on solid phases, especially oxyhydroxides of iron, a surface-mediated catalysis of Tc(VII) reduction is more rapid (Cui and Eriksen 1996a, Cui and Eriksen 1996b, Peretyazhko et al 2008a, Peretyazhko et al 2008b, Zachara et al 2007.…”

Section: Goethitementioning

confidence: 99%

Review of Potential Candidate Stabilization Technologies for Liquid and Solid Secondary Waste Streams

Pierce¹,

Mattigod²,

Westsik³

et al. 2010

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Executive SummaryPacific Northwest National Laboratory has initiated a waste-form testing program to support the longterm durability evaluation of a waste form for secondary wastes generated from the treatment and immobilization of Hanford radioactive tank wastes. The purpose of the work discussed in this report is to identify candidate stabilization technologies and getters that have the potential to successfully treat the secondary waste stream liquid effluent, mainly from off-gas scrubbers and spent solids, produced by the Hanford Tank Waste Treatment and Immobilization Plant (WTP). Down-selection to the most promising stabilization processes/waste forms is needed to support the design of a solidification treatment unit (STU) to be added to the Effluent Treatment Facility (ETF). To support key decision processes, an initial screening of the secondary liquid waste forms must be completed by February 2010. Later, more comprehensive and longer term performance testing will be conducted, following the guidance provided by the secondary waste-form selection, development, and performance evaluation roadmap. The resulting waste form will be compliant to regulations and performance criteria and will lead to cost-effective disposal of the secondary wastes.This report starts with a brief review of some of the most commonly used solidification formulations that would be candidates for secondary liquid waste streams. In this review, the available data on performance are discussed, and some preliminary recommendations are provided for materials that should undergo additional screening testing. We also 1) discuss options for disposal of WTP secondary solid waste streams, 2) provide a brief overview of standard regulatory test methods used for measuring contaminant leachability and waste-form physical strength (with emphasis on the U.S. Environmental Protection Agency's [EPA's] new methods as a screening tool for comparing waste solidification materials of interest), and 3) provide an overview of factors that must be considered in long-term performance testing, including state-of-the-art characterization tools that can provide the data needed to technically defend predictive modeling simulations of long-term material behavior. The long-term wasteform testing and solid and leachate characterization must be robust enough to effectively predict material performance in the Integrated Disposal Facility over the 10,000-year period of performance for the engineered system. The solidification technologies for liquid waste streams include cement/grout, containerized Cast Stone, phosphate-bonded ceramics, alkali-aluminosilicate geopolymers, hydroceramics, L-TEM, and fluidized-bed steam reforming (FBSR). In addition to these, other mature technologies and two compounds, namely goethite and sodalite (that are still being developed), that show considerable promise as waste forms or getters are also discussed. It is our recommendation, based upon the available literature, that Cast Stone, chemically bonded phosphate ceramics (Ceramicrete...

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“…It has been suggested that microbial DIR predates the aerobic respiration (3). Interest in DIR has intensified upon discovery of the ability of DIR microbes in bioremediation of contaminated environments polluted with heavy and radioactive metals such as U 6ϩ and Tc 7ϩ (4,5). A model organism extensively studied for DIR is Shewanella, which is a diverse genus of facultative anaerobic ␥-proteobacteria (6).…”

mentioning

confidence: 99%

SO2907, a Putative TonB-dependent Receptor, Is Involved in Dissimilatory Iron Reduction by Shewanella oneidensis Strain MR-1

Qian

Shi

2011

Journal of Biological Chemistry

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Shewanella oneidensis strain MR-1 utilizes soluble and insoluble ferric ions as terminal electron acceptors during anaerobic respiration. The components of respiratory metabolism are localized in the membrane fractions which include the outer membrane and cytoplasmic membrane. Many of the biological components that interact with the various iron forms are proposed to be localized in these membrane fractions. To identify the iron-binding proteins acting either as an iron transporter or as a terminal iron reductase, we used metal-catalyzed oxidation reactions. This system catalyzed the oxidation of amino acids in close proximity to the iron binding site. The carbonyl groups formed from this oxidation can then be labeled with fluoresceinamine (FLNH 2 ). The peptide harboring the FLNH 2 can then be proteolytically digested, purified by HPLC and then identified by MALDI-TOF tandem MS. A predominant peptide was identified to be part of SO2907 that encodes a putative TonB-dependent receptor. Compared with wild type (wt), the so2907 gene deletion (⌬SO2907) mutant has impaired ability to reduce soluble Fe(III), but retains the same ability to respire oxygen or fumarate as the wt. The ⌬SO2907 mutant was also impacted in reduction of insoluble iron. Iron binding assays using isothermal titration calorimetry and fluorescence tryptophan quenching demonstrated that a truncated form of heterologous-expressed SO2907 that contains the Fe(III) binding site, is capable of binding soluble Fe(III) forms with K d of approximate 50 M. To the best of our knowledge, this is the first report of the physiological role of SO2907 in Fe(III) reduction by MR-1.

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

Cited by 189 publications

References 46 publications

Biogeochemical behaviour of anionic radionuclides in soil: Evidence for biotic interactions

Biogeochemical behaviour of anionic radionuclides in soil: Evidence for biotic interactions

Review of Potential Candidate Stabilization Technologies for Liquid and Solid Secondary Waste Streams

SO2907, a Putative TonB-dependent Receptor, Is Involved in Dissimilatory Iron Reduction by Shewanella oneidensis Strain MR-1

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