Bioresource and Agricultural Engineering Commons^™

Hydrogenase- And Outer Membrane C-Type Cytochrome-Facilitated Reduction Of Technetium(Vii) By Shewanella Oneidensis Mr-1, Matthew J. Marshall, Andrew Plymale, David W. Kennedy, Liang Shi, Zheming Wang, Samantha B. Reed, Alice Dohnalkova, Cody Simonson, Chongxuan Liu, Daad A. Saffarini, Margaret F. Romine, John M. Zachara, Alexander S. Beliaev, James K. Fredrickson

United States Department of Energy: Publications

Pertechnetate, ⁹⁹Tc(VII)O₄^–, is a highly mobile radionuclide contaminant at US Department of Energy sites that can be enzymatically reduced by a range of anaerobic and facultatively anaerobic microorganisms, including Shewanella oneidensis MR-1, to poorly soluble Tc(IV)O_2(s). In other microorganisms, Tc(VII)O₄^– reduction is generally considered to be catalysed by hydrogenase. Here, we provide evidence that although the NiFe hydrogenase of MR-1 was involved in the H2-driven reduction of Tc(VII)O₄^– [presumably through a direct coupling of H₂ oxidation and Tc(VII) reduction], the deletion of both hydrogenase genes did not completely eliminate …

Electron Transfer At The Microbe–Mineral Interface: A Grand Challenge In Biogeochemistry, James K. Fredrickson, John M. Zachara

United States Department of Energy: Publications

The interplay between microorganisms and minerals is a complex and dynamic process that has sculpted the geosphere for nearly the entire history of the Earth. The work of Dr. Terry Beveridge and colleagues provided some of the first insights into metal–microbe and mineral–microbe interactions and established a foundation for subsequent detailed investigations of interactions between microorganisms and minerals. Beveridge also envisioned that interdisciplinary approaches and teams would be required to explain how individual microbial cells interact with their immediate environment at nano- or microscopic scales and that through such approaches and using emerging technologies that the details of such interactions …

The Minimum Information About A Genome Sequence (Migs) Specification, Dawn Field, George Garrity, Tanya Gray, Norman Morrison, Jeremy Selengut, Peter Sterk, Tatiana Tatusova, Nicholas Thomson, Michael J. Allen, Samuel V. Angiuoli, Michael Ashburner, Nelson Axelrod, Sandra Baldauf, Stuart Ballard, Jeffrey Boore, Guy Cochrane, James Cole, Peter Dawyndt, Paul De Vos, Claude Depamphilis, Robert Edwards, Nadeem Faruque, Robert Feldman, Jack Gilbert, Paul Gilna, Frank Oliver Glöckner, Philip Goldstein, Robert Guralnick, Dan Haft, David Hancock, Henning Hermjakob, Christiane Hertz-Fowler, Phil Hugenholtz, Ian Joint, Leonid Kagan, Matthew Kane, Jessie Kennedy, George Kowalchuk, Renzo Kottmann, Eugene Kolker, Saul Kravitz, Nikos Kyrpides, Jim Leebens-Mack, Suzanna E. Lewis, Kelvin Li, Allyson L. Lister, Phillip Lord, Natalia Maltsev, Victor Markowitz, Jennifer Martiny, Barbara Methe, Ilene Mizrachi, Richard Moxon, Karen Nelson, Julian Parkhill, Lita Proctor, Owen White, Susanna-Assunta Sansone, Andrew Spiers, Robert Stevens, Paul Swift, Chris Taylor, Yoshio Tateno, Adrian Tett, Sarah Turner, David Ussery, Bob Vaughan, Naomi Ward, Trish Whetzel, Ingio San Gil, Gareth Wilson, Anil Wipat

United States Department of Energy: Publications

With the quantity of genomic data increasing at an exponential rate, it is imperative that these data be captured electronically, in a standard format. Standardization activities must proceed within the auspices of open-access and international working bodies. To tackle the issues surrounding the development of better descriptions of genomic investigations, we have formed the Genomic Standards Consortium (GSC). Here, we introduce the minimum information about a genome sequence (MIGS) specification with the intent of promoting participation in its development and discussing the resources that will be required to develop improved mechanisms of metadata capture and exchange. As part of its …

Genomics: Gtl 2008 Strategic Plan, Sharlene Weatherwax

United States Department of Energy: Publications

Table of Contents:
Mission-Inspired Science
GTL Concept and History
National Academy of Sciences Evaluation of GTL Program
GTL’s Fundamental Research Approach to Its Mission
Hallmarks of the GTL Research Approach
Multiscale Explorations
Office of Biological and Environmental Research User Facilities
Metamethods: Metagenomics and Metaproteomics
Robust Computational Framework for GTL Research
GTL Information and Data Sharing Policy
Elaboration of GTL Science for DOE Missions
Systems Biology for Energy Solutions
Systems Biology for Understanding the Carbon Cycle
Planet-Transforming Microbes
Systems Biology for Understanding Contaminant Transport in the Environment
Microbe-Mineral Interface in Contaminated Environments
DOE Office of Science
DOE Office of Biological and …

Pursuing Energy Efficiency As A Hedge Against Carbon Regulatory Risks: Current Resource Planning Practices In The West, Ryan Wiser, Amol Phadke, Charles Goldman

United States Department of Energy: Publications

Uncertainty surrounding the nature and timing of future carbon regulations poses a fundamental and far-reaching financial risk for electric utilities and their ratepayers. Long-term resource planning provides a potential framework within which utilities can assess carbon regulatory risk and evaluate options for mitigating exposure to this risk through investments in energy efficiency and other low-carbon resources. In this paper, we examine current resource planning practices related to managing carbon regulatory risk, based on a comparative analysis of the most-recent long-term resource plans filed by fifteen major utilities in the Western U.S. First, we compare the assumptions and methods used by …

Tribal Renewable Energy – Final Report, A. David Lester

United States Department of Energy: Publications

DOE/CERT Cooperative Agreement has demonstrated that Indian Tribes are ready to undertake the positive steps in developing their internal governmental capacities in program planning and project development as well as the enterprise management capability to undertake the development of their substantial natural base of renewable energy resources and to learn the basic technologies in wind, solar, bio-mass and alternative energy production. The project also demonstrated that virtually every Indian Tribe and community in the United States would benefit socially, economically and in public health values thru a sustained federally coordinated Tribal energy efficiency initiative; and, that a small amount of …

Effects Of Gamma-Sterilization On The Physico-Chemical Properties Of Natural Sediments, T.L. Bank, Ravi K. Kukkadapu, A.S. Madden, M.A. Ginder-Vogel, M.E. Baldwin, P.M. Jardine

United States Department of Energy: Publications

Batch U(VI) sorption/reduction experiments were completed on sterilized and non-sterilized sediment samples to elucidate biological and geochemical reduction mechanisms. Results from X-ray absorption nearedge structure (XANES) spectroscopy revealed that γ-sterilized sediments were actually better sorbents of U(VI), despite the absence of any measurable biological activity. These results indicate that γ-irradiation induced significant physico-chemical changes in the sediment which is contrary to numerous other studies identifying γ-sterilization as an effective and minimally invasive technique. To identify the extent and method of alteration of the soil as a result of γ-sterilization, untreated soil samples, physically separated size fractions, …

Scale-Dependent Desorption Of Uranium From Contaminated Subsurface Sediments, Chongxuan Liu, John M. Zachara, Nikolla P. Qafoku, Zheming Wang

United States Department of Energy: Publications

Column experiments were performed to investigate the scale-dependent desorption of uranyl [U(VI)] from a contaminated sediment collected from the Hanford 300 Area at the U.S. Department of Energy (DOE) Hanford Site, Washington. The sediment was a coarse-textured alluvial flood deposit containing significant mass percentage of river cobble. U(VI) was, however, only associated with its minor fine-grained (<2 mm) mass fraction. U(VI) desorption was investigated both from the field-textured sediment using a large column (80 cm length by 15 cm inner diameter) and from its <2 mm U(VI)- associated mass fraction using a small column (10 cm length by 3.4 cm inner diameter). Dynamic advection conditions with intermittent flow and stop-flow events of variable durations were employed to investigate U(VI) desorption kinetics and its scale dependence. A multicomponent kinetic model that integrated a distributed rate of mass transfer with surface complexation reactions successfully described U(VI) release from the fine-grained U(VI)-associated materials. The field-textured sediment in the large column displayed dual-domain tracer-dependent mass transfer properties that affected the breakthrough curves of bromide, pentafluorobenzoic acid (PFBA), and tritium. The tritium breakthrough curve showed stronger nonequilibrium behavior than did PFBA and bromide and required a larger immobile porosity to describe. The dual-domain mass transfer properties were then used to scale the kinetic model of U(VI) desorption developed for the fine-grained materials to describe U(VI) release and reactive transport in the field-textured sediment. Numerical simulations indicated that the kinetic model that was integrated with the dual-domain properties determined from tracer PFBA and Br best described the experimental results. The kinetic model without consideration of the dual-domain properties overpredicted effluent U(VI) concentrations, while the model based on tritium mass transfer underpredicted the rate of U(VI) release. Overall, our results indicated that the kinetics of U(VI) release from the field-textured sediment were different from that of its fine-grained U(VI)-associated mass fraction. However, the desorption kinetics measured on the U(VI)-containing mass fraction could be scaled to describe U(VI) reactive transport in the contaminated field-textured sediment after proper consideration of the physical transport properties of the sediment. The research also demonstrated a modeling approach to integrate geochemical processes into field-scale reactive transport models.

Enhanced Polymer Grafting From Multiwalled Carbon Nanotubes Through Living Anionic Surface-Initiated Polymerization, Georgios Sakellariou, Haining Ji, Jimmy W. Mays, Durairaj Baskaran

United States Department of Energy: Publications

Anionic surface-initiated polymerization of ethylene oxide and styrene has been performed using multiwalled carbon nanotubes (MWNTs) functionalized with anionic initiators. The surface of MWNTs was modified via covalent attachment of precursor anions such as 4-hydroxyethyl benzocyclobutene (BCBEO) and 1-benzocyclobutene-1′-phenylethylene (BCB-PE) through Diels-Alder cycloaddition at 235 °C. Surface-functionalized MWNTs-_g-(BCB-EO) _n and MWNTs-_g-(BCB-PE) _{n with 23 and 54 wt % precursor initiators, respectively, were used for the polymerizations. Alkoxide anion on the surface of MWNTs-g-(BCB-EO) n was generated through reaction with potassium triphenylmethane for the polymerization of ethylene oxide in tetrahydrofuran and phenyl substituted alkyllithium was …}

Generic Simulation Models For Facilitating Stakeholder Involvement In Water Resources Planning And Management: A Comparison, Evaluation, And Identification Of Future Needs, H. Assata, E. Van Beek, C. Borden, P. Gijsbers, A. Jolma, S. Kaden, M. Kaltofen, J.W. Labadie, D.P. Loucks, N.W.T. Quinn, J. Sieber, A. Sulis, W.J. Werick, D.M. Wood

United States Department of Energy: Publications

Water resources planning and management tools have been moving away from a top down (command and control) approach to a bottom up (grass-roots) approach - which emphasizes the involvement of stakeholders, not only specialists, in all stages of planning - from the identification of problems and issues, the selection of potential solutions to project implementation and operation. Ideally, a participatory grassroots planning process should provide a transparent and flexible platform for all stakeholders to collectively: examine the main elements of their shared water system; understand the main issues and problems to be addressed; participate in identifying alternative policies; and select …

Advective Removal Of Intraparticle Uranium From Contaminated Vadose Zone Sediments, Hanford, U.S., Eugene Ilton, Nikolla P. Qafoku, Chongxuan Liu, Dean Moore, John M. Zachara

United States Department of Energy: Publications

A column study on U(VI)-contaminated vadose zone sediments from the Hanford Site, WA, was performed to investigate U(VI) release kinetics with water advection and variable geochemical conditions. The sediments were collected from an area adjacent to and below tank BX-102 that was contaminated as a result of a radioactive tank waste overfill event. The primary reservoir for U(VI) in the sediments are micro-meter size precipitates composed of nanocrystallite aggregates of a Na- U-Silicate phase, most likely Na-boltwoodite, that nucleated and grew within microfractures of the plagioclase component of sand-sized granitic clasts. Two sediment samples, with different U(VI) concentrations and intra-particle …

Direct Involvement Of Type Ii Secretion System In Extracellular Translocation Of Shewanella Oneidensis Outer Membrane Cytochromes Mtrc And Omca, Liang Shi, Shuang Deng, Matthew Marshall, Zheming Wang, David Kennedy, Alice Dohnalkova, Heather Mottaz, Eric Hill, Yuri Gorby, Alexander Beliaev, David Richardson, John M. Zachara, James K. Fredrickson

United States Department of Energy: Publications

MtrC and OmcA are cell surface-exposed lipoproteins important for reducing solid metal oxides. Deletions of type II secretion system (T2SS) genes reduced their extracellular release and their accessibility to the proteinase K treatment, demonstrating the direct involvement of T2SS in translocation of MtrC and OmcA to the bacterial cell surface.

Economic Benefits, Carbon Dioxide (Co2) Emissions Reductions, And Water Conservation Benefits From 1,000 Megawatts (Mw) Of New Wind Power In Nebraska, Eric Lantz, Suzanne Tegen

United States Department of Energy: Publications

Wind power is one of the fastest-growing forms of new power generation in the United States. Industry growth in 2007 was an astounding 45%. New wind power installations constituted 35% of all new electric power installations. This growth is the result of many drivers, includ¬ing increased economic competitiveness and favorable state policies such as Renewable Portfolio Standards. However, new wind power installations provide more than cost-competitive electricity. Wind power brings economic development to rural regions, reduces water consumption in the electric power sector, and reduces greenhouse gas production by displacing fossil fuels.
The U.S. Department of Energy’s Wind Powering America …

A Site-Wide Perspective On Uranium Geochemistry At The Hanford Site, John M. Zachara, C. Brown, J. Christensen, J.A. Davis, E. Dresel, Chongxuan Liu, S. Kelly, James Mckinley, J. Serne, W. Um

United States Department of Energy: Publications

Uranium (U) is an important risk-driving contaminant at the Hanford Site. Over 200,000 kg have been released to the vadose zone over the course of site operations, and a number of vadose zone and groundwater plumes containing the uranyl cation [UO₂²⁺, U(VI)] have been identified. U is recognized to be of moderate-to-high mobility, conditions dependent. The site is currently making decisions on several of these plumes with long-lasting implications, and others are soon to come.

Uranium is one of nature’s most intriguing and chemically complex elements. The fate and transport of U(VI) has been studied over the …

Global-Change Scenarios: Their Development And Use, Edward Parson, Virginia Burkett, Karen Fisher-Vanden, David Keith, Linda Mearns, Hugh Pitcher, Cynthia Rosenzweig, Mort Webster

United States Department of Energy: Publications

A scenario is a description of potential future conditions produced to inform decision-making under uncertainty. Scenarios can help inform decisions that involve high stakes and poorly characterized uncertainty, which may thwart other, conventional forms of analysis or decision support. Originally developed to study military and security problems, scenarios are now widely used for strategic planning and assessment in businesses and other organizations, and increasingly to inform planning, analysis, and decision-making for environmental issues, including climate change.
Scenarios can serve many purposes. They can help inform specific decisions, or can provide inputs to assessments, models, or other decision-support activities when these …

Scenarios Of Greenhouse Gas Emissions And Atmospheric Concentrations, Leon Clarke, James Edmonds, Henry Jacoby, Hugh Pitcher, John Reilly, Richard Richels

United States Department of Energy: Publications

This and a companion report constitute one of twenty-one Synthesis and Assessment Products called for in the Strategic Plan for the U.S. Climate Change Science Program. These studies are structured to provide high-level, integrated research results on important science issues with a particular focus on questions raised by decision-makers on dimensions of climate change directly relevant to the U.S. One element of the CCSP’s strategic vision is to provide decision support tools for differentiating and evaluating response strategies. Scenario-based analysis is one such tool. The scenarios in this report explore the implications of alternative stabilization levels of anthropogenic greenhouse …

Oxygenated Interface On Biomass Burn Tar Balls Determined By Single Particle Scanning Transmission X-Ray Microscopy, Alexei V. Tivanski, Rebecca J. Hopkins, Tolek Tyliszczak, Mary K. Gilles

United States Department of Energy: Publications

Carbonaceous particles originating from biomass burning can account for a large fraction of organic aerosols in a local environment. Presently, their composition, physical and chemical properties, as well as their environmental effects are largely unknown. Tar balls, a distinct type of highly spherical carbonaceous biomass burn particles, have been observed in a number of field campaigns. The Yosemite Aerosol Characterization Study that took place in summer 2002 occurred during an active fire season in the western United States; tar balls collected during this field campaign are described in this article. Scanning transmission X-ray microscopy and near-edge X-ray absorption fine structure …

Controlled Covalent Functionalization Of Multiwalled Carbon Nanotubes Using [4 + 2] Cycloaddition Of Benzocyclobutenes, Georgios Sakellariou, Haining Ji, Jimmy W. Mays, Nikos Hadjichristidis, Durairaj Baskaran

United States Department of Energy: Publications

Surface modification of carbon nanotubes (CNTs) through covalent functionalization is vital for the development of high-performance composite materials, chemosensors, nanoelectronics, photovoltaic devices, as well as for a range of biomedical applications. Several methods have been developed to functionalize CNTs. The introduction of acid groups by acid digestion disrupts the structural integrity of CNTs. Apart from shortening the tubes, oxidatively generated acid groups are inhomogenously located at the tips of broken CNTs and, hence, functionalization using acid groups as precursors does not give a statistical distribution of functional groups throughout the surface of the CNTs.

Controlled Covalent Functionalization Of Multiwalled Carbon Nanotubes Using [4 + 2] Cycloaddition Of Benzocyclobutenes, Georgios Sakellariou, Haining Ji, Jimmy W. Mays, Nikos Hadjichristidis, Durairaj Baskaran

United States Department of Energy: Publications

Surface modification of carbon nanotubes (CNTs) through covalent functionalization is vital for the development of high-performance composite materials, chemosensors, nanoelectronics, photovoltaic devices, as well as for a range of biomedical applications. Several methods have been developed to functionalize CNTs. The introduction of acid groups by acid digestion disrupts the structural integrity of CNTs. Apart from shortening the tubes, oxidatively generated acid groups are inhomogenously located at the tips of broken CNTs and, hence, functionalization using acid groups as precursors does not give a statistical distribution of functional groups throughout the surface of the CNTs.

Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight Mass Spectrometry Characterization Of Primary Amine End-Functionalized Polystyrene And Poly(Methyl Methacrylate) Synthesized By Living Anionic Polymerization Techniques, Haining Ji, Georgios Sakellariou, Jimmy W. Mays

United States Department of Energy: Publications

The reaction of living anionic polymers with 2,2,5,5-tetramethyl-1-(3-bromopropyl)-1-aza-2,5- disilacyclopentane (1) was investigated using coupled thin layer chromatography and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Structures of byproducts as well as the major product were determined. The anionic initiator having a protected primary amine functional group, 2,2,5,5-tetramethyl- 1-(3-lithiopropyl)-1-aza-2,5-disilacyclopentane (2), was synthesized using all-glass high-vacuum techniques, which allows the long-term stability of this initiator to be maintained. The use of 2 in the preparation of well-defined aliphatic primary amine R-end-functionalized polystyrene and poly(methyl methacrylate) was investigated. Primary amino R-end-functionalized poly(methyl methacrylate) can be obtained near-quantitatively by reacting 2 with 1,1-diphenylethylene in tetrahydrofuran …

Peridynamic States And Constitutive Modeling, S. A. Silling, M. Epton, O. Weckner, J. Xu, E. Askari

United States Department of Energy: Publications

A generalization of the original peridynamic framework for solid mechanics is proposed. This generalization permits the response of a material at a point to depend collectively on the deformation of all bonds connected to the point. This extends the types of material response that can be reproduced by peridynamic theory to include an explicit dependence on such collectively determined quantities as volume change or shear angle. To accomplish this generalization, a mathematical object called a deformation state is defined, a function that maps any bond onto its image under the deformation. A similar object called a force state is defined, …

Efficiency Of Gene Silencing In Arabidopsis: Direct Inverted Repeats Vs. Transitive Rnai Vectors, Sergei A. Filichkin, Stephen P. Difazio, Amy M. Brunner, John M. Davis, Zamin K. Yang, Udaya C. Kalluri, Renee S. Arias, Elizabeth Etherington, Gerald A. Tuskan, Steven H. Strauss

United States Department of Energy: Publications

We investigated the efficiency of RNA interference (RNAi) in Arabidopsis using transitive and homologous inverted repeat (hIR) vectors. hIR constructs carry self-complementary intron-spliced fragments of the target gene whereas transitive vectors have the target sequence fragment adjacent to an intron-spliced, inverted repeat of heterologous origin. Both transitive and hIR constructs facilitated specific and heritable silencing in the three genes studied (AP1 , ETTIN and TTG1 ). Both types of vectors produced a phenotypic series that phenocopied reduction of function mutants for the respective target gene. The hIR yielded up to fourfold higher proportions of events with strongly manifested reduction …

Phosphate Imposed Limitations On Biological Reduction And Alteration Of Ferrihydrite, Thomas Borch, Yoko Masue, Ravi K. Kukkadapu, Scott Fendorf

United States Department of Energy: Publications

Biogeochemical transformation (inclusive of dissolution) of iron (hydr)oxides resulting from dissimilatory reduction has a pronounced impact on the fate and transport of nutrients and contaminants in subsurface environments. Despite the reactivity noted for pristine (unreacted) minerals, iron (hydr)oxides within native environments will likely have a different reactivity owing in part to changes in surface composition. Accordingly, here we explore the impact of surface modifications induced by phosphate adsorption on ferrihydrite reduction by Shewanella putrefaciens under static and advective flow conditions. Alterations in surface reactivity induced by phosphate changes the extent, decreasing Fe(III) reduction nearly linearly with increasing P surface coverage, …

Reduction Of Pertechnetate [Tc(Vii)] By Aqueous Fe(Ii) And The Nature Of Solid Phase Redox Products, John M. Zachara, Steve M. Heald, Byong-Hun Jeon, Ravi K. Kukkadapu, Chongxuan Liu, James P. Mckinley, Alice C. Dohnalkova, Dean A. Moore

United States Department of Energy: Publications

The subsurface behaviour of ⁹⁹Tc, a contaminant resulting from nuclear fuels reprocessing, is dependent on its valence (e.g., IV or VII). Abiotic reduction of soluble Tc(VII) by Fe(II)_(aq) in pH 6–8 solutions was investigated under strictly anoxic conditions using an oxygen trap (<7.5 · 10^-9 atm O₂). The reduction kinetics were strongly pH dependent. Complete and rapid reduction of Tc(VII) to a precipitated Fe/Tc(IV) form was observed when 11 µmol/L of Tc(VII) was reacted with 0.4 mmol/L Fe(II) at pH 7.0 and 8.0, while no significant reduction was observed over 1 month at pH 6.0. Experiments conducted …

Biostimulation Of Iron Reduction And Subsequent Oxidation Of Sediment Containing Fe-Silicates And Fe-Oxides: Effect Of Redox Cycling On Fe(Iii) Bioreduction, John Komlos, Ravi K. Kukkadapu, John M. Zachara, Peter R. Jaffe

United States Department of Energy: Publications

Sediment containing a mixture of iron (Fe)-phases, including Fe-oxides (mostly Al-goethite) and Fe-silicates (illites and vermiculite) was bioreduced in a long-term flow through column experiment followed by re-oxidation with dissolved oxygen. The objective of this study was (a) to determine the nature of the re-oxidized Fe(III), and (b) to determine how redox cycling of Fe would affect subsequent Fe(III)-bioavailability. In addition, the effect of Mn on Fe(III) reduction was explored.⁵⁷Fe-Mössbauer spectroscopy measurements showed that biostimulation resulted in partial reduction (20%) of silicate Fe(III) to silicate Fe(II) while the reduction of goethite was negligible. Furthermore, the reduction of Fe …

Influence Of Calcium On Microbial Reduction Of Solid Phase Uranium(Vi), Chongxuan Liu, Byong-Hun Jeon, John M. Zachara, Zheming Wang

United States Department of Energy: Publications

The effect of calcium on the dissolution and microbial reduction of a representative solid phase uranyl [U(VI)], sodium boltwoodite (NaUO₂SiO₃OH •1.5H₂O), was investigated to evaluate the rate-limiting step of microbial reduction of the solid phase U(VI). Microbial reduction experiments were performed in a culture of a dissimilatory metal-reducing bacterium (DMRB), Shewanella oneidensis strain MR-1, in a bicarbonate medium with lactate as electron donor at pH 6.8 buffered with PIPES. Calcium increased the rate of Na-boltwoodite dissolution and U(VI) bioavailability by increasing its solubility through the formation of a ternary aqueous calcium-uranyl-carbonate species. The ternary …

Spectroscopic Evidence For Uranium Bearing Precipitates In Vadose Zone Sediments At The Hanford 300-Area Site, Yuji Arai, M. A. Marcus, N. Tamura, J. A. Davis, John M. Zachara

United States Department of Energy: Publications

Uranium (U) solid-state speciation in vadose zone sediments collected beneath the former North Process Pond (NPP) in the 300 Area of the Hanford site (Washington) was investigated using multi-scale techniques. In 30 day batch experiments, only a small fraction of total U (~7.4%) was released to artificial groundwater solutions equilibrated with1% pCO₂. Synchrotron-based micro-X-ray fluorescence spectroscopy analyses showed that U was distributed among at least two types of species: (i) U discrete grains associated with Cu and (ii) areas with intermediate U concentrations on grains and grain coatings. Metatorbernite (Cu[UO₂]₂[PO₄]₂•8H …

Cation Exchange Reactions Controlling Desorption Of 90sr2+ From Coarse-Grained Contaminated Sediments At The Hanford Site, Washington, James Mckinley, John M. Zachara, Steven Smith, Chongxuan Liu

United States Department of Energy: Publications

Nuclear waste that bore ⁹⁰Sr²⁺ was accidentally leaked into the vadose zone at the Hanford site, and was immobilized at relatively shallow depths in sediments containing little apparent clay or silt-sized components. Sr²⁺, ⁹⁰Sr²⁺, Mg2+, and Ca²⁺ was desorbed and total inorganic carbon concentration was monitored during the equilibration of this sediment with varying concentrations of Na⁺, Ca²⁺. A cation exchange model previously developed for similar sediments was applied to these results as a predictor of final solution compositions. The model included binary exchange reactions for the four …

Geochemical Processes Controlling Migration Of Tank Wastes In Hanford’S Vadose Zone, John M. Zachara, Jeff Serne, Mark Freshley, Fred Mann, Frank Anderson, Marcus Wood, Tom Jones, Dave Myers

United States Department of Energy: Publications

Nuclear wastes from Hanford’s processing for separation of plutonium are stored in massive, buried, single-shell tanks in 18 tank farms. These so-called tank wastes were initially thermally hot because of radioactive decay, and many exhibited extreme chemical character in terms of pH, salinity, and radionuclide concentration. At present, 67 of the 149 single shell tanks are suspected to have released over 1.9 million L of tank waste to the vadose zone, with most leak events occurring between 1950 and 1975. Boreholes have been placed through the largest vadose zone plumes to define the extent of contaminant migration and to develop …

Generation Of Electron Bunches At Low Repetition Rates Using A Beat-Frequency Technique, M. Poelker, J. Grames, J. Hansknecht, R. Kazimi, J. Musson

United States Department of Energy: Publications

Even at a continuous wave facility such as CEBAF at Jefferson Lab, an electron beam with long time intervals (tens of ns) between individual bunches can be useful, for example, to isolate sources of background via time of flight detection or to measure the energy of neutral particles that cannot be separated with a magnetic field. This paper describes a demonstrated method to quickly and easily deliver bunches with repetition rates of 20 to 100 MHz corresponding to time intervals between 50 and 10 ns (respectively). This is accomplished by changing the ON/OFF frequency of the photogun drive laser by …