Download or read book Investigation of Stable Carbon Compound Specific Isotope Analysis to Monitor and Quantify the Biodegradation of Chlorinated Ethenes in Groundwater Systems written by Penny Lea Morrill and published by . This book was released on 2004 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt: Identification and quantification of chlorinated ethene biodegradation were investigated using carbon compound specific isotope analysis (CSIA). A dynamic headspace sampling technique was developed and shown to be a robust, simple and effective method for isotopic analysis of dissolved chlorinated ethenes at low concentrations ([mu]g/L). This technique was used to monitor the biodegradation of tetrachloroethene (PCE) to ethene at a contaminated field site. At the field site, significant isotopic fractionation characteristic of biodegradation was observed in the isotope values of PCE and its degradation products trichloroethene (TCE), cis -1,2-dichloroethene (cDCE), and vinyl chloride (VC). During this study, stable carbon isotope analysis also provided one of the earliest lines of evidence for biodegradation. In laboratory and field experiments with an emplaced PCE dense nonaqueous phase liquid (DNAPL) source, isotopic fractionation was observed in the isotope values of the dechlorination intermediates produced by biodegradation, but not in the aqueous PCE near the DNAPL. These results confirm the hypothesis that isotopic fractionation due to biodegradation will not be observed in aqueous PCE close to the source zone. A model was developed to predict concentration values from isotope data for each step in the sequential reaction of PCE to non-toxic ethene. ...

Download or read book Investigation of Stable Carbon Compound Specific Isotope Analysis to Monitor and Quantify the Biodegradation Fo Chlorinated Ethenes in Groundwater Systems written by Penny Lea Morrill and published by . This book was released on 2005 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Constraining the Fate of Chlorinated Ethenes in Groundwater Systems Using Stable Carbon Compound Specific Isotope Analysis written by Gregory Franklin Slater and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The isotopic effects of subsurface processes on the stable carbon isotopic composition, [delta]13C, of chlorinated ethenes were investigated using Compound Specific Isotope Analysis (CSIA). Headspace analysis was determined to be a robust, simple and effective method for sample preparation and analysis using Gas Chromatography-Combustion-Isotope Ratio Mass Spectrometry (GC-C-IRMS). No significant isotopic fractionation (>0.5 ‰) was observed during equilibrium volatilization of the chlorinated ethenes from aqueous solution. Further, no significant isotopic fractionation (>0.5 ‰) was associated with equilibrium sorption of TCE and PCE. These results confirmed the hypothesis that non-degradative, physical subsurface processes would not result in significant isotopic fractionation of the [delta]13C of the chlorinated ethenes. In contrast, degradation of the chlorinated ethenes resulted in large isotopic enrichments of the residual reactant in 13C, consistent with preferential reaction of molecules containing the lighter 12C isotope. This isotopic enrichment could be described by a Rayleigh model enrichment factor ([epsilon]). Rayleigh enrichment factors ([epsilon]) described isotopic fractionation of the chlorinated ethenes during microbial reductive dechlorination of most of the chlorinated ethenes, during abiotic reductive dechlorination of TCE by zero-valent iron, and during aerobic co-metabolic degradation of TCE by toluene ortho-monooxygenase. Enrichment factors varied with specific microbial consortia, with degradation pathway (reductive dechlorination versus aerobic co-metabolism); and for abiotic experiments, with different iron types and surface treatments. The observation of these isotopic enrichment trends indicated that CSIA can provide direct evidence of the occurrence of chlorinated ethene degradation in the field, independent of mass loss due to non-degradative subsurface processes. CSIA was applied at three field sites. These studies confirmed that the [delta] 13CTCE can be conserved at a site where plume geometry is controlled by advective and partitioning processes. Most importantly, they confirmed that CSIA could give direct confirmation of the occurrence of degradation of the chlorinated ethenes at field sites. Therefore CSIA of the [delta] 13C of the chlorinated ethenes represents a powerful tool for the investigation and monitoring of sources and fate of chlorinated ethenes in subsurface systems.

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 Use of Stable Isotopoe Analyses to Assess Natural Attenuation of Chlorinated Ethenes in Groundwater written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Chlorinated ethenes are among the most frequently detected groundwater contaminants in industrially developed countries. Although their degradation pathways have been understood, assessing the progress of natural attenuation of chlorinated ethenes still remains a challenge. This thesis explored the possibilities and limits of the use of compound-specific stable isotope analysis as a field investigation tool to document and to quantify the progress of natural attenuation of chlorinated ethenes. The thesis focused particularly on the fate of reductive dechlorination intermediates such as cis-dichloroethene (cDCE) and vinyl chloride (VC) as the success of natural attenuation of chlorinated ethenes depends principally on the fate of these compounds. Two field investigations were carried out to demonstrate the use of stable isotope analysis to characterize the progress of natural attenuation of chlorinated ethenes. One site was characterized as a complex hydrological and geochemical system at the groundwater-surface water interface where a tetrachloroethene- (PCE) plume discharged through the streambed. Another site was located under relatively stable hydrological conditions and characterized by a 2-km long plume of chlorinated ethenes. Laboratory studies evaluated the use of combined carbon and chlorine isotope analysis to distinguish different degradation pathways of cDCE and VC, and the same approach was employed at a field site to determine the fate of cDCE. Numerical studies evaluated the field applicability of isotope-based quantification, according to the Rayleigh isotope fractionation model, to estimate the extent of degradation and the first-order reaction rate under various flow conditions. In addition, a scheme to quantify the reductive dechlorination rates of chlorinated ethenes based on field concentration and isotope data at one of the field sites was proposed and evaluated with a series of 3D analytical solutions to accommodate sequential reactions. The stu.

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 Constraining the Fate of Chlorinated Ethenes in Groundwater Systems Using Stable Carbon Compound Specific Isotope Analysis microform written by Gregory Franklin Slater and published by National Library of Canada = Bibliothèque nationale du Canada. This book was released on 2001 with total page 462 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Compound Specific Stable Isotope Analysis written by Safdar Bashir and published by Sudwestdeutscher Verlag Fur Hochschulschriften AG. This book was released on 2014-08-12 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the most promising tools for both characterizing contaminant sources and monitoring in situ degradation of organic contaminants in aquifers is compound-specific stable isotope analysis, in which the stable isotope ratios of one or more elements in a given compound are measured in order to investigate the transformation processes at work.The objective of this book was to validate the application of carbon-compound specific stable isotope analysis (CSIA) and enantiomer specific stable isotope analysis (ESIA) to characterize biotic and abiotic transformation of Hexachlorocyclohexane (HCH) in situ. Additionally, to prove that CSIA in combination with enantiomer-selective degradation of -HCH can be applied as an effective and reliable tool for monitoring natural attenuation of HCH. The variability in enrichment factors observed for enantiomers during biotic investigation showed the preferential reactivity of enzymes for one enantiomer over the other which is not observed in abiotic studies. Thus CSIA combined with ESIA and enantiomer fractions (EF) can help to distinguish biotic and abiotic reactions taking place in situ."

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2007 with total page 924 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Constraining the Fate of Chlorinated Ethenes in Groundwater Systems Using Stable Carbon Compound Specific Isotope Analysis written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Utilization of Stable Carbon Isotope in the Verification of Bioremediation of Chlorinated Hydrocarbons written by and published by . This book was released on 1996 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The overall goal of this work was to test the feasibility of using stable carbon isotope analysis to verify in situ biodegradation of hydrocarbons and chlorinated ethenes under aerobic conditions. Specific objectives were to 1) determine d13C values for TCE and the various compounds to be used as co-substrates for TCE degradation; 2) evaluate effects of aerobic biodegradation of co-substrate compounds and TCE on gross fractionation of carbon isotopes as measured in the resulting CO2; 3) test the carbon isotope method for its ability to differentiate the source of the CO2 resulting from aerobic biodegradation; and 4) use samples from an appropriately contaminated bioventing site. Different degrees of fractionation were measured in both pure and mixed cultures for the different compounds tested in this study. Fractionation for toluene was slightly more negative than the starting compound. For JP-4, the fractionation of JP-4 resulted in d13C values much more negative than the starting compound. Fractionation for TCE results in d13C values more positive, indicating the CO2 had a higher percentage of 13C than the source compound. A mixture of toluene and TCE had a d13C value intermediate between the two. These results indicate, with the d13C values for these co-substrates and chlorinated ethenes sufficiently different, the degradation of one or the other can be determined. When both are being degraded an intermediate value can be obtained.

Download or read book Use of compound specific stable isotopes of carbon and chlorine for source tracking and assessments of biodegradation potential in a chlorinated solvent plume in Fort Worth Texas written by Christopher Lee Braun and published by . This book was released on 2005 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Introduction to Environmental Forensics written by Brian L. Murphy and published by Academic Press. This book was released on 2014-07-30 with total page 747 pages. Available in PDF, EPUB and Kindle. Book excerpt: The third edition of Introduction to Environmental Forensics is a state-of-the-art reference for the practicing environmental forensics consultant, regulator, student, academic, and scientist, with topics including compound-specific isotope analysis (CSIA), advanced multivariate statistical techniques, surrogate approaches for contaminant source identification and age dating, dendroecology, hydrofracking, releases from underground storage tanks and piping, and contaminant-transport modeling for forensic applications. Recognized international forensic scientists were selected to author chapters in their specific areas of expertise and case studies are included to illustrate the application of these methods in actual environmental forensic investigations. This edition provides updates on advances in various techniques and introduces several new topics. - Provides a comprehensive review of all aspects of environmental forensics - Coverage ranges from emerging statistical methods to state-of-the-art analytical techniques, such as gas chromatography-combustion-isotope ratio mass spectrometry and polytopic vector analysis - Numerous examples and case studies are provided to illustrate the application of these forensic techniques in environmental investigations

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 Application of Stable Isotope Geochemistry to Assess TCE Biodegradation and Natural Attenuation in a Fractured Dolostone Bedrock written by Justin Allen Clark and published by . This book was released on 2011 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: Isotopic analyses have been developed over the last 10 years as a method for determining chemical interactions of chlorinated solvents. These methods are especially promising for chlorinated ethenes, such as TCE and DCE. This study further develops and employs TCE and DCE compound specific isotopic analyses, along with chemical analyses, to characterize the degradation of TCE in fractured bedrock aquifers. The site chosen, in Smithville, Ontario, was contaminated by extremely high levels of TCE that is currently undergoing monitored pump-and-treat remediation. A collection of historical data and a extended description of the site are provided for potential use in other research. From December 2008 until April 2010 samples were collected from the site to provide additional data, including isotopic data. The redox conditions at the site are anoxic to reducing, with sulfate reduction and methanogenesis as dominant terminal electron accepting processes. Redox data indicates that electrochemical conditions are highly variable within the site, including areas near the source zone that are less reducing. Documented changes in groundwater conditions to much more reducing environments indicate that increased oxidation of organic matter is occurring at the Smithville site in select wells. Chemical analyses of potential TCE degradation products are employed to identify degradation. Many wells on site have dechlorination products. Combined chemical and redox shows that degradation seems to be a removal process for TCE at the Smithville site. Reductive dechlorination is shown to be a significant process forming degradation products such as DCE, VC, ethene and ethane. Production of DCE in significant amounts, above 1.0 ppb, was observed to only occur after 2003. In addition to this, DCE data shows that the percentage of DCE made up of cDCE is above 96%. This indicates that microbes most likely mediate the processes that formed DCE from TCE. The isotopic data had a high range in both carbon and chlorine isotopes. Chlorine isotopic data ranges from a [delta]37ClTCE of 1.39 to 4.69, and a [delta]37ClcDCE of 3.57 to 13.86. Carbon isotopic data ranges from a [delta]13CTCE of -28.9 to -20.7, and a [delta]13CcDCE of -26.5 to -11.82. Samples collected in the well closest to the source zone returned the lightest carbon and chlorine isotopic signatures. The range in values indicate varying degrees of degradation throughout the site, however the same wells have similar isotopic trends. Based on isotopic evidence, degradation past DCE to more degraded compounds also occurs at the Smithville site. However, determination of the degree of degradation of TCE and DCE was not implemented due to the variability in isotopic data.

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 Stable Isotopes in Ecology and Environmental Science written by Robert Michener and published by John Wiley & Sons. This book was released on 2008-04-15 with total page 592 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book highlights new and emerging uses of stable isotope analysis in a variety of ecological disciplines. While the use of natural abundance isotopes in ecological research is now relatively standard, new techniques and ways of interpreting patterns are developing rapidly. The second edition of this book provides a thorough, up-to-date examination of these methods of research. As part of the Ecological Methods and Concepts series which provides the latest information on experimental techniques in ecology, this book looks at a wide range of techniques that use natural abundance isotopes to: follow whole ecosystem element cycling understand processes of soil organic matter formation follow the movement of water in whole watersheds understand the effects of pollution in both terrestrial and aquatic environments study extreme systems such as hydrothermal vents follow migrating organisms In each case, the book explains the background to the methodology, looks at the underlying principles and assumptions, and outlines the potential limitations and pitfalls. Stable Isotopes in Ecology and Environmental Science is an ideal resource for both ecologists who are new to isotopic analysis, and more experienced isotope ecologists interested in innovative techniques and pioneering new uses.