Download or read book Investigating Controls on Variation in Isotopic Fractionation During Biodegradation of Chlorinated Ethenes and Ethanes written by Lisa Marie Douglas and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Kinetic isotope effects occur due to different reaction rates for light and heavy isotope-containing molecules, and are controlled by the bonds broken during degradation. For many primary pollutants, stable carbon, hydrogen, and chlorine isotope effects have been found to fit a Rayleigh model, indicating a single rate-limiting step. This thesis examines biodegradation pathways where additional controls and rate-limiting steps may affect observed isotope fractionation. Two haloalkane dehalogenases catalyzed aerobic 1,2-dichloroethane (1,2-DCA) dechlorination with very different enzyme affinities and turnover rates. However, carbon isotope enrichment factors were the same for both enzymes, reflecting the intrinsic kinetic isotope effect associated with C-Cl bond breakage. Carbon isotope fractionation was also largely constant during anaerobic 1,1,1-trichloroethane (1,1,1-TCA) biodegradation, even when the rate of biodegradation was inhibited by trichloroethene (TCE) co-contamination. This finding provided the basis for carbon isotope-based assessment of 1,1,1-TCE biodegradation at a TCE co-contaminated field site. The wide range of carbon isotope fractionation observed for anaerobic tetrachloroethene (PCE) biodegradation has been a matter of longstanding controversy. This work found the magnitude of carbon isotope fractionation for PCE biodegradation is related to the phylogenetic relationships between PCE-degrading organisms, which may allow for better selection of enrichment factors when assessing PCE biodegradation at field sites. Unexpectedly large variations in carbon isotope fractionation have also been observed for anaerobic TCE biodegradation. During C-Cl bond breakage, slopes of dual element carbon and chlorine isotope effects are typically constant for a given reaction because additional rate-limiting steps affect both elements in a similar way. Hence, characteristic combinations of C/Cl isotope effects can be used to investigate the underlying mechanistic details of a reaction. For TCE biodegradation, C/Cl isotope slopes indicate different reductive dehalogenases may catalyze different reductive dechlorination reaction pathways. This thesis advances the application of compound specific isotope analysis for assessing bioremediation of chlorinated ethenes and ethanes, as well our understanding of the enzymatic degradation mechanisms that catalyze biodegradation.
Download or read book Investigating Mechanisms of Chlorinated Ethane Biotransformation Using Compound Specific Carbon Isotope Analysis written by Sarah Kathleen Hirschorn and published by . This book was released on 2007 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt: Stable carbon isotope fractionation during biotransformation of the chlorinated ethanes 1,2-dichloroethane (1,2-DCA), 1,1,1-trichloroethane (1,1,1-TCA) and 1,1-dichloroethane (1,1-DCA) was investigated. Isotopic fractionation during aerobic 1,2-DCA biotransformation in microcosms, enrichment cultures and pure microbial cultures was measured and was found to be pathway dependent. Biodegradation of 1,2-DCA under aerobic conditions produced a consistent bimodal distribution of enrichment factors (s) with one mean c centered on --3.9 +/- 0.6 and the other on --29.2 +/- 1.9. Reevaluation of epsilon in terms of kinetic isotope effects 12k/ 13k, gave values of 12k/13k = 1.01 and 1.06, which are typical of oxidation and hydrolytic dehalogenation (S N2) reactions, respectively. The relationship between degradation pathway and measured carbon isotope fractionation was applied to constrain the degradation pathway of 1,2-DCA in a microbial enrichment culture capable of degrading 1,2-DCA under both O2 and NO3-reducing conditions, but where the degradation pathway was previously uncharacterized. delta 13C values indicated biodegradation in the enrichment culture under both O2 and NO3-reducing conditions likely proceeded via a hydrolytic dehalogenase enzyme. Stable carbon isotope analysis during biotransformation of other chlorinated ethanes was then investigated. Isotopic enrichment factors of -1.9 and -10.4 were measured during reductive dechlorination of 1,1,1-trichloroethane (1,1,1-TCA) and 1,1-dichloroethane (1,1-DCA), respectively. These are the first reported isotopic enrichment factors for microbial biotransformation of these compounds, which can now potentially be applied to investigate and quantify biodegradation of 1,1,1-TCA and 1,1-DCA in the field. Stable carbon isotope analysis was used to provide a conservative estimate of the extent of 1,2-DCA and trichloroethene (TCE) biodegradation in a biostimulation field study. Isotope analysis was able to confirm that 1,2-DCA degradation, rather than degradation of vinyl chloride, was the primary mechanism of ethene production at the site. This thesis not only advances the application of compound specific carbon isotope fractionation to identify and quantify biodegradation of chlorinated ethanes in groundwater, but in particular progresses our understanding of the relationship between the enzymatic mechanisms of contaminant degradation and isotopic fractionation, and the ability to use that knowledge to predict degradation mechanisms for previously unconstrained pathways of contaminant remediation.
Download or read book Assessing Mechanisms of Isotopic Fractionation During Petroleum Hydrocarbon Biodegradation written by Silvia Alissa Mancini and published by . This book was released on 2007 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, mechanisms of carbon and hydrogen isotopic fractionation were investigated during biodegradation of petroleum hydrocarbons, benzene and toluene, in order to evaluate the potential to use Compound Specific Isotope Analysis (CSIA) to assess in situ biodegradation under various field conditions. Variation in carbon and hydrogen enrichment factors, determined using a Rayleigh model, was observed for benzene degradation under different terminal electron accepting processes in enrichment cultures derived from three field sites. This variation was controlled by different biodegradation pathways for the nitrate-reducing cultures, and the methanogenic and sulfate-reducing cultures, as determined by a two-element isotopic approach comparing delta 13C and delta2H values between degradation experiments. Significant differences in carbon and hydrogen enrichment factors were also observed in Pseudomonas putida mt-2 cultures grown under low and high iron concentrations during aerobic toluene biodegradation. These differences were related to changes in the rate-limiting steps of the enzyme-controlled reaction whereby a slower enzyme-catalyzed substrate conversion step (k 2) relative to the enzyme-substrate binding step (k-1) was suggested to occur. No significant differences in carbon and hydrogen isotopic fractionation were observed between a methanogenic enrichment culture and cell free extract experiments during toluene degradation. These results indicated that substrate transport across the cell membrane of the microorganisms involved in biodegradation did not influence isotopic fractionation in this culture.Overall, the results of this thesis demonstrated that resolvable differences in carbon and hydrogen isotopic fractionation were not random but occurred for different microbial communities, biodegradation pathways and growth conditions. Significant 13C and 2H enrichment occurred in all experiments carried out in this thesis, indicating that carbon and hydrogen CSIA has the potential to identify in situ biodegradation of benzene and toluene. In addition, the variability in carbon and hydrogen enrichment factors did not significantly impact the ability to use stable isotope analysis to quantify in situ biodegradation. The measurement of both carbon and hydrogen isotope analysis in laboratory experiments and a field study demonstrated that a two-element isotopic approach is the best approach to differentiate between in situ biodegradation and sources of groundwater contamination, as well as potentially delineate between biodegradation pathways.
Download or read book Compound specific Stable Isotope Analysis written by Maik A Jochmann and published by Royal Society of Chemistry. This book was released on 2015-11-09 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of Compound-specific Stable Isotope Analysis (CSIA) is increasing in many areas of science and technology for source allocation, authentication, and characterization of transformation reactions. Until now, there have been no textbooks available for students with an analytical chemical background or basic introductory books emphasising the instrumentation and theory. This book is the first to focus solely on stable isotope analysis of individual compounds in sometimes complex mixtures. It acts as both a lecture companion for students and a consultant for advanced scientists in fields including forensic and environmental science. The book starts with a brief history of the field before going on to explain stable isotopes from scratch. The different ways to express isotope abundances are introduced together with isotope effects and isotopic fractionation. A detailed account of the required technical equipment and general procedures for CSIA is provided. This includes sections on derivatization and the use of microextraction techniques in GC-IRMS. The very important topic of referencing and calibration in CSIA is clearly described. This differs from approaches used in quantitative analysis and is often difficult for the newcomer to comprehend. Examples of successful applications of CSIA in food authenticity, forensics, archaeology, doping control, environmental science, and extraterrestrial materials are included. Applications in isotope data treatment and presentation are also discussed and emphasis is placed on the general conclusions that can be drawn from the uses of CSIA. Further instrumental developments in the field are highlighted and selected experiments are introduced that may act as a basis for a short practical course at graduate level.
Download or read book The Geochemistry of Stable Chlorine and Bromine Isotopes written by Hans Eggenkamp and published by Springer. This book was released on 2014-08-25 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides detailed information on the history, analysis and applications of chlorine and bromine isotope geochemistry. Chlorine and bromine are geochemically unique as they prefer to exist as single charged negative ions. For this reason isotope fractionation reflects mostly processes that are not related to changes in the redox state and this fractionation is generally modest. The book will describe the processes that are most easily detected using these isotopes. Also isotope variations, and processes that cause them, measured in oxidised species such as perchlorates and in organic molecules will be described in this book.
Download or read book Water resources Investigations Report written by and published by . This book was released on 2002 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Transverse Dispersion in Liquid Flow Through Porous Media written by Eugene Sidney Simpson and published by . This book was released on 1962 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Environmental Isotopes in Biodegradation and Bioremediation written by C. Marjorie Aelion and published by CRC Press. This book was released on 2009-11-04 with total page 466 pages. Available in PDF, EPUB and Kindle. Book excerpt: Enhanced analytical capabilities and separation techniques, improved detection limits, and accessibility of instrumentation have led to massive strides in the use of isotopes to assess microbial processes in surface and subsurface sediments. Considering the rapid growth of research and commercial interest in stable isotope and radioisotope applicat
Download or read book Natural Attenuation of Chlorinated Volatile Organic Compounds in Ground Water at Operable Unit 1 Naval Undersea Warfare Center Division Keyport Washington written by Richard Steven Dinicola and published by . This book was released on 2002 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Organohalide Respiring Bacteria written by Lorenz Adrian and published by Springer. This book was released on 2016-08-03 with total page 620 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book summarizes the current state of knowledge concerning bacteria that use halogenated organic compounds as respiratory electron acceptors. The discovery of organohalide-respiring bacteria has expanded the range of electron acceptors used for energy conservation, and serves as a prime example of how scientific discoveries are enabling innovative engineering solutions that have transformed remediation practice. Individual chapters provide in-depth background information on the discovery, isolation, phylogeny, biochemistry, genomic features, and ecology of individual organohalide-respiring genera, including Dehalococcoides, Dehalogenimonas, Dehalobacter, Desulfitobacterium and Sulfurospirillum, as well as organohalide-respiring members of the Deltaproteobacteria. The book introduces readers to the fascinating biology of organohalide-respiring bacteria, offering a valuable resource for students, engineers and practitioners alike.
Download or read book Chlorinated Solvents written by Robert D Morrison and published by Royal Society of Chemistry. This book was released on 2015-11-09 with total page 437 pages. Available in PDF, EPUB and Kindle. Book excerpt: Environmental forensics is emerging and evolving into a recognized scientific discipline with numerous applications, especially regarding chlorinated solvents. This unique book provides the reader with a concise compilation of information regarding the use of environmental forensic techniques for age dating and identification of the source of a chlorinated solvent release. Concentrating on the five commonly encountered chlorinated solvents (perchloroethylene, trichloroethylene, methyl chloroform, carbon tetrachloride and CFC-113), forensic opportunities applicable to each are presented including the use of stabilizers, manufacturing impurities, surrogate chemicals and physical measurements and degradation products as diagnostic indicators. Detailed historical chronology of the applications of the solvents and specific chapters devoted to dry cleaning and vapor degreasing equipment are included as are generic forensic approaches. Forming a basis for further ideas in the evolution of environmental forensic techniques, Chlorinated Solvents will be an indispensable reference tool for researchers, regulators and analysts in the field.
Download or read book Isotope Effects In Chemistry and Biology written by Amnon Kohen and published by CRC Press. This book was released on 2005-11-01 with total page 1092 pages. Available in PDF, EPUB and Kindle. Book excerpt: The field of isotope effects has expanded exponentially in the last decade, and researchers are finding isotopes increasingly useful in their studies. Bringing literature on the subject up to date, Isotope Effects in Chemistry and Biology covers current principles, methods, and a broad range of applications of isotope effects in the physical, biolo
Download or read book Alternatives for Managing the Nation s Complex Contaminated Groundwater Sites written by National Research Council and published by National Academies Press. This book was released on 2013-02-27 with total page 423 pages. Available in PDF, EPUB and Kindle. Book excerpt: Across the United States, thousands of hazardous waste sites are contaminated with chemicals that prevent the underlying groundwater from meeting drinking water standards. These include Superfund sites and other facilities that handle and dispose of hazardous waste, active and inactive dry cleaners, and leaking underground storage tanks; many are at federal facilities such as military installations. While many sites have been closed over the past 30 years through cleanup programs run by the U.S. Department of Defense, the U.S. EPA, and other state and federal agencies, the remaining caseload is much more difficult to address because the nature of the contamination and subsurface conditions make it difficult to achieve drinking water standards in the affected groundwater. Alternatives for Managing the Nation's Complex Contaminated Groundwater Sites estimates that at least 126,000 sites across the U.S. still have contaminated groundwater, and their closure is expected to cost at least $110 billion to $127 billion. About 10 percent of these sites are considered "complex," meaning restoration is unlikely to be achieved in the next 50 to 100 years due to technological limitations. At sites where contaminant concentrations have plateaued at levels above cleanup goals despite active efforts, the report recommends evaluating whether the sites should transition to long-term management, where risks would be monitored and harmful exposures prevented, but at reduced costs.
Download or read book Novel Approaches for Bioremediation of Organic Pollution written by Raffi Fass and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 353 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of the 42nd OHOLO Conference held in Eilat, Israel, May 3-7, 1998
Download or read book Advanced Oxidation Processes for Water Treatment written by Mihaela I. Stefan and published by IWA Publishing. This book was released on 2017-09-15 with total page 712 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced Oxidation Processes (AOPs) rely on the efficient generation of reactive radical species and are increasingly attractive options for water remediation from a wide variety of organic micropollutants of human health and/or environmental concern. Advanced Oxidation Processes for Water Treatment covers the key advanced oxidation processes developed for chemical contaminant destruction in polluted water sources, some of which have been implemented successfully at water treatment plants around the world. The book is structured in two sections; the first part is dedicated to the most relevant AOPs, whereas the topics covered in the second section include the photochemistry of chemical contaminants in the aquatic environment, advanced water treatment for water reuse, implementation of advanced treatment processes for drinking water production at a state-of-the art water treatment plant in Europe, advanced treatment of municipal and industrial wastewater, and green technologies for water remediation. The advanced oxidation processes discussed in the book cover the following aspects: - Process principles including the most recent scientific findings and interpretation. - Classes of compounds suitable to AOP treatment and examples of reaction mechanisms. - Chemical and photochemical degradation kinetics and modelling. - Water quality impact on process performance and practical considerations on process parameter selection criteria. - Process limitations and byproduct formation and strategies to mitigate any potential adverse effects on the treated water quality. - AOP equipment design and economics considerations. - Research studies and outcomes. - Case studies relevant to process implementation to water treatment. - Commercial applications. - Future research needs. Advanced Oxidation Processes for Water Treatment presents the most recent scientific and technological achievements in process understanding and implementation, and addresses to anyone interested in water remediation, including water industry professionals, consulting engineers, regulators, academics, students. Editor: Mihaela I. Stefan - Trojan Technologies - Canada
Download or read book Contaminants in the Subsurface written by National Research Council and published by National Academies Press. This book was released on 2005-04-23 with total page 371 pages. Available in PDF, EPUB and Kindle. Book excerpt: At hundreds of thousands of commercial, industrial, and military sites across the country, subsurface materials including groundwater are contaminated with chemical waste. The last decade has seen growing interest in using aggressive source remediation technologies to remove contaminants from the subsurface, but there is limited understanding of (1) the effectiveness of these technologies and (2) the overall effect of mass removal on groundwater quality. This report reviews the suite of technologies available for source remediation and their ability to reach a variety of cleanup goals, from meeting regulatory standards for groundwater to reducing costs. The report proposes elements of a protocol for accomplishing source remediation that should enable project managers to decide whether and how to pursue source remediation at their sites.
Download or read book Bioaugmentation for Groundwater Remediation written by Hans F. Stroo and published by Springer Science & Business Media. This book was released on 2012-10-02 with total page 421 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume provides a review of the past 10 to 15 years of intensive research, development and demonstrations that have been on the forefront of developing bioaugmentation into a viable remedial technology. This volume provides both a primer on the basic microbial processes involved in bioaugmentation, as well as a thorough summary of the methodology for implementing the technology. This reference volume will serve as a valuable resource for environmental remediation professionals who seek to understand, evaluate, and implement bioaugmentation.
