Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 6 of 6
Full-Text Articles in Engineering
Characterization Of Vadose Zone Sediment: Uncontaminated Rcra Borehole Core Samples And Composite Samples, R. J. Serne, B. N. Bjornstad, H. T. Schaef, B. A. Williams, D. C. Lanigan, D. G. Horton, R. E. Clayton, A. V. Mitroshkov, V. L. Legore, M. J. O’Hara, C. F. Brown, K. E. Parker, I. V. Kutnyakov, J. N. Serne, G. V. Last, Steven Smith, C. W. Lindenmeier, John M. Zachara, D. B. Burke
Characterization Of Vadose Zone Sediment: Uncontaminated Rcra Borehole Core Samples And Composite Samples, R. J. Serne, B. N. Bjornstad, H. T. Schaef, B. A. Williams, D. C. Lanigan, D. G. Horton, R. E. Clayton, A. V. Mitroshkov, V. L. Legore, M. J. O’Hara, C. F. Brown, K. E. Parker, I. V. Kutnyakov, J. N. Serne, G. V. Last, Steven Smith, C. W. Lindenmeier, John M. Zachara, D. B. Burke
US Department of Energy Publications
The overall goal of the of the Tank Farm Vadose Zone Project, led by CH2M HILL Hanford Group, Inc., is to define risks from past and future single-shell tank farm activities. To meet this goal, CH2M HILL Hanford Group, Inc. asked scientists from Pacific Northwest National Laboratory to perform detailed analyses on vadose zone sediment from within the S-SX Waste Management Area. This report is one in a series of four reports to present the results of these analyses. Specifically, this report contains all the geologic, geochemical, and selected physical characterization data collected on vadose zone sediment recovered from Resource …
Biomineralization Of Poorly Crystalline Fe(Iii) Oxides By Dissimilatory Metal Reducing Bacteria (Dmrb), John M. Zachara, Ravi K. Kukkadapu, James K. Fredrickson, Yuri A. Gorby, Steven C. Smith
Biomineralization Of Poorly Crystalline Fe(Iii) Oxides By Dissimilatory Metal Reducing Bacteria (Dmrb), John M. Zachara, Ravi K. Kukkadapu, James K. Fredrickson, Yuri A. Gorby, Steven C. Smith
US Department of Energy Publications
Dissimilatory metal reducing bacteria (DMRB) catalyze the reduction of Fe(III) to Fe(II) in anoxic soils, sediments, and groundwater. Two-line ferrihydrite is a bioavailable Fe(III) oxide form that is exploited by DMRB as a terminal electron acceptor. A wide variety of biomineralization products result from the interaction of DMRB with 2-line ferrihydrite. Here we describe the state of knowledge on the biotransformation of synthetic 2-line ferrihydrite by laboratory cultures of DMRB using select published data and new experimental results. A facultative DMRB is emphasized (Shewanella putrefaciens) upon which most of this work has been performed. Key factors controlling the identity of …
Reduction Kinetics Of Fe(Iii), Co(Iii), U(Vi), Cr(Vi), And Tc(Vii) In Cultures Of Dissimilatory Metal-Reducing Bacteria, Chongxuan Liu, Yuri A. Gorby, John M. Zachara, James K. Fredrickson, Christopher F. Brown
Reduction Kinetics Of Fe(Iii), Co(Iii), U(Vi), Cr(Vi), And Tc(Vii) In Cultures Of Dissimilatory Metal-Reducing Bacteria, Chongxuan Liu, Yuri A. Gorby, John M. Zachara, James K. Fredrickson, Christopher F. Brown
US Department of Energy Publications
The reduction kinetics of Fe(III)citrate, Fe(III)NTA, Co(III)EDTA−, U(VI)O22+, Cr(VI)O42−, and Tc(VII)O4− were studied in cultures of dissimilatory metal reducing bacteria (DMRB): Shewanella alga strain BrY, Shewanella putrefaciens strain CN32, Shewanella oneidensis strain MR-1, and Geobacter metallireducens strain GS-15. Reduction rates were metal specific with the following rate trend: Fe (III)citrate ≥ Fe(III)NTA > Co(III)EDTA− ›› UO2 2+ > CrO42− > TcO4−, except for CrO42− when H2 was used as electron donor. The metal reduction rates were also electron donor dependent with faster rates …
Modeling The Inhibition Of The Bacterial Reduction Of U(Vi) By Β-Mno2(S), Chongxuan Liu, John M. Zachara, James K. Fredrickson, David W. Kennedy, Alice Dohnalkova
Modeling The Inhibition Of The Bacterial Reduction Of U(Vi) By Β-Mno2(S), Chongxuan Liu, John M. Zachara, James K. Fredrickson, David W. Kennedy, Alice Dohnalkova
US Department of Energy Publications
Pyrolusite (β-MnO2(s)) was used to assess the influence of a competitive electron acceptor on the kinetics of reduction of aqueous uranyl carbonate by a dissimilatory metal-reducing bacterium (DMRB), Shewanella putrefaciens strain CN32. The enzymatic reduction of U(VI) and β-MnO2(s) and the abiotic redox reaction between β-MnO2(s) and biogenic uraninite (UO2(s)) were independently investigated to allow for interpretation of studies of U(VI) bioreduction in the presence of β-MnO2(s). Uranyl bioreduction to UO2(s) by CN32 with H2 as the electron donor followed Monod kinetics, with a maximum specific reduction rate of 110 µM/h/10 …
Influence Of Mn Oxides On The Reduction Of Uranium(Vi) By The Metal-Reducing Bacterium Shewanella Putrefaciens, James K. Fredrickson, John M. Zachara, David Kennedy, Chongxuan Liu, Martine Duff, Douglas Hunter, Alice Dohnalkova
Influence Of Mn Oxides On The Reduction Of Uranium(Vi) By The Metal-Reducing Bacterium Shewanella Putrefaciens, James K. Fredrickson, John M. Zachara, David Kennedy, Chongxuan Liu, Martine Duff, Douglas Hunter, Alice Dohnalkova
US Department of Energy Publications
The potential for Mn oxides to modify the biogeochemical behavior of U during reduction by the subsurface bacterium Shewanella putrefaciens strain CN32 was investigated using synthetic Mn(III/IV) oxides (pyrolusite [β-MnO2], bixbyite [Mn2O3] and K+-birnessite [K4Mn14O27 • 8H2O]). In the absence of bacteria, pyrolusite and bixbyite oxidized biogenic uraninite (UO2[s]) to soluble U(VI) species, with bixbyite being the most rapid oxidant. The Mn(III/IV) oxides lowered the bioreduction rate of U(VI) relative to rates in their absence or in the presence of gibbsite …
Sorption Of Cs+ To Micaceous Subsurface Sediments From The Hanford Site, Usa, John M. Zachara, Steven Smith, Chongxuan Liu, James Mckinley, R. Jeffrey Serne, Paul Gassman
Sorption Of Cs+ To Micaceous Subsurface Sediments From The Hanford Site, Usa, John M. Zachara, Steven Smith, Chongxuan Liu, James Mckinley, R. Jeffrey Serne, Paul Gassman
US Department of Energy Publications
The sorption of Cs+ was investigated over a large concentration range (10-9–10-2 mol/L) on subsurface sediments from a United States nuclear materials site (Hanford) where high-level nuclear wastes (HLW) have been accidentally released to the vadose zone. The sediment sorbs large amounts of radiocesium, but expedited migration has been observed when HLW (a NaNO3 brine) is the carrier. Cs+ sorption was measured on homoionic sediments (Na+, K+, Ca2+) with electrolyte concentrations ranging from 0.01 to 1.0 mol/L. In Na+ electrolyte, concentrations were extended to near saturation with …