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United States Department of Energy: Publications

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Full-Text Articles in Bioresource and Agricultural Engineering

Murdock, Nebraska, Groundwater Flow And Transport Modeling In Support Of Long-Term Monitoring, Applied Geosciences And Environmental Management Section Environmental Research Division, Argonne National Laboratory Jan 2003

Murdock, Nebraska, Groundwater Flow And Transport Modeling In Support Of Long-Term Monitoring, Applied Geosciences And Environmental Management Section Environmental Research Division, Argonne National Laboratory

United States Department of Energy: Publications

Fall 2002 Assignments:
• Update all models to MODFLOW-2000
• Re-calibrate original Murdock steady-state groundwater flow model to November 25, 1998 observed water levels (Phase 1 hydrology)
• Determine time when climatological/hydrolic regime changed in eastern Nebraska. Groundwater levels observed in 2002 are significantly lower than all values observed previously (1997-1999). Palmer Hydrologic Drought Index.
• Determine appropriate groundwater level data for calibration of new (Phase 2) groundwater flow model representing current hydrologic regime (avg. of 2002 observations)
• Re-evaluate/recalculate initial CCl4 concentrations for MT3D-99 solute transport model calibration – 1996/97 concentration data. Too much CCl4 mass …

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Quantifying The Effects Of Small-Scale Heterogeneities On Flow And Transport In Undisturbed Cores From The Hanford Formation, M. N. Pace, M. A. Mayes, P. M. Jardine, T. L. Mehlhorn, John M. Zachara, B.N. Bjornstad Jan 2003

Quantifying The Effects Of Small-Scale Heterogeneities On Flow And Transport In Undisturbed Cores From The Hanford Formation, M. N. Pace, M. A. Mayes, P. M. Jardine, T. L. Mehlhorn, John M. Zachara, B.N. Bjornstad

United States Department of Energy: Publications

Accelerated migration of contaminants in the vadose zone has been observed beneath tank farms at the U.S. Department of Energy’s Hanford Reservation, Richland, WA. This paper focuses on quantifying hydrologic processes that control the fate and transport of contaminants in the unsaturated sediments beneath the Hanford tank farms. The experimental approach involved the use of field relevant, long-term unsaturated nonreactive transport experiments in undisturbed sediments from the Hanford Formation. Undisturbed sediment cores were collected from a laminated fine-grained sand unit within the Hanford Formation in both the vertical direction (flow cross bedding) and the horizontal direction (flow bedding parallel). Laboratory-scale …

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Deformation Of A Peridynamic Bar, S. A. Silling, M. Zimmermann, R. Abeyaratne Jan 2003

Deformation Of A Peridynamic Bar, S. A. Silling, M. Zimmermann, R. Abeyaratne

United States Department of Energy: Publications

The deformation of an infinite bar subjected to a self-equilibrated load distribution is investigated using the peridynamic formulation of elasticity theory. The peridynamic theory differs from the classical theory and other nonlocal theories in that it does not involve spatial derivatives of the displacement field. The bar problem is formulated as a linear Fredholm integral equation and solved using Fourier transform methods. The solution is shown to exhibit, in general, features that are not found in the classical result. Among these are decaying oscillations in the displacement field and progressively weakening discontinuities that propagate outside of the loading region. These …

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Heterogeneous Electron-Transfer Kinetics With Synchrotron 57fe Mossbauer Spectroscopy, J. E. Amonette, Ravi K. Kukkadapu, E. E. Alp, W. Sturhahn, T. S. Toellner Jan 2003

Heterogeneous Electron-Transfer Kinetics With Synchrotron 57fe Mossbauer Spectroscopy, J. E. Amonette, Ravi K. Kukkadapu, E. E. Alp, W. Sturhahn, T. S. Toellner

United States Department of Energy: Publications

In the first known kinetic application of the technique, synchrotron 57Fe-Mössbauer spectroscopy was used to follow the rate of heterogeneous electron transfer between aqueous reagents and a solid phase containing Fe. The solid, a synthetic 57Fe-enriched Fe (III)-bearing pyroaurite-like phase having terephthalate (TA) in the interlayer [Mg3Fe (OH)8(TA)0.5 • 2H2O], was reduced by Na2S2O4 and then reoxidized by K2Cr2O7 by means of a novel flow-through cell. Synchrotron Mössbauer spectra were collected in the time domain at 30-s intervals. Integration of the …

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Secondary Mineralization Pathways Induced By Dissimilatory Iron Reduction Of Ferrihydrite Under Advective Flow, Colleen M. Hansel, Shawn G. Benner, Jim Neiss, Alice Dohnalkova, Ravi K. Kukkadapu, Scott Fendorf Jan 2003

Secondary Mineralization Pathways Induced By Dissimilatory Iron Reduction Of Ferrihydrite Under Advective Flow, Colleen M. Hansel, Shawn G. Benner, Jim Neiss, Alice Dohnalkova, Ravi K. Kukkadapu, Scott Fendorf

United States Department of Energy: Publications

Iron (hydr)oxides not only serve as potent sorbents and repositories for nutrients and contaminants but also provide a terminal electron acceptor for microbial respiration. The microbial reduction of Fe (hydr)oxides and the subsequent secondary solid-phase transformations will, therefore, have a profound influence on the biogeochemical cycling of Fe as well as associated metals. Here we elucidate the pathways and mechanisms of secondary mineralization during dissimilatory iron reduction by a common iron-reducing bacterium, Shewanella putrefaciens (strain CN32), of 2-line ferrihydrite under advective flow conditions. Secondary mineralization of ferrihydrite occurs via a coupled, biotic-abiotic pathway primarily resulting in the production of magnetite …

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Inhibition Of Bacterial U(Vi) Reduction By Calcium, Scott Brooks, James K. Fredrickson, Sue Carroll, David Kennedy, John M. Zachara, Andrew Plymale, Shelly Kelley, Kenneth Kemner, Scott Fendorf Jan 2003

Inhibition Of Bacterial U(Vi) Reduction By Calcium, Scott Brooks, James K. Fredrickson, Sue Carroll, David Kennedy, John M. Zachara, Andrew Plymale, Shelly Kelley, Kenneth Kemner, Scott Fendorf

United States Department of Energy: Publications

The rapid kinetics of bacterial U(VI) reduction and low solubility of uraninite (UO2,cr) make this process an attractive option for removing uranium from groundwater. Nevertheless, conditions that may promote or inhibit U(VI) reduction are not well-defined. Recent descriptions of Ca-UO2- CO3 complexes indicate that these species may dominate the aqueous speciation of U(VI) in many environments. We monitored the bacterial reduction of U(VI) in bicarbonate buffered solution in the presence and absence of Ca. XAFS measurements confirmed the presence of a Ca- U(VI)-CO3 complex in the initial solutions containing calcium. Calcium, at millimolar concentrations …

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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 Feb 2002

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

United States 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 …

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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 Jan 2002

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

United States 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 …

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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 Jan 2002

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

United States 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 …

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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 Jan 2002

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

United States 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 …

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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 Jan 2002

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

United States 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 …

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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 Jan 2002

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

United States 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 …

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Chemical Insights From High-Resolution X-Ray Photoelectron Spectroscopy And Ab Initio Theory: Propyne, Trifluoropropyne, And Ethynylsulfur Pentafluoride, Leif J. Sæthre, Nora Berrah, John D. Bozek, Knut J. Borve, Thomas X. Carroll, Edwin Kukk, Gary L. Gard, Rolf Winter, T. Darrah Thomas Jan 2001

Chemical Insights From High-Resolution X-Ray Photoelectron Spectroscopy And Ab Initio Theory: Propyne, Trifluoropropyne, And Ethynylsulfur Pentafluoride, Leif J. Sæthre, Nora Berrah, John D. Bozek, Knut J. Borve, Thomas X. Carroll, Edwin Kukk, Gary L. Gard, Rolf Winter, T. Darrah Thomas

United States Department of Energy: Publications

High-resolution carbon 1s photoelectron spectroscopy of propyne (HC=CH3) shows a spectrum in which the contributions from the three chemically inequivalent carbons are clearly resolved and marked by distinct vibrational structure. This structure is well accounted for by ab initio theory. For 3,3,3-trifluoropropyne (HC=CF3) and ethynylsulfur pentafluoride (HC=SF5), the ethynyl carbons show only a broad structure and have energies that differ only slightly from one another. The core-ionization energies can be qualitatively understood in terms of conventional resonance structures; the vibrational broadening for the fluorinated compounds can be understood in terms of the effects of …

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Biotransformation Of Ni-Substituted Hydrous Ferric Oxide By An Fe(Iii)-Reducing Bacterium, James K. Fredrickson, John M. Zachara, Ravi K. Kukkadapu, Yuri A. Gorby, Steven C. Smith, Christopher F. Brown Jan 2001

Biotransformation Of Ni-Substituted Hydrous Ferric Oxide By An Fe(Iii)-Reducing Bacterium, James K. Fredrickson, John M. Zachara, Ravi K. Kukkadapu, Yuri A. Gorby, Steven C. Smith, Christopher F. Brown

United States Department of Energy: Publications

The reductive biotransformation of a Ni2+-substituted (5 mol %) hydrous ferric oxide (NiHFO) by Shewanella putrefaciens, strain CN32, was investigated under anoxic conditions at circumneutral pH. Our objectives were to define the influence of Ni2+ substitution on the bioreducibility of the HFO and the biomineralization products formed and to identify biogeochemical factors controlling the phase distribution of Ni2+ during bioreduction. Incubations with CN32 and NiHFO were sampled after 14 and 32 d, and both aqueous chemistry and solid phases were characterized. By comparison of these results with a previous study (Fredrickson, J. K.; Zachara, J. M.; …

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Dissimilatory Bacterial Reduction Of Al-Substituted Goethite In Subsurface Sediments, Ravi K. Kukkadapu, John M. Zachara, Steven C. Smith, James K. Fredrickson, Chongxuan Liu Jan 2001

Dissimilatory Bacterial Reduction Of Al-Substituted Goethite In Subsurface Sediments, Ravi K. Kukkadapu, John M. Zachara, Steven C. Smith, James K. Fredrickson, Chongxuan Liu

United States Department of Energy: Publications

The microbiologic reduction of a 0.2 to 2.0 µm size fraction of an Atlantic coastal plain sediment (Eatontown) was investigated using a dissimilatory Fe(III)-reducing bacterium (Shewanella putrefaciens, strain CN32) to evaluate mineralogic controls on the rate and extent of Fe(III) reduction and the resulting distribution of biogenic Fe(II). Mössbauer spectroscopy and X-ray diffraction (XRD) were used to show that the sedimentary Fe (III) oxide was Al-substituted goethite (13–17% Al) that existed as 1- to 5-µm aggregates of indistinct morphology. Bioreduction experiments were performed in two buffers [HCO3‑; 1,4-piperazinediethansulfonic acid (PIPES)] both without and with 2,6-anthraquinone …

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Kinetics And Mechanism Of Birnessite Reduction By Catechol, Christopher J. Matocha, Donald L. Sparks, James E. Amonette, Ravi K. Kukkadapu Jan 2001

Kinetics And Mechanism Of Birnessite Reduction By Catechol, Christopher J. Matocha, Donald L. Sparks, James E. Amonette, Ravi K. Kukkadapu

United States Department of Energy: Publications

The complex interactions of oxidizable organic ligands with soil Mn(III,IV) (hydr)oxide minerals have received little study by in situspectroscopic techniques.We used a combination of an in situ electron paramagnetic resonance stopped-flow (EPR-SF) spectroscopic technique and stirred-batch studies to measure the reductive dissolution kinetics of birnessite (δ-MnO2), a common Mn mineral in soils, by catechol (1,2-dihydroxybenzene). The reaction was rapid, independent of pH, and essentially complete within seconds under conditions of excess catechol at pH 4 to 6. The overall empirical second-order rate equation describing the reductive dissolution rate was d[Mn(II)]/dt = k[CAT]1.0[SA]1.0 where …

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Distribution And Retention Of 137cs In Sediments At The Hanford Site, Washington, James Mckinley, Cynthia Zeissler, John M. Zachara, R. Jeffrey Serne, Richard Lindstrom, Herbert Schaef, Robert Orr Jan 2001

Distribution And Retention Of 137cs In Sediments At The Hanford Site, Washington, James Mckinley, Cynthia Zeissler, John M. Zachara, R. Jeffrey Serne, Richard Lindstrom, Herbert Schaef, Robert Orr

United States Department of Energy: Publications

137Cesium and other contaminants have leaked from single-shell storage tanks (SSTs) into coarse-textured, relatively unweathered unconsolidated sediments. Contaminated sediments were retrieved from beneath a leaky SST to investigate the distribution of adsorbed 137Cs+ across different sediment size fractions. All fractions contained mica (biotite, muscovite, vermiculatized biotite), quartz, and plagioclase along with smectite and kaolinite in the clay-size fraction. A phosphor-plate autoradiograph method was used to identify particular sediment particles responsible for retaining 137Cs+. The Cs-bearing particles were found to be individual mica flakes or agglomerated smectite, mica, quartz, and plagioclase. Of these, only the …

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Kinetic Analysis Of The Bacterial Reduction Of Goethite, Chongxuan Liu, John M. Zachara, James K. Fredrickson, Cynthia Brinkman Jan 2001

Kinetic Analysis Of The Bacterial Reduction Of Goethite, Chongxuan Liu, John M. Zachara, James K. Fredrickson, Cynthia Brinkman

United States Department of Energy: Publications

The kinetics of dissimilatory reduction of goethite (RFeOOH) was studied in batch cultures of a groundwater bacterium, Shewanella putrefaciens, strain CN32 in pH 7 bicarbonate buffer. The rate and extent of goethite reduction were measured as a function of electron acceptor (goethite) and donor (lactate) concentrations. Increasing goethite concentrations increased both the rate and extent of Fe(III) reduction when cell and lactate concentrations were held constant. However, constant initial reduction rates were observed after normalization to the Fe(II) sorption capacity of FeOOH, suggesting that the bacterial reduction rate was first order with respect to surface site concentration. Increasing …

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Microbial Reduction Of Fe(Iii) And Sorption/Precipitation Of Fe(Ii) On Shewanella Putrefaciens Strain Cn32, Chongxuan Liu, John M. Zachara, Yuri Gorby, Jim Szecsody, Christopher Brown Jan 2001

Microbial Reduction Of Fe(Iii) And Sorption/Precipitation Of Fe(Ii) On Shewanella Putrefaciens Strain Cn32, Chongxuan Liu, John M. Zachara, Yuri Gorby, Jim Szecsody, Christopher Brown

United States Department of Energy: Publications

The influence of Fe(II) on the dissimilatory bacterial reduction of an Fe(III) aqueous complex (Fe(III)-citrateaq) was investigated using Shewanella putrefaciens strain CN32. The sorption of Fe(II) on CN32 followed a Langmuir isotherm. Least-squares fitting gave a maximum sorption capacity of Qmax = 4.19 x 10-3 mol/1012 cells (1.19 mmol/ m2 of cell surface area) and an affinity coefficient of log K = 3.29. The growth yield of CN32 with respect to Fe(III)aq reduction showed a linear trend with an average value of 5.24 (±0.12) x 109 cells/mmol of Fe(III). The reduction of …

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Uncertainties Of Monod Kinetic Parameters Nonlinearly Estimated From Batch Experiments, Chongxuan Liu, John M. Zachara Jan 2001

Uncertainties Of Monod Kinetic Parameters Nonlinearly Estimated From Batch Experiments, Chongxuan Liu, John M. Zachara

United States Department of Energy: Publications

Monod kinetic parameters (Ks, µmax, and Y) that are estimated from batch experimental data can have large uncertainties due to linear correlations between them. The degree of correlation and the resulting uncertainties of the Monod parameters are functions of the initial experimental conditions, the values of the parameters, the type and magnitude of measurement errors, and the sampling number. Careful manipulation of experimental conditions can reduce the correlations between Monod parameters allowing for the estimation of Monod kinetic parameters with the lowest degree of uncertainty. By dimensionless analysis, the correlation and relative standard deviations of Monod parameters …

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Uranium(Vi) Sorption Complexes On Montmorillonite As A Function Of Solution Chemistry, Catherine J. Chisholm-Brause, John M. Berg, Robert A. Matzner, David E. Morris Jan 2001

Uranium(Vi) Sorption Complexes On Montmorillonite As A Function Of Solution Chemistry, Catherine J. Chisholm-Brause, John M. Berg, Robert A. Matzner, David E. Morris

United States Department of Energy: Publications

We have investigated the effect of changes in solution chemistry on the nature of uranyl sorption complexes on montmorillonite (SAz-1) at different surface coverages (1.43–53.6 µmol/g). Uranyl uptake onto SAz-1 between pH 3 and 7 was determined in both titration and batch-mode experiments. These pH values result in solutions that contain a range of monomeric and oligomeric aqueous uranyl species. Continuous-wave and timeresolved emission spectroscopies were used to investigate the nature of U(VI) sorbed to SAz-1. A discrete set of uranyl surface complexes has been identified over a wide range of pH values at these low to moderate coverages. For …

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Vibrational Structure And Vibronic Coupling In The Carbon 1s Photoelectron Spectra Of Ethane And Deuteroethane, Tor Karlson, Leif J. Sæthre, Knut J. Børve, Nora Berrah, Edwin Kukk, John D. Bozek, Thomas X. Carroll, T. Darrah Thomas Jan 2001

Vibrational Structure And Vibronic Coupling In The Carbon 1s Photoelectron Spectra Of Ethane And Deuteroethane, Tor Karlson, Leif J. Sæthre, Knut J. Børve, Nora Berrah, Edwin Kukk, John D. Bozek, Thomas X. Carroll, T. Darrah Thomas

United States Department of Energy: Publications

The carbon 1s photoelectron spectrum of ethane, C2H6, has been measured at a photon energy of 329 eV and an instrumental resolution of 70 meV. The spectrum shows a rich vibrational structure which is resolved using least-squares fits to the data. Only C-H stretching and CCH bending modes contribute significantly to the spectrum. The lack of excitation of the C-C stretching mode is explained in terms of changes in hybridization at the spectator carbon. To investigate the possibility of incomplete localization of the core hole, the spectra of C2H6 and C2D …

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Solubilization Of Fe(Iii) Oxide-Bound Trace Metals By A Dissimilatory Fe(Iii) Reducing Bacterium, John M. Zachara, James K. Fredrickson, Steven Smith, Paul Gassman Jan 2001

Solubilization Of Fe(Iii) Oxide-Bound Trace Metals By A Dissimilatory Fe(Iii) Reducing Bacterium, John M. Zachara, James K. Fredrickson, Steven Smith, Paul Gassman

United States Department of Energy: Publications

Trace metals associate with Fe(III) oxides as adsorbed or coprecipitated species, and consequently, the biogeochemical cycles of iron and the trace metals are closely linked. This communication investigated the solubilization of coprecipitated Co(III) and Ni(II) from goethite (α-FeOOH) during dissimilatory bacterial iron reduction to provide insights on biogeochemical factors controlling trace-element fluxes in anoxic environments. Suspensions of homogeneously substituted Co-FeOOH (50 mmol/L as Co0.01Fe0.99OOH; 57Co-labeled) in eight different buffer/media solutions were inoculated with a facultative, metal-reducing bacteria isolated from groundwater (Shewanella putrefacians CN32), and incubated under strictly anaerobic conditions for periods up to 32 …

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Wind Powering America: Clean Energy For The 21st Century Apr 2000

Wind Powering America: Clean Energy For The 21st Century

United States Department of Energy: Publications

Since earliest recorded history, wind power has been used to move ships, grind grain, and pump water. Today, wind power is also being used to provide electricity to homes, schools, businesses, and entire communities. More than half the United States have wind resources that could support the development of utility scale wind power plants.

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Geothermal Heat Pumps In K–12 Schools: A Case Study Of The Lincoln, Nebraska Schools, John A. Shonder, Michaela A. Martin, Patrick J. Hughes, Jeff Thornton Apr 2000

Geothermal Heat Pumps In K–12 Schools: A Case Study Of The Lincoln, Nebraska Schools, John A. Shonder, Michaela A. Martin, Patrick J. Hughes, Jeff Thornton

United States Department of Energy: Publications

Geothermal heat pumps (GHPs) have been shown to have a number of benefits over other technologies used to heat and cool buildings and provide hot water, combining high levels of occupant comfort with low operating and maintenance costs. Public facilities represent an increasingly important market for GHPs, and schools are a particularly good application, given the large land area that normally surrounds them. Nevertheless, some barriers remain to the increased use of GHPs in institutional and commercial applications. First, because GHPs are perceived as having higher installation costs than other space conditioning technologies, they are sometimes not considered as an …

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Use Of The Generalized Integral Transform Method For Solving Equations Of Solute Transport In Porous Media, Chongxuan Liu, Jim E. Szecsody, John M. Zachara, William P. Ball Jan 2000

Use Of The Generalized Integral Transform Method For Solving Equations Of Solute Transport In Porous Media, Chongxuan Liu, Jim E. Szecsody, John M. Zachara, William P. Ball

United States Department of Energy: Publications

The generalized integral transform technique (GITT) is applied to solve the one-dimensional advection-dispersion equation (ADE) in heterogeneous porous media coupled with either linear or nonlinear sorption and decay. When both sorption and decay are linear, analytical solutions are obtained using the GITT for one-dimensional ADEs with spatially and temporally variable flow and dispersion coefficient and arbitrary initial and boundary conditions. When either sorption or decay is nonlinear the solutions to ADEs with the GITT are hybrid analytical-numerical. In both linear and nonlinear cases, the forward and inverse integral transforms for the problems described in the paper are apparent and straightforward. …

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Mineral Transformation Associated With The Microbial Reduction Of Magnetite, Hailiang Dong, James K. Fredrickson, David W. Kennedy, John M. Zachara, Ravi K. Kukkadapu, Tullis C. Onstott Jan 2000

Mineral Transformation Associated With The Microbial Reduction Of Magnetite, Hailiang Dong, James K. Fredrickson, David W. Kennedy, John M. Zachara, Ravi K. Kukkadapu, Tullis C. Onstott

United States Department of Energy: Publications

Although dissimilatory iron reducing bacteria (DIRB) are capable of reducing a number of metals in oxides and soluble forms, the factors controlling the raterextent of magnetite reduction and the nature of the mineral products resulting from magnetite reduction are not well understood. This study was carried out to investigate mechanisms and biogeochemical processes occurring during magnetite reduction by the DIRB, Shewanella putrefaciens strains CN32 and MR-1. Reduction experiments were performed with biogenic and synthetic magnetite in well-defined solutions. Biogenic magnetite was generated via microbial reduction of hydrous ferric oxide (HFO). Biogenic magnetite in solutions buffered with either bicarbonate (HCO3 …

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Reduction Of U(Vi) In Goethite (Α-Feooh) Suspensions By A Dissimilatory Metal-Reducing Bacterium, James K. Fredrickson, John M. Zachara, David Kennedy, Martine Duff, Yuri Gorby, Shu-Mei Li, Kenneth Krupka Jan 2000

Reduction Of U(Vi) In Goethite (Α-Feooh) Suspensions By A Dissimilatory Metal-Reducing Bacterium, James K. Fredrickson, John M. Zachara, David Kennedy, Martine Duff, Yuri Gorby, Shu-Mei Li, Kenneth Krupka

United States Department of Energy: Publications

Dissimilatory metal-reducing bacteria (DMRB) can utilize Fe(III) associated with aqueous complexes or solid phases, such as oxide and oxyhydroxide minerals, as a terminal electron acceptor coupled to the oxidation of H2 or organic substrates. These bacteria are also capable of reducing other metal ions including Mn(IV), Cr(VI), and U(VI), a process that has a pronounced effect on their solubility and overall geochemical behavior. In spite of considerable study on an individual basis, the biogeochemical behavior of multiple metals subject to microbial reduction is poorly understood. To probe these complex processes, the reduction of U(VI) by the subsurface bacterium, Shewanella …

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The Effect Of Biogenic Fe(Ii) On The Stability And Sorption Of Co(Ii)Edta22 To Goethite And A Subsurface Sediment, John M. Zachara, Steven Smith, James K. Fredrickson Jan 2000

The Effect Of Biogenic Fe(Ii) On The Stability And Sorption Of Co(Ii)Edta22 To Goethite And A Subsurface Sediment, John M. Zachara, Steven Smith, James K. Fredrickson

United States Department of Energy: Publications

Laboratory experiments were conducted with suspensions of goethite (α-FeOOH) and a subsurface sediment to assess the influence of bacterial iron reduction on the fate of Co(II)EDTA2-, a representative metal-ligand complex of intermediate stability (log KCo(II)EDTA = 17.97). The goethite was synthetic (ca. 55 m2/g) and the sediment was a Pleistocene age, Fe(III) oxide-containing material from the Atlantic coastal plain (Milford). Shewanella alga strain BrY, a dissimilatory iron reducing bacterium (DIRB), was used to promote Fe(III) oxide reduction. Sorption isotherms and pH adsorption edges were measured for Co2+, Fe2+, Co(II)EDTA2-, …

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Influence Of Aqueous And Solid-Phase Fe(Ii) Complexants On Microbial Reduction Of Crystalline Iron(Iii) Oxides, Matilde Urrutia, Eric E. Roden, John M. Zachara Jan 1999

Influence Of Aqueous And Solid-Phase Fe(Ii) Complexants On Microbial Reduction Of Crystalline Iron(Iii) Oxides, Matilde Urrutia, Eric E. Roden, John M. Zachara

United States Department of Energy: Publications

The influence of aqueous (NTA and EDTA) and solidphase (aluminum oxide, layer silicates) Fe(II) complexants on the long-term microbial reduction of synthetic goethite by Shewanella alga strain BrY was studied. NTA enhanced goethite reduction by promoting aqueous Fe(II) accumulation, in direct proportion to its concentration in culture medium (0.01-5 mM). In contrast, EDTA failed to stimulate goethite reduction at concentrations e1 mM, and 5 mM EDTA enhanced the final extent of reduction by only 25% in relation to nonchelator controls. The minor effect of EDTA compared to NTA, despite the greater stability of the Fe(II)- EDTA complex, likely resulted from …

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