The effect of U(VI) bioreduction kinetics on subsequent reoxidation of biogenic U(IV)

Senko, John M.; Kelly, Shelly D.; Dohnálková, Alice; McDonough, Jeffrey T.; Kemner, Kenneth M.; Burgos, William D.

doi:10.1016/j.gca.2007.07.021

Cited by 86 publications

(91 citation statements)

References 71 publications

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“…Because size directly impacts overall dissolution rates, such variability could influence the stability of these biogenic products where larger nanoparticles are more recalcitrant (31). Our observation of a conservation of particle size between interspecies products formed under nearly identical conditions suggests that formation diameter may have more to do with geochemical factors than with biological variability.…”

Section: Of the Supporting Information)mentioning

confidence: 84%

Structural Similarities between Biogenic Uraninites Produced by Phylogenetically and Metabolically Diverse Bacteria

Sharp

Schofield

Veeramani

et al. 2009

Environ. Sci. Technol.

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While the product of microbial uranium reduction is often reported to be "UO 2 ", a comprehensive characterization including stoichiometry and unit cell determination is available for only one Shewanella species. Here, we compare the products of batch uranyl reduction by a collection of dissimilatory metal-and sulfate-reducing bacteria of the genera Shewanella, Geobacter, Anaeromyxobacter, and Desulfovibrio under similar laboratory conditions. Our results demonstrate that U(VI) bioreduction by this assortment of commonly studied, environmentally relevant bacteria leads to the precipitation of uraninite with an approximate composition of UO 2.0 , regardless of phylogenetic or metabolic diversity. Coupled analyses, including electron microscopy, X-ray absorption spectroscopy, and powder diffraction, confirm that structurally and chemically analogous uraninite solids are produced. These biogenic uraninites have particle diameters of about 2-3 nm and lattice constants consistent with UO 2.0 and exhibit a high degree of intermediate-range order. Results indicate that phylogenetic and metabolic variability within delta-and gamma-proteobacteria has little effect on biouraninite structure or crystal size under the investigated conditions.

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Section: Of the Supporting Information)mentioning

confidence: 84%

Structural Similarities between Biogenic Uraninites Produced by Phylogenetically and Metabolically Diverse Bacteria

Sharp

Schofield

Veeramani

et al. 2009

Environ. Sci. Technol.

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show abstract

“…Subsequent studies have also reported biogenic uraninite particle sizes in the 2 to 10 nm range and slight but significant contraction of the first U-U shell (Renshaw et al 2005;Singer et al 2006;Senko et al 2007;Burgos et al 2008;Komlos et al 2008). Similar results have been reported for uraninite nanoparticles produced by abiotic reduction of U(VI) by green rust (O'Loughlin et al 2003).…”

Section: Structure and Composition Of Biogenic Uraninitementioning

confidence: 91%

“…Laboratory and field studies have observed the oxidation of U(IV), likely representing different mixtures of uraninite and U(IV) adsorbed on biomass, on timescales from hours to several months (Moon et al 2007;Senko et al 2007;Wu et al 2007;Komlos et al 2008). Oxidation rates increase with decreasing particle size and decreasing degree of aggregation.…”

Section: Dissolution Rates Of Biogenic Uraninitementioning

confidence: 99%

Biogenic Uraninite Nanoparticles and Their Importance for Uranium Remediation

et al. 2008

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Biogenic uraninite is of interest to geoscientists for its importance to bioremediation strategies, remarkably small particle size, and biological origin. Recent studies have begun to illuminate the chemical/structural complexities of this important natural nanomaterial. Intriguingly, in spite of its incredibly diminutive size, the molecular-scale structure, energetics, and surfacearea-normalized dissolution rates of hydrated biogenic uraninite appear to be similar to those of coarser-particle, abiotic, stoichiometric UO 2 . These findings have important implications for the role of size as a moderator of nanoparticle aqueous reactivity and for the bioremediation of subsurface U(VI) contamination.

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“…In order to measure the amount of Mn associated with uraninite, an aliquot of the NaOH-treated mineral was centrifuged, and the pellet was resuspended aerobically in 2 mL of concentrated HNO 3 . The suspension was placed on a rotary shaker overnight for complete dissolution.…”

Section: Methodsmentioning

confidence: 99%

“…A significant issue associated with uranium bioremediation is the susceptibility of biogenic uraninite, the product of microbial U(VI) reduction (2), to chemical oxidation by O 2 (3)(4)(5), nitrite (6), nitrate (4), and Fe(III) (hydr)oxides (7) and to biological oxidation coupled with nitrate reduction (8).…”

Section: Introductionmentioning

confidence: 99%

Effect of Mn(II) on the Structure and Reactivity of Biogenic Uraninite

Veeramani

Schofield

Sharp

et al. 2009

Environ. Sci. Technol.

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The efficacy of a site remediation strategy involving the stimulation of microbial U(VI) reduction hinges in part upon the long-term stability of the product, biogenic uraninite, toward environmental oxidants. Geological sedimentary uraninites (nominal formula UO 2 ) reportedly contain abundant cation impurities that enhance their resistance to oxidation. By analogy, incorporation of common groundwater solutes into biogenic uraninite could also impart stability-enhancing properties. Mn(II) is a common groundwater cation, which has a favorable ionic radius for substitution reactions. The structure and reactivity of Mn(II)-reacted biogenic uraninite are investigated in this study. Up to 4.4 weight percent Mn(II) was found to be structurally bound in biogenic uraninite. This Mn(II) incorporation was associated with decreasing uraninite particle size and structural order. Importantly, the equilibrium solubility of Mn-reacted uraninite was halved relative to unreacted uraninite, demonstrating changes in thermodynamic properties, while the dissolution rate was up to 38-fold lower than that of unreacted biogenic uraninite. We conclude that structural incorporation of Mn(II) into uraninite has an important stabilizing effect, leading to the prediction that other groundwater solutes may similarly stabilize biogenic uraninite.

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The effect of U(VI) bioreduction kinetics on subsequent reoxidation of biogenic U(IV)

Cited by 86 publications

References 71 publications

Structural Similarities between Biogenic Uraninites Produced by Phylogenetically and Metabolically Diverse Bacteria

Structural Similarities between Biogenic Uraninites Produced by Phylogenetically and Metabolically Diverse Bacteria

Biogenic Uraninite Nanoparticles and Their Importance for Uranium Remediation

Effect of Mn(II) on the Structure and Reactivity of Biogenic Uraninite

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