Download or read book Abiotic Degradation Rates for Carbon Tetrachloride written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This is a letter report summarizing work performed in FY2008 to determine the rates of carbon tetrachloride hydrolysis at temperatures close to actual groundwater temperatures. The report describes the project, the methodology, and the results obtained since the project's inception in FY2006. Measurements of hydrolysis rates in homogeneous solution have been completed for temperaturs of 70 C through 40 C, with additional data available at 30 C and 20 C. These results show no difference between the rates in deionized H2O and in filter-sterilized Hanford-Site groundwater. Moreover, the rates measured are 2-3 times slower than predicted from the open literature. Measurements of rates involving sterile suspensions of Hanford-Site sediment in Hanford-Site groundwater, however, show faster hydrolysis at temperatures below 40 C. Extrapolation of the current data available suggests a six-fold increase in rate would be expected at groundwater temperature of 16 C due to the presence of the sediment. This result translates into a 78-year half-life, rather than the 470-680 year half-life that would be predicted from rate determinations in homogeneous solution. The hydrolysis rate data at 20 C, in contrast to those at higher temperatures, are preliminary and have low statistical power. While significant (p
Download or read book Abiotic Degradation Rates for Carbon Tetrachloride and Chloroform written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Abiotic Degradation Rates for Carbon Tetrachloride and Chloroform written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This report documents the progress made through FY 2009 on a project initiated in FY 2006 to help address uncertainties related to the rates of hydrolysis in groundwater for carbon tetrachloride (CT) and chloroform (CF). The study seeks also to explore the possible effects of contact with minerals and sediment (i.e., heterogeneous hydrolysis) on these rates. In previous years the work was funded as two separate projects by various sponsors, all of whom received their funding from the U.S. Department of Energy (DOE). In FY2009, the projects were combined and funded by CH2MHill Plateau Remediation Corporation (CHPRC). Work in FY2009 was performed by staff at the Pacific Northwest National Laboratory (PNNL). Staff from the State University of New York at Cortland (SUNY-Cortland) contributed in previous years.
Download or read book Abiotic Degradation Rates for Carbon Tetrachloride and Chloroform written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This report documents the progress made through FY 2010 on a project initiated in FY 2006 to help address uncertainties related to the rates of hydrolysis in groundwater at the Hanford Site for carbon tetrachloride (CT) and chloroform (CF). The study also explores the possible effects of contact with minerals and sediment (i.e., heterogeneous hydrolysis) on these rates. The research was initiated to decrease the uncertainties in abiotic degradation rates of CT and chloroform CF associated with temperature and possible heterogeneous effects. After 2 years of data collection, the first evidence for heterogeneous effects was identified for hydrolysis of CT, and preliminary evidence for the effects of different mineral types on CF hydrolysis rates also was reported. The CT data showed no difference among mineral types, whereas significant differences were seen in the CF results, perhaps due to the fact that CF hydrolyzes by both neutral and base-catalyzed mechanisms whereas CT follows only the neutral hydrolysis path. In this report, we review the project objectives, organization, and technical approaches taken, update the status and results of the hydrolysis-rate experiments after 4 years of experimentation (i.e., through FY 2010), and provide a brief discussion of how these results add to scientific understanding of the behavior of the CT/CF plume at the Hanford Site.
Download or read book Comparing Rates of Microbial Reductive Mineral Formation and Abiotic Carbon Tetrachloride Degradation written by Yao Tan and published by . This book was released on 2008 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book In situ Biotransformation of Carbon Tetrachloride Under Anoxic Conditions written by Lewis Semprini and published by . This book was released on 1991 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Recent Site Wide Transport Modeling Related to the Carbon Tetrachloride Plume at the Hanford Site written by and published by . This book was released on 2004 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon tetrachloride transport in the unconfined aquifer system at the Hanford Site has been the subject of follow-on studies since the Carbon Tetrachloride Innovative Treatment Remediation Demonstration (ITRD) Program was completed in FY 2002. These scoping analyses were undertaken to provide support for strategic planning and guidance for the more robust modeling needed to obtain a final record of decision (ROD) for the carbon tetrachloride plume in the 200 West Area. This report documents the technical approach and the results of these follow-on, site-wide scale-modeling efforts. The existing site-wide groundwater model was used in this effort. The work extended that performed as part of the ITRD modeling study in which a 200 West Area scale submodel was developed to examine arrival concentrations at an arbitrary boundary between the 200 E and 200 W areas. These scoping analyses extended the analysis to predict the arrival of the carbon tetrachloride plume at the Columbia River. The results of these analyses illustrate the importance of developing field-scale estimates of natural attenuation parameters, abiotic degradation rate and soil/water equilibrium sorption coefficient, for carbon tetrachloride. With these parameters set to zero, carbon tetrachloride concentrations will exceed the compliance limit of 5 [mu]g/L outside the 200 Area Plateau Waste Management Area, and the aquifer source loading and area of the aquifer affected will continue to grow until arrival rates of carbon tetrachloride equal source release rates, estimated at 33 kg/yr. Results of this scoping analysis show that the natural attenuation parameters are critical in predicting the future movement of carbon tetrachloride from the 200 West Area. Results also show the significant change in predictions between continual source release from the vadose zone and complete source removal.
Download or read book Recent Site wide Transport Modeling Related to the Carbon Tetrachloride Plume at the Hanford Site written by Marcel P. Bergeron and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Project Work Plan Carbon Tetrachloride and Chloroform Attenuation Parameter Studies written by James E. Amonette and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Between 1955 and 1973, an estimated 750,000 kg of carbon tetrachloride were discharged to the soil in the 200 West Area of the Hanford Site as part of the plutonium production process. Of this amount, some carbon tetrachloride reached the groundwater more than 70 m below the ground surface and formed a plume of 10 km2. Recent information has shown that the carbon tetrachloride plume extends to a depth of at least 60 m below the water table. Some carbon tetrachloride has been degraded either by the original process or subsequent transformations in the subsurface to form a co-existing chloroform plume. Although current characterization efforts are improving the conceptual model of the source area, more information is needed to effectively assess the fate and transport of carbon tetrachloride and chloroform to support upcoming remediation decisions for the plume. As noted in a simulation study by Truex et al. (2001), parameters describing porosity, sorption, and abiotic degradation have the largest influence on predicted plume behavior. The work proposed herein will improve the ability to predict future plume movement by better quantifying abiotic degradation mechanisms and rates. This effort will help define how much active remediation may be needed and estimate where the plume will eventually stabilize - key factors in determining the most appropriate remedy for the plume.
Download or read book Factors Affecting the Reductive Dechlorination of Carbon Tetrachloride by Zero valent Iron written by Amanda S. Mutziger and published by . This book was released on 1996 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Abiotic Reductive Dechlorination of Carbon Tetrachloride and Hexachloroethane by Environmental Reductants written by Martin Reinhard and published by . This book was released on 1990 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Environmental Forensics written by Robert D Morrison and published by Royal Society of Chemistry. This book was released on 2010-08-06 with total page 337 pages. Available in PDF, EPUB and Kindle. Book excerpt: This publication includes peer-reviewed manuscripts from the 2009 International Network of Environmental Forensics (INEF) held in Calgary, Canada on August 31 through September 1, 2009. INEF is an organization founded by environmental forensic scientists for the express purpose of sharing and disseminating environmental forensic information to the international scientific community. Environmental forensic information presented at the Calgary conference included topics on contaminant age dating, chemical biomarkers, environmental statistics, the interpretation of forensic data, emerging analytical techniques used in forensic investigations, legal sampling and strategies, petroleum hydrocarbon fingerprinting and diagnostic markers used to age date chlorinated solvents. All of these topics were presented in the context of using these techniques to ultimately identify the origin and age of contaminants released into the environment. This professionally edited book is the first of a series of conference publications chronicling the current state of the art in environmental forensics. The intent of this publication and subsequent INEF conference volumes is to compile a library of state of the art scientific articles dealing with environmental forensic topics.
Download or read book Abiotic Reductive Dechlorination of Carbon Tetrachloride by Iron Sulfide Coatings on Iron Minerals written by Rebecca Jill Hanoch and published by . This book was released on 2003 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Transformation of Carbon Tetrachloride and Chloroform by Trichloroethene Respiring Anaerobic Mixed Cultures and Supernatant written by Kyle E. Vickstrom and published by . This book was released on 2016 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon tetrachloride (CT) and chloroform (CF) were transformed in batch reactor experiments conducted with anaerobic dechlorinating cultures and supernatant (ADC+S) harvested from continuous flow reactors. The Evanite (EV-5L) and Victoria/Stanford (VS-5L) cultures capable of respiring trichloroethene (TCE), 1,2-cis-dichloroethene (cDCE), and vinyl chloride (VC) to ethene (ETH) were grown in continuous flow reactors receiving an influent feed of saturated TCE (10 mM; 60 mEq) and formate (45 mM; 90 mEq) but no CT or CF. In all experiments, cells and supernatant were harvested from the chemostats and inoculated into batch reactors. Transformation of various concentrations of CT (0.86, 2.6, or 8.6 [micro]M), CF (2.1 or 21.1 [micro]M), dichloromethane (DCM; 23.1 [micro]M), and TCE (50 [micro]M) was examined. CT transformation was complete and exhibited pseudo-first order kinetics with CF as the primary measured transformation product in all treatments. Lesser amounts of DCM and carbon disulfide (CS2) were measured leading to an overall mass balance of 20-40% of the original mass as CT accounted for. An analytical first order solution was developed to model CT degradation and product formation under multiple conditions. Cells poisoned with 50 mM sodium azide (NaN3) catalyzed rapid and complete CT transformation suggesting a greater importance of redox active cofactors than live cells in the abiotic and cometabolic transformation. DCM and CS2 however were not produced in the poisoned treatments. TCE and CT simultaneous transformation occurred with an approximately two-fold increase in the CT degradation rate while maintaining complete TCE respiration to ETH. During the initial round of TCE respiration, the rate limiting step was VC to ETH, which was impacted by the presence of CT and CF. A subsequent addition of 50 [micro]M TCE showed a substantial decline in the rates of reductive dechlorination owing to the inhibitory effects of long term exposure to CF. The results clearly demonstrate that transformation can be promoted by anaerobic dechlorinating cultures and supernatant not previously acclimated to CT and CF. However, abiotic reactions account for much of the observed transformation. The role of CF inhibition on H2 utilization by the culture was also explored. Sodium formate was provided as a rapid release substrate, providing H2 as an electron donor. H2 partial pressures were tracked throughout the course of the kinetic experiments. The rapid transformation of CT to CF made it not possible to determine if CT inhibited H2 use by the anaerobic dechlorinating cultures. However, the rapid buildup and subsequent slow transformation of CF was found to reversibly inhibit H2 consumption for homoacetogenesis. It was found that an aqueous CF concentration above 0.4 [micro]M or 0.6 [micro]M inhibited H2 consumption by the EV-5L and VS-5L cultures, respectively. This result differed for the VS-5L culture when metabolizing TCE in the presence of CT and CF. The VS-5L culture consumed H2 at CF concentrations as high as 1.3 [micro]M. The culture may have been partially inhibited at CF concentrations greater than 0.6 [micro]M, which is shown by slower consumption of H2 than controls that did not contain CF. The results demonstrate that CF reversibly inhibits the consumption of H2 by the anaerobic dechlorinating cultures, and that more research is required to determine if it is through a chemical inhibition or toxicity.
Download or read book Health Assessment Document for Carbon Tetrachloride written by and published by . This book was released on 1984 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Effects of Temperature and PH on the Rate of Degradation of Carbon Tetrachloride in Anaerobic Aqueous Solution in the Presence of Bisulfide and the Minerals Biotite Or Vermiculite written by Cindy Gail Schreier and published by . This book was released on 1990 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
