Bioresource and Agricultural Engineering Commons^™

Simultaneous Observations Of Mesospheric Gravity Waves And Sprites Generated By A Midwestern Thunderstorm, D.D. Sentman, E.M. Wescott, R.H. Picard, J.R. Winick, H.C. Stenbaek-Nielsen, E.M. Dewan, D.R. Moudry, F.T. São Sabbas, M.J. Heavner, J. Morrill

United States Department of Energy: Publications

The present report investigates using simultaneous observations of coincident gravity waves and sprites to establish an upper limit on sprite-associated thermal energy deposition in the mesosphere. The University of Alaska operated a variety of optical imagers and photometers at two ground sites in support of the NASA Sprites99 balloon campaign. One site was atop a US Forest Service lookout tower on Bear Mt. in the Black Hills, in western South Dakota. On the night of 18 August 1999 we obtained from this site simultaneous images of sprites and OH airglow modulated by gravity waves emanating from a very active sprite …

Global Optical Lightning Flash Rates Determined With The Forte Satellite, Tracy E. Light, Sean M. Davis, William Boeck, Abram Jacobson, David Suszcynsky

United States Department of Energy: Publications

Using FORTE photodiode detector (PDD) observations of lightning, we have determined the geographic distribution of nighttime flash rate density. We estimate the PDD flash detection efficiency to be 62% for total lightning through comparison to lightning observations by the TRMM satellite's Lightning Imaging Sensor (LIS), using cases in which FORTE and TRMM viewed the same storm. We present here both seasonal and total flash rate maps. We examine some characteristics of the optical emissions of lightning in both high and low flash rate environments, and find that while lightning occurs less frequently over ocean, oceanic lightning flashes are somewhat more …

Transformation Of 2-Line Ferrihydrite To 6-Line Ferrihydrite Under Oxic And Anoxic Conditions, Ravi K. Kukkadapu, John M. Zachara, James K. Fredrickson, Steven C. Smith, Alice C. Dohnalkova, Colleen K. Russel

United States Department of Energy: Publications

Mineralogical transformations of 2-line ferrihydrite were studied under oxic and Fe³⁺-reducing conditions to establish the role, if any, of 6-line ferrihydrite (“well” organized ferrihydrite) in the reaction pathway and as a final product. In oxic experiments, concentrated suspensions (0.42 mol/L Fe³⁺ in 0.1 mol/L NaClO₄) of freshly synthesized 2-line ferrihydrite, with and without 3% Ni2+, were aged at an initial pH = 7.2 (unbuffered and unadjusted) and 25°C for more than three years. X-ray diffraction, transmission electron microscopy, and Mössbauer spectroscopy measurements were performed on the solids after different aging periods. The primary mineralogical products …

Microbial Reduction Of Structural Fe(Iii) In Illite And Goethite, Hailiang Dong, Ravi K. Kukkadapu, James K. Fredrickson, John M. Zachara, David W. Kennedy, Heather M. Kostandarithes

United States Department of Energy: Publications

Microbial reduction of Fe(III) in illite was studied to evaluate the possibility of microbial utilization of Fe(III) in sedimentary clays and to determine the effects of bioreduction on clay composition and structure. A subsurface bacterium (Shewanella putrefaciens CN32) and illite separates (

Mossbauer And Optical Spectroscopic Study Of Temperature And Redox Effects On Iron Local Environments In A Fe-Doped (0.5 Mol% Fe2o3)18na2o–72sio2 Glass, Ravi K. Kukkadapu, Hong Li, Gary L. Smith, J.D. Crum, Jun-Sik Jeoung, W. Howard Poisl, Michael C. Weinberg

United States Department of Energy: Publications

Local environments of ferric and ferrous irons were systematically studied with Mössbauer (at liquid helium temperature)and ultraviolet–visible–near infrared spectroscopic methods for various 18Na₂O–72SiO₂ glasses doped with 0.5 mol% Fe₂O₃. These were prepared at temperatures of 1300–1600 °C in ambient air or at 1500 °C under reducing conditions with oxygen partial pressures from 12.3 to 0.27 x 10^-7 atmospheres. The Mössbauer spectroscopic method identified three types of local environments, which were represented by the Fe³⁺ sextet, the Fe³⁺ doublet, and the Fe²⁺ doublet. The Fe³⁺ sextet ions were assigned …

Influence Of Electron Donor/Acceptor Concentrations On Hydrous Ferric Oxide (Hfo) Bioreduction, James K. Fredrickson, Sreenivas Kota, Ravi K. Kukkadapu, Chongxuan Liu, John M. Zachara

United States Department of Energy: Publications

Dissimilatory metal-reducing bacteria (DMRB) facilitate the reduction of Fe and Mn oxides in anoxic soils and sediments and play an important role in the cycling of these metals and other elements such as carbon in aqueous environments. Previous studies investigating the reduction of Fe(III) oxides by DMRB focused on reactions under constant initial electron donor (lactate) and electron acceptor (Fe oxide) concentrations. Because the concentrations of these reactants can vary greatly in the environment and would be expected to influence the rate and extent of oxide reduction, the influence of variable electron acceptor and donor concentrations on hydrous ferric oxide …

Effect Of Temperature On Cs+ Sorption And Desorption In Subsurface Sediments At The Hanford Site, U.S.A., Chongxuan Liu, John M. Zachara, Odeta Qafoku, Steve Smith

United States Department of Energy: Publications

The effects of temperature on Cs⁺ sorption and desorption were investigated in subsurface sediments from the U.S. Department of Energy Hanford Site. The site has been contaminated at several locations by the accidental leakage of high-level nuclear waste (HLW) containing ¹³⁷Cs⁺. The high temperature of the self-boiling, leaked HLW fluid and the continuous decay of various radionuclides carried by the waste supernatant have resulted in elevated vadose temperatures (currently up to 72 °C) below the Hanford S-SX tank farm that have dissipated slowly from the time of leakage (1970). The effect of temperature on Cs^{+ …}

Nonlocal Bacterial Electron Transfer To Hematite Surfaces, Kevin Rosso, John M. Zachara, James K. Fredrickson, Yuri Gorby, Steven Smith

United States Department of Energy: Publications

Mechanisms by which dissimilatory iron-reducing bacteria utilize iron and manganese oxide minerals as terminal electron acceptors for respiration are poorly understood. In the absence of exogenous electron shuttle compounds, extracellular electron transfer is generally thought to occur through the interfacial contact area between mineral surfaces and attached cells. Possible alternative reduction pathways have been proposed based on the discovery of a link between an excreted quinone and dissimilatory reduction. In this study, we utilize a novel experimental approach to demonstrate that Shewanella putrefaciens reduces the surface of crystalline iron oxides at spatial locations that are distinct from points of attachment.

Transport Of Multiple Tracers In Variably Saturated Humid Region Structured Soils And Semi-Arid Region Laminated Sediments, M.A. Mayes, P.M. Jardine, T.L. Mehlhorn, B.N. Bjornstad, J.L. Ladd, John M. Zachara

United States Department of Energy: Publications

The processes governing physical nonequilibrium (PNE)—coupled preferential flow and matrix diffusion—are diverse between humid and semi-arid regions, and are directly related to climate and rock/sediment type, and indirectly related to subsequent soil profile development. The fate and transport of contaminants in these variably saturated undisturbed media is largely a function of the influence of PNE processes. Large cores of laminated silts and sands were collected from the US Department of Energy Pacific Northwest National Laboratory (PNNL) in semi-arid south central Washington. Additional cores of weathered, fractured interbedded limestone and shale saprolite were collected from the Oak Ridge National Laboratory (ORNL) …

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 …

A Portable Eddy Covariance System For The Measurement Of Ecosystem–Atmosphere Exchange Of Co2, Water Vapor, And Energy, Dave P. Billesbach, M.L. Fischer, Margaret S. Torn, J.A. Berry

Department of Agricultural and Biological Systems Engineering: Faculty Publications

To facilitate the study of flux heterogeneity within a region, the authors have designed and field-tested a portable eddy covariance system to measure exchange of CO2, water vapor, and energy between the land surface and the atmosphere. The combination of instrumentation used in this system allows high precision flux measurements without requiring on-site infrastructure such as prepositioned towers or line power. In addition, the system contains sensors to measure a suit of soil, climatic, and energy-related parameters that are needed to quality control the fluxes and to characterize the flux footprint. The physical design and instrument packaging used in the …

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 …

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 …

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 …

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 …

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 (UO_2,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 …

Auger Timing Effects On Performance Of A Combine Unloading System, Todd Philip Cole

Open Access Master's Theses (through 2010)

Performance effects were measured on a combine unloading system using three different auger timing settings.Performance measures included maximum startup torque, mean operating torque, standard deviation of the operating torque, flow rate of grain through the system, and mechanical damage to the grain.The performance effects were measured with the system unloading corn and soybeans.

The data were statistically analyzed to check for interactions between the grains and differences between the timings.Using an alpha value of 0.1 it was found that timing 1 for both grains had a 3% (<2.4 L/s) higher flow rate over timings 2 and 3.Timings 1 and 2 for both grains had higher maximum startup torque, about 10% (60 N·m) more torque required than timing 3.In soybeans, timings 2 and 3 also had the smallest standard deviation in operating torque, about 30% (20 N·m) less than timing 1.We were unable to detect any differences in mechanical damage to corn or soybeans as a result of unloading auger timing.These findings suggest that timing 3, with the cross augers lagging 90° behind the vertical unloading auger, may require less maximum startup torque and less variation in torque for the cross augers to effectively fill the loosely filled space left after the vertical auger lifts the grain without extra torque effects of having the augers push against each other as they do in timing 1.

Advisor: Michael F. Kocher

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 …

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-MnO_2(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-MnO_2(s) and the abiotic redox reaction between β-MnO_2(s) and biogenic uraninite (UO_2(s)) were independently investigated to allow for interpretation of studies of U(VI) bioreduction in the presence of β-MnO_2(s). Uranyl bioreduction to UO_2(s) by CN32 with H2 as the electron donor followed Monod kinetics, with a maximum specific reduction rate of 110 µM/h/10 …

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 …

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 …

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 …

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 …

Ft-Nir Spectroscopic Analysis Of Nitrogen In Cotton Leaves, Mark R. Riley, Loreto C. Canaves

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Near-infrared spectroscopy was evaluated as a means to quantify the nitrogen content- in fresh cotton leaves (Gossypium hirsutum L. var. Delta Pine 90) subjected to a factorial design experiment of varying nitrogen and water applications. Absorbance spectra were collected in the 10000-4000 cm^-1 (1000-2500 nm) region from fresh cotton leaves over a two month portion of the growing season. Total nitrogen content was quantified by a wet chemistry Kjeldahl method for validation purposes. Partial least-squares regression analysis, using an automated grid search method, selected the spectral region 6041 to 5651 cm^-1 (1650-1770 nm) for analysis based on having …

Production Of Microcrystalline Cellulose By Reactive Extrusion, Milford Hanna, Gerald Biby, Vesselin Miladinov

Industrial Agricultural Products Center: Publications and Information

This process involves feeding cellulose into an extruder with an acid solution. The extruder is comprised of a screw and a barrel. The screw is rotated so as to pressurize the cellulose, and the cellulose undergoes acid hydrolysis and forms microcrystalline cellulose. The invented process can be accomplished by using pure cellulose or a lignocellulosic material as the starting material. If a lignocellulosic material is used, then a basic solution is added to it and the lignocellulosic material is fed through an extruder so as to obtain a mixture comprising lignin, hemicellulose and cellulose. The lignin and hemicellulose are extracted …

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 …

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.; …

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 …

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 …

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 …