Download or read book Reduction and Immobilization of Uranium in the Subsurface written by and published by . This book was released on 2015 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Effects of Bicarbonate and Mineral Surfaces on Uranium Immobilization Under Anaerobic Conditions written by Luis A. Jurado and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: For four decades, from 1940 through 1980, the U.S. Department of Energy (DoE) extensively mined and processed uranium at various sites. As a result, widespread uranium contamination exists in subsurface sediments and aquifers. In subsurface environments, uranium primarily exists as U(VI) or U(IV), oxidized and reduced species, respectively. U(VI) is highly soluble and toxic, U(IV), while relatively toxic, is insoluble which greatly reduces its exposure pathways. We seek to examine the role of ferric iron on U(VI) reduction by adsorbing U(VI) onto ferric and non-ferric mineral surfaces in the presence of a reductant. Further, we seek to understand the role that NaHCO3, a natural groundwater buffer, has in the reductive geochemical transformations of U(VI) adsorbed on ferric and non-ferric mineral surfaces. Bench top studies were performed using 100 uM U(VI) and the reductant AHQDS, in the presence and absence of Fe-Gel (amorphous ferric oxyhydroxide) and gamma-Al2O3. In the presence of a HEPES buffer at pH 8, results demonstrate direct homogeneous reduction in several hours in the absence of Fe-Gel or gamma-Al2O3, and reduction within a 48-hour period in the presence Fe-Gel or gamma-Al2O3. While adsorbed to both ferric and non-ferric mineral surfaces, U(VI) reduction is inhibited. U(VI) reduction in the presence of NaHCO3 buffer also inhibits U(VI) reduction.

Download or read book Idet written by and published by . This book was released on 1950 with total page 319 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Biostimulation of Iron Reduction and Uranium Immobilization 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 Florida State University (FSU), Rutgers University (RU), and the University of Illinois (U of I). FSU served as the lead institution and Dr. J.E. Kostka was responsible for project coordination, integration, and deliverables. This project was designed to elucidate the microbial ecology and geochemistry of metal reduction in subsurface environments at the U.S. DOE-NABIR Field Research Center at Oak Ridge, Tennessee (ORFRC). Our objectives were to: 1) characterize the dominant iron minerals and related geochemical parameters likely to limit U(VI) speciation, 2) directly quantify reaction rates and pathways of microbial respiration (terminal-electron-accepting) processes which control subsurface sediment chemistry, and 3) identify and enumerate the organisms mediating U(VI) transformation. A total of 31 publications and 47 seminars or meeting presentations were completed under this project. One M.S. thesis (by Nadia North) and a Ph. D. dissertation (by Lainie Petrie-Edwards) were completed at FSU during fall of 2003 and spring of 2005, respectively. Ph. D. students, Denise Akob and Thomas Gihring have continued the student involvement in this research since fall of 2004. All of the above FSU graduate students were heavily involved in the research, as evidenced by their regular attendance at PI meetings and ORFRC workshops.

Download or read book Microbially Mediated Reduction and Immobilization of Uranium in Aquifers at Konigstein Germany Using Indigenous Bacteria written by Zhu Chen and published by . This book was released on 2001 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dominant Mechanisms of Uranium VI phosphate Interactions in Subsurface Environments written by Vrajesh Sanat Mehta and published by . This book was released on 2014 with total page 191 pages. Available in PDF, EPUB and Kindle. Book excerpt: Anthropogenic activities associated with the production of nuclear materials have resulted in uranium contaminated soil and groundwater. The carcinogenic and toxic effects of uranium contamination pose a significant risk to the environment and human health. Phosphate addition to uranium-contaminated subsurface environments has been proposed as a strategy for in situ remediation. Addition of phosphate amendments can result in uranium sequestration in its oxidized +VI state without sustaining reducing conditions as is needed for in situ immobilization via chemical or biological reduction of U(VI) to less soluble U(IV) species. Phosphate addition can be used as a stand-alone process or as a complementary process to bioremediation-based methods, especially for sites with naturally oxic conditions. Although recent studies have reported phosphate-induced precipitation of U(VI)-phosphates in laboratory and field-scale tests, the fundamental mechanisms controlling U(VI) immobilization are not well known. Hence understanding the mechanisms at the microscopic and molecular levels is imperative to successfully designing and implementing phosphate-based in situ uranium immobilization. Interactions with phosphate can result in uranium immobilization through various processes. This study investigated the dominant mechanisms of U(VI)-phosphate reactions using an integrated approach of aqueous phase and solid phase characterization techniques. Batch experiments were performed to study the effect of pH and co-solutes (dissolved inorganic carbon (DIC), Na+ and Ca2+) on the products and solubility of uranium(VI) precipitated with phosphate. The results suggested that in the absence of co-solute cations, chernikovite [H3O(UO2)(PO4)·3H2O] precipitated despite uranyl orthophosphate [(UO2)3(PO4)2·4H2O] being thermodynamically more favorable under certain conditions. The presence of Na+ as a co-solute led to the precipitation of sodium autunite [Na2(UO2)2(PO4)2], and the dissolved U(VI) concentrations were generally in agreement with equilibrium predictions of sodium autunite solubility. In the calcium-containing systems, the observed concentrations were below the predicted solubility of autunite [Ca(UO2)2(PO4)2]. Consequently, specific batch studies were conducted to investigate the dependence of U(VI) uptake mechanisms on the starting forms of calcium and phosphate at concentrations relevant to field sites. Depending on the experimental conditions, uranium uptake occurred through adsorption on calcium-phosphate solids, precipitation of autunite, or incorporation into a calcium-phosphate solid. Extended X-ray absorption fine structure (EXAFS) spectroscopy analysis using structural model fittings and linear combination fitting allowed quantification of the contribution of each uranium uptake mechanism mentioned above. Following the batch experiments with simple systems, the effect of phosphate amendment on uranium immobilization was evaluated for sediments obtained from a field site in Rifle, Colorado using batch sorption studies and column experiments. Batch sorption studies showed that phosphate addition increased the U(VI) adsorption, however the net uranium uptake was limited due to the dominance of the aqueous speciation by Ca-U(VI)-carbonate complexes. Column experiments were performed under conditions that simulated the subsurface environment at the Rifle site. Remobilization experiments showed increased retention of uranium when phosphate was present in uranium-free influent. The response of dissolved uranium concentrations to stopped-flow events and the comparison of experimental data with a simple reactive transport model indicated that uranium transport was controlled by non-equilibrium processes. Intraparticle diffusion is thought to be acting as the rate-limiting process. Sequential extractions and laser induced fluorescence spectroscopy (LIFS) analysis indicated that adsorption was the dominant mode of uranium immobilization. When uranium and phosphate were added concurrently to columns packed with sediments, significant uptake of uranium continued as long as phosphate was present in the influent. Even when phosphate was removed from the influent, the columns retained significant amounts (~ 67 %) of the accumulated uranium. Sequential extractions showed that the uranium accumulated transformed into less easily extractable (i.e., more immobile) species with the relative amounts of accumulated uranium extracted in the acetic acid and hot acid digestion step being highest for the column that was treated with phosphate for the longest duration. The uranium retained in the sediments after the phosphate was removed from the influent was primarily in a form that could be extracted with acetic acid and ammonium acetate. The extraction results, aqueous phase analysis and LIFS analysis showed that uranium uptake occurred through multiple processes. For select conditions, EXAFS analysis was used to quantify the contribution of uranium uptake which confirmed that uranium uptake occurred through a combination of precipitation and adsorption. The information gained from this research project improved our understanding of U(VI)-phosphate reactions that can be used to identify and manipulate the conditions that lead to the greatest decreases in U(VI) mobility. The results illustrate that precipitation of uranyl-phosphates is not the only means of in situ uranium remediation and that a wide range of uranium immobilization mechanisms can control uranium mobility following phosphate addition. Although phosphate addition led to significant retardation of uranium release and also resulted in increased net uptake of uranium for conditions of the Rifle site, phosphate amendments could be more beneficial at sites with lower pH and dissolved inorganic carbon concentrations.

Download or read book Uranium Immobilization Via Phosphate Injection Into the Subsurface at the Hanford 300 Area written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Coupled Biogeochemical Processes for the Reduction and Immobilization of Uranium written by Harish Veeramani and published by . This book was released on 2010 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Uranium Immobilization by Cellulomonas Sp ES6 written by Vaideeswaran Sivaswamy and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Phosphate in Soils written by H. Magdi Selim and published by CRC Press. This book was released on 2018-10-08 with total page 381 pages. Available in PDF, EPUB and Kindle. Book excerpt: Edited by One of the Best Specialists in Soil Science Recent studies reveal that Phosphorus (P) in the form of phosphate, a macronutrient essential for plant growth, and crop yields can influence the bioavailability, retention, and mobility of trace elements, metal(loid)s, and radio nuclides in soils. When this occurs, phosphates can affect the dynamics of heavy metals and influence soil characteristics, impacting soil mobility and toxicity. Phosphate in Soils: Interaction with Micronutrients, Radionuclides and Heavy Metals utilizes the latest research to emphasize the role that phosphate plays in enhancing or reducing the mobility of heavy metals in soil, and the soil-water-plant environment. It provides an in-depth understanding of each heavy metal species, and expands on phosphate interactions in geological material. Composed of 12 chapters, this text: Provides an overview of the reactions of metal(loid)s and common P compounds that are used as fertilizer in soils Emphasizes the effect of phosphorus on copper and zinc adsorption in acid soils Discusses findings on the influence of phosphate compounds on speciation, mobility, and bioavailability of heavy metals in soils as well as the role of phosphates on in situ and phytoremediation of heavy metals for contaminated soils Places emphasis on the influence of phosphate on various heavy metals species in soils, and their solubility/mobility and availability Provides extensive information on testing various high phosphate materials for remediation of heavy metal, micronutrients, and radionuclides contaminated sites Explores the reactivity of heavy metals, micronutrients and radionuclides elements in several soils Presents a case study illustrating various remediation efforts of acidic soils and remediation of Cu, Zn, and lead (Pb) contaminated soils around nonferrous industrial plants Emphasizes the significance of common ions (cations and anions) on phosphate mobility and sorption in soils, and more The author includes analytical and numerical solutions along with hands-on applications, and addresses other topics that include the transport and sorption modeling of heavy metals in the presence of phosphate at different scales in the vadose zone.

Download or read book Microbial Interactions at Nanobiotechnology Interfaces written by R. Navanietha Krishnaraj and published by John Wiley & Sons. This book was released on 2021-11-02 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt: MICROBIAL INTERACTIONS AT NANOBIOTECHNOLOGY INTERFACES This book covers a wide range of topics including synthesis of nanomaterials with specific size, shape, and properties, structure-function relationships, tailoring the surface of nanomaterials for improving the properties, interaction of nanomaterials with proteins/microorganism/eukaryotic cells, and applications in different sectors. This book also provides a strong foundation for researchers who are interested to venture into developing functionalized nanomaterials for any biological applications in their research. Practical concepts such as modelling nanomaterials, and simulating the molecular interactions with biomolecules, transcriptomic or genomic approaches, advanced imaging techniques to investigate the functionalization of nanomaterials/interaction of nanomaterials with biomolecules and microorganisms are some of the chapters that offer significant benefits to the researchers.

Download or read book An Introduction to Nuclear Waste Immobilisation written by Michael I. Ojovan and published by Elsevier. This book was released on 2010-07-07 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt: Safety and environmental impact is of uppermost concern when dealing with the movement and storage of nuclear waste. The 20 chapters in 'An Introduction to Nuclear Waste Immobilisation' cover all important aspects of immobilisation, from nuclear decay, to regulations, to new technologies and methods. Significant focus is given to the analysis of the various matrices used in transport: cement, bitumen and glass, with the greatest attention being given to glass. The last chapter concentrates on the performance assessment of each matrix, and on new developments of ceramics and glass composite materials, thermochemical methods and in-situ metal matrix immobilisation. The book thoroughly covers all issues surrounding nuclear waste: from where to locate nuclear waste in the environment, through nuclear waste generation and sources, treatment schemes and technologies, immobilisation technologies and waste forms, disposal and long term behaviour. Particular attention is paid to internationally approved and worldwide-applied approaches and technologies.* Each chapter focuses on a different matrix used in nuclear waste immobilisation: Cement, bitumen, glass and new materials.* Keeps the most important issues surrounding nuclear waste – such as treatment schemes and technologies, and disposal - at the forefront.

Download or read book Emerging Environmental Technologies Volume II written by Vishal Shah and published by Springer Science & Business Media. This book was released on 2009-12-02 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt: Within the span of last couple of years, the increasing human interference with v- ious natural ecosystems and higher discharge of pollutants has presented numerous challenges to the society related to preserving the nature for a better tomorrow. The challenges also mount pressure on the scienti?c community to invent technologies that would provide solutions to the problems that are man made and also decrease the negative consequences that we are facing because of our own actions. This edited book attempts to present eight technological innovations that have shown potential to provide answers to a few challenges. Like the previous collection, the described innovations in the current volume also cover a range of areas including water and soil pollution, bio-sensors and energy. However, it is to be realized that no combination of technology can be enough to make a sizeable difference. As I said in my last collection, technological advances have to be integrated with a change in social behavior. The philosophy of sustainable development has to be the principle of future planning and growth. In this collection, I am pleased to include an article on noise pollution. Noise is a pollutant of our own behavior and can only be solved by a behavioral change. The change that is either voluntary or enforced by laws. As an environmental scientist noise is not normally a pollutant that would come in mind as a leading pollutant.

Download or read book An Introduction to Nuclear Waste Immobilisation written by Michael I Ojovan and published by Elsevier. This book was released on 2013-12-06 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Drawing on the authors' extensive experience in the processing and disposal of waste, An Introduction to Nuclear Waste Immobilisation, Second Edition examines the gamut of nuclear waste issues from the natural level of radionuclides in the environment to geological disposal of waste-forms and their long-term behavior. It covers all-important aspects of processing and immobilization, including nuclear decay, regulations, new technologies and methods. Significant focus is given to the analysis of the various matrices used, especially cement and glass, with further discussion of other matrices such as bitumen. The final chapter concentrates on the performance assessment of immobilizing materials and safety of disposal, providing a full range of the resources needed to understand and correctly immobilize nuclear waste.

Download or read book Microbial Metal and Metalloid Metabolism written by John F. Stolz and published by American Society for Microbiology Press. This book was released on 2011-08-02 with total page 562 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ideal reference for novice and experienced investigators interested in environmental biogeochemistry and bioremediation. • Offers a broad range of current topics and approaches in microbe-metal research, including microbial fuel cells, unique microbial physiology, genomics, proteomics, and transcriptomics. • Reviews the current state of the science in the field, and examines emerging developments and applications and forecasts future research directions. • The book is also recommended as a text for graduate courses in microbial physiology, microbial ecology, and applied and environmental microbiology.

Download or read book Experimental and Theoretical Approaches to Actinide Chemistry written by John K. Gibson and published by John Wiley & Sons. This book was released on 2018-03-19 with total page 534 pages. Available in PDF, EPUB and Kindle. Book excerpt: A review of contemporary actinide research that focuses on new advances in experiment and theory, and the interplay between these two realms Experimental and Theoretical Approaches to Actinide Chemistry offers a comprehensive review of the key aspects of actinide research. Written by noted experts in the field, the text includes information on new advances in experiment and theory and reveals the interplay between these two realms. The authors offer a multidisciplinary and multimodal approach to the nature of actinide chemistry, and explore the interplay between multiple experiments and theory, as well as between basic and applied actinide chemistry. The text covers the basic science used in contemporary studies of the actinide systems, from basic synthesis to state-of-the-art spectroscopic and computational techniques. The authors provide contemporary overviews of each topic area presented and describe the current and anticipated experimental approaches for the field, as well as the current and future computational chemistry and materials techniques. In addition, the authors explore the combination of experiment and theory. This important resource: Provides an essential resource the reviews the key aspects of contemporary actinide research Includes information on new advances in experiment and theory, and the interplay between the two Covers the basic science used in contemporary studies of the actinide systems, from basic synthesis to state-of-the-art spectroscopic and computational techniques Focuses on the interplay between multiple experiments and theory, as well as between basic and applied actinide chemistry Written for academics, students, professionals and researchers, this vital text contains a thorough review of the key aspects of actinide research and explores the most recent advances in experiment and theory.