107 Matching Results

Search Results

Advanced search parameters have been applied.

Glucose or Altered Ceramide Biosynthesis Mediate Oxygen Deprivation Sensitivity Through Novel Pathways Revealed by Transcriptome Analysis in Caenorhabditis elegans

Description: This article discusses how RNA-sequencing analysis was performed to assess how a glucose-supplemented diet and/or a hyl-2 mutation altered the transcriptome.
Date: August 5, 2016
Creator: Ladage, Mary L.; King, Skylar D.; Burks, David J.; Quan, Daniel L.; Garcia, Anastacia M.; Azad, Rajeev K. et al.
Partner: UNT College of Arts and Sciences

Functions, Evolution, and Application of the Supramolecular Machines of Hg Detoxification

Description: The bacterial mercury resistance (mer) operon functions in Hg biogeochemistry and bioremediation by converting reactive inorganic [Hg(II)] and organic [RHg(I)] mercurials to relatively inert monoatomic mercury vapor, Hg(0). Its genes regulate expression (MerR, MerD, MerOP), import Hg(II) (MerT, MerP, and MerC), and demethylate (MerB) and reduce (MerA) mercurials. We focus on how these components interact with each other and with the host cell to allow cells to survive and detoxify Hg compounds. Understanding how this ubiquitous detoxification system fits into the biology and ecology of its bacterial host is essential to guide interventions that support and enhance Hg remediation. At a more basic level, studies of interactions between the metal ion trafficking proteins in this pathway provide insights into general mechanisms used by proteins in pathways involved in trafficking of other metal ions in cells of all types of organisms, including pathways for essential metal ions such as Cu and Zn and other toxic metal ions such as Cd. In this project we focused on investigations of proteins from mer operons found in gamma-proteobacteria with specific objectives to use biophysical and biochemical approaches to detect and define (1) interactions between the structural components of the key detoxifying mer operon enzyme, mercuric ion reductase (MerA), (2) interactions between the components of MerA and the other mer operon enzyme, organomercurial lyase (MerB), and (3) to investigate the structure and interactions of integral membrane transport proteins, MerT and MerC, with MerA.
Date: November 27, 2009
Creator: Miller, Susan M.
Partner: UNT Libraries Government Documents Department

Apparatus and method for two-stage oxidation of wastes

Description: An apparatus and method for oxidizing wastes in a two-stage process. The apparatus includes an oxidation device, a gas-liquid contacting column and an electrocell. In the first stage of the process, wastes are heated in the presence of air to partially oxidize the wastes. The heated wastes produce an off-gas stream containing oxidizable materials. In the second stage, the off-gas stream is cooled and flowed through the contacting column, where the off-gas stream is contacted with an aqueous acid stream containing an oxidizing agent having at least two positive valence states. At least a portion of the oxidizable materials are transferred to the acid stream and destroyed by the oxidizing agent. During oxidation, the valence of the oxidizing agent is decreased from its higher state to its lower state. The acid stream is flowed to the electrocell, where an electric current is applied to the stream to restore the oxidizing agent to its higher valence state. The regenerated acid stream is recycled to the contacting column.
Date: September 28, 1993
Creator: Fleischman, S. D.
Partner: UNT Libraries Government Documents Department

Glucose and Altered Ceramide Biosynthesis Impact the Transcriptome and the Lipidome of Caenorhabditis elegans

Description: The worldwide rise of diabetes and obesity has spurred research investigating the molecular mechanisms that mediate the deleterious effects associated with these diseases. Individuals with diabetes and/or obesity are at increased risk from a variety of health consequences, including heart attack, stroke and peripheral vascular disease; all of these complications have oxygen deprivation as the central component of their pathology. The nematode Caenorhabditis elegans has been established as a model system for understanding the genetic and molecular regulation of oxygen deprivation response, and in recent years methods have been developed to study the effects of excess glucose and altered lipid homeostasis. Using C. elegans, I investigated transcriptomic profiles of wild-type and hyl-2(tm2031) ( a ceramide biosynthesis mutant) animals fed a standard or a glucose supplemented diet. I then completed a pilot RNAi screen of differentially regulated genes and found that genes involved in the endobiotic detoxification pathway (ugt-63 and cyp-25A1) modulate anoxia response. I then used a lipidomic approach to determine whether glucose feeding or mutations in the ceramide biosynthesis pathway or the insulin-like signaling pathway impact lipid profiles. I found that gluocose alters the lipid profile of daf-2(e1370) (an insulin-like receptor mutant) animals. These studies indicate that a transcriptomic approach can be used to discover novel pathways involved in oxygen deprivation response and further validate C. elegans as a model for understanding diabetes and obesity.
Date: August 2016
Creator: Ladage, Mary Lee
Partner: UNT Libraries

X-ray absorption spectroscopy at the Ni-K edge in Stackhousia tryonii Bailey hyperaccumulator

Description: Young plants of Stackhousia tryonii Bailey were exposed to 34 mM Ni kg-1 in the form of NiSO4- 6H2O solution and grown under controlled glasshouse conditions for a period of 20 days. Fresh leaf, stem and root samples were analysed in vivo by micro x-ray absorption spectroscopy (XAS) at the Ni-K edge.Both x-ray absorption near edge structure and extended x-ray absorption fine structure spectra were analysed, and theresulting spectra were compared with spectra obtained from nine biologically important Ni-containing model compounds. The results revealed that themajority of leaf, stem and root Ni in the hyperaccumulator was chelated by citrate.Our results also suggest that in leavesNi is complexed by phosphate and histidine, and in stems and roots, phytate and histidine. The XAS results provide an important physiological insightinto transport, detoxification and storage of Ni in S. tryonii plants.
Date: October 8, 2007
Creator: Ionescu, Mihail; Bhatia, Naveen P.; Cohen , David D.; Siegele, R.; Marcus, Matthew A.; Fakra, Sirine C. et al.
Partner: UNT Libraries Government Documents Department

Development of protein based bioremediation and drugs for heavy metal toxicity

Description: Structural studies were performed on several proteins of the bacterial detoxification system. These proteins are responsible for binding (MerP) and transport of heavy metals, including mercury, across membranes. The structural information obtained from NMR experiments provides insight into the selectivity and sequestration processes towards heavy metal toxins.
Date: September 18, 2001
Creator: Opella, Stanley J.
Partner: UNT Libraries Government Documents Department

Structural Biology of The sequestration & Transport of Heavy Metal Toxins: NMR Structure Determination of Proteins Containing the CYS-X-Y-Metal Binding Motif

Description: The support from the Department of Energy enabled us to initiate research on several proteins from the bacterial mercury detoxification system; in particular, we were able to determine the structures of MerP and related metal binding sequences. We have also worked on the membrane transport proteins MerF and MerT.
Date: March 10, 2004
Creator: Opella, Stanley J.
Partner: UNT Libraries Government Documents Department

Genetic Engineering of a Radiation-Resistant Bacterium for Biodegradation of Mixed Wastes

Description: The mixture of toxic chemicals, heavy metals, halogenated solvents and radionuclides in many DOE waste materials presents a challenging problem for separating the different species and disposing of individual contaminants. One approach for dealing with mixed wastes is to genetically engineer the radiation-resistant bacterium, Deinococcus radiodurans to survive in and detoxify DOE's mixed waste streams, and to develop process parameters for treating mixed wastes with such constructed strains. The goal for this project is to develop a suite of genetic tools for Deinococcus radiodurans and to use these tools to construct and test stable strains for detoxification of haloorganics in mixed wastes.
Date: June 10, 2002
Creator: Lidstrom, Mary E.
Partner: UNT Libraries Government Documents Department

Pilot-scale study of the solar detoxification of VOC-contaminated groundwater

Description: The Solar Detoxification Field Experiment was designed to investigate the photocatalytic decomposition of organic contaminants in groundwater at a Superfund site at Lawrence Livermore National Laboratory (LLNL). The process uses ultraviolet (UV) energy, available in sunlight, in conjunction with the photocatalyst, titanium dioxide, to decompose organic chemicals into nontoxic compounds. The field experiment was developed by three federal laboratories: the National Renewable Energy Laboratory (NREL), Sandia National Laboratory (SNLA), and LLNL. The US Department of Energy funded the experiment. The objectives of the pilot-scale study included the advancement of the solar technology into a nonlaboratory waste-remediation environment the compilation of test data to help guide laboratory research and future demonstrations and the development of safe operational procedures. Results of the pilot study are discussed, emphasizing the effect of several process variables on the system performance. These variables include alkalinity, catalyst loading, flow velocity through the reactor, and incident solar UV radiation. The performance of the solar detoxification process are discussed as it relates to concentrating and nonconcentrating collectors.
Date: August 1, 1992
Creator: Mehos, M.; Turchi, C.; Pacheco, J.; Boegel, A. J.; Merrill, T. & Stanley, R.
Partner: UNT Libraries Government Documents Department

Elucidating the Molecular Basis and Regulation of Chromium (VI) Reduction by Shewanella oneidensis MR-1 Using Biochemical, Genomic, and Proteomic Approaches

Description: Although microbial metal reduction has been investigated intensively from physiological and biochemical perspectives, little is known about the genetic basis and regulatory mechanisms underlying the ability of certain bacteria to transform, detoxify, or immobilize a wide array of heavy metals contaminating DOE-relevant environments. The major goal of this work is to elucidate the molecular components comprising the chromium(VI) response pathway, with an emphasis on components involved in Cr(VI) detoxification and the enzyme complex catalyzing the terminal step in Cr(VI) reduction by Shewanella oneidensis MR-1. We have identified and characterized (in the case of DNA-binding response regulator [SO2426] and a putative azoreductase [SO3585]) the genes and gene products involved in the molecular response of MR-1 to chromium(VI) stress using whole-genome sequence information for MR-1 and recently developed proteomic technology, in particular liquid chromatographymass spectrometry (LC-MS), in conjunction with conventional protein purification and characterization techniques. The proteome datasets were integrated with information from whole-genome expression arrays for S. oneidensis MR-1 (as illustrated in Figure 1). The genes and their encoded products identified in this study are of value in understanding metal reduction and bacterial resistance to metal toxicity and in developing effective metal immobilization strategies.
Date: October 30, 2006
Creator: Hettich, Robert L.
Partner: UNT Libraries Government Documents Department

Impact of elevated nitrate on sulfate-reducing bacteria: A comparative study of Desulfovibrio vulgaris

Description: Sulfate-reducing bacteria have been extensively studied for their potential in heavy-metal bioremediation. However, the occurrence of elevated nitrate in contaminated environments has been shown to inhibit sulfate reduction activity. Although the inhibition has been suggested to result from the competition with nitrate-reducing bacteria, the possibility of direct inhibition of sulfate reducers by elevated nitrate needs to be explored. Using Desulfovibrio vulgaris as a model sulfate-reducing bacterium, functional genomics analysis reveals that osmotic stress contributed to growth inhibition by nitrate as shown by the upregulation of the glycine/betaine transporter genes and the relief of nitrate inhibition by osmoprotectants. The observation that significant growth inhibition was effected by 70 mM NaNO{sub 3} but not by 70 mM NaCl suggests the presence of inhibitory mechanisms in addition to osmotic stress. The differential expression of genes characteristic of nitrite stress responses, such as the hybrid cluster protein gene, under nitrate stress condition further indicates that nitrate stress response by D. vulgaris was linked to components of both osmotic and nitrite stress responses. The involvement of the oxidative stress response pathway, however, might be the result of a more general stress response. Given the low similarities between the response profiles to nitrate and other stresses, less-defined stress response pathways could also be important in nitrate stress, which might involve the shift in energy metabolism. The involvement of nitrite stress response upon exposure to nitrate may provide detoxification mechanisms for nitrite, which is inhibitory to sulfate-reducing bacteria, produced by microbial nitrate reduction as a metabolic intermediate and may enhance the survival of sulfate-reducing bacteria in environments with elevated nitrate level.
Date: July 15, 2010
Creator: He, Q.; He, Z.; Joyner, D.C.; Joachimiak, M.; Price, M.N.; Yang, Z.K. et al.
Partner: UNT Libraries Government Documents Department

Advanced biochemical processes for geothermal brines: Annual operating plan, FY 1995

Description: An R and D program to identify methods for the utilization and/or low cost of environmentally acceptable disposal of toxic geothermal residues has been established at the Brookhaven National Laboratory (BNL). Laboratory work has shown that a biochemical process developed at BNL, would meet regulatory costs and environmental requirements. In this work, microorganisms which can convert insoluble species of toxic metals, including radionuclides, into soluble species, have been identified. These organisms serve as models in the development of a biochemical process in which toxic metals present in geothermal residual sludges are converted into water soluble species. The produced solution can be reinjected or processed further to concentrate and recover commercially valuable metals. After the biochemical detoxification of geothermal residual sludges, the end-products are non-toxic and meet regulatory requirements. The overall process is a technically and environmentally acceptable cost-efficient process. It is anticipated that the new biotechnology will reduce the cost of surface disposal of sludges derived from geothermal brines by 25% or better.
Date: February 1, 1995
Creator: Premuzic, E.T.
Partner: UNT Libraries Government Documents Department

The Department of Energy`s Solar Industrial Program: 1995 review

Description: During 1995, the Department of Energy`s Solar Industrial (SI) Program worked to bring the benefits of solar energy to America`s industrial sector. Scientists and engineers within the program continued the basic research, applied engineering, and economic analyses that have been at the heart of the Program`s success since its inception in 1989. In 1995, all three of the SI Program`s primary areas of research and development--solar detoxification, advanced solar processes, and solar process heat--succeeded in increasing the contribution made by renewable and energy-efficient technologies to American industry`s sustainable energy future. The Solar Detoxification Program develops solar-based pollution control technologies for destroying hazardous environmental contaminants. The Advanced Solar Processes Program investigates industrial uses of highly concentrated solar energy. The Solar Process Heat Program conducts the investigations and analyses that help energy planners determine when solar heating technologies--like those that produce industrial-scale quantities of hot water, hot air, and steam--can be applied cost effectively. The remainder of this report highlights the research and development conducted within in each of these subprograms during 1995.
Date: April 1, 1996
Partner: UNT Libraries Government Documents Department

Genetic Engineering of a Radiation-Resistant Bacterium for Biodegradation of Mixed Wastes

Description: The mixture of toxic chemicals, heavy metals, halogenated solvents and radionuclides in many DOE waste materials presents a challenging problem for separating the different species and disposing of individual contaminants. One approach for dealing with mixed wastes is to genetically engineer the radiation-resistant bacterium, Deinococcus radiodurans to survive in and detoxify DOE's mixed waste streams, and to develop process parameters for treating mixed wastes with such constructed strains. The goal for this project is to develop a suite of genetic tools for Deinococcus radiodurans and to use these tools to construct and test stable strains for detoxification of haloorganics in mixed wastes.
Date: June 1, 1999
Creator: Lidstrom, Mary E.
Partner: UNT Libraries Government Documents Department

Genetic Engineering of a Radiation-Resistant Bacterium for Biodegradation of Mixed Wastes

Description: The mixture of toxic chemicals, heavy metals, halogenated solvents and radionuclides in many DOE waste materials presents a challenging problem for separating the different species and disposing of individual contaminants. One approach for dealing with mixed wastes is to genetically engineer the radiation-resistant bacterium, Deinococcus radiodurans to survive in and detoxify DOE's mixed waste streams, and to develop process parameters for treating mixed wastes with such constructed strains. The goal for this project is to develop a suite of genetic tools for Deinococcus radiodurans and to use these tools to construct and test stable strains for detoxification of haloorganics in mixed wastes.
Date: June 11, 2001
Creator: Lidstrom, Mary E.
Partner: UNT Libraries Government Documents Department

Molecular Genetics of Metal Detoxification: Prospects for Phytoremediation

Description: We seek to define the genes involved in heavy metal tolerance and sequestration. Initially, two complementary strategies were taken: (1) clone and characterize the genes that complement cadmium hypersensitive mutants of fission yeast, specifically those responsible for production of metal-binding complexes, and (2) isolate genes that can confer cadmium hypertolerance to wild type strains of fission yeast. During the course of the investigation, we added a third strategy to the existing plan. In this third strategy, we sought to isolate the cDNAs that are specifically expressed during exposure to Cd. For the past year, the success in isolating a large number of genes using the second and third strategy has redirected our emphasis to concentrating on the characterization of these genes. Consequently, some of the work that was initiated with the first strategy has been put on hold.
Date: June 1, 1999
Creator: Ow, David W.
Partner: UNT Libraries Government Documents Department

Universal Oxidation for CBW Decontamination: L-Gel System Development and Deployment

Description: The general philosophy of this work is to develop an integrated set of decontamination methods and tools that will work on the major CBW threat agents. The work includes some near term techniques that can be demonstrated within a year and implemented soon thereafter as well as longer term research objectives. It is recognized that there is a balance between somewhat less effective methods which can be demonstrated quickly and more effective ones which may require a much longer time to fruition. The optimum goal of this study is to find a single decontamination system for chemical and biological agents which is non-toxic, non-corrosive, and easily deployable. One of the goals is to have decontamination systems that might be used by first responders as well as more complete systems to be used by specialized decontamination teams. Therefore, the overall project goal is to develop better decontamination methods that can be quickly implemented by these organizations. This includes early demonstrations and field work with companies or other government agencies who can identify implementation concerns and needs. The approach taken in this work is somewhat different than the standard military approach to decontamination. In a battlefield scenario, it is critical to decontaminate to a useful level in a very short time so the soldiers can continue their mission. In a domestic, urban scenario, time is of less consequence but collateral damage and recertification (public perception and stakeholder acceptance) are of much greater importance. The specific objective of the LLNL work to date has been to evaluate various oxidizer systems as reagents to allow for detoxification and/or degradation to non-toxic environmentally acceptable components rather than necessitate complete destruction. Detoxification requires less reagent material than total oxidation, thereby reducing the logistic burden for a decontamination team. Since we also wanted to maximize the contact ...
Date: December 16, 2000
Creator: Raber, E.; McGuire, R.; Hoffman, M.; Alcaraz, A.; Shepley, D.; Elliot, J. et al.
Partner: UNT Libraries Government Documents Department

Universal Oxidation for CBW Decontamination: L-Gel System Development and Deployment

Description: The optimum goal of this study is to develop a single decontamination system for chemical and biological agents which is non-toxic, non-corrosive, and easily deployable. The specific objective of this work was to evaluate oxidizer systems as reagents for detoxification and/or degradation to non-toxic environmentally acceptable components rather than necessitate complete destruction. Detoxification requires less reagent material than total oxidation, thereby reducing the logistic burden for a decontamination team. One of the goals is to develop decontamination systems for use by first responders as well as more complete systems to be used by specialized decontamination teams. Therefore, the overall project goal is to develop better decontamination methods that can be quickly implemented by these organizations. This includes early demonstrations and field work with companies or other government agencies who can identify implementation concerns and needs. The approach taken in this work is somewhat different than the standard military approach to decontamination. In a battlefield scenario, it is critical to decontaminate to a useful level in a very short time so the soldiers can continue their mission. In a domestic, urban scenario, time is of less consequence but collateral damage and re-certification (public perception and stakeholder acceptance) are of much greater importance. Since we wanted to maximize the contact time between the decontaminating reagent and the contaminant agent, we selected gelled reagents as the primary carrier material. Gels have the additional advantage of adhering to vertical or horizontal surfaces such as walls and ceilings. Lawrence Livermore National Laboratory, over a period of twenty years from the late 1960s to the late 1980s, developed a series of extrudable high explosives based on the gelling of polar energetic liquids. While never going into production, this development served as an experience base for formulation, characterization and dispersal system design and fabrication. It was a ...
Date: July 10, 2000
Creator: Raber, E.; McGuire, R.; Hoffman, M.; Shepley, D.; Carlsen, T.; Krauter, P. et al.
Partner: UNT Libraries Government Documents Department

Genetic Engineering of a Radiation-Resistant Bacterium for Biodegradation of Mixed Wastes

Description: The mixture of toxic chemicals, heavy metals, halogenated solvents and radionuclides in many DOE waste materials presents a challenging problem for separating the different species and disposing of individual contaminants. One approach for dealing with mixed wastes is to genetically engineer the radiation-resistant bacterium, Deinococcus radiodurans to survive in and detoxify DOE's mixed waste streams, and to develop process parameters for treating mixed wastes with such constructed strains. The goal for this project is to develop a suite of genetic tools for Deinococcus radiodurans and to use these tools to construct and test stable strains for detoxification of haloorganics in mixed wastes.
Date: June 1, 2000
Creator: Lidstrom, Mary E.
Partner: UNT Libraries Government Documents Department

Calcium promotes cadmium elimination as vaterite grains by tobacco trichomes

Description: In tobacco plants, elimination of Zn and Cd via the production of Ca-containing grains at the top of leaf hairs, called trichomes, is a potent detoxification mechanism. This study examines how Cd is incorporated in these biominerals, and how calcium growth supplement modifies their nature. Scanning electron microscopy coupled with energy dispersive X-ray microanalysis (SEM-EDX), microfocused X-ray diffraction ({mu}-XRD), and microfocused X-ray absorption near edge structure ({mu}-XANES) spectroscopy were used to image the morphology of the grains, identify the crystallized mineral phases, and speciate Cd, respectively. The mineralogy of the grains and chemical form of Cd varied with the amount of Ca. When tobacco plants were grown in a nutrient solution containing 25 {micro}M Cd and low Ca supplement (Ca/Cd = 11 mol ratio), most of the grains were oblong-shaped and low-Cd-substituted calcite. When exposed to the same amount of Cd and high Ca supplement (Ca/Cd = 131 mol ratio), grains were more abundant and diverse in compositions, and in total more Cd was eliminated. Most grains in the high Ca/Cd experiment were round-shaped and composed predominantly of Cd-substituted vaterite, a usually metastable calcium carbonate polymorph, and subordinate calcite. Calcium oxalate and a Ca amorphous phase were detected occasionally in the two treatments, but were devoid of Cd. The biomineralization of cadmium and implications of results for Cd exposure of smokers and phytoremediation are discussed.
Date: July 1, 2011
Creator: Isaure, Marie-Pierre; Sarret, Geraldine; Harada, Emiko; Choi, Yong-Eui; Marcus, Matthew A.; Fakra, Sirine C. et al.
Partner: UNT Libraries Government Documents Department

Energetic Consequences of nitrite stress in Desulfovibrio vulgarisHildenborough, inferred from global transcriptional analysis

Description: Many of the proteins that are candidates for bioenergetic pathways involved with sulfate respiration in Desulfovibrio spp. have been studied, but complete pathways and overall cell physiology remain to be resolved for many environmentally relevant conditions. In order to understand the metabolism of these microorganisms under adverse environmental conditions for improved bioremediation efforts, Desulfovibrio vulgaris Hildenborough was used as a model organism to study stress response to nitrite, an important intermediate in the nitrogen cycle. Previous physiological studies demonstrated that growth was inhibited by nitrite and that nitrite reduction was observed to be the primary mechanism of detoxification. Global transcriptional profiling with whole-genome microarrays revealed coordinated cascades of responses to nitrite in pathways of energy metabolism, nitrogen metabolism, oxidative stress response, and iron homeostasis. In agreement with previous observations, nitrite-stressed cells showed a decrease in the expression of genes encoding sulfate reduction functions in addition to respiratory oxidative phosphorylation and ATP synthase activity. Consequently, the stressed cells had decreased expression of the genes encoding ATP-dependent amino acid transporters and proteins involved in translation. Other genes up-regulated in response to nitrite include the genes in the Fur regulon, which is suggested to be involved in iron homeostasis, and genes in the Per regulon, which is predicted to be responsible for oxidative stress response.
Date: November 3, 2005
Creator: He, Qiang; Huang, Katherine H.; He, Zhili; Alm, Eric J.; Fields,Matthew W.; Hazen, Terry C. et al.
Partner: UNT Libraries Government Documents Department

Design and Cost of Solar Photocatalytic Systems for Groundwater Remediation

Description: Laboratory and small-scale field experiments have shown that sunlight in conjunction with a simple catalyst can be used to detoxify water contaminated with a variety of hazardous chemicals. This study builds on previous analyses and recent field test data to predict the cost and performance of a representative commercial water detoxification system. Three different solar operating configurations are explored for the treatment of 100,000 gal/day of groundwater contaminated with trichloroethylene. Current costs for solar water detoxification systems are projected to be comparable to those for conventional treatment technologies such as carbon adsorption and electric lamp-powered, ultraviolet light/hydrogen peroxide systems.
Date: May 1, 1992
Creator: Turchi, C. S.; Mehos, M. S. & Link, H. F.
Partner: UNT Libraries Government Documents Department

DEVELOPMENT OF PROCESS CONTROL EQUATIONS TO SUPPORT DETOXIFICATION OF COPPER USING NATURAL HUMATE AMENDMENTS

Description: Recent scientific research and changes in regulatory policies have led to reductions in the allowable discharges of several contaminant metals, including copper, into surface water. Low target concentrations and variable outfall conditions challenge the efficacy of traditional treatment technologies such as ion exchange. In reviewing various treatment options, scientists and engineers at the Savannah River Site (SRS) developed a treatment strategy focusing on toxicity reduction (rather than the removal of the copper) and demonstrated that the method is viable and promising for mitigating copper toxicity. The resulting outfall chemistry protects the ecosystem in the receiving stream in a manner that is equal to, or better than, technologies that remove copper to the emerging regulatory levels. Further, the proposed toxicity reduction strategy results in collateral beneficial changes in outfall water chemistry such that the outfall more closely matches the chemistry of natural streams for key parameters such as the dissolved organic carbon (DOC). The detoxification process is based on the EPA BLM. Specifically, modeling indicates that copper toxicity can be mitigated by modest additions of natural organic carbon and that the amount of amendment needed can be determined based on pH and stream flow. The organic carbon amendments proposed for the treatment/detoxification process are extracts of natural materials that are produced for use in organic agriculture. These extracts are known by several common names such as potassium humate, soluble humic acid, and a variety of brand trademarks. When used to reduce ecosystem toxicity in surface water, these amendments bind copper and compete with the biological receptor sites, resulting in a reduction of impacts to key food chain organisms such as the Daphnia ('water flea'). Design and implementation of the process is straightforward. The core equipment consists of storage tank(s), pH sensor(s), outfall flow monitor(s), variable speed pump(s), and a programmable logic ...
Date: August 21, 2009
Creator: Looney, B.; Millings, M.; Halverson, N. & Nichols, R.
Partner: UNT Libraries Government Documents Department

Final Report - Phase II - Biogeochemistry of Uranium Under Reducing and Re-oxidizing Conditions: An Integrated Laboratory and Field Study

Description: Our understanding of subsurface microbiology is hindered by the inaccessibility of this environment, particularly when the hydrogeologic medium is contaminated with toxic substances. Past research in our labs indicated that the composition of the growth medium (e.g., bicarbonate complexation of U(VI)) and the underlying mineral phase (e.g., hematite) significantly affects the rate and extent of U(VI) reduction and immobilization through a variety of effects. Our research was aimed at elucidating those effects to a much greater extent, while exploring the potential for U(IV) reoxidation and subsequent re-mobilization, which also appears to depend on the mineral phases present in the system. The project reported on here was an extension ($20,575) of the prior (much larger) project. This report is focused only on the work completed during the extension period. Further information on the larger impacts of our research, including 28 publications, can be found in the final report for the following projects: 1) Biogeochemistry of Uranium Under Reducing and Re-oxidizing Conditions: An Integrated Laboratory and Field Study Grant # DE-FG03-01ER63270, and 2) Acceptable Endpoints for Metals and Radionuclides: Quantifying the Stability of Uranium and Lead Immobilized Under Sulfate Reducing Conditions Grant # DE-FG03-98ER62630/A001 In this Phase II project, the toxic effects of uranium(VI) were studied using Desulfovibrio desulfuricans G20 in a medium containing bicarbonate or 1, 4-piperazinediethane sulfonic acid disodium salt monohydrate (PIPES) buffer (each at 30 mM, pH 7). The toxicity of uranium(VI) was dependent on the medium buffer and was observed in terms of longer lag times and in some cases, no measurable growth. The minimum inhibiting concentration (MIC) was 140 M U(VI) in PIPES buffered medium. This is 36 times lower than previously reported for D. desulfuricans. These results suggest that U(VI) toxicity and the detoxification mechanisms of G20 depend greatly on the chemical forms of U(VI) present ...
Date: September 28, 2006
Creator: Peyton, Brent & Sani, Rajesh
Partner: UNT Libraries Government Documents Department