Download or read book Structure and Function of Microbial Communities Controlling the Fate and Transformation of U VI in Radionuclide Contaminated Subsurface Sediments written by Denise Marie Akob and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A polyphasic approach employing microbiological and geochemical techniques was used in this dissertation to link the structure and function of microbial communities in subsurface sediments of the U.S. Department of Energy's Oak Ridge Field Research Center (ORFRC), in Oak Ridge, Tennessee. Subsurface sediments at the ORFRC site are cocontaminated with high levels of U(VI) and nitrate and microbial activity is limited by carbon availability and variable pH. The conditions at the ORFRC site are representative of many radionuclide-contaminated sites; therefore, results from this dissertation will have broader significance for development of bioremediation strategies that can be employed worldwide.
Download or read book STRUCTURE AND FUNCTION OF SUBSURFACE MICROBIAL COMMUNITIES AFFECTING RADIONUCLIDE TRANSPORT AND BIOIMMOBILIZATION written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The objectives of this project were to: (1) isolate and characterize novel anaerobic prokaryotes from subsurface environments exposed to high levels of mixed contaminants (U(VI), nitrate, sulfate), (2) elucidate the diversity and distribution of metabolically active metal- and nitrate-reducing prokaryotes in subsurface sediments, and (3) determine the biotic and abiotic mechanisms linking electron transport processes (nitrate, Fe(III), and sulfate reduction) to radionuclide reduction and immobilization. Mechanisms of electron transport and U(VI) transformation were examined under near in situ conditions in sediment microcosms and in field investigations at the Oak Ridge Field Research Center (ORFRC), in Oak Ridge, Tennessee, where the subsurface is exposed to mixed contamination predominated by uranium and nitrate. A total of 20 publications (16 published or 'in press' and 4 in review), 10 invited talks, and 43 contributed seminars/ meeting presentations were completed during the past four years of the project. PI Kostka served on one proposal review panel each year for the U.S. DOE Office of Science during the four year project period. The PI leveraged funds from the state of Florida to purchase new instrumentation that aided the project. Support was also leveraged by the PI from the Joint Genome Institute in the form of two successful proposals for genome sequencing. Draft genomes are now available for two novel species isolated during our studies and 5 more genomes are in the pipeline. We effectively addressed each of the three project objectives and research highlights are provided. Task I - Isolation and characterization of novel anaerobes: (1) A wide range of pure cultures of metal-reducing bacteria, sulfate-reducing bacteria, and denitrifying bacteria (32 strains) were isolated from subsurface sediments of the Oak Ridge Field Research Center (ORFRC), where the subsurface is exposed to mixed contamination of uranium and nitrate. These isolates which are new to science all show high sequence identity to sequences retrieved from ORFRC subsurface. (2) Based on physiological and phylogenetic characterization, two new species of subsurface bacteria were described: the metal-reducer Geobacter daltonii, and the denitrifier Rhodanobacter denitrificans. (3) Strains isolated from the ORFRC show that Rhodanobacter species are well adapted to the contaminated subsurface. Strains 2APBS1 and 116-2 grow at high salt (3% NaCl), low pH (3.5) and tolerate high concentrations of nitrate (400mM) and nitrite (100mM). Strain 2APBS1 was demonstrated to grow at in situ acidic pHs down to 2.5. (4) R. denitrificans strain 2APBS1 is the first described Rhodanobacter species shown to denitrify. Nitrate is almost entirely converted to N2O, which may account for the large accumulation of N2O in the ORFRC subsurface. (5) G. daltonii, isolated from uranium- and hydrocarbon-contaminated subsurface sediments of the ORFRC, is the first organism from the subsurface clade of the genus Geobacter that is capable of growth on aromatic hydrocarbons. (6) High quality draft genome sequences and a complete eco-physiological description are completed for R. denitrificans strain 2APBS1 and G. daltonii strain FRC-32. (7) Given their demonstrated relevance to DOE remediation efforts and the availability of detailed genotypic/phenotypic characterization, Rhodanobacter denitrificans strain 2APBS1 and Geobacter daltonii strain FRC-32 represent ideal model organisms to provide a predictive understanding of subsurface microbial activity through metabolic modeling. Tasks II and III-Diversity and distribution of active anaerobes and Mechanisms linking electron transport and the fate of radionuclides: (1) Our study showed that members of genus Rhodanobacter and Geobacter are abundant and active in the uranium and nitrate contaminated subsurface. In the contaminant source zone of the Oak Ridge site, Rhodanobacter spp. are the predominant, active organisms detected (comprising 50% to 100% of rRNA detected). (2) We demonstrated for the first time that the function of microbial communities can be quantified in subsurface sediments using messenger RNA assays (molecular proxies) under in situ conditions. (3) Active Geobacteraceae were identified and phylogenetically characterized from the cDNA of messenger RNA extracted from ORFRC subsurface sediment cores. Multiple clone sequences were retrieved from G. uraniireducens, G. daltonii, and G. metallireducens. (4) Results show that Geobacter strain FRC-32 is capable of growth on benzoate, toluene and benzene as the electron donor, thereby providing evidence that this strain is physiologically distinct from other described members of the subsurface Geobacter clade. (5) Fe(III)-reducing bacteria transform structural Fe in clay minerals from their layer edges rather than from their basal surfaces.
Download or read book Interactions of Microorganisms with Radionuclides written by M.J. Keith-Roach and published by Elsevier. This book was released on 2002-04-22 with total page 409 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many environmental processes are influenced, if not controlled, by microbial action and it is becoming increasingly important to develop an understanding of microbial roles in geochemistry. This book brings together state of the art research into microbiological processes and the extent to which they affect or can be used to control radioactive elements. The basic principles and fundamental mechanisms by which microbes and radionuclides interact are outlined, the methodology described, potential microbial influences on waste repositories examined, direct and indirect effects on transport both on local and global scales considered and potential technological applications identified.The book is directed towards advanced undergraduate students, postgraduates and researchers in the areas of environmental radioactivity, environmental microbiology, biotechnology and radioactive waste management. It will also be of interest to regulators, policy makers and non-governmental organisations.This novel and timely book offers a fully integrated approach to a topical international issue.
Download or read book Riste Olav An Idea and a Myth Roosevelt s Free Ports Scheme for North Norway written by and published by . This book was released on 1963 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fate and Transport of Radionuclides uranium VI Strontium Cesium in Vadose Zone Sediments at the Hanford Site written by Kenton Alan Rod and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Diffusion rate limited release of contaminants due to complex geometry contributes to control of Hanford subsurface contamination. We investigated diffusion of colloids into micro-channels. Colloids (0.2 microm) diffusion into larger factures (10 to 30 microm) could be modeled using the calculated infinite linear coefficient but diffusion into smaller fractures (3 to 5 microm) was reduced by as much as 2.68 times.
Download or read book Deep Subsurface Microbiology written by Andreas Teske and published by Frontiers Media SA. This book was released on 2015-07-01 with total page 305 pages. Available in PDF, EPUB and Kindle. Book excerpt: Deep subsurface microbiology is a highly active and rapidly advancing research field at the interface of microbiology and the geosciences; it focuses on the detection, identification, quantification, cultivation and activity measurements of bacteria, archaea and eukaryotes that permeate the subsurface biosphere of deep marine sediments and the basaltic ocean and continental crust. The deep subsurface biosphere abounds with uncultured, only recently discovered and – at best - incompletely understood microbial populations. In spatial extent and volume, Earth's subsurface biosphere is only rivaled by the deep sea water column. So far, no deep subsurface sediment has been found that is entirely devoid of microbial life; microbial cells and DNA remain detectable at sediment depths of more than 1 km; microbial life permeates deeply buried hydrocarbon reservoirs, and is also found several kilometers down in continental crust aquifers. Severe energy limitation, either as electron acceptor or donor shortage, and scarcity of microbially degradable organic carbon sources are among the evolutionary pressures that have shaped the genomic and physiological repertoire of the deep subsurface biosphere. Its biogeochemical role as long-term organic carbon repository, inorganic electron and energy source, and subduction recycling engine continues to be explored by current research at the interface of microbiology, geochemistry and biosphere/geosphere evolution. This Research Topic addresses some of the central research questions about deep subsurface microbiology and biogeochemistry: phylogenetic and physiological microbial diversity in the deep subsurface; microbial activity and survival strategies in severely energy-limited subsurface habitats; microbial activity as reflected in process rates and gene expression patterns; biogeographic isolation and connectivity in deep subsurface microbial communities; the ecological standing of subsurface biospheres in comparison to the surface biosphere – an independently flourishing biosphere, or mere survivors that tolerate burial (along with organic carbon compounds), or a combination of both? Advancing these questions on Earth’s deep subsurface biosphere redefines the habitat range, environmental tolerance, activity and diversity of microbial life.
Download or read book Mobility of Source Zone Heavy Metals and Radionuclides written by Brent Peyton and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Various U.S. Department of Energy (DOE) low and medium-level radioactive waste sites contain mixtures of heavy metals, radionuclides and assorted organic materials. Over time, water infiltrates the wastes, and releases metals and radionuclides causing transport into the surrounding environment. We propose that fermentative microorganisms are active in these sites and may control metal and radionuclide migration from source zones (Figure 1). The following overarching hypothesis will drive our research: 'Metals and radionuclides can be mobilized by infiltration of water into waste storage sites. Microbial communities of lignocellulose degrading and fermenting microorganisms present in the subsurface of contaminated DOE sites can significantly impact migration by directly reducing and immobilizing metals and radionuclides while degrading complex organic matter to low molecular weight organic compounds. These low molecular weight organic compounds can increase metal and radionuclide mobility by chelation (i.e., certain organic acids) or decrease mobility by stimulating respiratory metal reducing microorganisms.' The objective of our research is to determine the effect of carbon and energy flow through simulated waste environments on metal and radionuclide migration from waste pits and trenches across the DOE complex. Metals and radionuclides can be mobilized by infiltration of water into waste storage sites. Cellulolytic and non-cellulolytic fermentative microorganisms have been chosen as the focus of this research because their activity is a critical first step that we hypothesize will control subsequent fate and transport in contaminated natural systems. Microbial communities of lignocellulose degrading and fermenting microorganisms present in the subsurface of contaminated DOE sites can significantly impact migration by directly reducing and immobilizing metals and radionuclides while degrading complex organic matter to low molecular weight organic compounds. These low molecular weight organic acids and alcohols can increase metal and radionuclide mobility by chelation (i.e., certain organic acids) or decrease mobility by stimulating respiratory metal reducing microorganisms.
Download or read book Biomolecular Mechanisms Controlling Metal and Radionuclide Transformations in Anaeromyxobacter Dehalogenans written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Microbiological reduction and immobilization of U(VI) and Tc(VII) has been proposed as a strategy for remediating radionuclide-contaminated environments. Numerous studies focusing on the reduction kinetics and speciation of these metals have been carried out using contaminated sediment samples, microbial consortia, and pure bacterial cultures. While previous work with model organisms has increased the general understanding of radionuclide transformation processes, fundamental questions regarding radionuclide reduction mechanisms by indigenous microorganisms are poorly understood, especially under the commonly encountered scenario where multiple electron acceptors are present. Therefore, the overall goal of the proposed research is to elucidate the molecular mechanisms of radionuclide biotransformation by Anaeromyxobacter dehalogenans, a predominant member of indigenous microorganism commonly found in contaminated subsurface environments, and to assess the effects of relevant environmental factors affecting these transformation reactions.
Download or read book Characterization of Metal reducing Microbial Communities from Acidic Subsurface Sediments Contaminated with Uranium VI written by Ellen McLain Edwards and published by . This book was released on 2005 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: Iron(III)-reducing bacteria (FeRB) have been demonstrated to rapidly catalyze U(VI) reduction and Fe(III) is an abundant electron acceptor in uranium-contaminated subsurface sediments. Thus, FeRB communities were the focus of this dissertation. The abundance, diversity, and activity of indigenous metal-reducing microbial communities likely to contribute to uranium reduction was examined in the field and under more controlled conditions in the laboratory.
Download or read book Dynamics of Microbial Community Composition and Function During In situ Bioremediation of a Uranium contaminated Aquifer written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A pilot-scale system was established to examine the feasibility of in situ U(VI) immobilization at a highly contaminated aquifer (U.S. DOE Integrated Field Research Challenge site, Oak Ridge, TN). Ethanol was injected intermittently as an electron donor to stimulate microbial U(VI) reduction, and U(VI) concentrations fell to below the Environmental Protection Agency drinking water standard (0.03 mg liter−1). Microbial communities from three monitoring wells were examined during active U(VI) reduction and maintenance phases with GeoChip, a high-density, comprehensive functional gene array. The overall microbial community structure exhibited a considerable shift over the remediation phases examined. GeoChip-based analysis revealed that Fe(III)-reducing bacterial (FeRB), nitrate-reducing bacterial (NRB), and sulfate-reducing bacterial (SRB) functional populations reached their highest levels during the active U(VI) reduction phase (days 137 to 370), in which denitrification and Fe(III) and sulfate reduction occurred sequentially. A gradual decrease in these functional populations occurred when reduction reactions stabilized, suggesting that these functional populations could play an important role in both active U(VI) reduction and maintenance of the stability of reduced U(IV). These results suggest that addition of electron donors stimulated the microbial community to create biogeochemical conditions favorable to U(VI) reduction and prevent the reduced U(IV) from reoxidation and that functional FeRB, SRB, and NRB populations within this system played key roles in this process.
Download or read book An Integrated Assessment of Geochemical and Community Structure Determinants of Metal Reduction Rates in Subsurface Sediments written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This project represented a joint effort between Oak Ridge National Laboratory (ORNL), the University of Tennessee (UT), and Florida State University (FSU). ORNL served as the lead in-stitution with Dr. A.V. Palumbo responsible for project coordination, integration, and deliver-ables. In situ uranium bioremediation is focused on biostimulating indigenous microorganisms through a combination of pH neutralization and the addition of large amounts of electron donor. Successful biostimulation of U(VI) reduction has been demonstrated in the field and in the laboratory. However, little data is available on the dynamics of microbial populations capable of U(VI) reduction, and the differences in the microbial community dynamics between proposed electron donors have not been explored. In order to elucidate the potential mechanisms of U(VI) reduction for optimization of bioremediation strategies, structure-function relationships of microbial populations were investigated in microcosms of subsurface materials cocontaminated with radionuclides and nitrate from the Oak Ridge Field Research Center (ORFRC), Oak Ridge, Tennessee.
Download or read book Reductive Immobilization of U VI in Fe III Oxide reducing Subsurface Sediments written by and published by . This book was released on 2004 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: Although the fundamental microbiological and geochemical processes underlying the potential use of dissimilatory metal-reducing bacteria (DMRB) to create subsurface redox barriers for immobilization of uranium and other redox-sensitive metal/radionuclide contaminants are well-understood (Lovley et al., 1991; Gorby and Lovley, 1992; Lovley and Phillips, 1992; Lovley, 1995; Fredrickson et al., 2000; Wielinga et al., 2000; Wielinga et al., 2001), several fundamental scientific questions need to be addressed in order to understand and predict how such treatment procedures would function under in situ conditions in the subsurface. These questions revolve around the dynamic interactions between hydrologic flux and the coupled microbial-geochemical processes which are likely to occur within a redox barrier treatment zone. A brief summary of such questions includes the following: (1) What are the kinetic limitations to the efficiency of microbial U(VI) scavenging in subsurface sediments? (2) Is U(VI) sorbed to Fe(III) oxide and other solid-phase surfaces subject to enzymatic reduction? If so, what are the relative kinetics of aqueous vs. sorbed U(VI) reduction? (3) What are the relative kinetics of direct, enzymatic U(VI) reduction vs. abiotic reduction of U(VI) by surface-bound biogenic Fe(II)? (4) Can coupled Fe(III) oxide/U(VI) reduction be sustained long-term in subsurface environments? What are the kinetic relationships between Fe(III) oxide reduction, DMRB growth, and U(VI) reduction in advectively open sedimentary systems? The overall objective of our research is to address the questions listed above through laboratory-based batch and reactive transport experiments with natural Fe(III) oxide-bearing subsurface materials and a representative pure culture DMRB. A unique feature of our research is that we are using levels of total uranium (ca. 10−6 to 10−4 mol per dm3 bulk volume) and aqueous/solid-phase ratios ((less-than or equal to) ca. 10−3 mol U per kg sediment) which are much closer to those present in contaminated subsurface environments compared to levels employed in previous experimental studies of microbial U(VI) reduction. The goal is to develop a more realistic picture of the dynamics of U(VI) reduction and its interaction with Fe(III) oxide reduction in subsurface sedimentary environments. In doing so, our studies will provide benchmark information on process dynamics that will be useful for scaling up (e.g. through the use of field-scale reactive transport models) to in situ treatment scenarios. In addition, the experimental methodologies and modeling strategies developed for the project may applicable to the evaluation of in situ remediation technologies for other redox-sensitive metal-radionuclide contaminants such as Cr(VI) and Tc(VII). Numerical simulations are being developed hand-in-hand with the experimental work to aid in the interpretation of the observed dynamics of U(VI) behavior, and to contribute to the development of a predictive framework for assessing in situ metal-radionuclide remediation strategies driven by the activity of DMRB.
Download or read book Microbial Characterization of a Radionuclide and Metal contaminated Waste Site written by and published by . This book was released on 1993 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: The operation of nuclear processing facilities and defense-related nuclear activities has resulted in contamination of near-surface and deep-subsurface sediments with both radionuclides and metals. The presence of mixed inorganic contaminants may result in undetectable microbial populations or microbial populations that are different from those present in uncontaminated sediments. To determine the impact of mixed radionuclide and metal contaminants on sediment microbial communities, we sampled a processing pond that was used from 1948 to 1975 for the disposal of radioactive and metal-contaminated wastewaters from laboratories and nuclear fuel fabrication facilities on the Hanford Site in Washington State. Because the Hanford Site is located in a semiarid environment with average rainfall of 159 mm/year, the pond dried and a settling basin remained after wastewater input into the pond ceased in 1975. This processing pond basin offered a unique opportunity to obtain near-surface sediments that had been contaminated with both radionuclides and metals for several decades. Our objectives were to determine the viable populations of microorganisms in the sediments and to test several hypotheses about how the addition of both radionuclides and metals influenced the microbial ecology of the sediments. Our first hypothesis was that viable populations of microorganisms would be lower in the more contaminated sediments. Second, we expected that long-term metal exposure would result in enhanced metal resistance. Finally, we hypothesized that microorganisms from the most radioactive sediments should have had enhanced radiation resistance.
Download or read book Structure and Function of Subsurface Microbial Communities Affecting Radionuclide Transport and Bio immobilization written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this study was to provide comparative information regarding the changes in clay structure that occur due to biotic or abiotic reduction, as probed by variable-temperature MÃœssbauer spectroscopy.
Download or read book Role of Viruses Infecting Bacteria in Subsurface Sediments and Groundwater written by Donald Pan and published by . This book was released on 2015 with total page 215 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microorganisms play a fundamental role driving geochemical cycles. Viruses are the most abundant biological entity on Earth and often exceed cells. While microbiota influence geochemical cycling in the subsurface, the role of subsurface viruses is poorly understood. Viruses were investigated in relationship to carbon biogeochemistry within two aquifers. In the first study, subsurface sediment slurries collected in Alda, NE were amended with 13C-labeled organic carbon (OC) as acetate and nitrate. Biostimulation resulted in viral production concurrent with OC mineralization and nitrate reduction. Change in viral abundance was positively correlated to OC consumption (r 2=0.63) and 13CO2 production ( r2=0.66), whereas change in cell abundance was not, indicating that viruses lyse active cells. Change in viral abundance also correlated to changes in community structure (Gammaproteobacteria and Betaproteobacteria). In the second study, viral production was demonstrated in response to geochemical changes resulting from in-situ biostimulation (O2 injection) of an aquifer in Rifle, CO. Oxygenated groundwater injected into a previously bioreduced zone resulted in a decrease in reduction potential from -146-- -132mV to -317-- -304mV. Virus abundance increased 1.1x10 6--2.1x106 viruses/mL to 2.3x106--4.6x10 6 while cell abundance did not change. Virus-to-cell ratio increased 1.8-3.4 fold from 3.9-10.1 to 11.0-17.9, demonstrating stimulation of viral production. This supports the findings from the first study which showed that viruses are produced by stimulation of microbial activity. This occurred in conjunction with fluctuations in dissolved organic carbon (DOC) and reduction of U and Fe(III). When injection paused, U was oxidized. But at a higher rate (2.5x), U oxidation occurred, indicating that NRZs maintain a redox buffer which can be overcome when oxidants increase above a tipping point. After mineral precipitation occurred, viruses decreased from 2.3x106-4.6x10 6 viruses/mL to 3.2x105-2.4x106 , suggesting that viruses were removed from solution by adsorption or mineral precipitation. Lastly, the entire floodplain was examined under natural conditions. Viral and cell abundances were correlated (r s=0.73) to each other and to DOC (rs=0.46,0.53; respectively). Thus, viruses play a role in carbon biogeochemistry and indicate microbial activity. Viruses influence subsurface carbon cycling by infecting and lysing cells, liberating OC, thereby influencing the structure and function of microbial communities. Prokaryotes cannot be considered as the sole biological force in the subsurface. Viruses will influence carbon bioavailability and biogeochemical cycling.
Download or read book Assessment of Bacterial Communities and an Iron reducing Bacterium in Relation to an Engineered Bioremediation System Designed for the Treatment of Uranium nitric Acid Contaminated Groundwater written by Chiachi Hwang and published by . This book was released on 2009 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: The elucidation of how populations of interest interact in a given community and how the community responds to stress and perturbations can provide insight into the interplay between stress pathways and gene networks that help optimize bacterial biochemistry. The goal of the present study was to characterize the responses of bacterial communities at multiple levels of resolution to understand microbial biochemical capacity at DOE waste sites. The field work at the Field Research Center of the U.S. Department of Energy, Oak Ridge, TN, used a field scale denitrifying fluidized bed reactor (FBR) for nitrate treatment of the groundwater and a series of wells to stimulate microbial growth via ethanol for in situ U(VI) immobilization. Bacterial community dynamics were investigated during the initial start-up of the FBR while those from the groundwater of the wells were studied over a 1.5-yr period. In addition, the physiology and the genome of the isolate, Anaeromyxobacter Fw109-5, from the site were studied to examine its potential role in U(VI) remediation. The subsurface environment was altered via engineering controls during successive phases to better understand strategies that would improve the remediation process. Within this framework, the interrelationship of bacterial communities and geochemistry was studied at different spatial and temporal scales to characterize the ecosystem ecology of an engineered system. Bacterial communities from both FBR and groundwater samples were analyzed via clone libraries of partial SSU rRNA genes. Multivariate analyses were applied to correlate the changes in the bacterial communities to the measured physicochemical parameters. Our results from the field experiments indicated that there was an important interaction between the engineering controls that altered the subsurface geochemistry over time that influenced bacterial population responses. Growth study experiments and genomic analysis also revealed insights to the physiological potential of an iron-reducing isolate, Anaeromyxobacter Fw109-5. The strong associations between particular environmental variables and certain population distributions will provide insights into establishing practical and successful remediation strategies in radionuclide-contaminated environments with respect to engineering controls.
