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Construction of bending magnet beamline at the APS for environmental studies. Progress report, September 1996--September 1997

Description: 'The items that were accomplished during this period are: (1) preparation and submission of the preliminary design report for the bending magnet beamline; (2) construction of the first optical enclosure (FOE) hutch for the BM beamline and ordering of the installation of utilities, in addition to the FOE hutch, the authors have started construction on the experimental hutch, although this is being supported by other funds; (3) the package has been ordered for the shutter assembly and monochromator for the bending magnet beamline, consisting of the monochromator, white beam stop, and bremstrahlung stop, all integrated on a table; (4) the beamline scientist for the bending magnet has been hired and is active on design and construction activities. In summary, the construction of the bending magnet beamline is proceeding as scheduled. The authors have obtained additional funding necessary to complete construction of the beamline and, according to the estimates, this additional funding plus the funding from the EMSP grant should allow us to complete construction of the bending magnet beamline during the three-year tenure of this grant.'
Date: January 1, 1997
Creator: Stern, E. A.
Partner: UNT Libraries Government Documents Department
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Optimization of Thermochemical, Kinetic, and Electrochemical Factors Governing Partitioning of Radionuclides During Melt Decontamination of Radioactively Contaminated Stainless Steel. 1998 Annual Progress Report

Description: 'Melt decontamination of radioactive scrap metal could convert a disposal liability into a final product that would reduce the total volume of material necessary for burial and save substantial material costs. The goal of this project is to optimize a melt decontamination process through a basic understanding of the factors which govern the partitioning of various radionuclides between metal, slag, and gas phases. Radionuclides which are captured by a slag phase may be stabilized by promoting the formation of synthetic minerals within a leach resistant matrix. The main focus of this project is the application of electroslag remelting (ESR) toward cleanup of surface contaminated stainless steels. This report summarizes work accomplished after 9-months of a 3-year project. Activities are ongoing at Sandia National Laboratories and at Boston University.'
Date: June 1998
Creator: Van den Avyle, J. A.
Partner: UNT Libraries Government Documents Department
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Peptide Based Radiopharmaceuticals: Specific Construct Approach

Description: The objective of this project was to develop receptor based peptides for diagnostic imaging and therapy. A series of peptides related to cell adhesion molecules (CAM) and immune regulation were designed for radiolabeling with <sup>99m</sup>Tc and evaluated in animal models as potential diagnostic imaging agents for various disease conditions such as thrombus (clot), acute kidney failure, and inflection/inflammation imaging. The peptides for this project were designed by the industrial partner, Palatin Technologies, (formerly Rhomed, Inc.) using various peptide design approaches including a newly developed rational computer assisted drug design (CADD) approach termed MIDAS (Metal ion Induced Distinctive Array of Structures). In this approach, the biological function domain and the <sup>99m</sup>Tc complexing domain are fused together so that structurally these domains are indistinguishable. This approach allows construction of conformationally rigid metallo-peptide molecules (similar to cyclic peptides) that are metabolically stable in-vivo. All the newly designed peptides were screened in various in vitro receptor binding and functional assays to identify a lead compound. The lead compounds were formulated in a one-step <sup>99m</sup>Tc labeling kit form which were studied by BNL for detailed in-vivo imaging using various animals models of human disease. Two main peptides usingMIDAS approach evolved and were investigated: RGD peptide for acute renal failure and an immunomodulatory peptide derived from tuftsin (RMT-1) for infection/inflammation imaging. Various RGD based metallopeptides were designed, synthesized and assayed for their efficacy in inhibiting ADP-induced human platelet aggregation. Most of these peptides displayed biological activity in the 1-100 µM range. Based on previous work by others, RGD-I and RGD-II were evaluated in animal models of acute renal failure. These earlier studies showed that after acute ischemic injury the renal cortex displays RGD receptor with higher density. The results have indicated good diagnostic potential for their use in this clinical situation, as an imaging agent to …
Date: October 21, 1997
Creator: Som, P.; Rhodes, B. A. & Sharma, S. S.
Partner: UNT Libraries Government Documents Department
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In-situ spectro-electrochemical studies of radionuclide contaminated surface films on metals and the mechanism of their formation and dissolution. 1998 annual progress report

Description: 'The objective of this research program is to gain a fundamental understanding of the structure, composition, and mechanism of formation of radionuclide-containing surface films on metals that are relevant to the problem of decontamination of piping systems and waste storage tanks at DOE nuclear processing facilities. As of May 1998, after about a year and a half of work towards implementing this project, considerable progress has been made in understanding the mechanism and structure of heavy metal ions incorporated into simulated corrosion films of nickel. The nature of iron and chromium oxide films, which are used to model the other components of steels used in piping systems and waste storage tanks in nuclear facilities, has also been elucidated. The principal techniques used in these investigations consist of coupled electrochemical and in-situ synchrotron X-ray absorption spectroscopy, as well as vibrational spectroscopy (infrared and laser Raman).'
Date: June 1, 1998
Creator: Melendres, C.A. & Mini, S.M.
Partner: UNT Libraries Government Documents Department
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In-Situ Spectroelectrochemical Studies of Radionuclide Contaminated Surface Films on Metals and the Mechanism of Their Formation and Dissolution. 1997 Annual Progress Report

Description: 'The incorporation of radioactive contaminants into corrosion product scales on metals is being investigated using in-situ spectroscopic and electrochemical techniques. To facilitate the study, stable isotopes are used initially, while the corrosion films are simulated by electrodeposition of the appropriate oxide (hydroxide) onto a graphite substrate. Synchrotron x-ray absorption spectroscopy (XAS) is used to determine the structure and composition of the host oxide film, as well as the local structure of the impurity ion. Results on the incorporation of Sr and Ce into surface films of Ni(OH){sub 2} and NiOOH are reported. Cathodically deposited Ni(OH){sub 2} was found to be mainly in the {alpha} form while anodically prepared NiOOH consists of Ni{sup +2} and Ni{sup +4} phases. Sr in the films consists mainly of Sr{sup 2+} which appears to be coordinated to oxygen atoms and is likely to exist as small domains of co-precipitated material. Ce in Ni(OH){sub 2} exists mainly as Ce{sup +3} and as a Ce{sup +4} species when co-deposited with NiOOH. The structure of the Ce{sup +4} phase appears similar to a Ce(OH){sub 4} standard. However, x-ray diffraction and laser Raman measurements indicate that the latter chemical formulation is probably incorrect and that the material is more likely to be a disordered hydrous cerium oxide. Ce chemisorbed on Ni(OH){sub 2} and NiOOH films is predominantly in the +3 valency state. Iron oxide films prepared by anodic deposition from borate buffer solution containing Fe{sup +2}, has been found by XAS to consist mainly of {alpha} FeOOH. The latter has been found by others to be the constituent of the corrosion film on iron; this lends credence to the present simulation approach. Future work will involve studies on the incorporation of radioactive Sr, Ce, and Cs, as well as U, into nickel and iron oxide films. Investigations on the …
Date: September 1, 1997
Creator: Melendres, C. A.; Balasubramanian, M.; Papapanayiotou, D.; Mini, S. & Mansour, A. N.
Partner: UNT Libraries Government Documents Department
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Atmospheric-pressure plasma cleaning of contaminated surfaces. 1998 annual progress report

Description: 'The object of this research program is to develop an atmospheric-pressure plasma jet for converting transuranic wastes (TRUs) into low-level radioactive wastes (LLWs). This plasma process will be used to efficiently decontaminate a wide range of structures and equipment. This report summarizes work after 1 year and 9 months of a 3-year project. A picture of the atmospheric-pressure plasma jet is shown in Fig. 1. This new plasma source consists of two concentric electrodes through which a mixture of helium and reactive gases flow. The plasma is ignited by applying 13.56 MHz RF power to the inner electrode. The characteristics of this discharge are different from other atmospheric-pressure plasmas, such as transferred arcs, torches, coronas and silent discharges. Shown in Fig. 2 is the current-voltage curve for the plasma jet. Spark breakdown occurs at 0.01 A, and is proceeded by a normal glow region, in which the voltage remains constant with increasing current, and an abnormal glow region, in which the voltage increases rapidly with current. At about 1.0 A and 225 V, the plasma begins to arc. The normal glow region is rarely observed in atmospheric pressure plasmas. They usually proceed directly from spark breakdown to arcing. The trend shown in the figure indicates that the plasma jet is stable over a wide range of operating conditions. The distribution of reactive species in a plasma jet, containing oxygen and helium, has been characterized by Langmuir probe measurements, optical emission spectroscopy, and ultraviolet absorption spectroscopy. The charged particle density ranges from about 5 x 10{sup 11} cm{sup -3} inside the plasma to 1 x 10{sup 10} cm{sup -3} in the jet exit. The concentration of metastable oxygen molecules (a 1 Dg and b 1 Sg{sup +} ) is estimated to be between 10{sup 12} to 10{sup 13} cm{sup -3} . …
Date: June 1, 1998
Creator: Hicks, R.F. & Selwyn, G.
Partner: UNT Libraries Government Documents Department
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Atmospheric pressure plasma cleaning of contamination surfaces. 1997 mid-year progress report

Description: 'Goals of the project are to (1) identify the key physics and chemistry underlying the use of high pressure plasmas for etching removal of actinides and actinide surrogates; and (2) identify key surface reactions and plasma physics necessary for optimization of the atmospheric pressure plasma jet. Technical description of the work decommissioning of transuranic waste (TRU) into low-level radioactive waste (LLW) represents the largest cleanup cost associated with the nuclear weapons complex. This work is directed towards developing a low-cost plasma technology capable of converting TRU into LLW, based upon highly selective plasma etching of plutonium and other actinides from contaminated surfaces. In this way, only the actinide material is removed, leaving the surface less contaminated. The plasma etches actinide material by producing a volatile halide compound, which may be efficiently trapped using filters. To achieve practical, low-cost operation of a plasma capable of etching actinide materials, the authors have developed a y-mode, resonant-cavity, atmospheric pressure plasma jet (APPJ). In contrast to conventional, low pressure plasmas, the APPJ produces a purely-chemical effluent free of ions, and so achieves very high selectivity and produces negligible damage to the surface. Since the jet operates outside a chamber, many nuclear wastes may be treated including machinery, duct-work, concrete and other building materials. In some cases, it may be necessary to first remove paint from contaminated surfaces using a plasma selective for that surface, then to switch to the actinide etching chemistry for removal of actinide contamination. The goal of this work is to develop the underlying science required for maturation of this technology and to establish early version engineering prototypes. Accomplishments to Date The authors have made significant progress in this program. The work conducted jointly at Los Alamos and at UCLA. This has been facilitated by exchange of people, equipment and designs …
Date: June 1, 1997
Creator: Selwyn, G.S. & Hicks, R.
Partner: UNT Libraries Government Documents Department
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Development and In Situ Characterization of New Electrolyte and Electrode materials for Rechargeable Lithium Batteries

Description: The object of this project is to develop new electrolyte and cathode materials for rechargeable lithium batteries, especially for lithium ion and lithium polymer batteries. Enhancing performance, reducing cost, and replacing toxic materials by environmentally benign materials, are strategic goals of DOE in lithium battery research. This proposed project will address these goals on two important material studies, namely the new electrolytes and new cathode materials. For the new electrolyte materials, aza based anion receptors as additives, organic lithium salts and plasticizers which have been developed by BNL team under Energy Research programs of DOE, will be evaluated by Gould for potential use in commercial battery cells. All of these three types of compounds are aimed to enhance the conductivity and lithium transference number of lithium battery electrolytes and reduce the use of toxic salts in these electrolytes. BNL group will be working closely with Gould to further develop these compounds for commercialization. For the cathode material studies, BNL efforts wi U be focused on developing new superior characterization methclds, especially in situ techniques utilize the unique user facility of DOE at BNL, namely the National Synchrotrons Light Source (NSLS). In situ x-ray absorption and x-ray diftlaction spectroscopy will be used to study the relationship between performance and the electronic and structural characteristics of intercalation compounds such as LiNi0<sub>2</sub>, LiCo0<sub>2</sub>, and LiMn<sub>2</sub>0<sub>4</sub> spinel. The study will be focused on LiMn<sub>2</sub>0<sub>4</sub> spinel materials. Gould team will contribute their expertise in choosing the most promising compounds, providing overall performance requirements, and will use the results of this study to guide their procedure for quality control. The knowledge gained through this project will not only benefit Gould and BNL, but will be very valuable to the scientific community in battery research.
Date: January 3, 2000
Creator: Yang, X -Q; Xing, X K & Daroux, M
Partner: UNT Libraries Government Documents Department
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The migration and entrapment of DNAPLs in physically and chemically heterogeneous porous media. 1998 annual progress report

Description: 'The migration and entrapment of dense nonaqueous phase liquids (DNAPLs) at hazardous waste sites is typically believed to be controlled by physical heterogeneities. This belief is based upon the assumption that permeability and capillary properties are determined by soil texture. These transport properties however, also depend on porous media wettability characteristics, which may vary spatially in a formation due to variations in aqueous phase chemistry, contaminant aging, and/or variations in mineralogy and organic matter distributions. The overall objective of this research is to investigate the influence of such coupled physical and chemical heterogeneities on the migration and entrapment of DNAPLs in the saturated zone. This research includes laboratory and numerical investigations for a matrix of organic contaminants and solid media encompassing a range of wettability characteristics. Specific objectives include: (1) quantification of system wettability and interfacial tensions; (2) determination of transport property relations; (3) two-dimensional infiltration experiments; (4) modification of a continuum based multiphase flow simulator to account for physical heterogeneity, saturation independent and saturation dependent wettability, and concentration dependent wettability and interfacial tension; and (5) utilization of this model to explore the potential influence of coupled physical and chemical heterogeneities on the migration of DNAPLs and the development of innovative remediation schemes. The accomplishment of the above research objectives will facilitate the characterization and remediation of contaminated field sites. This section summarizes research conducted towards the accomplishment of goals (1), (2), (4), and (5) during the first 1.5 years of this 3-year project. Goal (3) builds upon results from the other objectives and will be initiated in the coming year.'
Date: June 1, 1998
Creator: Abriola, L.M. & Demond, A.H.
Partner: UNT Libraries Government Documents Department
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Behavior of dense immiscible solvents in fractured clay-rich soils. Technical progress report, 1997

Description: 'The overall goal of the research program is to develop a better understanding of the physical and chemical factors and processes influencing fate and transport of immiscible and dissolved-phase dense solvents in groundwater in fractured, highly weathered clays and shales. These widespread materials are much different, physically and chemically, from granular soils or fractured low porosity rocks, which are the media used for most previous investigations of solvent behavior. The investigations are needed to provide a basic scientific framework for assessment of solvent transport and remediation in fractured clay-rich deposits. Specific experimental objectives include: (1) Determine the nature and distribution of porosity in these materials, and its influence on pressure-saturation behavior for immiscible solvents. This includes determining values for entry pressure, residual saturation, fracture aperture and matrix pore size distribution, as well as assessment of methodologies for measuring/characterizing these parameters. (2) Determine the influence of dissolution, sorption and diffusion into the matrix on long term disappearance of residual solvents in the fractured materials. (3) Assessment of the potential for natural attenuation of common solvents, especially TCE, in these deposits. This includes investigating the natural geochemistry and microbiology of the deposits, and assessing biologically-mediated degradation of solvents in the laboratory and at existing contaminated field sites.'
Date: October 13, 1997
Creator: McKay, L.D.
Partner: UNT Libraries Government Documents Department
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Stable isotopic investigations of in situ bioremediation of chlorinated organic solvents. 1997 annual progress report

Description: 'The author has made significant progress in developing innovative methods for investigating the mechanism and extent of in situ bioremediation of chlorinated organic solvents. These methods use precise isotopic ratio measurements of chlorine and carbon in reactant and product species in laboratory experiments and in materials from field demonstration sites. Specific tasks completed during FY 1997 include: (1) refinement and publication of a new analytical method for precise determination of chlorine and carbon isotope ratios in chlorinated volatile organic compounds; (2) laboratory experiments involving biological degradation of chlorinated solvents in liquid cultures and soil columns; and (3) use of chlorine and carbon isotope ratios to investigate natural attenuation of trichloroethene at the Paducah Gaseous Diffusion Plant. This work can have immediate impact because it will provide the fundamental basis for a new and cost-effective means of evaluating and monitoring the effectiveness of in situ bioremediation schemes for chlorinated organic solvents in soils, vadose horizons, and groundwater plumes.'
Date: January 1, 1997
Creator: Sturchio, N.C.
Partner: UNT Libraries Government Documents Department
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Reduction and immobilization of radionuclides and toxic metal ions using combined zero valent iron and anaerobic bacteria. 1998 annual progress report

Description: 'Previous research findings indicate that both zero valent iron and sulfate reducing bacteria (SRB) can yield significant decreases in Cr(VI) or U(VI) concentrations due to abiotic and microbial reduction, respectively. The major hypothesis associated with this research project is that a combined abiotic-biological system can synergistically combine both processes to maximize metal ion reduction in an engineered permeable reactive barrier. The overall goal of this project is to design a combined abiotic/microbial, reactive, permeable, in-situ barrier with sufficient reductive potential to prevent downgradient migration of toxic metal ions. The field-scale application of this technology would utilize anaerobic digester sludge, Fe(O) particles for supporting anaerobic biofilms, and suitable aquifer material for construction of the barrier. Successful completion of this goal requires testing of the two hypotheses listed above by evaluating: (1) the rates of abiotic metal ion reduction, and (2) the rates of microbial metal ion reduction in microbial and combined abiotic/microbial reduction systems under a range of environmental conditions. This report summarizes work after one and one-half years of a three year project. Abiotic studies: The thrust of the abiotic research conducted to date has been to determine the rates of Cr(VI) reduction in batch reactors and to evaluate the role of aquifer materials on those rates. Experiments have been conducted to determine the rates of reduction by Fe(II) and Fe(O). The parameters that have been evaluated are the effect of pH and the presence of sulfide and aquifer material.'
Date: June 1, 1998
Creator: Weathers, L.
Partner: UNT Libraries Government Documents Department
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In situ, field scale evaluation of surfactant enhanced DNAPL recovery using a single-well, push-pull test. 1998 annual progress report

Description: 'The overall goal of this project is to develop the single-well, push-pull test method as a new site characterization and feasibility assessment tool for studying the fundamental fate and transport behavior of injected surfactants and their ability to solubilize and mobilize dense nonaqueous phase liquids (DNAPLs) in the subsurface. The specific objectives are: (1) to develop a modified push-pull test for use in identifying and quantifying the effects of sorption, precipitation, and biodegradation on the fate and transport of injected surfactants, (2) to use the developed test method to quantify the effects of these processes on the ability of injected surfactants to solubilize and mobilize residual phase trichloroethylene, and (3) to demonstrate the utility of the developed test method for performing site characterization and feasibility studies for surfactant enhanced DNAPL recovery systems. This report summarizes work as of June 1, 1998 (after 20 months of a 36-month project); laboratory and field work as been successfully completed for all three objectives.'
Date: June 1, 1998
Creator: Istok, J.D.
Partner: UNT Libraries Government Documents Department
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Containment of toxic metals and radionuclides in porous and fractured media: Optimizing biogeochemical reduction versus geochemical oxidation. 1998 annual progress report

Description: 'The purpose of this research is to provide an improved understanding and predictive capability of the mechanisms that allow metal-reducing bacteria to be effective in the bioremediation of subsurface environments contaminated with toxic metals and radionuclides. The study is motivated by the likelihood that subsurface microbial activity can effectively alter the redox state of toxic metals and radionuclides so that they are immobilized for long time periods. The objectives are to: (1) develop an improved understanding of the rates and mechanisms of competing geochemical oxidation and microbiological reduction reactions that govern the fate and transport of redox-sensitive metals and radionuclides in the subsurface, and (2) quantify the conditions that optimize the microbial reduction of toxic metals and radionuclides, for the purpose of contaminant containment and remediation in heterogeneous systems that have competing geochemical oxidation, sorption, and organic ligands. The overall goal of this project is to use basic research to develop a cost effective remediation strategy that employs in-situ contaminant immobilzation. Specifically, the authors will develop active biowall technologies to contain priority EM contaminant plumes in groundwater. This report summarizes work after 1.5 y of a 3 y project.'
Date: June 1, 1998
Creator: Jardine, P. M. & Brooks, S. C.
Partner: UNT Libraries Government Documents Department
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Stable isotopic investigations of in-situ bioremediation of chlorinated organic solvents. 1998 annual progress report

Description: 'Contamination of soils and groundwaters with chlorinated aliphatic hydrocarbons (CAHs) is one of the most serious environmental problems in the DOE system and in the nation at large. These compounds are designated as priority pollutants by the US Environmental Protection Agency (EPA) and are known or suspected to be carcinogenic or mutagenic in humans. These compounds are readily transported by groundwater and are not reduced to acceptable concentrations for human consumption by most municipal water supply treatments; thus the compounds represent a significant hazard to a large portion of the human population. In situ bioremediation is an emerging technology that shows great promise for mitigation of CAH contamination at many sites. One of the most severe limitations of in-situ bioremediation is the difficulty of proving when it is working at a given site. The concentrations of CAHs and their degradation products in plumes may be difficult to relate to the efficiency of the remediation process because of dilution effects, but this problem is mitigated to a large extent by measuring isotope ratios. If there is a significant isotopic fractionation between CAHs and derivative chlorine-bearing products, then the fraction of CAH that is dechlorinated can be inferred from the {sup 37}Cl/{sup 35}Cl and {sup 13}C/{sup 12}C isotope ratios of the residual CAH. It is important to point out that there is currently no published information available on the magnitude of chlorine and carbon isotopic fractionation associated with biological degradation of CAHs. The authors plan to help eliminate this important gap in the knowledge with the work being performed here. This work is relevant to EMSP goals because it will provide a new and cost-effective means of evaluating and monitoring the effectiveness of in-situ bioremediation. It will employ newly developed techniques to characterize isotopic fractionation (of chlorine and carbon) associated with biotic …
Date: June 1, 1998
Creator: Sturchio, N.C.
Partner: UNT Libraries Government Documents Department
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Behavior of dense, immiscible solvents in fractured clay-rich soils. 1998 annual progress report

Description: 'This research project addresses the nature and and distribution of DNAPL sources (typically chlorinated solvents) in fractured clays or shales and the potential for natural attenuation of plumes derived from these sources. Specific goals include: (1) determining whether typical DNAPLs can penetrate fractures and the fine-grained matrix pore structure for head values within the range expected for a typical DNAPL spill; (2) investigate methods of measuring or estimating fracture or matrix entry pressure and pressure-saturation curves for these materials; (3) experimentally determine whether DNAPL residuals in fractures can be significantly depleted by dissolution and diffusion into the fine-grained matrix over the time-frame relevant to many contaminant investigation and remediation programs; and (4) assess potential for natural attenuation of common DNAPLs (TCE and its degradation products) in these deposits. Preliminary investigations indicate that DNAPL source removal will be a much more difficult and slower process for fractured clay-rich deposits than for granular deposits. These basic research investigations are needed to build the scientific framework for assessment of remediation options or for determining whether remediation, at least for the source zone, should be considered Technically Impractible (TI). This report summarizes progress made during the first 1.7 years of a 3-year project. The project investigates the behavior of DNAPLs in two fractured clay-rich materials: weathered shales at Oak Ridge National Lab. in east Tennessee; and weathered glacial till in southern Ontario. The materials, although very different in origin, are similar in terms of fracturing, porosity and hydraulic conductivity and DNAPLs are expected to behave in similar fashions in the two materials. This allows the researchers to share their expertise, as well as helping to determine whether the findings of these studies are applicable to a broader spectrum of fractured clay-rich materials. Results to date for the major sub-projects are briefly described.'
Date: June 1, 1998
Creator: Mckay, L. D.; Sanseverino, J.; Jardine, P. M.; Brooks, S. C.; Cherry, J. A. & Parker, B. L.
Partner: UNT Libraries Government Documents Department
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Estimation of potential population level effects of contaminants on wildlife. 1998 annual progress report

Description: 'The objective of this project is to provide DOE with improved methods to assess risks from contaminants to wildlife populations. The current approach for wildlife risk assessment consists of comparison of contaminant exposure estimates for individual animals to literature-derived toxicity test endpoints. These test endpoints are assumed to estimate thresholds for population-level effects. For several reasons, uncertainties associated with this approach are considerable. First, because toxicity data are not available for most potential wildlife endpoint species, extrapolation of toxicity data from test species to the species of interest is required. There is no consensus on the most appropriate extrapolation method. Second, toxicity data are represented as statistical measures (e.g., NOAELs or LOAELs) that provide no information on the nature or magnitude of effects. The level of effect is an artifact of the replication and dosing regime employed, and does not indicate how effects might increase with increasing exposure. Consequently, slight exceedance of a LOAEL is not distinguished from greatly exceeding it. Third, the relationship of toxic effects on individuals to effects on populations is poorly estimated by existing methods. It is assumed that if the exposure of individuals exceeds levels associated with impaired reproduction, then population level effects are likely. Uncertainty associated with this assumption is large because depending on the reproductive strategy of a given species, comparable levels of reproductive impairment may result in dramatically different population-level responses. The authors are working on several tasks to address these problems: (1) investigation of the validity of the current allometric scaling approach for interspecies extrapolation and development of new scaling models; (2) development of dose-response models for toxicity data presented in the literature; and (3) development of matrix-based population models that, coupled with dose-response models, will allow for realistic estimation of population-level effects for individual responses. Uncertainties associated with the current …
Date: June 1, 1998
Creator: Sample, B. E.; Suter, G. W. II & Rose, K. A.
Partner: UNT Libraries Government Documents Department
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The migration and entrapment of DNAPLs in physically and chemically heterogeneous porous media. Annual progress report, September 15, 1996--August 25, 1997

Description: 'The overall objective of this research is to investigate the influence of coupled physical and chemical heterogeneity on the migration and entrapment of DNAPLs in the saturated zone. This research includes laboratory and numerical investigations for a matrix of fluid and solid properties encompassing a range of wettability characteristics. Specific objectives include: (1) quantification of medium wettability and interfacial tensions; (2) determination of hydraulic property relations; (3) two-dimensional infiltration experiments; (4) modification of a continuum based multiphase flow simulator to account for physical heterogeneity, saturation independent and saturation dependent wettability, and concentration dependent wettability and interfacial tension; and (5) utilization of this model to explore the potential influence of coupled physical and chemical heterogeneities on the migration of DNAPLs and the development of innovative remediation schemes. Research conducted during this period was directed primarily towards the accomplishment of goals (1), (2), (4) and (5); specific details are given below. Goal (3) builds upon results from the other objectives and will, therefore, be started in the coming year.'
Date: January 1, 1997
Creator: Abriola, L.M. & Demond, A.H.
Partner: UNT Libraries Government Documents Department
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Advanced experimental analysis of controls on microbial Fe(III) oxide reduction. 1998 annual progress report

Description: 'Understanding factors which control the long-term survival and activity of Fe(III)-reducing bacteria (FeRB) in subsurface sedimentary environments is important for predicting their ability to serve as agents for bioremediation of organic and inorganic contaminants. This project seeks to refine the authors quantitative understanding of microbiological and geochemical controls on bacterial Fe(III) oxide reduction and growth of FeRB, using laboratory reactor systems which mimic to varying degrees the physical and chemical conditions of subsurface sedimentary environments. Methods for studying microbial Fe(III) oxide reduction and FeRB growth in experimental systems which incorporate advective aqueous phase flux are being developed for this purpose. These methodologies, together with an accumulating database on the kinetics of Fe(III) reduction and bacterial growth with various synthetic and natural Fe(III) oxide minerals, will be applicable to experimental and modeling studies of subsurface contaminant transformations directly coupled to or influenced by bacterial Fe(III) oxide reduction and FeRB activity. This report summarizes research accomplished after approximately 1.5 yr of a 3-yr project. A central hypothesis of the research is that advective elimination of the primary end-product of Fe(III) oxide reduction, Fe(II), will enhance the rate and extent of microbial Fe(III) oxide reduction in open experimental systems. This hypothesis is based on previous studies in the laboratory which demonstrated that association of evolved Fe(II) with oxide and FeRB cell surfaces (via adsorption or surface precipitation) is a primary cause for cessation of Fe(III) oxide reduction activity in batch culture experiments. Semicontinuous culturing was adopted as a first approach to test this basic hypothesis. Synthetic goethite or natural Fe(III) oxide-rich subsoils were used as Fe(III) sources, with the Fe(III)-reducing bacterium Shewanella alga as the test organism.'
Date: June 1, 1998
Creator: Roden, E.E. & Urrutia, M.M.
Partner: UNT Libraries Government Documents Department
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Improved risk estimated from carbon tetrachloride. Annual progress report, October 1, 1996--September 30, 1997

Description: 'Carbon tetrachloride (CCl{sub 4}) has been used extensively within the Department of Energy (DOE) nuclear weapons facilities. Rocky Flats was formerly the largest volume user of CCl{sub 4} in the US, with 5,000 gallons used there in 1977 alone. At the Hanford site, several hundred thousand gallons of CCl{sub 4} were discharged between 1955 and 1973 into underground cribs for storage. Levels of CCl{sub 4} in groundwater at highly contaminated sites at the Hanford. facility have exceeded the drinking water standard of 5 ppb by several orders of magnitude. High levels of CCl{sub 4} at these facilities represent a potential health hazard for workers conducting cleanup operations and for surrounding communities. The level of CCl{sub 4} cleanup required at these sites and associated costs are driven by current human health risk estimates which assume that CCl{sub 4} is a genotoxic carcinogen. The overall purpose of these studies is to improve the scientific basis for assessing the health risk associated with human exposure to CCl{sub 4}. Specifically, the authors will determine the toxicokinetics of inhaled and ingested CCl{sub 4} in F344/Crl rats, B6C3F1 mice, and Syrian hamsters. They will also evaluate species differences in the metabolism of CCl{sub 4} by rats, mice, hamsters, and man. Dose-response relationships will be determined in all these studies. This information will be used to improve the physiologically based pharmacokinetic (PBPK) model for CCl4 originally developed by Paustenbach et al. (1988) and more recently revised by Thrall and Kenny (1996). They will also provide scientific evidence that CCl{sub 4} , like chloroform, is a hepatocarcinogen only when exposure results in cell damage, cell killing, and regenerative cell proliferation. In combination, the studies outlined in this proposal will provide the exact types of information needed to enable refined cancer risk estimates for CCl{sub 4} under the new …
Date: October 27, 1997
Creator: Benson, J.M.
Partner: UNT Libraries Government Documents Department
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Physics of DNAPL migration and remediation in the presence of heterogeneities. 1997 annual progress report

Description: 'The authors are in the process of conducting well-controlled laboratory experiments to better understand the physics of DNAPL migration and remediation in the presence of heterogeneities. These experiments are being used to develop and test an upscaled percolation model, a new approach for modeling DNAPL migration. In addition, numerical simulators under current use in evaluating remediation techniques will be compared against the remediation experiments. They are making use of their unique experimental capabilities in the Subsurface Flow and Transport Processes Laboratory at Sandia to conduct controlled, systematic, repeatable experiments that first consider the physics of DNAPL migration in initially water-saturated, heterogeneous porous media and then evaluate the efficacy of a suite of promising remediation techniques for remediating DNAPLs from heterogeneous aquifers. The results of the migration experiments are being used to test and continue development of new modeling approaches based on upscaled percolation theory developed by us. The remediation experiments include visual and quantitative measures of each remediation technique''s performance. The results of the remediation experiments will be used to test, for the first time, within heterogeneous media, the quantitative performance of remediation design codes (two-phase flow codes that incorporate compositional models).'
Date: January 1, 1997
Creator: Conrad, S. & Glass, R.
Partner: UNT Libraries Government Documents Department
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Reduction and immobilization of radionuclides and toxic metal ions using combined zero valent iron and anaerobic bacteria. Year one technical progress report

Description: 'The objective of this project is to design a combined abiotic/microbial, reactive, permeable, in-situ barrier with sufficient reductive potential to prevent downgradient migration of toxic metal ions. The field-scale application of this technology would utilize anaerobic digester sludge, Fe(O) particles for supporting anaerobic biofilms, and suitable aquifer material for construction of the barrier. The major goals for Year 1 were to establish the sulfate reducing mixed culture, to obtain sources of iron metal, and to conduct background experiments which will establish baseline rates for abiotic chromium reduction rates. Research completed to date is described.'
Date: October 1, 1997
Creator: Weathers, L.J. & Katz, L.E.
Partner: UNT Libraries Government Documents Department
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Nuclear magnetic resonance imaging of subsurface water content. 1997 annual progress report

Description: 'During the period from October 1997 to January 1998 the author has further developed the understanding of NMR physics, improved software for forward and inverse modeling of the NMR signal, and conducted field tests on sites in Colorado and New Mexico. One important result from the forward modeling was that the field strength of the signals is concentrated under the loop. This indicates that little lateral dissipation occurs. The author received the NUMIS/NMR system (manufactured by IRIS Instruments, France) in late July, 1997. In July and early August, 1997, potential test sites were visited, and several test sites were selected and permitted. The first NMR test measurements were made in mid-August, 1997. The instrument malfunctioned during mid-September, 1997, and was returned to IRIS for repairs. Time lost due to malfunction, repairs, and shipping was about one month. Many NMR measurements have been made at sites in Colorado and New Mexico. Parks often have been selected as test sites due to ease of permitting, the relatively large open space, and general lack of powerlines. Noise from power lines severely degrades the NMR data quality. The NMR data acquired at the first three sites in Colorado (Bear Creek, Clear Creek, and Prospect) was either severely distorted by powerline noise or did not indicate significant groundwater occurrences. The NMR data taken at Cherry Creek were of good quality and also indicated significant groundwater. The NMR data acquired at three sites with relatively shallow ground water levels around Socorro, New Mexico, did not detect any ground water due to severe signal distortion by magnetite, a magnetic mineral. Measurements in a compact sand stone near Santa Rosa and in a limestone near Artesia, New Mexico, gave excellent results. Overall, the NMR technique proves capable of detecting subsurface ground water under the right conditions: little noise …
Date: January 1, 1997
Creator: Hendrickx, J.M.H.
Partner: UNT Libraries Government Documents Department
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Partitioning tracers for in situ detection and quantification of dense nonaqueous phase liquids in groundwater systems. 1998 annual progress report

Description: 'The overall goal of the proposed project is to explore the use of an innovative in-situ method for the detection and quantification of dense nonaqueous phase liquids (DNAPLs) in water-saturated and unsaturated heterogeneous media. Effective risk assessment and remediation of DNAPL contaminated sites is constrained by the limitations of current site characterization techniques. A major weakness of the current methods is that they provide data at discrete points, such that the probability of sampling a zone of localized DNAPL is quite small. The results of the proposed research will lead to improved techniques for characterizing DNAPL contaminated sites and will enhance the understanding of the distribution of DNAPLs in the subsurface. The use of this methods will reduce the uncertainty associated with risk assessments and remediation planning. The project objectives include exploring partitioning tracers for the detection and quantification of DNAPLs in saturated systems using aqueous tracers and in unsaturated systems using gas-phase tracers. This report summarizes work completed mid-way through year 2 of a 3-year project. Batch experiments have been conducted for a suite of bulk-phase partitioning tracers to determine water- trichloroethene (TCE) partitioning coefficients. Interfacial tension measurements have been made between TCE and solutions of several potential interface partitioning tracers. Preliminary column experiments have been conducted for the aqueous bulk-phase partitioning tracers using columns packed with a homogeneous sand and containing a residual saturation of TCE. These preliminary sets of experiments have enabled selection of suitable tracers for the water-saturated experiments and have lead to improved experimental designs and methods.'
Date: June 1, 1998
Creator: Brusseau, M. L.; White, M.; Nelson, N. & Oostrom, M.
Partner: UNT Libraries Government Documents Department
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