BIOGENIC MANGANESE OXIDES: Properties and Mechanisms of Formation

Tebo, Bradley M.; Bargar, John R.; Clement, Brian; Dick, Gregory J.; Murray, Karen J.; Parker, Dorothy L.; Verity, Rebecca; Webb, Samuel M.

doi:10.1146/annurev.earth.32.101802.120213

Cited by 1,168 publications

(1,063 citation statements)

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“…26,32,33 The oxides are also polycrystalline as proven by the appearance of distinct rings in the Fast Fourier Transform (FFT) of high-resolution images (inset in bottom in Figure 3). Chemical maps (energy dispersive X-ray spectroscopy, EDS) of the localization of Mn and U in the same area as an HAADF image (high angle annular dark field) show the colocalization of the two elements.…”

Section: Environmental Science and Technologymentioning

confidence: 99%

Impact of Microbial Mn Oxidation on the Remobilization of Bioreduced U(IV)

Plathe

Lee

Tebo

et al. 2013

Environ. Sci. Technol.

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Effects of Mn redox cycling on the stability of bioreduced U(IV) are evaluated here. U(VI) can be biologically reduced to less soluble U(IV) species and the stimulation of biological activity to that end is a salient remediation strategy; however, the stability of these materials in the subsurface environments where they form remains unproven. Manganese oxides are capable of rapidly oxidizing U(IV) to U(VI) in mixed batch systems where the two solid phases are in direct contact. However, it is unknown whether the same oxidation would take place in a porous medium. To probe that question, U(IV) immobilized in agarose gels was exposed to conditions allowing biological Mn(II) oxidation (HEPES buffer, Mn(II), 5% O2 and Bacillus sp. SG-1 spores). Results show the oxidation of U(IV) to U(VI) is due primarily to O2 rather than to MnO2. U(VI) produced is retained within the gel to a greater extent when Mn oxides are present, suggesting the formation of strong surface complexes. The implication for the long-term stability of U in a bioremediated site is that, in the absence of competing ligands, biological Mn(II) oxidation may promote the immobilization of U(VI) produced by the oxidation of U(IV).

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Section: Environmental Science and Technologymentioning

confidence: 99%

Impact of Microbial Mn Oxidation on the Remobilization of Bioreduced U(IV)

Plathe

Lee

Tebo

et al. 2013

Environ. Sci. Technol.

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“…The addition or stimulation of Mn(II)-oxidizing bacteria has been proposed as a remediation strategy for some metals and organics (3). However, in the case of chromium, the hazard is increased in Mn(II)-oxidizing bacteria are a diverse group and found in almost all environments, but a single ecological advantage of Mn(II) oxidation has not been found (9,10). Hastings and Emerson (11) showed that bacteria oxidize Mn(II) up to five orders of magnitude faster than abiotic reactions.…”

Section: Introductionmentioning

confidence: 99%

Cr(III) Is Indirectly Oxidized by the Mn(II)-Oxidizing Bacterium Bacillus sp. Strain SG-1

Murray

Tebo

2006

Environ. Sci. Technol.

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Manganese oxides are the only known oxidants of Cr(III) in the environment, and predictions of the fate of Cr(III) have been based on Cr(III) oxidation rates with well-characterized Mn(III,IV) oxide minerals. Our research, however, indicates that the presence of Mn(II)-oxidizing bacteria, may accelerate these rates through the production of very reactive Mn oxides or intermediates formed in the oxidation process. Experiments with the Mn(II)-oxidizing Bacillus sp. strain SG-1 show that this bacterium can accelerate Cr(III) oxidation compared to both abiotic and biologically produced Mn oxides. Initial rates of Cr(III) oxidation by biogenic oxides were approximately 7 times faster than Cr(III) oxidation rates by equivalent amounts of synthetic δ-MnO 2 and 25 times faster by SG-1 spores with Mn(II). Cr(III) oxidation by SG-1 is not direct; Mn is required, but only in small amounts, indicating that it is recycled. Cr(III) oxidation is inhibited above 5 μM dissolved Mn(II), while Mn(II) oxidation is not, suggesting that the processes are controlled by different mechanisms. These results illustrate the need to consider bacterial activity and the concentration of Mn when predicting the potential for Cr(III) oxidation.

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“…Biogenic Mn oxides are poorly crystalline nano-size particulates with huge specific surface area and higher binging energy (Tebo et al 2004). Therefore, Cr(III) could be easily adsorbed on the surface of biogenic Mn oxide and then be oxidized.…”

Section: Discussionmentioning

confidence: 99%

“…Natural Mn oxides in the environment are believed to be derived either directly from biogenic Mn(II) oxidation or from the subsequent alteration of biogenic Mn oxides ( (Kim et al 2003); (Tebo et al 2004)). Mn oxidation in natural aquatic systems often proceeds at very slow rate if there is no participation of microorganisms (Nealson et al 1988).…”

Section: Introductionmentioning

confidence: 99%

“…Mn-oxidizing bacteria are a diverse group and have been found in various environments such as soils ; ), fresh water ( (Nelson et al 1999); (Villalobos et al 2003)), and oceans (Rosson and Nealson 1982). Molecular genetic approaches have revealed that all Mn-oxidizing organisms share sequence similarity with multicopper oxidase enzymes (Tebo et al 2004). Biogenic Mn oxides are often poorly crystalline nano-sized particulates with many structural defects .…”

Section: Introductionmentioning

confidence: 99%

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