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1

Gaseous TCE and PCE removal by an activated carbon biofilter  

Microsoft Academic Search

Gaseous trichloroethylene (TCE) and tetrachloroethylene (PCE) are emitted in the treatment of contaminated groundwaters with air stripping and\\/or the remediation of contaminated soils using vapor extraction techniques. This study investigated the application of biofiltration using cometabolic process to remediate gaseous TCE and PCE that are highly recalcitrant to biodegradation. The investigation was conducted using two specially built stainless steel columns,

Jong O Kim

1997-01-01

2

ROLE OF PHARMACOKINETIC MODELING IN RISK ASSESSMENT -- PERCHLOROETHYLENE (PCE) AS AN EXAMPLE  

EPA Science Inventory

Available metabolic and pharmacokinetic data on perchloroethylene (PCE) are used as a basis for discussion of the use of such data in quantitative risk assessment. he emphasis is on methodologies for improving risk assessment rather than on the risk assessment of PCE per se. he d...

3

COMPLETE NATURAL ATTENUATION OF PCE AND TCE WITHOUT VINYL CHLORIDE AND ETHENE ACCUMULATION  

EPA Science Inventory

A shallow aquifer at the Twin Cities Army Ammunition Plant (TCAAP) was contaminated with tetrachloroethylene (PCE) and trichloroethylene (TCE). Cisdichloroethylene (cis-DCE) is found in ground water at the site, indicating that reductive dehalogenation of PCE and TCE is occurrin...

4

BINARY DESORPTION ISOTHERMS OF TCE AND PCE FROM SILICA GEL AND NATURAL SOLIDS. (R822626)  

EPA Science Inventory

Binary solute desorption isotherms of trichloroethylene (TCE) and tetrachloroethylene (PCE) at 100% relative humidity from silica gel and two well-characterized natural solids were investigated. Results indicated that the ideal adsorbed solution theory (IAST) was able to descr...

5

Sulfur removal from high-sulfur Illinois coal by low-temperature perchloroethylene (PCE) extraction  

SciTech Connect

A pre-combustion coal desulfurization process at 120{degree}C using perchloroethylene (PCE) to remove up to 70% of the organic sulfur has been developed by the Midwest Ore Processing Co. (MWOPC). However, this process has not yet proven to be as successful with Illinois coals as it has for Ohio and Indiana coals. The organic sulfur removal has been achieved only with highly oxidized Illinois coals containing high sulfatic sulfur. A logical explanation for this observation is vital to successful process optimization for the use of Illinois coals. In addition, the high levels of organic sulfur removals observed by the MWOPC may be due to certain errors involved in the ASTM data interpretation; this needs verification. For example, elemental sulfur extracted by the PCE may be derived from pyrite oxidation during coal pre-oxidation, but it may be interpreted as organic sulfur removed by the PCE using ASTM analysis. The goals of this research are: (1) to independently confirm and possibly to improve the organic sulfur removal from Illinois coals with the PCE desulfurization process reported by the MWOPC, (2) to verify the forms-of-sulfur determination using the ASTM method for the PCE process evaluation, and (3) to determine the suitability of Illinois coals for use in the PCE desulfurization process. This project involves the Illinois State Geological Survey (ISGS), Eastern Illinois University (EIU), the University of Illinois-Urbana/Champaign (UI-UC), and the University of Kentucky, Lexington (UK). This is the first year of a two-year project.

Chou, M.I.M.

1991-01-01

6

ADVANCED OXIDATION PROCESSES FOR TREATING GROUNDWATER CONTAMINATED WITH TCE (TRICHLOROETHYLENE) AND PCE (TETRACHLOROETHYLENE): LABORATORY STUDIES (JOURNAL VERSION)  

EPA Science Inventory

Oxidation of trichloroethylene (TCE) and tetrachloroethylene (PCE) with various dosages of ozone or ozone plus hydrogen peroxide was studied in laboratory experiments. The results show that hydrogen peroxide accelerates the oxidation of TCE and PCE by ozone. At peroxide-to-ozone ...

7

COMPLETE NATURAL ATTENUATION OF A PCE AND TCE PLUME AFTER SOURCE REMOVAL  

EPA Science Inventory

Disposal of the chlorinated solvents PCE and TCE at the Twin Cities Army Ammunition Plant (TCAAP) resulted in the contamination of groundwater in a shallow, unconsolidated sand aquifer. The resulting plume had moved over 1000 feet from the disposal source area and had impacted p...

8

Transformation efficiency and formation of transformation products during photochemical degradation of TCE and PCE at micromolar concentrations  

PubMed Central

Background Trichloroethene and tetrachloroethene are the most common pollutants in groundwater and two of the priority pollutants listed by the U.S. Environmental Protection Agency. In previous studies on TCE and PCE photolysis and photochemical degradation, concentration ranges exceeding environmental levels by far with millimolar concentrations of TCE and PCE have been used, and it is not clear if the obtained results can be used to explain the degradation of these contaminants at more realistic environmental concentration levels. Methods Experiments with micromolar concentrations of TCE and PCE in aqueous solution using direct photolysis and UV/H2O2 have been conducted and product formation as well as transformation efficiency have been investigated. SPME/GC/MS, HPLC/UV and ion chromatography with conductivity detection have been used to determine intermediates of degradation. Results The results showed that chloride was a major end product in both TCE and PCE photodegradation. Several intermediates such as formic acid, dichloroacetic acid, dichloroacetaldehyede, chloroform, formaldehyde and glyoxylic acid were formed during both, UV and UV/H2O2 treatment of TCE. However chloroacetaldehyde and chloroacetic acid were only detected during direct UV photolysis of TCE and oxalic acid was only formed during the UV/H2O2 process. For PCE photodegradation, formic acid, di- and trichloroacetic acids were detected in both UV and UV/H2O2 systems, but formaldehyde and glyoxylic acid were only detected during direct UV photolysis. Conclusions For water treatment UV/H2O2 seems to be favorable over direct UV photolysis because of its higher degradation efficiency and lower risk for the formation of harmful intermediates.

2014-01-01

9

Sulfur removal from high-sulfur Illinois coal by low-temperature perchloroethylene (PCE) extraction. Technical report, December 1, 1991--February 29, 1992  

SciTech Connect

A pre-combustion coal desulfurization process at 120{degree}C using perchloroethylene (PCE) to remove up to 70% of the organic sulfur has been developed by the Midwest Ore Processing Co. (MWOPC). However, this process has not yet proven to be as successful with Illinois coals as it has for Ohio and Indiana coals. In addition, the high levels of organic sulfur removals observed by the MWOPC may be due to certain errors involved in the ASTM data interpretation; this needs verification. For example, elemental sulfur extracted by the PCE may be derived from pyrite oxidation during coal preoxidation, but it may be interpreted as organic sulfur removed by the PCE using ASTM analysis. The purposes of this research are to independently confirm and possibly to improve the organic sulfur removal from Illinois coals with the PCE desulfurization process reported by the MWOPC and to verify the forms-of-sulfur determination using the ASTM method for the PCE process evaluation.

Chou, M.I.M; Lytle, J.M.; Ruch, R.R.; Kruse, C.W.; Chaven, C.; Hackley, K.C.; Hughes, R.E.; Harvey, R.D.; Frost, J.K. [Illinois State Geological Survey, Champaign, IL (United States); Buchanan, D.H. [Eastern Illinois Univ., Charleston, IL (United States); Stucki, J.W. [Illinois Univ., Urbana, IL (United States); Huffman, G.; Huggins, F.E. [Kentucky Univ., Lexington, KY (United States)

1992-09-01

10

Sulfur removal from high-sulfur Illinois coal by low-temperature perchloroethylene (PCE) extraction. Final technical report, 1 September, 1992--31 August, 1993  

SciTech Connect

The Midwest Ore Processing Co. (MWOPC) has reported a precombustion coal desulfurization process using perchloroethylene (PCE) at 120 C to remove up to 70% of the organic sulfur. The purposes of this research were to independently confirm and possibly to improve the organic sulfur removal from Illinois coals with the PCE desulfurization and to verify the ASTM forms-of-sulfur determination for evaluation of the process. An additional goal was to develop a dechlorination procedure to remove excess PCE from the PCE-treated coal. A laboratory scale operation of the MWOPC PCE desulfurization process was demonstrated, and a dechlorination procedure to remove excess PCE from the PCE-treated coal was developed. The authors have determined that PCE desulfurization removed mainly elemental sulfur from coal. The higher the level of coal oxidization, the larger the amount of elemental sulfur that is removed by PCE extraction. The increased elemental sulfur during short-term preoxidation is found to be pH dependent and is attributed to coal pyrite oxidation under acidic (pH < 2) conditions. The non-ASTM sulfur analyses confirmed the hypothesis that the elemental sulfur produced by oxidation of pyrite complicates the interpretation of analytical data for PCE process evaluations when only the ASTM forms-of-sulfur is used. When the ASTM method is used alone, the elemental sulfur removed during PCE desulfurization is counted as organic sulfur. A study using model compounds suggests that mild preoxidation treatment of coal described by MWOPC for removal of organic sulfur does not produce enough oxidized organic sulfur to account for the amounts of sulfur removal reported. Furthermore, when oxidation of coal-like organosulfur compounds does occur, the products are inconsistent with production of elemental sulfur, the product reported by MWOPC. Overall, it is demonstrated that the PCE process is not suitable for organic sulfur removal.

Chou, M.I.M.; Lytle, J.M.; Ruch, R.R.; Kruse, C.W.; Chaven, C.; Hackley, K.C.; Hughes, R.E.; Harvey, R.D.; Frost, J.K. [Illinois State Geological Survey, Champaign, IL (United States); Buchanan, D.H. [Eastern Illinois Univ., Charleston, IL (United States); Stucki, J.W. [Univ. of Illinois, Urbana, IL (United States); Huffman, G.P.; Huggins, F.E. [Univ. of Kentucky, Lexington, KY (United States)

1993-12-31

11

Effect of source variability and transport processes on carbon isotope ratios of TCE and PCE in two sandy aquifers.  

PubMed

Chlorinated ethenes often migrate over extended distances in aquifers and may originate from different sources. The aim of this study was to determine whether stable carbon isotope ratios remain constant during dissolution and transport of chlorinated ethenes and whether the ratios can be used to link plumes to their sources. Detailed depth-discrete delineation of the carbon isotope ratio in a tetrachloroethene (PCE) plume and in a trichloroethene (TCE) plume was done along cross-sections orthogonal to groundwater flow in two sandy aquifers in the Province of Ontario, Canada. At the TCE site, TCE concentrations up to solubility were measured in one high concentration zone close to the bottom of the aquifer from where dense non-aqueous phase liquid (DNAPL) was collected. A laboratory experiment using the DNAPL indicated that only very small carbon isotope fractionation occurs during dissolution of TCE (0.26 per thousand), which is consistent with field observations. At most sampling points, the delta(13)C of dissolved TCE was similar to that of the DNAPL except for a few sampling points at the bottom of the aquifer close to the underlying aquitard. At these points, a (13)C enrichment of up to 2.4 per thousand was observed, which was likely due to biodegradation and possibly preferential diffusion of TCE with (12)C into the aquitard. In contrast to the TCE site, several distinct zones of high concentration were observed at the PCE site and from zones to zone, the delta(13)C values varied substantially from -24.3 per thousand to -33.6 per thousand. Comparison of the delta(13)C values in the high concentration zones made it possible to divide the plume in the three different domains, each probably representing a different episode and location of DNAPL release. The three different zones could still be distinguished 220 m from the DNAPL sources. This demonstrates that carbon isotope ratios can be used to differentiate between different zones in chlorinated ethene plumes and to link plume zones to their sources. In addition, subtle variations in delta(13)C at plume fringes provided insight into mechanisms of plume spreading in transverse vertical direction. These variations were identified because of the high-resolution provided by the monitoring network. PMID:15358496

Hunkeler, D; Chollet, N; Pittet, X; Aravena, R; Cherry, J A; Parker, B L

2004-10-01

12

Sulfur removal from high-sulfur Illinois coal by low-temperature perchloroethylene (PCE) extraction. Technical report, September 1, 1991--November 30, 1991  

SciTech Connect

A pre-combustion coal desulfurization process at 120{degree}C using perchloroethylene (PCE) to remove up to 70% of the organic sulfur has been developed by the Midwest Ore Processing Co. (MWOPC). However, this process has not yet proven to be as successful with Illinois coals as it has for Ohio and Indiana coals. The organic sulfur removal has been achieved only with highly oxidized Illinois coals containing high sulfatic sulfur. A logical explanation for this observation is vital to successful process optimization for the use of Illinois coals. In addition, the high levels of organic sulfur removals observed by the MWOPC may be due to certain errors involved in the ASTM data interpretation; this needs verification. For example, elemental sulfur extracted by the PCE may be derived from pyrite oxidation during coal pre-oxidation, but it may be interpreted as organic sulfur removed by the PCE using ASTM analysis. The goals of this research are: (1) to independently confirm and possibly to improve the organic sulfur removal from Illinois coals with the PCE desulfurization process reported by the MWOPC, (2) to verify the forms-of-sulfur determination using the ASTM method for the PCE process evaluation, and (3) to determine the suitability of Illinois coals for use in the PCE desulfurization process. This project involves the Illinois State Geological Survey (ISGS), Eastern Illinois University (EIU), the University of Illinois-Urbana/Champaign (UI-UC), and the University of Kentucky, Lexington (UK). This is the first year of a two-year project.

Chou, M.I.M.

1991-12-31

13

Photochemical Reactivity of Perchloroethylene.  

National Technical Information Service (NTIS)

Perchloroethylene (PCE), a solvent used in dry cleaning, has been suspected of contributing significantly to photochemical ozone/oxidant (O3/Ox) problems in urban atmospheres. Past evidence, however, was neither complete nor consistent. To interpret more ...

B. Dimitriades B. W. Gay R. R. Arnts R. L. Seila

1983-01-01

14

Understanding pH Effects on Trichloroethylene and Perchloroethylene Adsorption to Iron in Permeable Reactive Barriers for Groundwater Remediation  

PubMed Central

Metallic iron filings are becoming increasing used in permeable reactive barriers for remediating groundwater contaminated by chlorinated solvents. Understanding solution pH effects on rates of reductive dechlorination in permeable reactive barriers is essential for designing remediation systems that can meet treatment objectives under conditions of varying groundwater properties. The objective of this research was to investigate how the solution pH value affects adsorption of trichloroethylene (TCE) and perchloroethylene (PCE) on metallic iron surfaces. Because adsorption is first required before reductive dechlorination can occur, pH effects on halocarbon adsorption energies may explain pH effects on dechlorination rates. Adsorption energies for TCE and PCE were calculated via molecular mechanics simulations using the Universal force field and a self-consistent reaction field charge equilibration scheme. A range in solution pH values was simulated by varying the amount of atomic hydrogen adsorbed on the iron. The potential energies associated TCE and PCE complexes were dominated by electrostatic interactions, and complex formation with the surface was found to result in significant electron transfer from the iron to the adsorbed halocarbons. Adsorbed atomic hydrogen was found to lower the energies of TCE complexes more than those for PCE. Attractions between atomic hydrogen and iron atoms were more favorable when TCE versus PCE was adsorbed to the iron surface. These two findings are consistent with the experimental observation that changes in solution pH affect TCE reaction rates more than those for PCE.

Luo, Jing; Farrell, James

2013-01-01

15

PHOTOCHEMICAL REACTIVITY OF PERCHLOROETHYLENE  

EPA Science Inventory

Perchloroethylene (PCE), a solvent used in dry cleaning, has been suspected of contributing significantly to photochemical ozone/oxidant (O3/Ox) problems in urban atmospheres. Past evidence, however, was neither complete nor consistent. To interpret more conclusively the past evi...

16

Sulfur removal from high-sulfur Illinois coal by low-temperature perchloroethylene (PCE) extraction. Technical report, December 1, 1992--February 28, 1993  

SciTech Connect

The purpose of this project are to independently confirm and possibly to improve the organic sulfur removal from Illinois coals with the PCE process developed by the Midwest Ore Processing Co.(MWOPC), to verify the forms-of-sulfur determination using the ASTM method for evaluation of the PCE process, and to develop a dechlorination procedure to remove excess PCE from the PCE-treated coal. The objectives for year-2 study are to verify the possible effect of PCE treatment on coal-derived FeS{sub 2}, FeSO{sub 4}, and Fe{sub 2}(SO{sub 4}){sub 3} on ASTM coal analysis, to investigate the behavior of sulfur during oxidation and PCE desulfurization using the isotopically signatured coal sample to investigate the proprietary reagent on the oxidation of the organic sulfur model compounds with and without additives, to evaluate this new oxidation on the organic sulfur removal by PCE desulfurization, and to study other innovative pretreatment processes for the removal of organic sulfur from coal under mild conditions. Oxidation study on the organosulfur model compounds alone was completed in first quarter. The oxidation reactions were repeated on the organosulfur model compounds with the presence of hydrocarbon additives. These additives are known to easily produce hydroperoxides during air oxidation. Analysis of the reaction products is in progress.

Chou, M.I.M.; Lytle, J.M.; Ruch, R.R.; Kruse, C.W.; Chaven, C.; Hackley, K.C.; Hughes, R.E.; Harvey, R.D. [Illinois Dept. of Energy and Natural Resources, Springfield, IL (United States). Geological Survey; Buchanan, D.H. [Eastern Illinois Univ., Charleston, IL (United States); Stucki, J.W. [Illinois Univ., Urbana, IL (United States); Huffman, G.; Huggins, F.E. [Kentucky Univ., Lexington, KY (United States); Ho, K.K. [Institute of Gas Technology, Chicago, IL (United States)

1993-05-01

17

Sulfur removal from high-sulfur Illinois coal by low-temperature perchloroethylene (PCE) extraction. [Quarterly] technical report, March 1, 1993--May 31, 1993  

SciTech Connect

The purposes of this project are: to independently confirm and possibly to improve the organic sulfur removal from Illinois coals with the PCE process developed by the Midwest Ore Processing Co. (MWOPC), to verify the forms-of-sulfur determination using the ASTM method for evaluation of the PCE process, and to develop a dechlorination procedure to remove excess PCE from the PCE-treated coal. The objectives for the second year are: to verify the possible effects of PCE treatment on coal-derived FeS{sub 2}, FeSO{sub 4}, and Fe{sub 2}(SO{sub 4}){sub 3} on ASTM coal analysis, to investigate the behavior of sulfur during oxidation and PCE desulfurization using the isotopically signatured coal sample, to investigate the effects of conditions and/or reagents on the oxidation of the organic-sulfur-model compounds, to evaluate the extended oxidation condition on the organic sulfur removal by PCE desulfurization, and to study other innovative pretreatment processes for the removal of organic sulfur from coal under mild conditions.

Chou, M.I.M. [Illinois State Geological Survey, Champaign, IL (United States); Buchanan, D.H. [Eastern Illinois Univ., Charleston, IL (United States); Stucki, J.W. [Illinois Univ., Urbana, IL (United States)

1993-09-01

18

Photochemical Reactivity of Perchloroethylene: A New Appraisal.  

National Technical Information Service (NTIS)

Perchloroethylene (PCE), a solvent used in dry cleaning, has been suspected of contributing significantly to photochemical ozone/oxidant (O3/O(x)) problems in urban atmospheres. Past evidence, however, was neither complete nor consistent. To interpret mor...

B. Dimitriades B. W. Gay R. R. Arnts R. L. Seila

1983-01-01

19

PHOTOCHEMICAL REACTIVITY OF PERCHLOROETHYLENE: A NEW APPRAISAL  

EPA Science Inventory

Perchloroethylene (PCE), a solvent used in dry cleaning, has been suspected of contributing significantly to photochemical ozone/oxidant (O3/O(x)) problems in urban atmospheres. Past evidence, however, was neither complete nor consistent. To interpret more conclusively the past e...

20

PBPK Modeling of the Percutaneous Absorption of Perchloroethylene from a Soil Matrix in Rats and Humans  

Microsoft Academic Search

Perchloroethylene (PCE) is a widely used volatile organic chemi- cal. Exposures to PCE are primarily through inhalation and dermal contact. The dermal absorption of PCE from a soil matrix was compared in rats and humans using real-time MS\\/MS exhaled breath technology and physiologically based pharmacokinetic (PBPK) mod- eling. Studies with rats were performed to compare the effects of loading volume,

Torka S. Poet; Karl K. Weitz; Richard A. Gies; Jeffrey A. Edwards; Karla D. Thrall; Richard A. Corley; Hanafi Tanojo; Xiaoying Hui; Howard I. Maibach; Ronald C. Wester

2002-01-01

21

RESPONSE TO ISSUES AND DATA SUBMISSIONS ON THE CARCINOGENICITY OF TETRACHLOROETHYLENE (PERCHLOROETHYLENE)  

EPA Science Inventory

The scientific debate over the potential carcinogenicity of tetrachloroethylene (perchloroethylene, perc, PCE) spans several years. his document reviews the issues considered by the EPA's Science Advisory Board (SAB) during its review of the Draft Addendum to the Health Assessmen...

22

Perchloroethylene Coal Beneficiation  

Microsoft Academic Search

The effect of grinding coal in perchloroethylene, use of different sulfur extraction conditions, and separation of coal from other mineral matter were studied using the Midwest Ore Processing Co., Inc. proprietary perchloroethylene coal beneficiation process. Solvent grinding of coal in perchloroethylene reduces generation of fine (? 0.149 mm) particles, increases the mill capacity, and reduces power consumption. Extraction at atmospheric pressure and

GLENN A. ATWOOD; HENRY H. LEEHE

1992-01-01

23

Optimization of simultaneous chemical and biological mineralization of perchloroethylene  

SciTech Connect

Optimization of the simultaneous chemical and biological mineralization of perchloroethylene (PCE) by modified Fenton`s reagent and Xanthobacter flavus was investigated by using a central composite rotatable experimental design. Concentrations of PCE, hydrogen peroxide, and ferrous iron and the microbial cell number were set as variables. Percent mineralization of PCE to CO{sub 2} was investigated as a response. A second-order, quadratic response surface model was generated and fit the data adequately, with a correlation coefficient of 0.72. Analysis of the results showed that the PCE concentration had no significant effect within the tested boundaries of the model, while the other variables, hydrogen peroxide and iron concentrations and cell number, were significant at {alpha} = 0.05 for the mineralization of PCE. The {sup 14}C radiotracer studies showed that the simultaneous chemical and biological reactions increased the extent of mineralization of PCE by more than 10% over stand-alone Fenton reactions.

Bueyueksoenmez, F.; Hess, T.F.; Crawford, R.L.; Paszczynski, A. [Univ. of Idaho, Moscow, ID (United States). Center for Hazardous Waste Remediation Research; Watts, R.J. [Washington State Univ., Pullman, WA (United States). Dept. of Civil and Environmental Engineering

1999-06-01

24

PHASE BEHAVIOR OF WATER/PERCHLOROETHYLENE/ANIONIC SURFACTANT SYSTEMS  

EPA Science Inventory

Winsor Type I (o/w), Type II (w/o), and Type III (middle phase) microemulsions have been generated for water and perchloroethylene (PCE) in combination with anionic surfactants and the appropriate electrolyte concentration. The surfactant formulation was a combination of sodium d...

25

Health risk assessment of tetrachloroethylene (PCE) in California drinking water  

SciTech Connect

This document presents an assessment of the potential health risks associated with exposure to tetrachloroethylene (also known as perchloroethylene or PCE) dissolved in California drinking waters. A primary goal of this health-risk assessment is to evaluate dose-response relationships for observed and potential toxic end points of PCE in order to define dose rates that can be used to establish standards that will protect members of the general public from adverse health effects resulting solely from water-based exposures to PCE. We also analyze the extent of human exposures attributable to PCE-contaminated ground water in California.

Bogen, K.T.; Hall, L.C.; McKone, T.E.; Layton, D.W.; Patton, S.E.

1987-04-10

26

Effect of temperature on perchloroethylene dechlorination by a methanogenic consortium  

SciTech Connect

The effect of temperature on the kinetics of growth, substrate metabolism, and perchloroethylene (PCE) dechlorination by a methanogenic consortium is reported. In all cases, a simple kinetic model accurately reflected experimental data. Values for the substrate and methane yield coefficients, and the maximum specific growth rate are fairly consistent at each temperature. Also, the substrate and methane yield coefficients show little temperature sensitivity. In contrast, both the maximum specific growth rate and the PCE dechlorination yield coefficient (Y{sub PCE}) are temperature dependent.

Gao, J.; Skeen, R.S.; Hooker, B.S.

1995-04-01

27

A mass balance study of the phytoremediation of perchloroethylene-contaminated groundwater  

PubMed Central

A mass balance study was performed under controlled field conditions to investigate the phytoremediation of perchloroethylene (PCE) by hybrid poplar trees. Water containing 7–14 mg L?1 PCE was added to the test bed. Perchloroethylene, trichloroethylene, and cis-dichloroethylene were detected in the effluent at an average of 0.12 mg L?1, 3.9 mg L?1, and 1.9 mg L?1, respectively. The total mass of chlorinated ethenes in the water was reduced by 99%. Over 95% of the recovered chlorine was as free chloride in the soil, indicating near-complete dehalogenation of the PCE. Transpiration, volatilization, and accumulation in the trees were all found to be minor loss mechanisms. In contrast, 98% of PCE applied to an unplanted soil chamber was recovered as PCE in the effluent water or volatilized into the air. These results suggest that phytoremediation can be an effective method for treating PCE-contaminated groundwater in field applications.

James, C. Andrew; Xin, Gang; Doty, Sharon L.; Muiznieks, Indulis; Newman, Lee; Strand, Stuart E.

2010-01-01

28

Interaction of Perchloroethylene with Cerium Oxide in Three-Way Catalysts.  

PubMed

The role of cerium oxide on direct oxidation of perchloroethylene (PCE) by a three-way catalyst was explored. In the absence of an external oxidizing agent, PCE was oxidized over an alumina supported Pt/Rh three-way catalyst. We hypothesize that the chlorine atoms in the adsorbed PCE interact with oxygen in CeO(2), reducing the cerium to create CeCl(3). PMID:21218178

Rupp, Erik C; Betterton, Eric A; Arnold, Robert G; Sáez, A Eduardo

2009-09-01

29

Interaction of Perchloroethylene with Cerium Oxide in Three-Way Catalysts  

PubMed Central

The role of cerium oxide on direct oxidation of perchloroethylene (PCE) by a three-way catalyst was explored. In the absence of an external oxidizing agent, PCE was oxidized over an alumina supported Pt/Rh three-way catalyst. We hypothesize that the chlorine atoms in the adsorbed PCE interact with oxygen in CeO2, reducing the cerium to create CeCl3.

Rupp, Erik C.; Betterton, Eric A.; Arnold, Robert G.

2010-01-01

30

Contamination of ground water by PCE - A national perspective  

USGS Publications Warehouse

Perchloroethylene (PCE) has physical and chemical properties that make it likely to persist in groundwater if released to the environment. The US Geological Survey has collected or compiled data on the occurrence of PCE in groundwater from major aquifers around the US. These data represent the occurrence of PCE in the groundwater resource as a whole and not occurrence at specific release sites. PCE was detected at measurable concentrations in nearly one in 10 wells in major aquifers throughout the country. Trichloroethylene was found most commonly with PCE and its presence may be due, in part, to reductive dechlorination of PCE. This is an abstract of a paper presented at the Petroleum Hydrocarbons and Organic Chemicals in Ground Water: Prevention, Assessment, and Remediation Conference (Houston, TX 11/6-7/2006).

Moran, M. J.; Delzer, G. C.

2006-01-01

31

ACUTE NEUROTOXIC EFFECTS OF INHALED PERCHLOROETHYLENE ON PATTERN VISUAL EVOKED POTENTIALS AS A FUNCTION OF EXPOSURE AND ESTIMATED BLOOD AND BRAIN CONCENTRATION.  

EPA Science Inventory

Previous experiments have shown the effects of acute inhalation exposure to trichloroethylene (TCE) and toluene are related to the target tissue concentration at the time of testing. The current studies examined exposure to another volatile organic compound, perchloroethylene (P...

32

Removal of perchloroethylene from a layered soil system by steam flushing  

Microsoft Academic Search

Steam flushing experiments were conducted in a two-dimensional chamber containing two layers of F75 silica sand separated by a layer of finer F110 silica sand. Perchloroethylene (PCE), which had spilled into the chamber under water-saturated conditions, formed a pool on the F110 sand layer. Steam was injected above the F110 sand layer. Temperatures, moisture content, and PCE concentrations in the

Hugh Y. She; Brent E. Sleep

1999-01-01

33

WASHABILITY CURVES FOR PYRITE REMOVAL IN COAL USING PERCHLOROETHYLENE AS HEAVY MEDIUM  

Microsoft Academic Search

Pyritic sulfur is removed from raw, high sulfur coal by gravitational separation using a suitable solvent, or heavy medium. This is possible due to the inherent difference in the specific gravity of clean coal and the mineral matter in it. The effectiveness of perchloroethylene (PCE) as a heavy medium was experimentally evaluated. The most important factors governing the efficiency of

Padmakar Vishnubhatt; Sunggyu Lee

1993-01-01

34

Molecular Characterization of the PceA Reductive Dehalogenase of Desulfitobacterium sp. Strain Y51  

PubMed Central

The tetrachloroethene (PCE) reductive dehalogenase (encoded by the pceA gene and designated PceA dehalogenase) of Desulfitobacterium sp. strain Y51 was purified and characterized. The expression of the enzyme was highly induced in the presence of PCE and trichloroethene (TCE). The purified enzyme catalyzed the reductive dehalogenation of PCE via TCE to cis-1,2-dichloroethene at a specific activity of 113.6 nmol?·?min?1?· mg of protein?1. The apparent Km values for PCE and TCE were 105.7 and 535.3 ?M, respectively. Chlorinated ethenes other than PCE and TCE were not dehalogenated. However, the enzyme exhibited dehalogenation activity for various chlorinated ethanes such as hexachloroethane, pentachloroethane, 1,1,1,2-tetrachloroethane, and 1,1,2,2-tetrachloroethane. The pceA gene of Desulfitobacterium sp. strain Y51 was identified in a 2.8-kb DNA fragment and used to express the protein in Escherichia coli for the preparation of antibodies. Immunoblot analyses located PceA in the periplasm of the cell.

Suyama, Akiko; Yamashita, Masaki; Yoshino, Sadazo; Furukawa, Kensuke

2002-01-01

35

Catalytic Dechlorination of Gas-phase Perchloroethylene under Mixed Redox Conditions  

PubMed Central

The validity of a new method to destroy gas-phase perchloroethylene (PCE) is demonstrated at bench scale using a fixed-bed reactor that contains a Pt/Rh catalyst. Hydrogen and oxygen were simultaneously fed to the reactor together with PCE. The conversion efficiencies of PCE were sensitive to H2/O2 ratio and reactor temperature. When the temperature was ? 400 °C and H2/O2 was ? 2.15, PCE conversion efficiency was maintained at ? 90%. No catalyst deactivation was observed for over two years, using only mild, convenient regeneration procedures. It is likely that PCE reduction steps precede oxidation reactions and that the importance of oxidation lies in its elimination of intermediates that would otherwise lead to catalyst poisoning. In practice, this catalytic dechlorination method holds potential for low-cost, large-scale field operation.

Orbay, Ozer; Gao, Song; Barbaris, Brian; Rupp, Erik; Saez, A. Eduardo; Arnold, Robert G.; Betterton, Eric A.

2008-01-01

36

ACUTE BEHAVIORAL EFFECTS OF INHALED PERCHLOROETHYLENE IN RATS ARE DIRECTLY RELATED TO ITS CONCENTRATION IN THE BRAIN.  

EPA Science Inventory

Perchloroethylene (PCE) is a volatile organic compound (VOC), frequently used in dry cleaning processes, that is currently being assessed by EPA for its risk to human health. Many VOCs are acutely neurotoxic and have been shown to affect attentional processes in humans and animal...

37

Electrochemical degradation of perchloroethylene in aqueous media: an approach to different strategies.  

PubMed

An approaching study to the electrochemical degradation of perchloroethylene (PCE) in water has been carried out using controlled current density degradation electrolyses. The different electrochemical strategies to degrade perchloroethylene in aqueous media (i.e. cathodic, anodic and dual treatments) have been checked using divided and undivided configurations. The influence of the initial concentration, pH and current density on the general behavior of the system has been studied, and special attention was paid to the nature of the byproducts formed and to the analysis of the closed mass balance at the end of the reaction. Results from several analytical techniques have been compared. Undivided configuration provides the best results in these experimental conditions, with degradation percentages higher than 50% and with only 6% of the initial perchloroethylene concentration remaining in the system. PMID:19303130

Sáez, Verónica; Esclapez Vicente, M D; Frías-Ferrer, Angel J; Bonete, Pedro; González-García, José

2009-05-01

38

Remediation of Perchloroethylene Contaminated Groundwater by Permeable Reactive Barrier Using Iron, Granular Activated Carbon, and Soil  

Microsoft Academic Search

The objective of this study is to evaluate the effects of zero-valent iron (ZVI), granular activated carbon (GAC) and soil as materials to build permeable reactive barrier (PRB). Flow-through Column experiments were conducted to evaluate the reactivity and adsorptive capacity of various materials for Perchloroethylene(PCE) contaminated groundwater. Columns were packed with various materials such as ZVI, GAC, and Soil. A

L. Jeon; D. Lee; H. Chang

2005-01-01

39

Influence of different electron donors and acceptors on dehalorespiration of tetrachloroethene by Desulfitobacterium frappieri TCE1  

SciTech Connect

Strain TCE1, a strictly anaerobic bacterium that can grow by reductive dechlorination of tetrachloroethene (PCE) and trichloroethane (TCE), was isolated by selective enrichment from a PCE-dechlorinating chemostat mixed culture. Strain TCE1 is a gram-positive, motile, curved rod-shaped organism that is 2 to 4 by 0.6 to 0.8 {micro}m and has approximately six lateral flagella. The pH and temperature optima for growth are 7.2 and 35 C, respectively. On the basis of a comparative 16S rRNA sequence analysis, this bacterium was identified as a new strain of Desulfitobacterium frappieri, because it exhibited 99.7% relatedness to the D. frappieri type strain, strain PCP-1. Growth with H{sub 2}, format, L-lactate, butyrate, crotonate, or ethanol as the electron donor depends on the availability of an external electron acceptor. Pyruvate and serine can also be used fermentatively. Electron donors (except format and H{sub 2}) are oxidized to acetate and CO{sub 2}. when L-lactate is the growth substrate, strain TCE1 can use the following electron acceptors: PCE and TCE (to produce cis-1,2-dichloroethene), sulfite and thiosulfate (to produce sulfide), nitrate (to produce nitrite), and fumarate (to produce succinate). Strain TCE1 is not able to reductively dechlorinate 3-chloro-4-hydroxyphenylacetate. The growth yields of the newly isolated bacterium when PCE is the electron acceptor are similar to those obtained for other dehalorespiring anaerobes (e.g., Desulfitobacterium sp. strain PCE1 and Desulfitobacterium hafniense) and the maximum specific reductive dechlorination rates are 4 to 16 times higher. Dechlorination of PCE and TCE is an inducible process. In PCE-limited chemostat cultures of strain TCE1, dechlorination is strongly inhibited by sulfite but not by other alternative electron acceptors, such as fumate or nitrate.

Gerritse, J.; Drzyzga, O.; Kloetstra, G.; Keijmel, M.; Wiersum, L.P.; Hutson, R.; Collins, M.D.; Gottschal, J.C.

1999-12-01

40

Thermocatalytic Destruction of Gas-Phase Perchloroethylene Using Propane as a Hydrogen Source  

PubMed Central

The use of propane in combination with oxygen to promote the destruction of perchloroethylene (PCE) over a platinum (Pt)/rhodium (Rh) catalyst on a cerium/zirconium oxide washcoat supported on an alumina monolith was explored. Conversions of PCE were measured in a continuous flow reactor with residence times less than 0.5 s and temperatures ranging from 200 to 600°C. The presence of propane was shown to increase significantly the conversion of PCE over oxygen-only conditions. Conversions close to 100% were observed at temperatures lower than 450°C with 20% oxygen and 2% propane in the feed, which makes this process attractive from a practical standpoint. In the absence of oxygen, PCE conversion is even higher, but the catalyst suffers significant deactivation in less than an hour. Even though results show that oxygen competes with reactants for active sites on the catalyst, the long-term stability that oxygen confers to the catalyst makes the process an efficient alternative to PCE oxidation. A Langmuir-Hinshelwood competitive adsorption model is proposed to quantify PCE conversion.

Willinger, Marty; Rupp, Erik; Barbaris, Brian; Gao, Song; Arnolda, Robert; Betterton, Eric; Saez, A. Eduardo

2009-01-01

41

Coal desulfurization by perchloroethylene processing  

Microsoft Academic Search

The rate of filtration for clean coal and the ash-pyrite from PCE processing was determined. The filtration rates were very rapid and the specific filter cake resistance was 7.3 à 10⁷ in.⁻¹. There was no statistical difference between the specific resistance for cleaned coal and for the ash pyrite. The sulfur balance for PCE treated coals was balanced. The sulfur

H. Leehe; G. A. Atwood; G. Snell

1992-01-01

42

The remediation performance of a specific electrokinetics integrated with zero-valent metals for perchloroethylene contaminated soils  

Microsoft Academic Search

This research was conducted to evaluate an integrated technique, combination of the electrokinetics (EK) and zero-valent metal (ZVM), for remediation of the perchloroethylene (PCE) contaminated soils. Various experimental conditions were controlled such as different voltage gradients, the position of ZVM, and ZVM species. The appropriate operational parameters are concluded as follows: (1) 0.01M sodium carbonate serves as the working solution;

Jih-Hsing Chang; Shu-Fen Cheng

2006-01-01

43

Removal of perchloroethylene from a layered soil system by steam flushing  

SciTech Connect

Steam flushing experiments were conducted in a two-dimensional chamber containing two layers of F75 silica sand separated by a layer of finer F110 silica sand. Perchloroethylene (PCE), which had spilled into the chamber under water-saturated conditions, formed a pool on the F110 sand layer. Steam was injected above the F110 sand layer. Temperatures, moisture content, and PCE concentrations in the chamber were monitored. Samples, taken from the various locations in the sand chamber, indicated that complete removal of PCE from the steam zone was achieved, with an 84% overall recovery. Some downward displacement of PCE-contaminated water through the F110 sand layer was observed and a small amount of gravity override occurred. Channeling of steam was minimal. The experiment indicates that steam flushing may be used successfully for removal of PCE from relatively homogeneous soils. Issues of gravity override and downward mobilization of contaminants must be considered in applying steam flushing at the field scale.

She, H.Y.; Sleep, B.E.

1999-10-01

44

Remediation of Perchloroethylene Contaminated Groundwater by Permeable Reactive Barrier Using Iron, Granular Activated Carbon, and Soil  

NASA Astrophysics Data System (ADS)

The objective of this study is to evaluate the effects of zero-valent iron (ZVI), granular activated carbon (GAC) and soil as materials to build permeable reactive barrier (PRB). Flow-through Column experiments were conducted to evaluate the reactivity and adsorptive capacity of various materials for Perchloroethylene(PCE) contaminated groundwater. Columns were packed with various materials such as ZVI, GAC, and Soil. A peristaltic pump was used to feed this medium at 2.5mL/h resulting in a hydraulic retention time of approximately 70h. The column which packed only the soil shows PCE contamination came out passing after 10 pore volumes. But the other columns are continued purification effect.

Jeon, L.; Lee, D.; Chang, H.

2005-12-01

45

Evolving TCE Biodegraders  

NSDL National Science Digital Library

A hypothetical scenario is introduced in which the class is asked to apply their understanding of the forces that drive natural selection to prepare a proposal along with an environmental consulting company to help clean up an area near their school that is contaminated with trichloroethylene (TCE). Students use the Avida-ED software application to test hypotheses for evolving (engineering) a strain of bacteria that can biodegrade TCE, resulting in a non-hazardous clean-up solution. Conduct this design challenge activity after completion of the introduction to digital evolution activity, Studying Evolution with Digital Organisms.

Bio-Inspired Technology and Systems (BITS) RET,

46

TRICHLOROETHYLENE (TCE) ISSUE PAPERS  

EPA Science Inventory

These issue papers are a part of EPA's effort to develop a trichloroethylene (TCE) human health risk assessment. These issue papers were developed by EPA to provide scientific and technical information to the National Academy of Sciences (NAS) for use in developing their advice ...

47

HORIZONTAL LASAGNA TO BIOREMEDIATE TCE  

EPA Science Inventory

Removal of TCE from these tight clay soils has been technically difficult and expensive. However, the LASAGNATM technique allows movement of the TCE into treatment zones for biodegradation or dechlorination in place, lessening the costs and exposure to TCE. Electroosmosis was c...

48

Microwave-induced nanoscale zero-valent iron degradation of perchloroethylene and pentachlorophenol.  

PubMed

Microwave (MW) is applied to enhance perchloroethylene (PCE) or pentachlorophenol (PCP) removal using zero-valent iron (ZVI; Fe(0)) as the dielectric medium. ZVI has a much higher dielectric loss factor (39.5) than other media; it is capable of absorbing MW radiation rapidly to speed up the release of electrons, leading to rises of the ZVI particle surface temperature. If the MW power is continued, excessive electricity will accumulated inside ZVI particles, resulting in sparks. The results show that during the initial 5 sec (700 W), the linear aliphatic PCE has a faster decomposing rate than the ringed PCP (82.0% vs. 4.8%) because less energy is required for decomposing the linear-chlorine bond (90 kcal mol(-1)) than ring-chlorine bonds (95 kcal mol(-1)). Later the removal rate for either PCE or PCP remains the same when the exposure time is between 5 and 60 sec. Without MW irradiation, linear PCE molecules have larger surface area to contact ZVI, and hence they have better removal efficiencies than PCP molecules. Using Fe(0) as a microwave dielectric medium to treat PCE or PCP is a new and worthwhile treatment technology; it is environmentally friendly, and its use will eliminate the secondary pollution. Implications: Nanoscale iron particles are characterized by high surface-area-to-volume ratios, high specific surface area, and high surface reactivity. With a much higher dielectric loss factor, it is capable of absorbing MW radiation rapidly to speed up the release of electrons, leading to rise in temperature. The time needed to achieve a satisfactory treatment is also reduced, leading to significant saving of energy consumption to make this method cost-effective and also environmentally friendly for the industry to pursuit sustainable development. PMID:23362763

Lee, Chien-Li; Lin, Chitsan; Jou, Chih-Ju G

2012-12-01

49

Chlorine Isotope Effects from Isotope Ratio Mass Spectrometry Suggest Intramolecular C-Cl Bond Competition in Trichloroethene (TCE) Reductive Dehalogenation.  

PubMed

Chlorinated ethenes are prevalent groundwater contaminants. To better constrain (bio)chemical reaction mechanisms of reductive dechlorination, the position-specificity of reductive trichloroethene (TCE) dehalogenation was investigated. Selective biotransformation reactions (i) of tetrachloroethene (PCE) to TCE in cultures of Desulfitobacterium sp. strain Viet1; and (ii) of TCE to cis-1,2-dichloroethene (cis-DCE) in cultures of Geobacter lovleyi strain SZ were investigated. Compound-average carbon isotope effects were -19.0‰ ± 0.9‰ (PCE) and -12.2‰ ± 1.0‰ (TCE) (95% confidence intervals). Using instrumental advances in chlorine isotope analysis by continuous flow isotope ratio mass spectrometry, compound-average chorine isotope effects were measured for PCE (-5.0‰ ± 0.1‰) and TCE (-3.6‰ ± 0.2‰). In addition, position-specific kinetic chlorine isotope effects were determined from fits of reactant and product isotope ratios. In PCE biodegradation, primary chlorine isotope effects were substantially larger (by -16.3‰ ± 1.4‰ (standard error)) than secondary. In TCE biodegradation, in contrast, the product cis-DCE reflected an average isotope effect of -2.4‰ ± 0.3‰ and the product chloride an isotope effect of -6.5‰ ± 2.5‰, in the original positions of TCE from which the products were formed (95% confidence intervals). A greater difference would be expected for a position-specific reaction (chloride would exclusively reflect a primary isotope effect). These results therefore suggest that both vicinal chlorine substituents of TCE were reactive (intramolecular competition). This finding puts new constraints on mechanistic scenarios and favours either nucleophilic addition by Co(I) or single electron transfer as reductive dehalogenation mechanisms. PMID:24853618

Cretnik, Stefan; Bernstein, Anat; Shouakar-Stash, Orfan; Löffler, Frank; Elsner, Martin

2014-01-01

50

NEUROTOXICITY OF TETRACHLOROETHYLENE (PERCHLOROETHYLENE): DISCUSSION PAPER  

EPA Science Inventory

This paper is a background document for a meeting of neurotoxicity experts to discuss the central nervous system effects of exposure to perchloroethylene (perc). The document reviews the literature on neurological testing of people exposed to perc occupationally in dry cleanin...

51

A study of the effect of perchloroethylene exposure on semen quality in dry cleaning workers  

SciTech Connect

The purpose of this investigation was to determine the effects of perchloroethylene (PCE) exposure on human semen quality. We compared the semen quality of 34 dry cleaners with that of 48 laundry workers. We examined the relationships of 17 semen parameters to expired air levels of PCE and to an index of exposure based on job tasks in the last three months. The average sperm concentration was over 80 million for both dry cleaners and laundry workers, but approximately one-quarter of each group was oligospermic. The overall percentage of abnormal forms was similar for the two groups; however, sperm of dry cleaners were significantly more likely to be round (t = -3.29, p = 0.002) and less likely to be narrow (t = 2.35, p = 0.02) than the sperm of laundry workers. These effects were dose-related to expired air levels and to the exposure index after controlling for potential confounders (e.g., heat exposure). The average percent motile sperm for both groups was slightly over 60%; however, sperm of dry cleaners tended to swim with greater amplitude of lateral head displacement (ALH) than those of laundry workers (t = -1.73, p = 0.09), and level of PCE in expired air was a significant predictor of ALH in the multiple regression model (t = 2.00, p = 0.05). In addition, exposure index was a significant negative predictor of the sperm linearity parameter (t = -2.57, p = 0.01). These results suggest that occupational exposures to PCE can have subtle effects on sperm quality. Additional analyses are required to determine whether these effects are associated with changes in fertility.

Eskenazi, B.; Wyrobek, A.J.; Fenster, L.; Katz, D.F.; Sadler, M.; Lee, J.; Hudes, M.; Rempel, D.M. (Program of Maternal and Child Health, School of Public Health, University of California, Berkeley (United States))

1991-01-01

52

Effect of dechlorinating bacteria on the longevity and composition of PCE-containing nonaqueous phase liquids under equilibrium dissolution conditions  

SciTech Connect

The influence of dechlorinating microorganisms on PCE and its reduced end products in the presence of a PCE-containing nonaqueous phase liquid (NAPL) was investigated. Experiments were conducted in continuous-flow stirred-tank reactors (CFSTRs) containing a mixed PCE dechlorinating culture and a model NAPL consisting of PCE and tridecane. Comparisons between biotic and abiotic CFSTRs demonstrated that dechlorination resulted in a factor of 14 increase in PCE removal rates from the NAPL. The formation of dechlorination daughter products trichloroethene and cis-dichloroethene were observed, and cis-dichloroethene was not dechlorinated further. Partitioning of daughter products between phases caused temporal changes in the chlorinated ethenes distribution within the NAPL. The combined effects of dissolution and dechlorination on the removal of chlorinated ethenes from the NAPL were described using a mathematical model that approximated dechlorination as a pseudo-first-order process. Pseudo-first-order dechlorination rate coefficients for PCE and TCE were determined and were 0.18 and 0.27 h{sup {minus}1}, respectively. It was determined that total chlorinated ethenes removal from the NAPL would be achieved in 13 days in biotic CFSTRs, as compared to 77 days in the abiotic CFSTRs--corresponding to an 83% reduction in longevity of the chlorinated ethenes component of the NAPL.

Carr, C.S.; Garg, S.; Hughes, J.B.

2000-03-15

53

TCE treatment pasta-bilities.  

PubMed

Monsanto's "Lasagna" process uses layers of treatment zones spaced between buried electrodes to remove trichloroethylene (TCE) from contaminated soil and groundwater. TCE is used primarily as a metal degreaser as well as in products such as dyes, printing ink, and paint. TCE can eventually make its way into the environment and is prevalent in the water and soil of industrialized nations. Although TCE breaks down in a few days when released into the atmosphere, it degrades much more slowly in soil, taking months or years. Moreover, it is often broken down by microbes into toxic substances such as vinylidene chloride (a suspected human carcinogen) and vinyl chloride (a known human carcinogen). The Lasagna process is based on the principle of electro-osmosis, in which an electric current draws water from low--permeability soils such as clays, silts, and fine sands. To remove TCE from contaminated soils, Monsanto scientists added layers of filtering media, which attack the contaminant as it is pulled from electrode to electrode. The technology has been tested at the Paducah Gaseous Diffusion Plant in western Kentucky, where it removed over 98% of TCE from contaminated soil. PMID:10464086

Holton, W C

1999-09-01

54

TCE treatment pasta-bilities.  

PubMed Central

Monsanto's "Lasagna" process uses layers of treatment zones spaced between buried electrodes to remove trichloroethylene (TCE) from contaminated soil and groundwater. TCE is used primarily as a metal degreaser as well as in products such as dyes, printing ink, and paint. TCE can eventually make its way into the environment and is prevalent in the water and soil of industrialized nations. Although TCE breaks down in a few days when released into the atmosphere, it degrades much more slowly in soil, taking months or years. Moreover, it is often broken down by microbes into toxic substances such as vinylidene chloride (a suspected human carcinogen) and vinyl chloride (a known human carcinogen). The Lasagna process is based on the principle of electro-osmosis, in which an electric current draws water from low--permeability soils such as clays, silts, and fine sands. To remove TCE from contaminated soils, Monsanto scientists added layers of filtering media, which attack the contaminant as it is pulled from electrode to electrode. The technology has been tested at the Paducah Gaseous Diffusion Plant in western Kentucky, where it removed over 98% of TCE from contaminated soil.

Holton, W C

1999-01-01

55

FTIR quantification of industrial hydraulic fluids in perchloroethylene  

NASA Technical Reports Server (NTRS)

The purpose of this summer research project was to investigate whether perchloroethylene can be used as a solvent for the quantitative analysis of industrial hydraulic fluids by infrared spectroscopy employing Beer's law. Standard calibration curves using carbon-hydrogen stretching (generic) and ester absorption peaks were prepared for a series of standard dilutions at low ppm levels of concentration of seven hydraulic fluids in perchloroethylene. The absorbance spectras were recorded with 1.5-10 mm fixed and variable path length sample cells made of potassium bromide. The results indicate that using ester infrared spectral peak, it is possible to detect about 20 ppm of the hydraulic fluid in perchloroethylene.

Mehta, Narinder K.

1993-01-01

56

IRIS TOXICOLOGICAL REVIEW OF TETRACHLOROETHYLENE (PERCHLOROETHYLENE) (INTERAGENCY SCIENCE DISCUSSION DRAFT)  

EPA Science Inventory

EPA is releasing the draft report, Toxicological Review of Tetrachloroethylene (Perchloroethylene), that was distributed to Federal agencies and White House Offices for comment during the Science Discussion step of the IRIS Assessment...

57

Enhanced reduction of chromate and PCE by pelletized surfactant-modified zeolite/zerovalent iron  

SciTech Connect

The current research focuses on enhanced removal of chromate and perchloroethylene from contaminated water by a combination of a reduction material (represented by zerovalent iron, ZVI) and a sorption material (represented by surfactant-modified zeolite, SMZ). Natural zeolite and ZVI were homogenized and pelletized to maintain favorable hydraulic properties while minimizing material segregation due to bulk density differences. The zeolite/ZVI pellets were modified with the cationic surfactant hexadecyltrimethylammonium bromide to increase contaminant sorption and, thus, the contaminant concentration on the solid surface. Results of chromate sorption/reduction indicate that the chromate sorption capacity of pelletized SMZ/ZVI is at least 1 order of magnitude higher than that of zeolite/ZVI pellets. Compared to SMZ pellets, the chromate removal capacity of SMZ/ZVI pellets in a 24-h period is about 80% higher, due to the combined effects o sorption by SMZ and reduction by ZVI. The chromate and PCE degradation rates with and without surfactant modification were determined separately. The pseudo-first-order reduction constant increased by a factor of 3 for PCE and by a factor of 9 for chromate following surfactant modification. The enhanced contaminant reduction capacity of SMZ/ZVI pellets may lead to a decrease in the amount of material required to achieve a given level of contaminant removal.

Li, Z.; Jones, H.K.; Bowman, R.S.; Helferich, R.

1999-12-01

58

Biotreatment of TCE-contaminated groundwater  

SciTech Connect

A trickle-bed bioreactor containing a consortium of microorganisms using methane as the primary carbon source was used to treat a synthetic groundwater containing trichloroethylene (TCE) and trans-1,2-dichloroethylene (DCE). With influent concentrations of TCE and DCE of 1 mg/L each and an average residence time of about 50 min, >50% of the TCE and >90% of the DCE was degraded. The reactor exhibited first-order kinetics with respect to TCE degradation. 5 refs., 1 tab.

Donaldson, T.L.; Strandberg, G.W.; Palumbo, A.V.

1989-01-01

59

HORIZONTAL LASAGNA^TM TO BIOREMEDIATE TCE  

EPA Science Inventory

Removal of TCE from these tight clay soils has been technically difficult and expensive. However, the LASAGNA technique allows movement of the TCE into treatment zones for biodegradation or dechlorination in place, lessening the costs and exposure to TCE. Electroosmosis wa...

60

Physiological Adaptation of Desulfitobacterium hafniense Strain TCE1 to Tetrachloroethene Respiration?†  

PubMed Central

Desulfitobacterium spp. are ubiquitous organisms with a broad metabolic versatility, and some isolates have the ability to use tetrachloroethene (PCE) as terminal electron acceptor. In order to identify proteins involved in this organohalide respiration process, a comparative proteomic analysis was performed. Soluble and membrane-associated proteins obtained from cells of Desulfitobacterium hafniense strain TCE1 that were growing on different combinations of the electron donors lactate and hydrogen and the electron acceptors PCE and fumarate were analyzed. Among proteins increasingly expressed in the presence of PCE compared to fumarate as electron acceptor, a total of 57 proteins were identified by mass spectrometry analysis, revealing proteins involved in stress response and associated regulation pathways, such as PspA, GroEL, and CodY, and also proteins potentially participating in carbon and energy metabolism, such as proteins of the Wood-Ljungdahl pathway and electron transfer flavoproteins. These proteomic results suggest that D. hafniense strain TCE1 adapts its physiology to face the relative unfavorable growth conditions during an apparent opportunistic organohalide respiration.

Prat, Laure; Maillard, Julien; Grimaud, Regis; Holliger, Christof

2011-01-01

61

Decontamination of TCE and U-rich waters by granular iron: Role of sorbed Fe(II)  

Microsoft Academic Search

Uranium (UOâ{sup 2+}) and chlorinated aliphatics [tetrachloroethane (PCE) and trichloroethane (TCE)] can be reduced and thus immobilized or degraded, respectively, by the same abiotic mechanism. In this mechanism the reduction reaction is coupled to the oxidation of Fe(II) sorbed on iron corrosion products such as hematite. This is indicated by the equilibrium E{sub h} values measured during uranium immobilization and

Laurent Charlet; E. Liger; P. Gerasimo

1998-01-01

62

TEMPERATURE DEPENDENCE OF THE EMISSION OF PERCHLOROETHYLENE FROM DRY CLEANED FABRICS  

EPA Science Inventory

The article discusses an evaluation of the emission of perchloroethylene (tetrachloroethylene) from freshly dry cleaned fabrics using small environment test chambers. he temperature dependence of the release of perchloroethylene was evaluated over a temperature range of 20 to 45 ...

63

Effect of nonionic surfactant partitioning on the dissolution kinetics of residual perchloroethylene in a model porous medium  

NASA Astrophysics Data System (ADS)

At concentrations above the critical micelle concentration, surfactants can significantly enhance the solubilization of residual nonaqueous phase liquids (NAPL) and, for this reason, are the focus of research on surfactant-enhanced aquifer remediation (SEAR). As a consequence of their amphiphilic nature, surfactants may also partition to various extents between the organic and aqueous phases, thereby affecting SEAR performance. We report here on the observation and analysis of the effect of surfactant partitioning on the dissolution kinetics of residual perchloroethylene (PCE) by aqueous solutions (1000 mg/L) of the non-ionic surfactant Triton X-100 in a model porous medium. For this fluid system, batch equilibration experiments showed that the surfactant partitions strongly into the NAPL (NAPL-water partition coefficient equal to 12.5). Dynamic interfacial tension (IFT) measurements were employed to study surfactant diffusion and interfacial adsorption. The dynamic IFT measurements were consistent with partitioning of the surfactant between the two liquid phases. PCE dissolution experiments, conducted in a transparent glass micromodel using an aqueous surfactant solution, were contrasted to experiments using clean water. Surfactant partitioning was observed to delay significantly the onset of micellar solubilization of PCE, an observation reproduced by a numerical model. This effect is attributed to the reduction of surfactant concentration in the immediate vicinity of the NAPL-water interface, which accompanies transport of the surfactant into the NAPL. Accordingly, it is suggested that both the rate and the extent of diffusion of the surfactant into the NAPL affect the onset of and the driving force for micellar solubilization. While many surfactants do not readily partition in NAPL, this possibility must be considered when selecting non-ionic surfactants for the enhanced solubilization of residual chlorinated solvents in porous media.

Sharmin, Rumana; Ioannidis, Marios A.; Legge, Raymond L.

2006-01-01

64

INHIBITORY EFFECTS OF PERCHLOROETHYLENE ON HUMAN NEURONAL NICOTINIC ACETYLCHOLINE RECEPTORS.  

EPA Science Inventory

Perchloroethylene (PERC) is a volatile organic solvent with a variety of industrial uses. PERC exposure has been shown to cause adverse neurological effects including deficits in vision and memory in exposed individuals. Despite knowledge of these effects, the mechanisms by whi...

65

SOURCES, EMISSION AND EXPOSURE TO TRICHLOROETHYLENE (TCE) AND RELATED CHEMICALS  

EPA Science Inventory

This report documents the sources, emission, environmental fate and exposures for TCE, some of its metabolites, and some other chemicals known to produce identical metabolites. The major findings for TCE are: The primary sources releasing TCE to the environment ...

66

Transactions Cost Economics (TCE) Approach to Optimal Contract Type.  

National Technical Information Service (NTIS)

This study examines defense acquisition through the new lens of Transaction Cost Economics (TCE). TCE is an emergent field in economics that has multiple applications to defense acquisition practices. TCE's original focus was to guide 'make-or-buy' decisi...

F. Melese J. Dillard R. E. Franck

2006-01-01

67

Superfund Record of Decision (EPA Region 3): Croyden TCE Spill, PA. (First Remedial Action), December 1988  

SciTech Connect

The Croyden TCE Spill site is located in Bristol Township, Buck County, Pennsylvania. VOC contamination in the ground water was detected over a 3.5-square mile area, predominantly residential, with an estimated 3,000 residents. The study area is bordered on the south by the Delaware River. Neshaminy Creek, which borders the study area to the west, and Hog Run Creek which flows through the focused area of investigation, both discharge to the river. Although the source of contamination has not been identified, the contaminant plume appears to be flowing south-southeast into the East Branch of Hog Run Creek and probably into the Delaware River. The primary contaminants of concern affecting the ground water are TCE and PCE. The selected remedial action for the site includes connecting approximately 13 residences to the public water supply system via the construction of new water services lines, mains, hydrants, and valves; and ground water monitoring to ensure that homes located outside of the TCE-contaminated zone will not be at risk from the migrating plume.

Not Available

1988-12-28

68

Numerical simulation of transport and sequential biodegradation of chlorinated aliphatic hydrocarbons using CHAIN_2D  

Microsoft Academic Search

Microbiological degradation of perchloroethylene (PCE) under anaerobic conditions follows a series of chain reactions, in which, sequentially, trichloroethylene (TCE), cis-dichloroethylene (c-DCE), vinylchloride (VC) and ethene are generated. First-order degradation rate constants, partitioning coefficients and mass exchange rates for PCE, TCE, c-DCE and VC were compiled from the literature. The parameters were used in a case study of pump-and-treat remediation of

J. Schaerlaekens; D. Mallants; M. Th. van Genuchten; J. Feyen

1999-01-01

69

Self-inhibition can limit biologically enhanced TCE dissolution from a TCE DNAPL.  

PubMed

Biodegradation of trichloroethene (TCE) near a Dense Non Aqueous Phase Liquid (DNAPL) can enhance the dissolution rate of the DNAPL by increasing the concentration gradient at the DNAPL-water interface. Two-dimensional flow-through sand boxes containing a TCE DNAPL and inoculated with a TCE dechlorinating consortium were set up to measure this bio-enhanced dissolution under anaerobic conditions. The total mass of TCE and daughter products in the effluent of the biotic boxes was 3-6 fold larger than in the effluent of the abiotic box. However, the mass of daughter products only accounted for 19-55% of the total mass of chlorinated compounds in the effluent, suggesting that bio-enhanced dissolution factors were maximally 1.3-2.2. The enhanced dissolution most likely primarily resulted from variable DNAPL distribution rather than biodegradation. Specific dechlorination rates previously determined in a stirred liquid medium were used in a reactive transport model to identify the rate limiting factors. The model adequately simulated the overall TCE degradation when predicted resident microbial numbers approached observed values and indicated an enhancement factor for TCE dissolution of 1.01. The model shows that dechlorination of TCE in the 2D box was limited due to the short residence time and the self-inhibition of the TCE degradation. A parameter sensitivity analysis predicts that the bio-enhanced dissolution factor for this TCE source zone can only exceed a value of 2 if the TCE self-inhibition is drastically reduced (when a TCE tolerant dehalogenating community is present) or if the DNAPL is located in a low-permeable layer with a small Darcy velocity. PMID:22749126

Haest, P J; Springael, D; Seuntjens, P; Smolders, E

2012-11-01

70

Public health assessment for Malvern Tce Site, Malvern, Chester County, Pennsylvania, Region 3. Cerclis No. PAD014353445. Final report  

SciTech Connect

The Chemclene (Malvern TCE) site is a National Priorities List (NPL) site in Chester County, Pennsylvania, 5.5 miles south of Phoenixville. Over the years, careless waste handling and waste burial have contaminated soil and groundwater with trichloroethene (TCE), 1,1,1-trichloroethane (TCA), and tetrachloroethene (PCE). Based upon the information reviewed, the Pennsylvania Department of Health and the Agency for Toxic Substances and Disease Registry have concluded that this site is a public health hazard because past exposures through the use of contaminated well water were at levels of public health concern. Human exposure to volatile organic compounds (VOCs) may still be occurring through the use of private well water, and the potential for exposure from the nearby public well exists should the contaminant plume reach that well.

Not Available

1994-01-06

71

PCE oxidation by sodium persulfate in the presence of solids.  

PubMed

Batch reactor experiments were performed to determine the effects of solids on the oxidation of tetracholoroethylene (PCE) by sodium persulfate in aqueous solution. Based on the rates of PCE degradation and chloride formation, PCE oxidation by heat-activated sodium persulfate at 50 °C in the presence of solids ranged from no detectable oxidation of PCE to the levels observed in water-only reactors. Repeated doses of sodium persulfate, undertaken to overcome the inherent solids oxidant demand, improved the rate and extent of PCE oxidation in reactors containing reference solids; however, no improvement was observed in reactors containing field soils. Additionally, no improvements in PCE oxidation were observed after pretreating Great Lakes and Appling soils with ca. 15 g/kg of sodium persulfate or 30% hydrogen peroxide to remove oxidizable fractions, or acetic acid to remove the carbonate fraction. Based on these results, in situ treatment of Great Lakes and Appling soils with heat-activated sodium persulfate is not anticipated to result in substantial PCE oxidation, while in situ treatment of Fort Lewis soils is anticipated to result in PCE oxidation. This work demonstrates the need to perform soil-specific contaminant treatability tests rather than soil oxidant demand tests when determining oxidant dosage requirements. PMID:21070044

Costanza, Jed; Otaño, Gretell; Callaghan, John; Pennell, Kurt D

2010-12-15

72

Industrial Hygiene Report Perchloroethylene at Happy Cleaner Man Cleaners, New York, New York.  

National Technical Information Service (NTIS)

Worker exposures to perchloroethylene (127184) were determined at Happy Cleaner Man Cleaners (SIC-7216) in New York, New York, on August 29, 1979. The survey was part of a NIOSH study of the health effects of occupational perchloroethylene exposure. The a...

D. R. Roberts

1980-01-01

73

BIODEGRADATION OF PCE AND TCE IN LANDFILL, LEACHATE PREDICTED FROM CONCENTRATIONS OF MOLECULAR HYDROGEN: A CASE STUDY  

EPA Science Inventory

The Refuse Hideaway Landfill (23-acre) was designed as a "natural attenuation" landfill and no provision was made to collect and treat contaminated water. Natural biological degradation through sequential reductive dechlorination had been an important mechanism for natural atten...

74

Health Assessment Document for Tetrachloroethylene (Perchloroethylene) (Final Report)  

EPA Science Inventory

Tetrachloroethylene (PCE) is a volatile solvent with important commercial applications. It has been detected in the ambient air of a variety of urban and nonurban areas of the United States. It has less frequently been detected in water but has been monitored generally at levels ...

75

Review of the epidemiologic literature on residential exposure to perchloroethylene.  

PubMed

Perchloroethylene is a solvent that is widely used for dry cleaning. There has been considerable interest in the toxicity of this chemical because of the potential for low-level exposure among a large portion of the US population. Although substantial epidemiologic literature exists on high-level occupational exposure to perchloroethylene, there are relatively few studies dealing with lower-level residential exposure. In the current paper, the author reviews this limited residential literature, with special emphasis on strengths, limitations, and consistency. Reviewed studies primarily address neurobehavioral, cancer, and reproductive endpoints. Most studies used an ecological or cross-sectional design, with exposure defined by either drinking-water contamination or proximity to dry cleaning. In general, reviewed studies were highly exploratory, with inconsistencies and potential for bias that detract from interpretation of study findings. The magnitudes of reported effects are frequently incompatible with the effects reported from much higher occupational and human-chamber exposures. Overall, few reliable conclusions can be drawn from this sparse and highly limited body of literature. PMID:21728756

Bukowski, John A

2011-10-01

76

Gaseous Behavior of TCE (Trichloroethylene) Overlying a Contaminated Aquifer.  

National Technical Information Service (NTIS)

Shallow soil gas (<2 meters deep) was collected and analyzed for trichloroethylene (TCE) to determine the relationship with ground-water contamination directly below. The gaseous TCE plume was mapped with 46 probes and spanned three orders of magnitude in...

D. L. Marrin G. M. Thompson

1987-01-01

77

PCE: web tools to compute protein continuum electrostatics.  

PubMed

PCE (protein continuum electrostatics) is an online service for protein electrostatic computations presently based on the MEAD (macroscopic electrostatics with atomic detail) package initially developed by D. Bashford [(2004) Front Biosci., 9, 1082-1099]. This computer method uses a macroscopic electrostatic model for the calculation of protein electrostatic properties, such as pK(a) values of titratable groups and electrostatic potentials. The MEAD package generates electrostatic energies via finite difference solution to the Poisson-Boltzmann equation. Users submit a PDB file and PCE returns potentials and pK(a) values as well as color (static or animated) figures displaying electrostatic potentials mapped on the molecular surface. This service is intended to facilitate electrostatics analyses of proteins and thereby broaden the accessibility to continuum electrostatics to the biological community. PCE can be accessed at http://bioserv.rpbs.jussieu.fr/PCE. PMID:15980492

Miteva, Maria A; Tufféry, Pierre; Villoutreix, Bruno O

2005-07-01

78

Complex electrical resistance tomography of a subsurface PCE plume.  

National Technical Information Service (NTIS)

A controlled experiment was conducted to evaluate the performance of complex electrical resistivity tomography (CERT) for detecting and delineating free product dense non-aqueous phase liquid (DNAPL) in the subsurface. One hundred ninety liters of PCE wer...

A. Ramirez W. Daily D. LeBrecque

1996-01-01

79

SUMMARY REPORT OF THE PEER REVIEW WORKSHOP ON THE NEUROTOXICITY OF TETRACHLOROETHYLENE (PERCHLOROETHYLENE) DISCUSSION PAPER  

EPA Science Inventory

The report, Summary Report of the Peer Review Workshop on the Neurotoxicity of Tetrachloroethylene (Perchloroethylene) Discussion , summarizes the discussions at a February 25, 2004, workshop that brought together recognized scientific experts to engage in a public discussi...

80

TCE diffusion to the atmosphere in phytoremediation applications.  

PubMed

The phytoremediation of trichloroethylene (TCE) and other chlorinated compounds has been studied over the past decade, and full-scale systems are in place. The results regarding TCE fates and removal pathways are inconclusive and conflicting, particularly the results regarding volatilization to the atmosphere. Research presented here demonstrates that TCE is taken up by trees and volatilized to the atmosphere. TCE diffusion along the transpiration pathway is shown to be the primary process for TCE volatilization, although volatilization can occur from both stems and leaves. Two concurrent processes influence the eventual fate: transport with transpiration stream through xylem tissues and diffusion from transpiration stream to atmosphere. TCE diffusion flux invariably decreased with height for trees planted in soil or grown hydroponically. In both laboratory experiments and field sampling, TCE concentrations in the transpiration stream (e.g., xylem tissues) decreased with elevation. In field samples, TCE concentrations also decreased in the radial direction, providing fundamental evidence for diffusion. The TCE concentrations in tissues responded linearly to the exposure concentrations at the roots, while TCE diffusion from tree stems was influenced by concentration and transpiration rates. PMID:12831040

Ma, Xingmao; Burken, Joel G

2003-06-01

81

Sorption of nonionic surfactant oligomers to sediment and PCE DNAPL: Effects on PCE distribution between water and sediment  

SciTech Connect

Introduction of surfactant mixtures to the subsurface for the purpose of surfactant-enhanced aquifer remediation requires consideration of the effects of surfactant sorption to sediment and nonaqueous phase liquids. These effects include alteration of the solubilizing properties of the surfactant mixture and alteration of the sorption properties of the stationary phase. Sorption of octylphenol ethoxylate (EO) surfactant oligomers to a low organic carbon content (f{sub oc}) aquifer sediment and to dense nonaqueous phase liquid (DNAPL) consisting of tetrachloroethene (PCE) was examined in batch experiments. At aqueous surfactant concentrations far below the critical micelle concentration (CMC) of the mixture, sorption to sediment was characterized by an initial steep isotherm for both high and low EO content oligomers, with somewhat greater uptake of high EO content oligomers. This stage of sorption resulted in mild increases in the equilibrium constant, k{sub d,PCEr} for distribution of PCE between solution (including surfactant) and sediment (including sorbed surfactant). As the aqueous surfactant concentration increased, surface aggregation of low EO content oligomers on the sediment commenced, and a dramatic increase in K{sub d,PCE} was observed. At aqueous surfactant concentrations increasing above the CMC, the formation of solution micelles caused the sorbed surfactant concentrations to plateau and then decrease. This decrease in sorbed surfactant, along with competition by micelles for contaminant, likely contributed to the observed rapid decrease in K{sub d,PCE} toward zero. Surfactant sorption to PCE DNAPL was greater relative to sediment by 1--2 orders of magnitude, with much greater uptake of the low EO content oligomers. Sorption of all but the lowest EO content oligomers to the PCE DNAPL was terminated by micellization.

John, W.W.; Bao, G.; Johnson, W.P.; Stauffer, T.B.

2000-02-15

82

Health risk assessment of trichloroethylene (TCE) in California drinking water  

SciTech Connect

This document presents an assessment of the potential health risks associated with exposure to trichloroethylene (TCE) dissolved in California drinking waters. This assessment is being provided to the California Department of Health Services (CDHS) for the development of drinking-water standards to manage the health risks of TCE exposures. Other assessments required in the risk-management process include analyses of the technical and economic feasibility of treating water supplies contaminated with TCE. A primary goal of this health-risk assessment is to evaluate dose-response relationships for observed and potential toxic end points of TCE in order to define dose rates that can be used to establish standards that will protect members of the general public from adverse health effects resulting solely from water-based exposures to TCE. We also analyze the extent of human exposures attributable to TCE-contaminated groundwater in California. 363 refs., 8 figs., 22 tabs.

Bogen, K.T.; Hall, L.C.; Perry, L.; Fish, R.; McKone, T.E.; Dowd, P.; Patton, S.E.; Mallon, B.

1988-01-28

83

Methanotrophic TCE biodegradation in a multi-stage bioreactor  

SciTech Connect

A two-stage bioreactor system was continuously fed a solution of TCE (concentrations ranging between 0.2 and 20 mg L{sup -1}) at 2 mL min{sup -1}; the system utilized a mutant (PP358) of the methane oxidizing bacterium Methylosinus trichosporium OB3b for the fortuitous cooxidation of TCE by the enzyme-soluble methane monooxygenase (sMMO). A methane-free environment was maintained in the TCE treatment portion of the reactor (plug-flow columns), minimizing the effects of competitive inhibition between TCE and methane for the sMMO. The reactor was operated in two separate flow configurations, single-pass and cross-flow, with TCE removal percentages exceeding 78% (for a TCE feed concentration of 20 mg L{sup -1}) and 93% (for a TCE feed concentration of 10 mg L{sup -1}), respectively. A r{sub max} of 109.4 mg of TCE (g of VS){sup -1} d{sup -1} for a TCE feed concentration of 20 mg L{sup -1} was obtained, suggesting that high rates of degradation occurred within the reactor. TCE-induced toxicity effects occurred at TCE feed concentrations of 10 mg L{sup -1} and greater, resulting in declines of the biomass concentrations and the enzyme activities. A model describing the rate of TCE degradation in the plug-flow columns was proposed by Alvarez-Cohen et al. and was modified to incorporate the suboptimal activities of sMMO. 29 refs., 7 figs., 1 tab.

Tschantz, M.L.F.; Bowman, J.P.; Bienkowski, P.R.; Sayler, G.S. [Univ. of Tennessee, Knoxville, TN (United States); Donaldson, T.L.; Strong-Gunderson, J.M.; Palumbo, A.V.; Herbes, S.E. [Oak Ridge National Lab., TN (United States)

1995-08-01

84

Activities for Career Education: PCE/K-10. Volume 1.  

ERIC Educational Resources Information Center

The Portland (Oregon) Public School Project Career Education (PCE) guide for grades 7-8 opens with an outline of the eight concepts to be implemented into the curriculum and a brief description of the four interwoven and interdependent life role definitions (vocational, leisure, family, and citizen). This is followed by a sample 7-8 implementation…

Portland Public Schools, OR.

85

PCE solubilization and mobilization by commercial humic acid  

NASA Astrophysics Data System (ADS)

In this paper, comparison is made of terms describing solubilization of hydrophobic organic compounds (HOC) by dissolved humic substances (DHS) and commercial non-ionic surfactants. This paper examines the ability of a commercial humic acid (Aldrich humic acid) to solubilize and mobilize tetrachlorothene (PCE) residual in porous media. The constant for solubilization of PCE by Aldrich humic acid is shown to be a factor of two to thirty times less than that published for dodecyl alcohol ethoxylate surfactants, showing that Aldrich humic acid is less capable than some non-ionic surfactants at solubilizing residual PCE. The depression of PCE-water interfacial tension in the presence of DHS is shown to be significantly less than published values for a non-ionic surfactant, and surfactant mixtures, indicating that the DHS used in this study is less prone to cause mobilization of non-aqueous phase liquids relative to surfactants. Several possible advantages of DHS use in the remediation of subsurface media contaminated with HOC are described, including the ability of DHS to solubilize HOC irrespective of the DHS concentration, and potential lesser tendency of DHS to depress the interfacial tension between non-aqueous phases and water relative to surfactants (an advantage when mobilization is undesired).

Johnson, William P.; John, W. Wynn

1999-01-01

86

Complex electrical resistance tomography of a subsurface PCE plume  

Microsoft Academic Search

A controlled experiment was conducted to evaluate the performance of complex electrical resistivity tomography (CERT) for detecting and delineating free product dense non-aqueous phase liquid (DNAPL) in the subsurface. One hundred ninety liters of PCE were released at a rate of 2 liters per hour from a point 0.5 m below ground surface. The spill was conducted within a double

A. Ramirez; W Daily; D. LeBrecque

1996-01-01

87

Genome Sequence of the PCE-Dechlorinating Bacterium Dehalococcoides ethenogenes  

Microsoft Academic Search

Dehalococcoides ethenogenes is the only bacterium known to reductively dechlorinate the groundwater pollutants, tetrachloroethene (PCE) and trichloroethene, to ethene. Its 1,469,720-base pair chromosome contains large dynamic duplicated regions and integrated elements. Genes encoding 17 putative reductive dehalogenases, nearly all of which were adjacent to genes for transcription regulators, and five hydrogenase complexes were identified. These findings, plus a limited repertoire

Rekha Seshadri; Lorenz Adrian; Derrick E. Fouts; Adam M. Phillippy; Barbara A. Methe; Naomi L. Ward; William C. Nelson; Robert T. Deboy; Hoda M. Khouri; James F. Kolonay; Robert J. Dodson; Sean C. Daugherty; Lauren M. Brinkac; Steven A. Sullivan; Ramana Madupu; Karen E. Nelson; Katherine H. Kang; Marjorie Impraim; Kevin Tran; Jeffrey M. Robinson; Heather A. Forberger; Claire M. Fraser; Stephen H. Zinder; John F. Heidelberg

2005-01-01

88

Design and construction techniques for permeable reactive barriers  

Microsoft Academic Search

Adequate site characterization, bench-scale column testing, and hydrogeologic modeling formed the basis for the design and construction of permeable reactive barriers for groundwater remediation at various sites, such as Dover Air Force Base, DE and Naval Air Station, Moffett Field, CA. Dissolved chlorinated solvents, such as perchloroethylene (PCE) and trichloroethylene (TCE), have been the focus at many sites because the

Arun R. Gavaskar

1999-01-01

89

Bulk provisioning of LSP requests with shared path protection in a PCE-based WDM network  

Microsoft Academic Search

The Path Computation Element (PCE) is a network entity utilized for network path computation operations, especial- ly useful in optical networks based on wavelength division mul- tiplexing (WDM). In the PCE paradigm, the communication between a node and the PCE is specified by the Path Computa- tion Element Communication Protocol (PCEP). According to PCEP protocol, multiple LSP (Label Switched Path)

Jawwad Ahmed; Cicek Cavdar; Paolo Monti; Lena Wosinska

2011-01-01

90

Expert system methodology for evaluating reductive dechlorination at TCE sites  

Microsoft Academic Search

An expert knowledge site-screening methodology has been developed to evaluate naturally occurring reductive dechlorination as a remedial option for sites with TCE-contaminated groundwater. This methodology combines a causative model for the reductive dechlorination of TCE and expert knowledge within a Bayesian Belief Network. The knowledge base for this expert system was obtained from 22 experts via an expert elicitation protocol

Neil A. Stiber; Marina Pantazidou; Mitchell J. Small

1999-01-01

91

PCE algorithm for PAPR reduction in OFDM-ROF system  

Microsoft Academic Search

In this paper, a novel constellation extension algorithm, named as peak-restricted constellation extension (PCE), is proposed for peak-to-average power ratio (PAPR) reduction in orthogonal frequency division multiplexing (OFDM) system. This algorithm actively selects outer constellation points which contribute to the large peak magnitudes, and dynamically alter the amplitudes of these points to reduce PAPR. It does not require transmitting any

Jianping Wang; Bosheng Liu; Xianwei Zhou

2009-01-01

92

Complex electrical resistance tomography of a subsurface PCE plume  

SciTech Connect

A controlled experiment was conducted to evaluate the performance of complex electrical resistivity tomography (CERT) for detecting and delineating free product dense non-aqueous phase liquid (DNAPL) in the subsurface. One hundred ninety liters of PCE were released at a rate of 2 liters per hour from a point 0.5 m below ground surface. The spill was conducted within a double walled tank where saturated layers of sand, bentonite and a sand/bentonite mixture were installed. Complex electrical resistance measurements were performed. Data were taken before the release, several times during, and then after the PCE was released. Magnitude and phase were measured at 1 and 64 Hz. Data from before the release were compared with those during the release for the purpose of imaging the changes in conductivity resulting from the plume. Conductivity difference tomographs showed a decrease in electrical conductivity as the DNAPL penetrated the soil. A pancake-shaped anomaly developed on the top of a bentonite layer at 2 m depth. The anomaly grew in magnitude and extent during the release and borehole television surveys data confirmed the anomaly to be free-product PCE whose downward migration was stopped by the low permeability clay. The tomographs clearly delineated the plume as a resistive anomaly.

Ramirez, A.; Daily, W,; LeBrecque, D.

1996-01-01

93

Decontamination of TCE- and U-rich waters by granular iron: Role of sorbed Fe(II)  

SciTech Connect

Uranium (UO{sub 2}{sup 2+}) and chlorinated aliphatics [tetrachloroethane (PCE) and trichloroethane (TCE)] can be reduced and thus immobilized or degraded, respectively, by the same abiotic mechanism. In this mechanism the reduction reaction is coupled to the oxidation of Fe(II) sorbed on iron corrosion products such as hematite. This is indicated by the equilibrium E{sub h} values measured during uranium immobilization and PCE degradation reactions of zerovalent iron. These values fit closely with those measured in the Fe(II)-{alpha}Fe{sub 2}O{sub 3}-H{sub 2}O system (in the absence of U or PCE), not those of the Fe(o)/Fe(II) or H{sub 2}(g)/H{sub 2}O couples. Because iron (II) is very unstable in environments that are not strictly anaerobic, Fe(o) serves as a source of Fe(II). The reduction kinetic rate, analyzed in detail for the reduction of U(VI), is found to be a function of the concentration of OH{sup {minus}}, Fe{sup 2+} and reactive surface sites, and is given in terms of sorbed species concentrations by {l_brace}d[U(VI)]{sub ads}{r_brace}/dt = {l_brace}{minus}k{prime}[{triple_bond}FeOFeOH{sup 0}][U(VI)]{sub ads}{r_brace}. This rate law applies to organic pollutants as well, as long as they can be reduced by surface Fe(II): {l_brace}d[Pollutant]{r_brace}/dt = {l_brace}{minus}k{prime}[{triple_bond}FeOFeOH{sup 0}][Pollutant]{r_brace}. This mechanism suggests new possibilities for the improvement of low-cost decontamination techniques for U- and chlorinated aliphatic-rich waters.

Charlet, L.; Liger, E. [Univ. of Grenoble-I (France); Gerasimo, P. [Service de Protection Radiologique des Armees, Clamart (France)

1998-01-01

94

PERCHLOROETHYLENE (PERC) INHIBITS FUNCTION OF VOLTAGE-GATED CALCIUM CHANNELS IN PHEOCHROMOCYTOMA CELLS.  

EPA Science Inventory

The industrial solvent perchloroethylene (PERC) is listed as a hazardous air pollutant in the 1990 Ammendments to Clean Air Act and is a known neurotoxicant. However, the mechanisms by which PERC alters nervous system function are poorly understood. In recent years, it has been d...

95

CATALYTIC STEAM REFORMING OF CHLOROCARBONS: TRICHLOROETHANE, TRICHLOROETHYLENE AND PERCHLOROETHYLENE. (R826694C633)  

EPA Science Inventory

The effective destruction of trichloroethane, trichloroethylene and perchloroethylene by steam reforming with a commercial nickel catalyst has been demonstrated. Conversion levels of up to 0.99999 were attained in both laboratory and semi-pilot experiments, with the products c...

96

Multiple Co-Substrates for Biostimulation of TCE Degradation.  

National Technical Information Service (NTIS)

The objective of this Phase II SBIR project was to test and demonstrate the feasibility of using multiple co-substrates to stimulate in situ biodegradation of volatile organochloride compounds (VOCs) including trichloroethylene (TCE), cis- 1,2 dichloroeth...

R. J. Steffan

2000-01-01

97

TCE adsorption by GAC preloaded with humic substances  

SciTech Connect

Adsorption of trichloroethylene (TCE) by activated carbon preloaded with humic and fulvic acids was studied under several conditions in completely mixed batch systems. The authors investigated how molecular weight and molecular-weight distribution of preloaded humic substances affected subsequent adsorption of TCE. The capacity of carbon to adsorb TCE was most greatly reduced in carbon that was preloaded with humic acid components having molecular weights less than about 1,400 g/mol as polystyrene sulfonate. The adsorption capacity was greatly reduced in carbon that was preloaded with whole humic mixtures in which lower molecular weights predominated. The energy distributions of adsorbent indicate that preloaded compounds preferentially occupy high-energy sites, making them inaccessible to subsequently encountered TCE.

Kilduff, J.E. [Rensselaer Polytechnic Inst., Troy, NY (United States). Dept. of Environmental and Energy Engineering; Karanfil, T. [Clemson Univ., Anderson, SC (United States). Environmental Systems Engineering Dept.; Weber, W.J. Jr. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Civil and Environmental Engineering

1998-05-01

98

Field demonstration of vapor phase TCE bioreactor. Final report  

SciTech Connect

The objective of this Cooperative Research and Development Agreement (CRADA), was to demonstrate the effectiveness of a vapor-phase bioreactor system for the destruction of trichloroethylene (TCE) from contaminated groundwater. A field demonstration was per-formed using groundwater at the Oak Ridge K-25 Site contaminated with a complex mixture of organic chemicals. This site is managed and operated by Martin Marietta Energy Systems, Inc. for the Department of Energy (DOE). Analysis of the data generated during the test can be summarized in three major observations. First, TCE was degraded in the presence of all the organics found in the steam strip condensate. This was observed during treatment of both the steam strip condensate and condensate amended with TCE to increase its concentration relative to the other components. The conclusion that TCE was being biodegraded was supported by performing mass balance control experiments with the reactor and by tracking recalcitrant chemicals also present in the steam stripper condensate. Second, there appeared to be an initial lag period of up to 24 hours before onset of TCE degradation in the reactor. The source of this lag was not determined but could be related to either an acclimation of the microorganisms to other chemicals found in the condensate or reversible inhibitory effects on TCE degradation. The duration of TCE degradative activity was relatively short for only 2 to 5 days. compared to previous demonstrations where TCE was the sole contaminant. However, several of the runs were interrupted due to mechanical and not biological issues. Third, other chemical contaminants were also degraded. by the bacteria used in the vapor phase reactor which is consistent with previous work performed both at ENVIROGEN and elsewhere.

NONE

1994-12-14

99

Trichloroethene Reductive Dehalogenase from Dehalococcoides ethenogenes: Sequence of tceA and Substrate Range Characterization  

Microsoft Academic Search

The anaerobic bacterium Dehalococcoides ethenogenes is the only known organism that can completely dechlorinate tetrachloroethene or trichloroethene (TCE) to ethene via dehalorespiration. One of two corrinoid- containing enzymes responsible for this pathway, TCE reductive dehalogenase (TCE-RDase) catalyzes the dechlorination of TCE to ethene. TCE-RDase dehalogenated 1,2-dichloroethane and 1,2-dibromoethane to ethene at rates of 7.5 and 30 mmol\\/min\\/mg, respectively, similar to

JON K. MAGNUSON; MARGARET F. ROMINE; DAVID R. BURRIS; MARK T. KINGSLEY

2000-01-01

100

Large two-dimensional laboratory experiment with biodegradation of a PCE source zone  

NASA Astrophysics Data System (ADS)

To investigate the effects of bioremediation on DNAPL source zones, we carried out an experiment in a two-dimensional tank filled with sand. A microbial assemblage originating from a contaminated field site was used for inoculation without enrichment. Injection of 250 ml PCE into the tank yielded a residual zone of PCE with a pool at the bottom. After this injection, the tank was continuously flushed with anaerobic water containing sufficient electron donor and various nutrients. Chlorinated ethenes analysis, microbial groups counting, and the visual observation of the colored PCE show that PCE was degraded in the source zone. Bio-enhanced dissolution occurred as cDCE concentrations were measured four times the solubility limit of PCE and because the PCE solubility limit in the source zone increased. Degradation of cDCE to VC and ethene occurred when PCE concentrations were low (<0.1 mM). After one year of experiment, approximately 135 ml of chlorinated ethenes were removed from the tank. PCE left in the tank was 90 ml and was only present in the pool. keywords: 2D tank experiment, PCE-DNAPL, reductive dechlorination, source zone, bio-enhanced dissolution, mobilization.

Langevoort, M.; Hassanizadeh, S.; Kleingeld, P.; Heimovaara, T.; Leijnse, T.

2008-12-01

101

Variations in expression of carbon isotope fractionation of chlorinated ethenes during biologically enhanced PCE dissolution close to a source zone.  

PubMed

The stable carbon isotope values of tetrachloroethene (PCE) and its degradation products were monitored during studies of biologically enhanced dissolution of PCE dense nonaqueous phase liquid (DNAPL) to determine the effect of PCE dissolution on observed isotope values. The degradation of PCE was monitored in a 2-dimensional model aquifer and in a pilot test cell (PTC) at Dover Air Force Base, both with emplaced PCE DNAPL sources. Within the plume down gradient from the source, the isotopic fractionation of dissolved PCE and its degradation products were consistent with those observed in biodegradation laboratory studies. However, close to the source zone significant shifts in the isotope values of dissolved PCE were not observed in either the model aquifer or PTC due to the constant input of newly dissolved, non fractionated PCE, and the small isotopic fractionation associated with PCE reductive dechlorination by the mixed microbial culture used. Therefore the identification of reductive dechlorination in the presence of PCE DNAPL was based upon the appearance of daughter products and the isotope values of those daughter products. An isotope model was developed to simulate isotope values of PCE during the dissolution and degradation of PCE adjacent to a DNAPL source zone. With the exception of very high degradation rate constants (>1/day) stable carbon isotope values of PCE estimated by the model remained within error of the isotope value of the PCE DNAPL, consistent with measured isotope values in the model aquifer and in the PTC. PMID:19818530

Morrill, P L; Sleep, B E; Seepersad, D J; McMaster, M L; Hood, E D; LeBron, C; Major, D W; Edwards, E A; Lollar, B Sherwood

2009-11-01

102

Drip Irrigation Aided Phytoremediation for Removal of TCE from Groundwater  

SciTech Connect

Groundwater in D-Area at the Savannah River Site (SRS) is contaminated with trichloroethylene (TCE) and by-products resulting from discharges of this organic solvent during past disposal practices. This contaminated groundwater occurs primarily at depths of 9 meters to 15 meters below ground surface, well below the depths that are typically penetrated by plant roots. The process investigated in this study involved pumping water from the contaminated aquifer and discharging the water into overlying test plots two inches below the surface using drip irrigation. The field treatability study was conducted from 8/31/00 to 4/18/02 using six 0.08 hectare test plots, two each containing pines, cottonwoods, and no vegetation (controls). The primary objective was to determine the overall effectiveness of the process for TCE removal and to determine the principal biotic and abiotic pathways for its removal. Results demonstrated that the process provides a viable method to remove TCE-contaminated groundwater. The data clearly showed that the presence of trees reduced volatilization of TCE from the drip irrigation system to the atmosphere. Influent groundwater TCE concentrations averaging 89 mg/L were reduced to non-detectable levels (less than 5 mg/L) within the upper two feet of soil (rhizosphere).

Wilde, E.W.

2003-04-24

103

Bioenhanced Dissolution of PCE from DNAPL Pools: Large Tank Experiments  

NASA Astrophysics Data System (ADS)

Long-term persistence of chlorinated DNAPL has driven interest in source-depletion technologies. Recent flow- cell experiments demonstrated that microbial reductive dehalogenation can significantly enhance dissolution of high saturation pools of DNAPL. Modeling of these experiments showed that bioenhanced mass transfer can be simulated by linking abiotic DNAPL dissolution with aqueous-phase biodegradation and solute transport. For many technologies, the scale of application affects DNAPL removal efficiency and downgradient mass flux. However, detailed characterization of processes at field scales rarely is possible. As described in this presentation, scale-dependency of bioenhanced mass transfer was characterized in detail by conducting dissolution experiments in large 2-D tanks packed with homogeneous or heterogeneous sand units. Biotic and abiotic dissolution experiments were conducted with DNAPL pools at a range of saturations. Key experimental results follow. (1) Mass flux from intermediate-scale sources was significantly enhanced by biological activity. Compared with results of flow-cell experiments at similar saturations and Darcy velocities, enhancement did not decline with increasing source volume. (2) Saturation transition zones at tops of pools were key zones of bioenhanced dissolution. Electron-donor advection within these zones promoted PCE degradation, lowering aqueous PCE concentrations, and enhancing dissolution gradients. (3) Biodegradation to DCE occurred in the vicinity of pools, followed by downgradient conversion to vinyl chloride and ethene. (4) Gas accumulation, associated with ethene and vinyl chloride production downstream and electron-donor consumption upstream of sources, was significant. (5) Though inoculation occurred solely within the source zone, dechlorinating microbes migrated rapidly into downgradient areas. After three months, microbe distribution was nearly uniform, regardless of porous media heterogeneity. These results suggest that biotechnologies can be effective remediation strategies for source depletion while simultaneously treating downgradient contamination. Results also provide insight to strategies for upscaling models of bioenhanced dissolution.

Glover, K. C.; Illangasekare, T. H.; Munakata Marr, J.; Philippe, P.

2006-12-01

104

Large two-dimensional laboratory experiment with biodegradation of a PCE source zone  

Microsoft Academic Search

To investigate the effects of bioremediation on DNAPL source zones, we carried out an experiment in a two-dimensional tank filled with sand. A microbial assemblage originating from a contaminated field site was used for inoculation without enrichment. Injection of 250 ml PCE into the tank yielded a residual zone of PCE with a pool at the bottom. After this injection,

M. Langevoort; S. Hassanizadeh; P. Kleingeld; T. Heimovaara; T. Leijnse

2008-01-01

105

Sources, Emission and Exposure for Trichloroethylene(TCE) and Related Chemicals.  

National Technical Information Service (NTIS)

This report is an exposure assessment of Trichloroethylene (TCE), its metabolites, and other chemical compounds known to produce identical metabolites. In addition to TCE, other parent compounds considered here are 1,1,1-trichloroethane (methyl chloroform...

2001-01-01

106

FRACTIONATION OF STABLE CARBON ISOTOPES DURING ABIOTIC TRANSFORMATION OF TCE  

EPA Science Inventory

At a Superfund Site in Minnesota, ground water is contaminated with trichloroethylene (TCE) with the contaminant plume stretching over five miles long. The ground water is iron and manganese reducing, and the complete absence of dichloroethylene, vinyl chloride, and ethene in th...

107

TCE TRANSPORT AND DEGRADATION IN SOIL USING ELECTROOSMOSIS  

EPA Science Inventory

Laboratory experiments were used to characterize the transport and chemical transformation of TCE in undisturbed soil cores. Electroosmotic fluid flow was vertically downwards from anode to cathode. A voltage of 1.4 V/cm was applied to the soil for 4 weeks. More than 95% of the T...

108

IRIS Toxicological Review of Trichloroethylene (TCE) (External Review Draft)  

EPA Science Inventory

EPA is conducting a peer review and public comment of the scientific basis supporting the human health hazard and dose-response assessment of Trichloroethylene (TCE) that when finalized will appear on the Integrated Risk Information System (IRIS) database. Please refer to ...

109

In Situ Dechlorination of TCE During Aquifer Heating  

SciTech Connect

Laboratory and field efforts were undertaken to examine trichloroethene (TCE) dechlorination as a function of temperature as an aquifer is heated to temperatures approaching boiling. Experiments were conducted using sediment samples during electrical resistance heating (ERH) treatment at the Fort Lewis East Gate Disposal Yard, which contains non-aqueous phase TCE and hydrocarbon contamination. Laboratory microcosms with these sediments showed TCE dechlorination at 70oC with measured products of acetylene, ethene, and ethane, indicating an abiotic component of the degradation. In contrast, TCE was dechlorinated to cis-1,2-dichloroethene in experiments at 10oC, likely by biological reductive dechlorination. The observed products at 70oC suggest dechlorination catalyzed by reduced sediment iron. Indications of in situ dechlorination were observed in periodic groundwater samples collected during field-scale electrical resistance heating from an average ambient temperature of about 19oC to near boiling. Dechlorination indicators included an increase in chloride concentration at the onset of heating and observation of acetylene, ethene, and methane at elevated temperatures. The data collected in this study suggest that dechlorination can occur during ERH. The overall cost-effectiveness of ERH may be enhanced by fortuitous in situ dechlorination and, potentially, can be further enhanced by specifically designing and operating ERH to maximize in situ dechlorination.

Truex, Michael J.; Powell, Thomas; Lynch, Kira P.

2007-04-01

110

Anaerobic granule formation and tetrachloroethylene (TCE) removal in an upflow anaerobic sludge blanket (UASB) reactor  

Microsoft Academic Search

The granulation process was examined using synthetic wastewater containing tetrachloroethylene (TCE) in a 2 liters laboratory upflow anaerobic sludge blanket (UASB) reactor. The anaerobic biotransformation of TCE was investigated during the granulation process by reducing the HRT and increasing the chemical oxygen demand (COD) and TCE loadings. Anaerobic unacclimated sludge and glucose were used as seed and primary substrate, respectively.

Delia Teresa Sponza

2001-01-01

111

76 FR 30243 - Tax Counseling for the Elderly (TCE) Program Availability of Application Packages  

Federal Register 2010, 2011, 2012, 2013

...TREASURY Internal Revenue Service Tax Counseling for the Elderly (TCE) Program Availability...Application Packages for the 2012 Tax Counseling for the Elderly (TCE) Program. DATES...package to the IRS for the 2012 Tax Counseling for the Elderly (TCE) Program is...

2011-05-24

112

75 FR 25319 - Tax Counseling for the Elderly (TCE) Program Availability of Application Packages; Correction  

Federal Register 2010, 2011, 2012, 2013

...TREASURY Internal Revenue Service Tax Counseling for the Elderly (TCE) Program Availability...a correction to a notice of the Tax Counseling for the Elderly (TCE) Program Availability...application packages for the 2011 Tax Counseling for the Elderly (TCE) Program....

2010-05-07

113

78 FR 17777 - Tax Counseling for the Elderly (TCE) Program Availability of Application Packages  

Federal Register 2010, 2011, 2012, 2013

...TREASURY Internal Revenue Service Tax Counseling for the Elderly (TCE) Program Availability...Application Packages for the 2014 Tax Counseling for the Elderly (TCE) Program. DATES...application package to the IRS for the Tax Counseling for the Elderly (TCE) Program is...

2013-03-22

114

77 FR 20695 - Tax Counseling for the Elderly (TCE) Program Availability of Application Packages  

Federal Register 2010, 2011, 2012, 2013

...TREASURY Internal Revenue Service Tax Counseling for the Elderly (TCE) Program Availability...Application Packages for the 2013 Tax Counseling for the Elderly (TCE) Program. DATES...application package to the IRS for the Tax Counseling for the Elderly (TCE) Program is...

2012-04-05

115

75 FR 22437 - Tax Counseling for the Elderly (TCE) Program Availability of Application Packages  

Federal Register 2010, 2011, 2012, 2013

...TREASURY Internal Revenue Service Tax Counseling for the Elderly (TCE) Program Availability...Application Packages for the 2011 Tax Counseling for the Elderly (TCE) Program. DATES...package to the IRS for the 2011 Tax Counseling for the Elderly (TCE) Program is...

2010-04-28

116

COMPARISON OF HYDROGEN CONCENTRATIONS IN PCE-DEHALOGENATING AND SULFATE-REDUCING ESTUARINE SEDIMENTS  

EPA Science Inventory

The primary transformation pathway for PCE in anoxic environments is through sequential reductive dehalogenation, and information concerning dehalogenation processes that occur in environments containing alternative electron acceptors (sulfate) is limited. Hydrogen is postulated ...

117

Characterization of Microbial Communities in TCE-Contaminated Seep Zone Sediments  

SciTech Connect

Hundreds of sites across the United States contain trichloroethene (TCE) contamination, including the Department of Energy's Savannah River Site (SRS) in Aiken, South Carolina. Previous studies have indicated that microorganisms are capable of efficiently degrading TCE to nonhazardous end products. In this project, molecular and growth based methods were used for microbial characterization of a TCE impacted seepzone where TCE degradation is naturally occurring. The results from this work provide clear evidence that the SRB may play a significant role in TCE degradation along the Twin Lakes seepline.

ROBIN, BRIGMON

2005-03-07

118

Coupling Surfactants with Permanganate for PCE DNAPL Removal: Coinjection or Sequential Application as Delivery Methods  

NASA Astrophysics Data System (ADS)

Batch experiments and two-dimensional (2-D) flow-through cell experiments were conducted to investigate coupling surfactant-enhanced aquifer remediation (SEAR) with in situ chemical oxidation (ISCO) of tetrachloroethene (PCE) dense nonaqueous phase liquid (DNAPL) for PCE mass destruction. Previous batch screening tests were performed on surfactants and cosolvents in the presence of the oxidant potassium permanganate, to assess compatibility for coupling with permanganate. The anionic surfactants sodium dioctyl sulfosuccinate (Aerosol OT), and sodium hexadecyl diphenyl oxide disulfonate (Dowfax 8390) were compatible and selected for use. Two delivery methods were investigated: (1) coinjection of 0.66 pore volumes (PVs) of 1.0-wt% Aerosol-OT, 0.5-wt% Dowfax 8390, 0.35-wt% CaBr2, and 0.75-wt% NaBr, (for enhanced PCE solubilization) with 0.5-wt% permanganate(for DNAPL mass destruction), and (2) sequential application of 0.66 PVs of the same surfactant solution followed by 0.66 PVs of 0.5-wt% permanganate flush. The 2-D cell packing configuration consisted of a fine-grained silica sand matrix with an embedded medium- grained sand lens, which allowed for the development of a high saturation PCE DNAPL source zone (~9-11% v/v) within the lens of each cell. For both experiments the flushing solutions were delivered at a linear velocity of 52 cm/day. Water quality samples were collected from eight point sampling ports, as well as the cell effluent. Samples were analyzed for PCE, chloride, and permanganate. At the conclusion of the experiments, the mass of PCE removed was quantified by destructively analyzing the cell. Results indicate complete mass removal using sequential application as a delivery method. In the coinjection experiment, cores extracted at the conclusion revealed that 99.8% of PCE DNAPL mass was removed. However, it was not possible to close a mass balance between the initial PCE added and the PCE removed. It is hypothesized this result was due to incomplete oxidation whereby destruction of PCE occurs without mineralization. Results indicate that coupling surfactants with permanganate holds promise as a viable method for in situ mass depletion of PCE DNAPL using sequential application as a delivery method. Although experimental results were encouraging with respect to the coinjection of surfactants and permanganate for DNAPL mass removal, further bench-scale research is warranted prior to implementation in the field.

Dugan, P. J.; Siegrist, R. L.; Crimi, M. L.

2008-12-01

119

Effectiveness of nanoscale zero-valent iron for treatment of a PCE-DNAPL source zone  

NASA Astrophysics Data System (ADS)

Nanoscale zero-valent iron (nZVI) has received considerable attention as a potential in situ remediation technology for treating chlorinated solvent source zones. Experimental and mathematical modeling studies were conducted to investigate the performance of nZVI in the transformation of tetrachloroethene (PCE) entrapped as a dense nonaqueous phase liquid (DNAPL). Injection of a 60 g/L suspension of nZVI into a column containing 20-30 mesh Ottawa sand and PCE-DNAPL at a residual saturation of 5.5% resulted in a uniform distribution of nZVI and minimal displacement of PCE. Subsequent flushing with 267 pore volumes of water containing 3 mM CaCl 2 at a Darcy velocity of 0.75 m/day resulted in steady-state effluent concentrations of PCE near the solubility limit (ca. 200 mg/L) and production of dissolved-phase ethene (10-30 mg/L). Over the duration of the experiment, approximately 30% of the initial PCE-DNAPL mass reacted to form ethene, 50% was eluted as dissolved-phase PCE, and 20% remained in the column as PCE-DNAPL. To further explore the implications of the nZVI column results, a multiphase transport model was developed that incorporated rate-limited PCE-DNAPL dissolution and reactions with nZVI. Using a fitted pseudo first-order transformation rate coefficient of 1.42 1/h, the model accurately captured observed trends in effluent concentrations of PCE and ethene and overall mass balance. A model sensitivity study reveals a strong dependence of treatment effectiveness on system characteristics. The sensitivity analysis suggests that an increase in the extent of PCE transformation is facilitated by decreasing flow rate, emplacement of nZVI down-gradient of the DNAPL source zone, and decreasing length of the DNAPL source zone. These findings indicate that, although emplacement of high concentrations of nZVI within a PCE-DNAPL source zone can result in substantial transformation of the parent compound, careful attention to design parameters (e.g. flow rate, location and amount nZVI delivered) will be required to achieve complete conversion to benign reaction products.

Taghavy, Amir; Costanza, Jed; Pennell, Kurt D.; Abriola, Linda M.

2010-11-01

120

Effectiveness of nanoscale zero-valent iron for treatment of a PCE-DNAPL source zone.  

PubMed

Nanoscale zero-valent iron (nZVI) has received considerable attention as a potential in situ remediation technology for treating chlorinated solvent source zones. Experimental and mathematical modeling studies were conducted to investigate the performance of nZVI in the transformation of tetrachloroethene (PCE) entrapped as a dense nonaqueous phase liquid (DNAPL). Injection of a 60 g/L suspension of nZVI into a column containing 20-30 mesh Ottawa sand and PCE-DNAPL at a residual saturation of 5.5% resulted in a uniform distribution of nZVI and minimal displacement of PCE. Subsequent flushing with 267 pore volumes of water containing 3mM CaCl(2) at a Darcy velocity of 0.75 m/day resulted in steady-state effluent concentrations of PCE near the solubility limit (ca. 200mg/L) and production of dissolved-phase ethene (10-30 mg/L). Over the duration of the experiment, approximately 30% of the initial PCE-DNAPL mass reacted to form ethene, 50% was eluted as dissolved-phase PCE, and 20% remained in the column as PCE-DNAPL. To further explore the implications of the nZVI column results, a multiphase transport model was developed that incorporated rate-limited PCE-DNAPL dissolution and reactions with nZVI. Using a fitted pseudo first-order transformation rate coefficient of 1.421/h, the model accurately captured observed trends in effluent concentrations of PCE and ethene and overall mass balance. A model sensitivity study reveals a strong dependence of treatment effectiveness on system characteristics. The sensitivity analysis suggests that an increase in the extent of PCE transformation is facilitated by decreasing flow rate, emplacement of nZVI down-gradient of the DNAPL source zone, and decreasing length of the DNAPL source zone. These findings indicate that, although emplacement of high concentrations of nZVI within a PCE-DNAPL source zone can result in substantial transformation of the parent compound, careful attention to design parameters (e.g. flow rate, location and amount nZVI delivered) will be required to achieve complete conversion to benign reaction products. PMID:20888664

Taghavy, Amir; Costanza, Jed; Pennell, Kurt D; Abriola, Linda M

2010-11-25

121

Enhanced reductive dechlorination of PCE DNAPL with TBOS as a slow-release electron donor.  

PubMed

Tetrabutoxysilane (TBOS), which yields 1-butanol upon abiotic hydrolysis, was evaluated as a slow-release substrate for the reductive dechlorination of tetrachloroethylene (PCE) as a dense non-aqueous-phase liquid (DNAPL). Dechlorination was achieved using an anaerobic binary mixed (BM) culture, which consisted of the Pt. Mugu (PM) and the Evanite (EV) mixed cultures. In batch reactor experiments, TBOS was mixed with PCE DNAPL to achieve different PCE mol fractions (PCEmol/(PCE mol+TBOSmol)), and different PCE aqueous concentrations based on Raoult's Law. The reductive dechlorination activity was determined based on the amount of chloride ions released and the mass balances of the transformation products formed. The mass balances of the total chlorinated aliphatic hydrocarbons (CAHs) between water, NAPL and gas phases were performed using independently measured NAPL/water partition coefficients. The amounts of chloride released (directly measured in aqueous samples) agreed with the total chloride produced based on the mass balances. The abiotic rates of TBOS hydrolysis were first-order with respect to TBOS NAPL concentration. A higher electron transfer efficiency to dechlorination was correlated with lower rates of TBOS hydrolysis. The total amounts of PCE DNAPL and TBOS were important factors for the reductive dechlorination of PCE. The dechlorination activity was suppressed at high NAPL concentrations. Direct contact of the PCE/TBOS NAPL mixture may have caused toxicity to the dechlorinating bacteria. Decreases in pH likely lowered the microbial activity for reductive dechlorination due to the accumulation of acetate and/or butyrate. These studies showed the potential of TBOS as a slow-release substrate for enhancing bioremediation of DNAPL contaminated sites. PMID:19179006

Yu, Seungho; Semprini, Lewis

2009-08-15

122

Mobilization of trichloroethene (TCE) during ethanol flooding in uniform and layered sand packs under confined conditions  

NASA Astrophysics Data System (ADS)

Five horizontal flow experiments were conducted in homogeneous and layered sand packs to evaluate the effectiveness of mobilization of trichloroethene (TCE) by ethanol flooding. A small quantity (5-7 mL) of pure TCE was injected into the center of each sand pack, and then horizontal ethanol floods were conducted at darcy velocities between 4 and 12 m d-1. Once ethanol contacted the region initially affected by TCE in uniform sand packs, rapid downward and upgradient flow of TCE occurred along sloping ethanol-water interfaces. In layered sand packs the bulk mobilization of TCE appeared to be associated more with phenomena resulting from interfacial tension reduction rather than with enhanced dissolution processes. Heterogeneities promoted a variety of bypassing and mixing phenomena that resulted in, but were not limited to, physical displacement of TCE at the edges of discrete fine-grained lenses due to localized confined flow conditions; upward migration of ethanol through finer-grained soils due to buoyancy; rapid downward mobilization of TCE; upgradient mobilization of TCE around heterogeneities; and migration of TCE into finer-grained soils at locations both upgradient and downgradient of the TCE source zone. Enhanced TCE dissolution was also observed.

Grubb, Dennis G.; Sitar, Nicholas

1999-11-01

123

Transport of Trichloroethylene (TCE) in Natural Soil by Electroosmosis  

Microsoft Academic Search

Contamination in low permeability soils poses a significant technical challenge to in situ remediation, primarily due to low\\u000a mobilization of the contaminants and difficulty in uniform delivery of treatment reagents. An alternative approach using electroosmosis\\u000a (EO) is used to mobilize Trichloroethylene (TCE) in soil. However, the EO approach causes significant chemical changes in\\u000a the soil which may affect transport and\\/or

Souhail R. Al-Abed; Jiann-Long Chen

124

Characterization of Uranium Surfaces Machined with Aqueous Propylene Glycol-Borax or Perchloroethylene-Mineral Oil Coolants.  

National Technical Information Service (NTIS)

The use of perchloroethylene (perc) as an ingredient in coolants for machining enriched uranium at the Oak Ridge Y-12 Plant has been discontinued because of environmental concerns. A new coolant was substituted in December 1985, which consists of an aqueo...

S. S. Cristy R. K. Bennett J. J. Dillon H. L. Richards R. D. Seals

1986-01-01

125

Enhanced Reductive Dechlorination of TCE in a Basalt Aquifer  

SciTech Connect

A field evaluation of enhanced reductive dechlorination of trichloroethene (TCE) in groundwater has been in progress since November 1998 to determine whether in situ biodegradation can be significantly enhanced through the addition of an electron donor (lactate). An in situ treatment cell was established in the residual source area of a large TCE plume in a fractured basalt aquifer utilizing continuous ground water extraction approximately 150 meters downgradient of the injection location. After a 1-month tracer test and baseline sampling period, the pulsed injection of lactate was begun. Ground water samples were collected from 11 sampling points on a biweekly basis and in situ water quality parameters were recorded every 4 hours at two locations. Within 2 weeks after the initial lactate injection, dissolved oxygen and redox potential were observed to decrease substantially at all sampling locations within 40 m of the injection well. Decreases in nitrate and sulfate concentrations were also observed. Both quantitative in situ rate estimation methods and qualitative measures such as changes in redox conditions, decreases in chlorine number, and changes in biomass indicator parameters are being used throughout the test to evaluate the extent to which biodegradation of TCE is enhanced.

K. S. Sorenson; L. N. Peterson (INEEL); R. Ely (U of Idaho)

1999-04-01

126

Enhanced Reductive Dechlorination of TCE in a Basalt Aquifer  

SciTech Connect

A field evaluation of enhanced reductive dechlorination of trichloroethene (TCE) in ground water has been in progress since November 1998 to determine whether in situ biodegradation can be significantly enhanced through the addition of an electron donor (lactate). An in situ treatment cell was established in the residual source area of a large TCE plume in a fractured basalt aquifer utilizing continuous ground water extraction approximately 150 meters downgradient of the injection location. After a 1-month tracer test and baseline sampling period, the pulsed injection of lactate was begun. Ground water samples were collected from 11 sampling points on a biweekly basis and in situ water quality parameters were recorded every 4 hours at two locations. Within 2 weeks after the initial lactate injection, dissolved oxygen and redox potential were observed to decrease substantially at all sampling locations within 40 m of the injection well. Decreases in nitrate and sulfate concentrations were also observed. Both quantitative in situ rate estimation methods and qualitative measures such as changes in redox conditions, decreases in chlorine number, and changes in biomass indicator parameters are being used throughout the test to evaluate the extent to which biodegradation of TCE is enhanced.

Sorenson, Kent Soren; Peterson, Lance Nutting; Ely, R. L.

1999-04-01

127

A Planet Hunters Search of the Kepler TCE Inventory  

NASA Astrophysics Data System (ADS)

NASA's Kepler spacecraft has spent the past 4 years monitoring ~160,000 stars for the signatures of transiting exoplanets. Planet Hunters (http://www.planethunters.org), part of the Zooniverse (http://www.zooniverse.org) collection of citizen science projects, uses the power of human pattern recognition via the World Wide Web to identify transits in the Kepler public data. We have demonstrated the success of a citizen science approach with the project's discoveries including PH1 b, a transiting circumbinary planet in a four star system., and over 20 previously unknown planet candidates. The Kepler team has released the list of 18,406 potential transit signals or threshold-crossing events (TCEs) identified in Quarters 1-12 (~1000 days) by their automated Transit Planet Search (TPS) algorithm. The majority of these detections found by TPS are triggered by transient events and are not valid planet candidates. To identify planetary candidates from the detected TCEs, a human review of the validation reports, generated by the Kepler pipeline for each TCE, is performed by several Kepler team members. We have undertaken an independent crowd-sourced effort to perform a systematic search of the Kepler Q1-12 TCE list. With the Internet we can obtain multiple assessments of each TCE's data validation report. Planet Hunters volunteers evaluate whether a transit is visible in the Kepler light curve folded on the expected period identified by TPS. We present the first results of this analysis.

Schwamb, Meg; Lintott, Chris; Fischer, Debra; Smith, Arfon; Boyajian, Tabetha; Brewer, John; Giguere, Matt; Lynn, Stuart; Schawinski, Kevin; Simpson, Rob; Wang, Ji

2013-07-01

128

Hydrogeologic investigation of the Malvern TCE Superfund Site, Chester County, Pennsylvania  

USGS Publications Warehouse

The Malvern TCE Superfund Site, a former solvent recycling facility that now stores and sells solvents, consists of a plant and disposal area, which are approximately 1,900 ft (feet) apart. The site is underlain by an unconfined carbonate bedrock aquifer in which permeability has been enhanced in places by solution. Water levels respond quickly to precipitation and show a similar seasonal variation, response to precipitation, and range of fluctuation. The altitude of water levels in wells at the disposal area is nearly identical because of the small hydraulic gradient. A comparison of water-table maps for 1983, 1993, and 1994 shows that the general shape of the water table and hydraulic gradients in the area have remained the same through time and for different climatic conditions. The plant area is underlain by dolomite of the Elbrook Formation. The dolomite at the plant area does not yield as much water as the dolomite at the disposal area because it is less fractured, and wells penetrate few water-bearing fractures. Yields of nine wells at the plant area range from 1 to 200 gal/min (gallons per minute); the median yield is 6 gal/min. Specific capacities range from 0.08 to 2 (gal/min)/ft (gallons per minute per foot). Aquifer tests were conducted in two wells; median transmissivities estimated from the aquifer-test data ranged from 528 to 839 feet squared per day. Maximum concentrations of volatile organic compounds (VOC's) in ground water at the plant area in 1996 were 53,900 ug/L (micrograms per liter) for trichloroethylene (TCE), 7,110 ug/L for tetrachloroethylene (PCE), and 17,700 ug/L for 1,1,1-trichloroethane (TCA). A ground-water divide is located between the plant area and the disposal area. Ground-water withdrawal for dewatering the Catanach quarry has caused a cone of depression in the water-table surface that reaches to the plant area. From the plant area, ground water flows 1.2 miles to the northeast and discharges to the Catanach quarry. The regional hydraulic gradient between the plant and the Catanach quarry is 0.019. Concentrations of VOC's in water from wells drilled northeast and donwgradient of the plant property boundary are one to two orders of magnitude less than concentrations in water from wells less than 100 ft away at the plant. A capture-zone analysis was performed for two wells at the plant area. The analysis showed that pumping well CC-19 at 20 gal/min would be sufficient to capture all ground-water flow from the plant area. Although water from other wells at the plant site contains higher concentrations of VOC's than water from well CC-19, pumping well CC-19 would induce the flow of water with higher concentrations of VOC's; however, pumping well CC-19 might causes VOC's to move lower into the aquifer. The disposal area is underlain by the Ledger Dolomite. The dolomite at the disposal area is much more fractured than the dolomite at the plant area. Although many of the fractures are filled or partially filled with clay, the dolomite at the disposal area yields more water than the dolomite at the plant area. Yields of eight wells at the disposal area range from 15 to more than 200 gal/min; the median yield is greater than 100 gal/min. Specific capacities range from 2 to 280 (gal/min)/ft. Aquifer tests were conducted in two wells; estimated transimissivities were 34,900 and 56,300 feet squared per day. Concentrations of VOC's in ground water are lower at the disposal area than at the plant area. Water samples collected from wells at the disposal area in 1996 had maximum concentrations of TCE of 768 ug/L, PCE of 111 ug/L, and TCA of 108 ug/L. These concentrations are lower than concentrations in water samples collected before cleanup of drums in the disposal area was completed in 1984. Ground water from the disposal area flows south-southeast toward Valley Creek. The hydraulic gradient between the disposal area and Valley Creek is 0.001. A well-defined p

Sloto, Ronald A.

1997-01-01

129

Dissolution Coupled Biodegradation of Pce by Inducing In-Situ Biosurfactant Production Under Anaerobic Conditions  

NASA Astrophysics Data System (ADS)

Biosurfactants have proven to enhance the bioavailability and thereby elevate the rate of degradation of Light Non Aqueous Phase Liquids (LNAPLs) such as crude oil and petroleum derivatives. In spite of their superior characteristics, use of these biomolecules for remediation of Dense Non Aqueous Phase Liquids (DNAPLs) such as chlorinated solvents is still not clearly understood. In this present study, we have investigated the fate of tetrachloroethylene (PCE) by inducing in-situ biosurfactants production, a sustainable option which hypothesizes increase in bioavailability of LNAPLs. In order to understand the effect of biosurfactants on dissolution and biodegradation under the inducement of in-situ biosurfactant production, batch experiments were conducted in pure liquid media. The individual influence of each process such as biosurfactant production, dissolution of PCE and biodegradation of PCE were studied separately for getting insights on the synergistic effect of each process on the fate of PCE. Finally the dissolution coupled biodegradation of non aqueous phase PCE was studied in conditions where biosurfactant production was induced by nitrate limitation. The effect of biosurfactants was differentiated by repeating the same experiments were the biosurfactant production was retarded. The overall effect of in-situ biosurfactant production process was evaluated by use of a mathematical model. The process of microbial growth, biosurfactant production, dissolution and biodegradation of PCE were translated as ordinary differential equations. The modelling exercise was mainly performed to get insight on the combined effects of various processes that determine the concentration of PCE in its aqueous and non-aqueous phases. Model simulated profiles of PCE with the kinetic coefficients evaluated earlier from individual experiments were compared with parameters fitted for observations in experiments with dissolution coupled biodegradation process using optimization routines. Complete disappearance of PCE from DNAPL and aqueous phase was observed in a span of 14 days in systems triggered with biosurfactant production through enhanced dissolution and biodegradation. Synergistic effect of dissolution process towards biodegradation was observed as bioavailability of PCE was increased by 3.1 times in systems with biosurfactant production. Modelling studies illustrate that biodegradation on the other hand synergistically enhanced dissolution by elevating the dissolution rates by 1.4 times. This study also suggests a mass transfer phenomenon is greatly influenced not only by surface active molecules but by microbes as well.

Dominic, J.; Nambi, I. M.

2013-12-01

130

Field test of six-phase soil heating at the Savannah River Site  

Microsoft Academic Search

Six-Phase Soil Heating (SPSH) was demonstrated as a viable technology for heating low permeability soils containing volatile organic contaminants as part of the Volatile Organic Compounds in Non-Arid Soils Integrated Demonstration (VOC Non-Arid ID) at the Savannah River Site. The soil at the integrated demonstration site is contaminated with perchloroethylene (PCE) and trichloroethylene (TCE); the highest soil contamination occurs in

P. A. Gauglitz; J. S. Roberts; T. M. Bergsman

1994-01-01

131

Six-phase soil heating accelerates VOC extraction from clay soil  

Microsoft Academic Search

Six-Phase Soil Heating (SPSH) was demonstrated as a viable technology for heating low permeability soils containing volatile organic contaminants. Testing was performed as part of the Volatile Organic Compounds in Non-Arid Soils Integrated Demonstration (VOC Non-Arid ID) at the Savannah River Site. The soil at the integrated demonstration site is contaminated with perchloroethylene (PCE) and trichloroethylene (TCE); the highest soil

P. A. Gauglitz; J. S. Roberts; T. M. Bergsman; S. M. Caley; W. O. Heath; M. C. Miller; R. W. Moss; R. Schalla; T. R. Jarosch; C. A. Eddy-Dilek

1994-01-01

132

Surface-plasmon-resonance-enhanced cavity ring-down detection  

Microsoft Academic Search

The cavity ring-down technique is used to probe the absolute optical response of the localized surface plasmon resonance (SPR) of a gold nanoparticle distribution to adsorption of trichloroethylene (TCE) and perchloroethylene (PCE) from the gas phase. Extended Mie theory for a coated sphere with a particle-size-dependent dielectric function is used to elucidate size-dispersion effects, the size-dependence of the SPR sensitivity

Andrew C. R. Pipino; John T. Woodward; Curtis W. Meuse; Vitalii Silin

2004-01-01

133

Kinetics of micronucleated polychromatic erythrocyte (MN-PCE) induction in vivo by aneuploidogens.  

PubMed

The aim of the present study was to make inferences about the cytotoxic and genotoxic action of the antineoplastic aneuploidogens, vinblastine and vincristine, by analyzing the kinetics of MN-PCE induction in mice in vivo. The kinetics of MN-PCE induction was assessed by taking blood samples from the tail, before the single i.p. injection of different doses of vinblastine or vincristine and every 8h after that. The analysis was done in groups consisting of three or four animals. The results indicate that both agents have similar kinetics of MN-PCE induction which differs from the kinetics previously obtained for colchicine in the following aspects: (i) vinblastine and vincristine cause a longer delay after exposure, (ii) they produce a higher maximal velocity of induction, and (iii) higher doses give rise to more than one peak in the curve of MN-PCE frequency versus time. The results of the present study indicate that the different mechanisms of action of vinca alkaloids and colchicine are reflected in their kinetics of MN-PCE induction, and that such mechanisms could also explain the differences in their efficiency. Vinca alkaloids seem to block the cell division immediately, but the cell appears to be capable of reverting the blockage during the period of time corresponding to the first division. Moreover, evidence was obtained indicating that high doses could induce a long lasting aneuploidogen effect, probably related to the accumulation of vinca alkaloids that are either free or associated to tubulin. PMID:15576241

Morales-Ramírez, Pedro; Vallarino-Kelly, Teresita; Cruz-Vallejo, Virginia

2004-12-31

134

Field study of TCE diffusion profiles below DNAPL to assess aquitard integrity  

Microsoft Academic Search

An area where a free-product accumulation of trichloroethylene (TCE) dense non-aqueous phase liquid (DNAPL) occurs at the bottom of a 10-m-thick surficial sand aquifer was studied to determine the integrity of the underlying, 20-m-thick, clayey silt aquitard formed of glaciolacustrine sediment. TCE concentration-versus-depth profiles determined from aquitard cores collected at five locations indicated penetration of detectable TCE 2.5 to 3.0

Beth L. Parker; John A. Cherry; Steven W. Chapman

2004-01-01

135

Biodegradation of high concentrations of tetrachloroethene in a continuous flow column system  

SciTech Connect

A long-term (2.5 years) study of the anaerobic biodegradation of high concentrations of perchloroethylene (PCE) was carried out in a continuously operated laboratory column filled with sand which was inoculated with biomass from an anaerobic digester. Concentrations of PCE fed to the column were increased from 12 {micro}M to over 600 {micro}M over 21 months, with methanol added as electron donor. Vinyl chloride (VC) was the terminal product of PCE dechlorination for the first 21 months at which point significant conversion of VC to ethylene (ETH) was detected. The onset of ETH production coincided with acetogenesis becoming the primary pathway for methanol metabolism. ETH production occurred in the column in the presence of PCE and TCE. Varying methanol:PCE molar ratios from 1.4 to 7.5 had little effect on the transformation of PCE and TCE to VC. The degradation of VC to ETH was much more sensitive, and VC accumulated when the methanol:PCE molar ratio dropped below 5.0. Withdrawal of PCE from the system for a 5 month period and maintenance of the column on methanol alone did not result in the loss of PCE degradation capability of the consortium.

Isalou, M; Sleep, B.E. [Univ. of Toronto, Ontario (Canada). Dept. of Civil Engineering] [Univ. of Toronto, Ontario (Canada). Dept. of Civil Engineering; Liss, S.N. [Ryerson Polytechnic Univ., Toronto, Ontario (Canada). Dept. of Applied Chemical and Biological Sciences] [Ryerson Polytechnic Univ., Toronto, Ontario (Canada). Dept. of Applied Chemical and Biological Sciences

1998-11-15

136

Use of a Plasma Cathode Electron (PCE) source in an Electron Beam Integrated Thruster (EBIT)  

NASA Astrophysics Data System (ADS)

The electron Beam Integrated Thruster (EBIT) plasma propulsion concept centers around the use of an electron beam to ionize a propellant; a more efficient ionization mechanism than conventional electric propulsion concepts. In this paper we outline the EBIT concept, in particular, the generation of the electron beam in a Plasma Cathode Electron (PCE) source. The PCE beam source utilizes a plasma as an electron beam cathode, eliminating lifetime and heating issues associated with material cathodes. Our PCE source was created using 1.5kW of microwave power at 2.45GHz delivered in a static magnetic field of 875Gauss. We were able to drive electron beams of greater than 100A in our source with very high beam efficiencies by biasing the ECR source chamber to -120V.

Light, Max; Madziwa-Nussinov, Tsitsi; Colestock, Pat; Kashuba, Ron; Faehl, Rick

2006-10-01

137

Risk of learning and behavioral disorders following prenatal and early postnatal exposure to tetrachloroethylene (PCE)-contaminated drinking water  

Microsoft Academic Search

This population-based retrospective cohort study examined the association between developmental disorders of learning, attention and behavior and prenatal and early postnatal drinking water exposure to tetrachloroethylene (PCE) on Cape Cod, Massachusetts. Subjects were identified through birth records from 1969 through 1983. Exposure was modeled using information from town water departments, a PCE leaching and transport algorithm, EPANet water flow modeling

Patricia A. Janulewicz; Roberta F. White; Michael R. Winter; Janice M. Weinberg; Lisa E. Gallagher; Veronica Vieira; Thomas F. Webster; Ann Aschengrau

2008-01-01

138

MICROFRACTURE SURFACE GEOCHEMISTRY AND ADHERENT MICROBIAL POPULATION METABOLISM IN TCE-CONTAMINATED COMPETENT BEDROCK  

EPA Science Inventory

A TCE-contaminated competent bedrock site in Portsmouth, NH was used to determine if a relation existed between microfracture (MF) surface geochemistry and the ecology and metabolic activity of attached microbes relative to terminal electron accepting processes (TEAPs) and TCE bi...

139

Heterologous expression, purification and cofactor reconstitution of the reductive dehalogenase PceA from Dehalobacter restrictus.  

PubMed

Organohalide respiration is used by a limited set of anaerobic bacteria to derive energy from the reduction of halogenated organic compounds. The enzymes that catalyze the reductive dehalogenation reaction, the reductive dehalogenases, represent a novel and distinct class of cobalamin and Fe-S cluster dependent enzymes. Until now, biochemical studies on reductive dehalogenases have been hampered by the lack of a reliable protein source. Here we present an efficient and robust heterologous production system for the reductive dehalogenase PceA from Dehalobacter restrictus. Large quantities of Strep-tagged PceA fused to a cold-shock induced trigger factor could be obtained from Escherichia coli. The recombinant enzyme was conveniently purified in milligram quantities under anaerobic conditions by StrepTactin affinity chromatography, and the trigger factor could be removed through limited proteolysis. Characterization of the purified PceA by UV-Vis and electron paramagnetic resonance (EPR) spectroscopy reveal that the recombinant protein binds methylcobalamin in the base-on form after proteolytic cleavage of the trigger factor, and that 4Fe-4S clusters can be chemically reconstituted under anoxic conditions. This study demonstrates a novel PceA production platform that allows further study of this new enzyme class. PMID:22940504

Sjuts, Hanno; Fisher, Karl; Dunstan, Mark S; Rigby, Stephen E; Leys, David

2012-10-01

140

Sewer Gas: An Indoor Air Source of PCE to Consider During Vapor Intrusion Investigations  

PubMed Central

The United States Environmental Protection Agency (USEPA) is finalizing its vapor intrusion guidelines. One of the important issues related to vapor intrusion is background concentrations of volatile organic chemicals (VOCs) in indoor air, typically attributed to consumer products and building materials. Background concentrations can exist even in the absence of vapor intrusion and are an important consideration when conducting site assessments. In addition, the development of accurate conceptual models that depict pathways for vapor entry into buildings is important during vapor intrusion site assessments. Sewer gas, either as a contributor to background concentrations or as part of the site conceptual model, is not routinely evaluated during vapor intrusion site assessments. The research described herein identifies an instance where vapors emanating directly from a sanitary sewer pipe within a residence were determined to be a source of tetrachloroethylene (PCE) detected in indoor air. Concentrations of PCE in the bathroom range from 2.1 to 190 ug/m3 and exceed typical indoor air concentrations by orders of magnitude resulting in human health risk classified as an “Imminent Hazard” condition. The results suggest that infiltration of sewer gas resulted in PCE concentrations in indoor air that were nearly two-orders of magnitude higher as compared to when infiltration of sewer gas was not known to be occurring. This previously understudied pathway whereby sewers serve as sources of PCE (and potentially other VOC) vapors is highlighted. Implications for vapor intrusion investigations are also discussed.

Pennell, Kelly G.; Scammell, Madeleine Kangsen; McClean, Michael D.; Ames, Jennifer; Weldon, Brittany; Friguglietti, Leigh; Suuberg, Eric M.; Shen, Rui; Indeglia, Paul A.; Heiger-Bernays, Wendy J.

2013-01-01

141

Adult neuropsychological performance following prenatal and early postnatal exposure to tetrachloroethylene (PCE)-contaminated drinking water.  

PubMed

This population-based retrospective cohort study examined adult performance on a battery of neuropsychological tests in relation to prenatal and early postnatal exposure to tetrachloroethylene (PCE)-contaminated drinking water on Cape Cod, Massachusetts. Subjects were identified through birth records from 1969 through 1983. Exposure was modeled using pipe network information from town water departments, a PCE leaching and transport algorithm, EPANet water flow modeling software, and a Geographic Information System (GIS). Results of crude and multivariate analyses among 35 exposed and 28 unexposed subjects showed no association between prenatal and early postnatal exposure and decrements on tests that assess abilities in the domains of omnibus intelligence, academic achievement or language. The results were suggestive of an association between prenatal and early postnatal PCE exposure and diminished performance on tests that assessed abilities in the domains of visuospatial functioning, learning and memory, motor, attention and mood. Because the sample size was small, most findings were not statistically significant. Future studies with larger sample sizes should be conducted to further define the neuropsychological consequences of early developmental PCE exposure. PMID:22522125

Janulewicz, Patricia A; White, Roberta F; Martin, Brett M; Winter, Michael R; Weinberg, Janice M; Vieira, Veronica; Aschengrau, Ann

2012-01-01

142

National exposure registry Trichloroethylene (TCE) subregistry followup 1 technical report. Final report  

SciTech Connect

This report gives an overview of the Trichlorethylene (TCE) Subregistry and the first TCE Subregistry followup (Followup 1), and the results of the statistical analyses of the Followup 1 data. The TCE Subregistry file is composed of information collected on 4,280 persons (4,041 living, 239 deceased) who had documented environmental exposure to TCE. The registrants had resided in one of 13 areas in three states (Illinois, Indiana, and Michigan). Two sites were subsequently added to the TCE Subregistry, one in Pennsylvania and one in Arizona for a total of 15 sites in 5 states raising the total to 4,421 exposed registrants (4,172 living, 259 decreased at Baseline.)

Burg, J.; Pallos, L.; Gist, G.; Radtke, T.; Cusack, C.

1996-03-01

143

Effect of perchloroethylene and its metabolites on intercellular communication in clone 9 rat liver cells  

SciTech Connect

Gap junction intercellular communication (IC) is thought to be important in chemical carcinogenesis as abnormalities in IC have been found in cancer cells. Perchloroethylene (PERC) is metabolized in rodent liver to dichloroacetic acid (DCA) and trichloroacetic acid (TCA), which are rodent liver carcinogens. Chloral hydrate (CH) and trichloroethanol (TCEth) are kidney metabolites. We used Lucifer yellow scrape-load dye transfer as a measure of IC to look at the effect of PERC, DCA, TCA, CH, and TCEth on Clone 9 cell cultures (normal rat liver cells). Four independent experiments were performed for each chemical using exposure times of 1, 4, 6, 24, 48, and 168 h. Concentrations for each chemical varied and were based on preliminary data on effect and cytotoxicity. To compare the relative effectiveness of each chemical to cause biological change, we identified the lowest concentration needed to produce 50% reduction in IC, were PERC (0.3 mM) >> TCA (3.8 mM) > TCEth (6.6 mM) = CH (7.0 mM) >> DCA (41 mM). Time-course data indicated that PERC, DCA, and TCA produced reduction in IC in a similar fashion, but 5 mM CH or TCEth exhibited variances from these results and may indicate specific cell responses to these chemicals. The mechanism(s) responsible for inhibition of IC by these structurally related chemicals needs to be established. 44 refs., 5 figs.

Benane, S.G.; Blackman, C.F.; House, D.E. [National Health and Environmental Effects Research Lab., Research Triangle Park, NC (United States)

1996-08-09

144

Enhancement of granule formation and sludge retainment for tetrachloroethylene (TCE) removal in an upflow anaerobic sludge blanket (UASB) reactor  

Microsoft Academic Search

Tetrachloroethylene (TCE) in wastewater was effectively removed at 35 °C over 200 days in an upflow anaerobic sludge blanket (UASB) reactor in order to investigate the formation of TCE degrading granules. Anaerobic unacclimated sludge and glucose were used as seed and primary substrate, respectively. TCE degrading massive initial granules were developed after 1.5 months of start-up, which grew at an

Delia Teresa Sponza

2003-01-01

145

Factors Influencing TCE Anaerobic Dechlorination Investigated via Simulations of Microcosm Experiments  

NASA Astrophysics Data System (ADS)

SABRE (Source Area BioREmediation) is a public-private consortium whose charter is to determine if enhanced anaerobic bioremediation can result in effective and quantifiable treatment of chlorinated solvent DNAPL source areas. The focus of this 4-year, $5.7 million research project is a field site in the United Kingdom containing a TCE DNAPL source area. In preparation, a microcosm study was performed to determine the optimal combination of factors to support reductive dechlorination of TCE in site soil and groundwater. The study consisted of 168 bottles distributed between four laboratories (Dupont, GE, SiREM, and Terra Systems) and tested the impact of six carbon substrates (lactate, acetate, methanol, SRS (soybean oil), hexanol, butyl acetate), bioaugmentation with KB-1 bacterial culture, three TCE levels (100 mg/L, 400 mg/L, and 800 mg/L) and two sulphate levels (200 mg/L, >500 mg/L) on TCE dechlorination. This research presents a numerical model designed to simulate the main processes occurring in the microcosms, including substrate fermentation, sequential dechlorination, toxic inhibition, and the influence of sulphate concentration. In calibrating the model to over 60 of the microcosm experiments, lumped parameters were employed to quantify the effect of key factors on the conversion rate of each chlorinated ethene in the TCE degradation sequence. Results quantify the benefit (i.e., increased stepwise dechlorination rate) due to both bioaugmentation and the presence of higher sulphate concentrations. Competitive inhibition is found to increase in significance as TCE concentrations increase; however, inclusion of Haldane inhibition is not supported. Over a wide range of experimental conditions and dechlorination steps, SRS appears to induce relatively little hydrogen limitation, thereby facilitating relatively quick conversion of TCE to ethene. In general, hydrogen limitation is found to increase with increasing TCE concentration and with bioaugmentation, and is most pronounced in the dechlorination of TCE to DCE.

Mao, X.; Harkness, M.; Lee, M. D.; Mack, E. E.; Dworatzek, S.; Acheson, C.; McCarty, P.; Barry, D. A.; Gerhard, J. I.

2006-12-01

146

Use of emulsified vegetable oil to support bioremediation of TCE DNAPL in soil columns  

NASA Astrophysics Data System (ADS)

The interaction between emulsified vegetable oil (EVO) and trichloroethylene (TCE) dense non-aqueous phase liquid (DNAPL) was observed using two soil columns and subsequent reductive dechlorination of TCE was monitored over a three year period. Dyed TCE DNAPL (~ 75 g) was emplaced in one column (DNAPL column), while the second was DNAPL-free (plume column). EVO was added to both columns and partitioning of the EVO into the TCE DNAPL was measured and quantified. TCE (1.9 mM) was added to the influent of the plume column to simulate conditions down gradient of a DNAPL source area and the columns were operated independently for more than one year, after which they were connected in series. Initially limited dechlorination of TCE to cDCE was observed in the DNAPL column, while the plume column supported complete reductive dechlorination of TCE to ethene. Upon connection and reamendment of the plume column with EVO, near saturation levels of TCE from the effluent of the DNAPL column were rapidly dechlorinated to c-DCE and VC in the plume column; however, this high rate dechlorination produced hydrochloric acid which overwhelmed the buffering capacity of the system and caused the pH to drop below 6.0. Dechlorination efficiency in the columns subsequently deteriorated, as measured by the chloride production and Dehalococcoides counts, but was restored by adding sodium bicarbonate buffer to the influent groundwater. Robust dechlorination was eventually observed in the DNAPL column, such that the TCE DNAPL was largely removed by the end of the study. Partitioning of the EVO into the DNAPL provided significant operational benefits to the remediation system both in terms of electron donor placement and longevity.

Harkness, Mark; Fisher, Angela

2013-08-01

147

Solubilities of Toluene, Benzene and TCE in High-Biomass Systems  

SciTech Connect

We report measurements of solubility limits for benzene, toluene, and TCE in systems that contain varying levels of biomass up to 0.13 g/mL. The solubility limit increased from 20 to 48 mM when biomass (in the form of yeast) was added to aqueous batch systems containing benzene. The toluene solubility limit increased from 4.9 to greater than 20 mM. For TCE, the solubility increased from 8 mM to more than 1000 mM. Solubility for TCE was most heavily impacted by biomass levels, changing by two orders of magnitude.

Barton, John W. [Battelle Eastern Science & Technology Center; Vodraska, Christopher D [ORNL; Flanary, Sandie A. [Oak Ridge National Laboratory (ORNL); Davison, Brian H [ORNL

2008-01-01

148

Experimental Results on the Destruction of PCE using a Photo-Chemical Remediation Reactor  

NASA Astrophysics Data System (ADS)

A vapor-phase tetrachloroethylene (PCE) destruction experiment using a newly constructed photo-chemical remediation (PCR) reactor is performed. One of the applications for the PCR reactor is subsurface remediation of volatile organic compounds (VOCs). Ultraviolet (UV) light, when emitted at an effective absorption frequency (primary wavelengths of 185 and 254 nm), cleaves a VOC's carbon-chlorine bond thus reducing harmful contaminants to harmless products. The PCR reactor consists of a stainless steel tubular vessel with internal dimensions 0.32 m in diameter and 1.05 m in length. Sixteen Suprasil glass sleeves (Heraeus Inc.) with external dimensions of 25 mm in diameter and 1.1 m in length are inserted along the length of the reactor. The Suprasil sleeves are positioned in a geometrical pattern to provide maximum UV exposure. An amalgam UV lamp (Heraeus Inc. NIQ 200/110) is placed inside every Suprasil sleeve. Each UV lamp has its own igniter and ballast for versatile power control. The Suprasil sleeves provide barrier protection between the UV lamps and the vapor-phase contaminant, and at the same time allow transmission of UV light to the interior of the PCR reactor. A gas heater is installed to increase the influent vapor-phase temperature and the PCR reactor is insulated to minimize heat loss. However, the PCE destruction experiment is presently being performed without the aid of the gas heater. During the experiment, the PCR reactor temperature reached in excess of 200 degrees Celsius from heat generated from the UV lamps. Vapor-phase samples are collected at the influent and effluent reactor sampling ports prior and after UV lamp ignitions. Preliminary results show good PCE destruction efficiency for the range of influent PCE concentrations considered in this study.

Lee, J. J.; Lee, K. Y.; Stencel, J. R.; Khinast, J.

2001-12-01

149

Insights into pneumococcal pathogenesis from the crystal structure of the modular teichoic acid phosphorylcholine esterase Pce  

Microsoft Academic Search

Phosphorylcholine, a specific component of the pneumococcal cell wall, is crucial in pathogenesis. It directly binds to the human platelet-activating factor (PAF) receptor and acts as a docking station for the family of surface-located choline-binding proteins (CBP). The first structure of a complete pneumococcal CBP, Pce (or CbpE), has been solved in complex with the reaction product and choline analogs.

Laura Lagartera; Ana González; Meike Stelter; Pedro García; Martín Martínez-Ripoll; José L García; Margarita Menéndez; Juan A Hermoso

2005-01-01

150

Development of a Plasma Cathode Electron (PCE) source for use in a plasma thruster  

NASA Astrophysics Data System (ADS)

At Los Alamos National laboratory, we are in the process of developing a new plasma thruster system that employs a Plasma Cathode Electron (PCE) source. By biasing an ECR source chamber to high voltages, we can drive out a highly energetic electron beam that ionizes a propellant in a downstream chamber. This is a more efficient ionization mechanism than conventional electric propulsion concepts since we do not have lifetime issues that normally come with the presence of grids as in other plasma thruster systems. In this presentation we outline the thruster concept, in particular, the generation of the electron beam in a Plasma Cathode Electron (PCE) source. Our PCE source was created using 1.5kW of microwave power at 2.45GHz delivered in a static magnetic field of 875Gauss. We were able to drive electron beams of greater than 100A in our source with very high beam efficiencies by biasing the ECR source chamber to -120V.work was funded by DARPA.

Light, Max; Madziwa-Nussinov, Tsitsi; Colestock, Pat; Kashuba, Ron; Faehl, Rick

2006-10-01

151

IDENTIFICATION OF CHLOROMETHANE FORMATION PATHS DURING ELECTROCHEMICAL DECHLORINATION OF TCE USING GRAPHITE ELECTRODES  

EPA Science Inventory

The purpose of this research is to investigate the formation of chloromethane during TCE dechlorination in a mixed electrochemical reactor using graphite electrodes. Chloromethane was the major chlorinated organic compound detected in previous dechlorination experiments. In order...

152

IDENTIFICATION OF CHLOROMETHANE FROMATION PATHS DURING ELECTROCHEMICAL DECHLORINATION OF TCE USING GRAPHITE ELECTRODES  

EPA Science Inventory

The purpose of this research is to investigate the formation of chloromethane during TCE dechlorination in a mixed electrochemical reactor using graphite electrodes. Chloromethane was the major chlorinated organic compound detected in previous dechlorination experiments. In order...

153

Degradation of Tce Using Sequential Anaerobic Biofilm and Aerobic Immobilized Bed Reactor.  

National Technical Information Service (NTIS)

Bacteria capable of degrading trichloroethylene (TCE) were isolated from contaminated wastewaters and soil sites. The aerobic cultures were identified as Pseudomonas aeruginosa (four species) and Pseudomonas fluorescens. The optimal conditions for the gro...

K. D. Chapatwala G. R. V. Babu L. Baresi R. M. Trunzo

1995-01-01

154

Comparison of TCeMA and TDMA for Inter-Satellite Communications using OPNET Simulation  

NASA Technical Reports Server (NTRS)

A robust data link protocol, enabling unique physical and MAC layer technologies and sub-network level protocols, is needed in order to take advantage of the full potential of using both TDMA and CDMA in a satellite communication network. A novel MAC layer protocol, TDMA with CDMA-encoding multiple access (TCeMA) integrated with null-steered digital beam-forming spatial multiplexing, is investigated to support flexible spacecraft communications. Abstract models of the TCeMA and TDMA processes are developed in OPNFiT and a comparison of the performances of TCeMA and TDMA in a satellite network simulation are made. TCeMA provides the better connectivity and capacity with respect to TDMA for satellite communication traffic.

Hain, Regina Rosales; Ramanathan, Ram; Bergamo, Marcos; Wallett, Thomas M.

2003-01-01

155

Chemical Oxidation of Tetrachloroethene (PCE) Contamination in a Fractured Saprolitic Bedrock Aquifer Using Fenton's Reagent and Sodium Permanganate  

Microsoft Academic Search

This describes the progressive remediation of a PCE contaminant plume using two separate chemical oxidizers in a fractured saprolitic bedrock aquifer in Rockville, Maryland. The geology consists of fine-grained soils overlying weathered-fractured schist and phyllitic bedrock (saprolite). The state of Maryland required that the onsite source be remediated to a risk-based PCE cleanup goal of 253 micrograms per liter (ug\\/L)

Paul G. Werner

156

TETRACHLOROETHYLENE (TCE) REMOVAL DURING ANAEROBIC GRANULATION IN AN UPFLOW ANAEROBIC SLUDGE BLANKET (UASB) REACTOR  

Microsoft Academic Search

The anaerobic biotransformation of TCE was investigated during the granulation process by reducing the HRT and increasing the chemical oxygen demand (COD) and TCE loadings in a 2 l laboratory-scale upflow anaerobic sludge blanket (UASB) reactor. Anaerobic unacclimated sludge and glucose were used as seed and primary substrate, respectively. Initial granules were developed after 1.5 months of start-up, which grew at

Delia Teresa Sponza

2002-01-01

157

Endophytic bacteria improve phytoremediation of Ni and TCE co-contamination  

SciTech Connect

The aim of this work was to investigate if engineered endophytes can improve phytoremediation of co-contaminations by organic pollutants and toxic metals. As a model system, yellow lupine was inoculated with the endophyte Burkholderia cepacia VM1468 possessing (a) the pTOM-Bu61 plasmid, coding for constitutive trichloroethylene (TCE) degradation, and (b) the ncc-nre Ni resistance/sequestration system. Plants were exposed to Ni and TCE and (a) Ni and TCE phytotoxicity, (b) TCE degradation and evapotranspiration, and (c) Ni concentrations in the roots and shoots were determined. Inoculation with B. cepacia VM1468 resulted in decreased Ni and TCE phytotoxicity, as measured by 30% increased root biomass and up to 50% decreased activities of enzymes involved in anti-oxidative defence in the roots. In addition, TCE evapotranspiration showed a decreasing trend and a 5 times higher Ni uptake was observed after inoculation. Engineered endophytes can improve phytoremediation of mixed contaminations via enhanced degradation of organic contaminants and improved metal uptake and translocation.

Weyens, N.; van der Lelie, D.; Croes, S.; Dupae, J.; Newman, L.; Carleer, R.; Vangronsveld, J.

2010-07-01

158

In situ iron activated persulfate oxidative fluid sparging treatment of TCE contamination — A proof of concept study  

NASA Astrophysics Data System (ADS)

In situ chemical oxidation (ISCO) is considered a reliable technology to treat groundwater contaminated with high concentrations of organic contaminants. An ISCO oxidant, persulfate anion (S 2O 82-) can be activated by ferrous ion (Fe 2+) to generate sulfate radicals ( Eo = 2.6 V), which are capable of destroying trichloroethylene (TCE). The property of polarity inhibits S 2O 82- or sulfate radical (SO 4rad - ) from effectively oxidizing separate phase TCE, a dense non-aqueous phase liquid (DNAPL). Thus the oxidation primarily takes place in the aqueous phase where TCE is dissolved. A bench column study was conducted to demonstrate a conceptual remediation method by flushing either S 2O 82- or Fe 2+ through a soil column, where the TCE DNAPL was present, and passing the dissolved mixture through either a Fe 2+ or S 2O 82- fluid sparging curtain. Also, the effect of a solubility enhancing chemical, hydroxypropyl-?-cyclodextrin (HPCD), was tested to evaluate its ability to increase the aqueous TCE concentration. Both flushing arrangements may result in similar TCE degradation efficiencies of 35% to 42% estimated by the ratio of TCE degraded/(TCE degraded + TCE remained in effluent) and degradation byproduct chloride generation rates of 4.9 to 7.6 mg Cl - per soil column pore volume. The addition of HPCD did greatly increase the aqueous TCE concentration. However, the TCE degradation efficiency decreased because the TCE degradation was a lower percentage of the relatively greater amount of dissolved TCE by HPCD. This conceptual treatment may serve as a reference for potential on-site application.

Liang, Chenju; Lee, I.-Ling

2008-09-01

159

In situ iron activated persulfate oxidative fluid sparging treatment of TCE contamination--a proof of concept study.  

PubMed

In situ chemical oxidation (ISCO) is considered a reliable technology to treat groundwater contaminated with high concentrations of organic contaminants. An ISCO oxidant, persulfate anion (S(2)O(8)(2-)) can be activated by ferrous ion (Fe(2+)) to generate sulfate radicals (E(o)=2.6 V), which are capable of destroying trichloroethylene (TCE). The property of polarity inhibits S(2)O(8)(2-) or sulfate radical (SO(4)(-)) from effectively oxidizing separate phase TCE, a dense non-aqueous phase liquid (DNAPL). Thus the oxidation primarily takes place in the aqueous phase where TCE is dissolved. A bench column study was conducted to demonstrate a conceptual remediation method by flushing either S(2)O(8)(2-) or Fe(2+) through a soil column, where the TCE DNAPL was present, and passing the dissolved mixture through either a Fe(2+) or S(2)O(8)(2-) fluid sparging curtain. Also, the effect of a solubility enhancing chemical, hydroxypropyl-beta-cyclodextrin (HPCD), was tested to evaluate its ability to increase the aqueous TCE concentration. Both flushing arrangements may result in similar TCE degradation efficiencies of 35% to 42% estimated by the ratio of TCE degraded/(TCE degraded+TCE remained in effluent) and degradation byproduct chloride generation rates of 4.9 to 7.6 mg Cl(-) per soil column pore volume. The addition of HPCD did greatly increase the aqueous TCE concentration. However, the TCE degradation efficiency decreased because the TCE degradation was a lower percentage of the relatively greater amount of dissolved TCE by HPCD. This conceptual treatment may serve as a reference for potential on-site application. PMID:18649972

Liang, Chenju; Lee, I-Ling

2008-09-10

160

Microbial enhancement of TCE and 1,2-DCA solute flux in UF-membrane bioreactors  

SciTech Connect

An ultrafiltration membrane process was used to remove and biograde chlorinated aliphatic hydrocarbons trichloroethylene (TCE) and 1,2-dichloroethane (1,2-DCA) from dilute aqueous streams. The effect of microbial biodegradative activity on TCE and 1,2-DCA solute flux in a polypropylene membrane was examined using microbial strains Pseudomonas cepacia PRI{sub 31} for the biodegradation of TCE and Xanthobacter autotrophicus GJ10 for the biodegradation of 1,2-DCA. Initial experiments were conducted in diaphragm cells in the absence of microorganisms to determine the diffusion coefficient of 1,2-DCA and TCE in the polypropylene ultrafiltration (UF) membranes. The diffusivities were 4.7 {times} 10{sup {minus}8} cm{sup 2}/s for 1,2-DCA and 1.41 {times} 10{sup {minus}7} cm{sup 2}/s for TCE. Subsequent experiments were conducted with microorganisms on the permeate side to examine the effect of microbial degradation of 1,2-DCA and TCE on the solute flux across the UF membrane. Experiments were conducted sequentially in batch and flow diaphragm cells and then in a hollow-fiber UF module to systematically examine the effect of microbial activity on the solute flux in each configuration and the ability of mathematical models to predict the microbial enhancement of solute flux. Microbial biodegradation of TCE and 1,2-DCA significantly enhanced the solute flux, and experimental results were correlated with steady- and nonsteady-state solute component balance models for the flow and batch diaphragm cells, respectively. Model and experimental results agree well. Implications for using membrane bioreactors to treat CAH contaminated groundwater and industrial effluents are discussed.

Inguva, S.; Boensch, M.; Shreve, G.S. [Wayne State Univ., Detroit, MI (United States). Dept. of Chemical Engineering and Materials Science] [Wayne State Univ., Detroit, MI (United States). Dept. of Chemical Engineering and Materials Science

1998-09-01

161

Pneumococcal phosphorylcholine esterase, Pce, contains a metal binuclear center that is essential for substrate binding and catalysis  

PubMed Central

The phosphorylcholine esterase from Streptococcus pneumoniae, Pce, catalyzes the hydrolysis of phosphorylcholine residues from teichoic and lipoteichoic acids attached to the bacterial envelope and comprises a globular N-terminal catalytic module containing a zinc binuclear center and an elongated C-terminal choline-binding module. The dependence of Pce activity on the metal/enzyme stoichiometry shows that the two equivalents of zinc are essential for the catalysis, and stabilize the catalytic module through a complex metal-ligand coordination network. The pH dependence of Pce activity toward the alternative substrate p-nitrophenylphosphorylcholine (NPPC) shows that kcat and kcat/Km depend on the protonation state of two protein residues that can be tentatively assigned to the ionization of the metal-bound water (hydrogen bonded to D89) and to H228. Maximum activity requires deprotonation of both groups, although the catalytic efficiency is optimum for the single deprotonated form. The drastic reduction of activity in the H90A mutant, which still binds two Zn2+ ions at neutral pH, indicates that Pce activity also depends on the geometry of the metallic cluster. The denaturation heat capacity profile of Pce exhibits two peaks with Tm values of 39.6°C (choline-binding module) and 60.8°C (catalytic module). The H90A mutation reduces the high-temperature peak by about 10°C. Pce is inhibited in the presence of 1 mM zinc, but this inhibition depends on pH, buffer, and substrate species. A reaction mechanism is proposed on the basis of kinetic data, the structural model of the Pce:NPPC complex, and the currently accepted mechanism for other Zn-metallophosphoesterases.

Lagartera, Laura; Gonzalez, Ana; Hermoso, Juan A.; Saiz, Jose L.; Garcia, Pedro; Garcia, Jose L.; Menendez, Margarita

2005-01-01

162

TCE Transport to Woburn Wells G and H  

NSDL National Science Digital Library

To prepare to view the TCE animation, students could view the 'A Civil Action' movie and the instructor could read to them excerpts from the trial testimony and images from Woburn, wells G and H, geologic materials, geologic cross sections, the trial participants, and the federal courtroom in Boston (available as a attachment to this activity and at a website listed below). The discussion in Bair (2001) about scientists in the courtroom, the specific (excerpted) testimony presented by the three expert witnesses in the 'A Civil Action' trial, a chart summarizing the differences in their testimony, and the views of a federal judge on the goal of science versus the goal of a civil trial may also be worthwhile reading by the class prior to the assignment. The instructor could also show students the large plates included in the USGS report by Myette and others (1987) that display potentiometric data and contours before and after the famous aquifer test performed in December 1985 and January 1986, just before the trial, and discuss the ramifications of having only two sets of water-level measurements to characterize all the changes in the flow system between 1964 and 1979, when wells G and H periodically operated. This makes students consider the substantial differences in making predictions based on a steady-state conceptualization of the flow system or a transient conceptualization. The instructor could also show the animation of induced infiltration from the Aberjona River to wells G and H that also was created by Martin van Oort (M.S., 2005) and based on the research of Maura Metheny (M.S., 1998; Ph.D., 2004) at Ohio State University. Viewing both animations enables students to see that the water produced by wells G and H is a highly transient mixture derived from many different source areas within the valley. The article by Bair and Metheny (2002) concerning the remediation activities at the Wells G & H Superfund Site could be used to show how groundwater contamination is cleaned up, why different remediation schemes needed to be used in different hydrogeologic settings, and why cleanup to U.S. EPA standards can take decades.

Bair, Scott

163

A study of the effect of perchloroethylene exposure on the reproductive outcomes of wives of dry-cleaning workers  

SciTech Connect

The purpose of this investigation was to compare the reproductive outcomes of wives of men exposed to perchloroethylene in the dry-cleaning industry compared to those of wives of laundry workers. Seventeen female partners of dry cleaners and 32 partners of laundry workers were interviewed. The number of pregnancies and the standardized fertility ratios were similar between the two groups. Wives of dry cleaners did not have higher rates of spontaneous abortions. However, wives of dry cleaners were more than twice as likely to have a history of attempting to become pregnant for more than 12 months or to have sought care for an infertility problem. Cox proportional hazards models indicated that dry-cleaners' wives had half of the per-cycle pregnancy rate of wives of laundry workers, when controlling for other potential confounders (estimated rate ratio of 0.54, 95% C.I. = 0.23, 1.27).

Eskenazi, B.; Fenster, L.; Hudes, M.; Wyrobek, A.J.; Katz, D.F.; Gerson, J.; Rempel, D.M. (Program of Maternal and Child Health, School of Public Health, University of California, Berkeley (United States))

1991-01-01

164

Applications of ultrasound in NAPL remediation: sonochemical degradation of TCE in aqueous surfactant solutions.  

PubMed

Surfactant-enhanced pump-and-treat technologies increase the efficiency of nonaqueous-phase liquids (NAPLs) removal from soils. However, high concentrations of surfactants in groundwater impose severe limitations to water treatment. In this paper, we explore the applicability of ultrasonic irradiation as an alternative method for surfactant recovery and contaminant degradation. The combined effects of temperature, initial substrate concentration, and concentration of added surfactant (sodium dodecyl sulfate, SDS) were analyzed for the sonolysis of trichloroethylene (TCE) in batch experiments at an ultrasonic frequency of 500 kHz and 77 W/L applied power density. In the range of 5-30 degrees C, TCE sonolysis becomes faster at higher temperatures, both in the absence and in the presence of surfactant. This indicates that gas-phase pyrolysis prevails over other chemical reactions in the liquid phase. Inhibition of TCE sonolysis was observed in the presence of surfactant at all SDS concentrations. Changes in the initial TCE concentration (from 250 microM to 1.2 mM) showed no effect on the degradation rates in the presence of SDS. For surfactant levels below its critical micelle concentration (cmc), the inhibition of TCE sonolysis exhibited a highly nonlinear dependence with increasing SDS concentration. A correlation was observed in this range between the relative inhibition of sonolysis and the decreasing surface tension of the solutions. Above the cmc up to an SDS concentration of 5%, the reaction rate decreased less markedly. Micellar sequestration of the contaminant seems to be the main reason for this additional inhibition. Bubble growth prior to collapse may incorporate some of the TCE dissolved in the micelles through their adsorption in the expanding bubble walls, thus partially overcoming the scavenging effect due to micellar entrapment of the contaminant. PMID:11478257

Destaillats, H; Alderson, T W; Hoffmann, M R

2001-07-15

165

Visualization of TCE recovery mechanisms using surfactant polymer solutions in a two-dimensional heterogeneous sand model  

NASA Astrophysics Data System (ADS)

This research focused on the optimization of TCE dissolution in a physical two-dimensional model providing a realistic representation of a heterogeneous granular aquifer. TCE was infiltrated in the sand pack where it resided both in pools and in zones of residual saturation. Surfactant was initially injected at low concentration to minimize TCE remobilization at first contact but was incrementally increased later during the experiment. Xanthan gum was added to the injected surfactant solution to optimize the sweep efficiency through the heterogeneous medium. Photographs and digital image analysis illustrated the interactions between TCE and the injected fluids. During the polymer flood, the effects of heterogeneities inside the sand pack were greatly reduced by the increased fluid viscosity and the shear-thinning effects of the polymer. The polymer also improved the contact between the TCE ganglia and the surfactant-polymer solution, thereby promoting dissolution. Surfactants interacted with the polymer reducing the overall viscosity of the solution. At first contact with a 0.5% mass surfactant solution, the TCE pools drained and some remobilization occurred. However, no TCE bank was formed and TCE did not penetrate into any previously uncontaminated areas. As a result, TCE surface area was increased. Subsequent surfactant floods at higher surfactant concentrations did not trigger more remobilization. TCE was mainly dissolved by the solution with the highest surfactant concentration. Plugging from bacterial growth or microgel formation associated to the polymer at the inflow screen prevented the full completion of the experiment. However, more than 90% of TCE was recovered with the circulation of less than 6 pore volumes of surfactant-polymer solution.

Robert, Thomas; Martel, Richard; Conrad, Stephen H.; Lefebvre, René; Gabriel, Uta

2006-06-01

166

Impacts of Residual Surfactant on Tetrachloroethene (PCE) Degradation Following Pilot-Scale SEAR Treatment at a Chloroethene-Impacted Site  

NASA Astrophysics Data System (ADS)

A pilot-scale surfactant-enhanced aquifer remediation (SEAR) demonstration was completed during the summer of 2000 at the Bachman Road site (Oscoda, MI USA). For this test, an aqueous solution of 60 g/L Tween 80 (polyoxyethylene (20) sorbitan monooleate) was used to recover tetrachloroethene (PCE) from a suspected source zone, located underneath a former dry-cleaning facility. Tween 80 was selected for use based upon its demonstrated capacity to solubilize PCE, “food-grade” status, and biodegradative potential. Hydraulic control was maintained throughout the test, with 95% of the injected surfactant mass recovered by a single extraction well. Source-zone monitoring conducted 15 months after SEAR treatment revealed the presence of previously undetected volatile fatty acids (acetate and formate) and PCE degradation products (trichloroethene, cis-1,2-dichloroethene, trans-1,2-dichlorethene, and vinyl chloride), in conjunction with PCE concentration reductions of approximately two orders-of-magnitude. The detection of volatile fatty acids is relevant, as they are likely fermentation products of residual Tween 80. Microbial reductive dechlorination is limited by available electron donors, and microcosm studies demonstrated that both acetate and formate support reductively dechlorinating populations present at the oligotrophic Bachman Road site aquifer. Surfactant transport simulations, using a regional flow model developed for the site, were employed to determine appropriate down-gradient monitoring locations. Drive point samples taken 15 months post-treatment in the vicinity of the simulated residual surfactant plume, contained elevated concentrations of acetate and PCE daughter products. Ongoing efforts include continued site-monitoring, and microcosm studies to corroborate a causal relationship between Tween 80 fermentation and PCE dechlorination.

Ramsburg, C. A.; Abriola, L. M.; Pennell, K. D.; Löffler, F. E.; Gamache, M.; Petrovskis, E. A.

2003-04-01

167

Remediation of PCE-contaminated aquifer by an in situ two-layer biobarrier: laboratory batch and column studies.  

PubMed

The industrial solvent tetrachloroethylene (PCE) is among the most ubiquitous chlorinated compounds found in groundwater contamination. The objective of this study was to develop an in situ two-layer biobarrier system consisting of an organic-releasing material layer followed by an oxygen-releasing material layer. The organic-releasing material, which contained sludge cakes from a domestic wastewater treatment plant, is able to release biodegradable organics continuously. The oxygen-releasing material, which contained calcium peroxide, is able to release oxygen continuously upon contact with water. The first organic-releasing material layer was to supply organics (primary substrates) to reductively dechlorinate PCE in situ. The second oxygen-releasing material layer was to release oxygen to aerobic biodegrade or cometabolize PCE degradation byproducts from the first anaerobic layer. Batch experiments were conducted to design and identify the components of the organic and oxygen-releasing materials, and evaluate the organic substrate (presented as chemical oxygen demand (COD) equivalent) and oxygen release rates from the organic-releasing material and oxygen-releasing materials, respectively. The observed oxygen and COD release rates were approximately 0.0368 and 0.0416 mg/d/g of material, respectively. A laboratory-scale column experiment was then conducted to evaluate the feasibility of this proposed system for the bioremediation of PCE-contaminated groundwater. This system was performed using a series of continuous-flow glass columns including a soil column, an organic-releasing material column, two consecutive soil columns, and an oxygen-releasing material column, followed by two other consecutive soil columns. Anaerobic acclimated sludges were inoculated in the first four columns, and aerobic acclimated sludges were inoculated in the last three columns to provide microbial consortia for contaminant biodegradation. Simulated PCE-contaminated groundwater with a flow rate of 0.25 L/d was pumped into this system. Effluent samples from each column were analyzed for PCE and its degradation byproducts. Results show that up to 99% of PCE removal efficiency was obtained in this passive system. Thus, the biobarrier treatment scheme has the potential to be developed into an environmentally and economically acceptable remediation technology for the in situ treatment of PCE-contaminated aquifer. PMID:12465785

Kao, C M; Chen, S C; Wang, J Y; Chen, Y L; Lee, S Z

2003-01-01

168

In situ redox manipulation of subsurface sediments from Fort Lewis, Washington: Iron reduction and TCE dechlorination mechanisms  

Microsoft Academic Search

Pacific Northwest National Laboratory (PNNL) conducted a bench-scale study to determine how effective chemically treated Ft. Lewis sediments can degrade trichloroethylene (TCE). The objectives of this experimental study were to quantify: (1) sediment reduction and oxidation reactions, (2) TCE degradation reactions, and (3) other significant geochemical changes that occurred. Sediment reduction and oxidation were investigated to determine the mass of

JE Szecsody; JS Fruchter; DS Sklarew; JC Evans

2000-01-01

169

PCE-based scalable dynamic path control for large-scale photonic networks  

NASA Astrophysics Data System (ADS)

This paper proposes an inter-domain path control system based on PCE (Path Computation Element) for large-scale photonic networks, especially for a photonic network across over multiple carrier domains. We discuss the overall architecture of multi-domain optical network control system. The system utilizes maximum flow information in path computation and Path Key scheme in signaling, which improve the load-balancing and the confidentiality of the inside information for the route computation and the path provisioning among different carriers. We also provide measured performance results for inter-domain path computation and path setups using global optimization scheme, estimating the path provisioning time at the network scale dependency with the route computation time and the signaling time. As a result, we show its applicability to a 1000-node scale photonic network.

Araki, Soichiro; Shimada, Kohei; Hasegawa, Hiroshi; Sato, Ken-Ichi; Iizawa, Yohei; Ishida, Shinya; Nishioka, Itaru

2011-01-01

170

INFLUENCE OF HYDRAULIC RETENTION TIME ON EXTENT OF PCE DECHLORINATION AND PRELIMINARY CHARACTERIZATION OF THE ENRICHMENT CULTURE. (R826694C703)  

EPA Science Inventory

The extent of tetrachloroethene (PCE) dechlorination in two chemostats was evaluated as a function of hydraulic retention time (HRT). The inoculum of these chemostats was from an upflow anaerobic sludge blanket (UASB) reactor that rapidly converts PCE to vinyl chloride (VC) an...

171

Remediation of TCE-contaminated groundwater by a permeable reactive barrier filled with plant mulch (Biowall)  

Microsoft Academic Search

A pilot-scale permeable reactive barrier filled with plant mulch was installed at Altus Air Force Base in Oklahoma, USA to treat trichloroethylene (TCE) contamination in groundwater emanating from a landfill. The barrier was constructed in June 2002. It was 139 meters long, 7 meters deep, and 0.5 meters wide. The barrier is also called a Biowall because one of the

Xiaoxia Lu; John T. Wilson; Hai Shen; Bruce M. Henry; Donald H. Kampbell

2007-01-01

172

Formulation design for target delivery of iron nanoparticles to TCE zones  

NASA Astrophysics Data System (ADS)

Nanoparticles of zero-valent iron (NZVI) are effective reducing agents for some dense non-aqueous phase liquid (DNAPL) contaminants such as trichloroethylene (TCE). However, target delivery of iron nanoparticles to DNAPL zones in the aquifer remains an elusive feature for NZVI technologies. This work discusses three strategies to deliver iron nanoparticles to DNAPL zones. To this end, iron oxide nanoparticles coated with oleate (OL) ions were used as stable analogs for NZVI. The OL-coated iron oxide nanoparticles are rendered lipophilic via (a) the addition of CaCl2, (b) acidification, or (c) the addition of a cationic surfactant, benzethonium chloride (BC). Mixtures of OL and BC show promise as a target delivery strategy due to the high stability of the nanoparticles in water, and their preferential partition into TCE in batch experiments. Column tests show that while the OL-BC coated iron oxide nanoparticles remain largely mobile in TCE-free columns, a large fraction of these particles are retained in TCE-contaminated columns, confirming the effectiveness of this target delivery strategy.

Wang, Ziheng; Acosta, Edgar

2013-12-01

173

Superfund Record of Decision (EPA Region 4): Davis Park Road TCE, Gastonia, NC, September 29, 1998  

SciTech Connect

This decision document presents the selected remedial action for the Davis Park Road TCE Site in Gastonia, Gaston County, North Carolina. This remedy addressees the principle threat posed by the Site. The major threat is the contaminated groundwater emanating from beneath the Site.

NONE

1998-10-01

174

Initial Results of ISCO for a Large TCE DNAPL Source Area  

Microsoft Academic Search

This paper will describe the results of an in situ chemical oxidation (ISCO) remedial action currently in progress to address subsurface contamination by trichloroethene (TCE) dense nonaqueous phase liquid (DNAPL). The U.S. Department of Energy is responsible for the cleanup of environmental media at the Portsmouth Gaseous Diffusion Plant (PORTS) in southern Ohio. The X-701B Solid Waste Management Unit is

Steven L. Thompson; Paul E. Cross

2008-01-01

175

Field performance of air-sparging system for removing TCE from groundwater  

Microsoft Academic Search

The removal of volatile organic compounds from groundwater by air sparging (AS) is well-established, although reliable methods for predicting the time required to reach site closure have not been established. To develop and improved understanding of mass transfer processes that limit AS performance, two extended controlled shutdowns of an operating AS system were performed. Monitoring of TCE concentrations in source

Alan J. Rabideau; James M. Blayden; Chandragupta Ganguly

1999-01-01

176

Treatment of co-mingled benzene, toluene and TCE in groundwater.  

PubMed

This work addressed a hypothetical but practical scenario that includes biological oxidation and reductive dechlorination in treating groundwater containing co-mingled plume of trichloroethene (TCE), benzene and toluene. Groundwater immediately downgradient from the commonly used zero-valent iron (ZVI) has shown alkaline pH (up to 10.7). The elevated pH may influence BTEX compounds (i.e., benzene, toluene, ethyl benzene, and xylenes) biodegradation, which could also be inhibited by elevated concentrations of TCE. Data from this work suggests that the inhibition coefficients (IC) value for 100?g/L and 500?g/L of TCE on benzene and toluene degradation are 2.1-2.8 at pH 7.9, and 3.5-6.1 at pH 10.5. For a co-mingled plume, it appears to be more effective to reduce TCE by ZVI before addressing benzene and toluene biodegradation. The ample buffering capacity of most groundwater and the adaptation of benzene and toluene-degrading microbes are likely able to eliminate the adverse influence of pH shifts downgradient from a ZVI-PRB. PMID:24857895

Chen, Liang; Liu, Yulong; Liu, Fei; Jin, Song

2014-06-30

177

FIELD SCALE EVALUATION OF TREATMENT OF TCE IN A BIOWALL AT THE OU-1 SITE  

EPA Science Inventory

A passive reactive barrier (Biowall) was installed at the OU-1 site at Altus Air Force Base, Oklahoma to treat TCE contamination in ground water from a landfill. Depth to ground water varies from 1.8 to 2.4 meters below land surface. To intercept and treat the plume of contamin...

178

Modeling of TCE diffusion to the atmosphere and distribution in plant stems.  

PubMed

Fate of chlorinated solvents in phytoremediation has been delineated by many discoveries made in recent years. Plant uptake, metabolism, rhizosphere degradation, accumulation, and volatilization were shown to occur to differing degrees for many organic contaminants including chlorinated solvents. Among these mechanistic findings, recent research confirmed that volatile organic compounds (VOCs) volatilize from stems and that the resulting diffusive flux to the atmosphere is related to exposure concentration and to height up the stem. A comprehensive model was developed based upon all identified fate and transport mechanisms for VOCs, including translocation in the xylem flow and diffusion. The dispersion and diffusion in the radial direction were considered as one process (effective diffusion) as the two could not be investigated individually. The mechanism-based model mathematically indicates an exponential decrease of concentrations with height. While an analytic solution for the comprehensive model was not attained, it can serve as a starting point for other modeling efforts. The comprehensive model was simplified in this work for practical application to experimentally obtained data on trichloroethylene (TCE) fate. Model output correlated well with experimental results, and effective diffusivities for TCE in plant tissues were obtained through the model calibrations. The simplified model approximated TCE concentrations in the transpiration stream as well as TCE volatilization to the atmosphere. Xylem transport, including advection, dispersion, and diffusion through cell walls with subsequent volatilization to the atmosphere, is a major fate for VOCs in phytoremediation. PMID:15461166

Ma, Xingmao; Burken, Joel

2004-09-01

179

Abiotic and Biotic Transformation of TCE under Sulfate Reducing Conditions: the Role of Spatial Heterogeneity  

EPA Science Inventory

At a number of sites in the USA, passive reactive barriers built with shredded plant mulch have been constructed to treat ground water contaminated with TCE. These barriers are called biowalls because anaerobic biodegradation of the plant mulch is expected to provide substrates...

180

Formulation design for target delivery of iron nanoparticles to TCE zones.  

PubMed

Nanoparticles of zero-valent iron (NZVI) are effective reducing agents for some dense non-aqueous phase liquid (DNAPL) contaminants such as trichloroethylene (TCE). However, target delivery of iron nanoparticles to DNAPL zones in the aquifer remains an elusive feature for NZVI technologies. This work discusses three strategies to deliver iron nanoparticles to DNAPL zones. To this end, iron oxide nanoparticles coated with oleate (OL) ions were used as stable analogs for NZVI. The OL-coated iron oxide nanoparticles are rendered lipophilic via (a) the addition of CaCl2, (b) acidification, or (c) the addition of a cationic surfactant, benzethonium chloride (BC). Mixtures of OL and BC show promise as a target delivery strategy due to the high stability of the nanoparticles in water, and their preferential partition into TCE in batch experiments. Column tests show that while the OL-BC coated iron oxide nanoparticles remain largely mobile in TCE-free columns, a large fraction of these particles are retained in TCE-contaminated columns, confirming the effectiveness of this target delivery strategy. PMID:24096200

Wang, Ziheng; Acosta, Edgar

2013-12-01

181

Validation and application of pharmacokinetic models for interspecies extrapolations in toxicity risk assessments of volatile organics. Annual report No. 2, 1 July 1988-30 June 1989  

SciTech Connect

In pursuit of the goal of establishing a scientific basis for the interspecies extrapolation of pharmacokinetic data in health-risk assessments, a series of studies were conducted involving pharmacokinetic determinations in rats to several aliphatic halocarbons (with parallel studies initiated in the dog). Direct measurements of the uptake and elimination of halocarbon in rats were completed during the following inhalation exposures and following oral administration of dichloroethylene (DCE) and perchloroethylene (PCE). An assay for the measurement of halocarbons in the tissues of exposed animals has been successfully developed, and tissue-concentration profiles in the liver, kidney, lung, fat, brain, muscle, and heart were completed for oral and intraarterial administrations of PCE. The utility of the physiologically-based pharmacokinetic model for the accurate computer simulations of the pharmacokinetics of three halocarbons with wide variation in physicochemical properties (TRI, TCE, and PCE) has been demonstrated.

Dallas, C.E.; Bruckner, J.V.; Gallo, J.; Ramanathan, R.; Muralidhara, S.

1989-07-21

182

Initial Results of ISCO for a Large TCE DNAPL Source Area  

SciTech Connect

This paper will describe the results of an in situ chemical oxidation (ISCO) remedial action currently in progress to address subsurface contamination by trichloroethene (TCE) dense nonaqueous phase liquid (DNAPL). The U.S. Department of Energy is responsible for the cleanup of environmental media at the Portsmouth Gaseous Diffusion Plant (PORTS) in southern Ohio. The X-701B Solid Waste Management Unit is an unlined surface impoundment at PORTS which was operated from 1954 to 1988. A TCE plume in groundwater emanates from the unit and is approximately 2,200 feet in length. Metals, radioactive inorganics, and other organic chemicals are also present at lower concentrations in the groundwater. An ongoing 1.6-acre TCE DNAPL source area for the plume is believed to exist up-gradient in the vicinity of the X-701B pond. The extent of the source area is inferred from actual recovery of DNAPL in production wells and from detection of TCE concentrations between 100 and 1,000 mg/L in monitoring wells. Previous remedial activities at X-701B have included a Resource Conservation and Recovery Act (RCRA) closure and a technology demonstration that recirculated permanganate solutions between two horizontal wells. Results of sampling after these remedial activities showed that the permanganate effectively destroyed TCE in portions of the aquifer where adequate contact was achieved, but that uniform distribution by the recirculation system was problematic. As a result, the TCE concentration in the groundwater eventually rebounded after the treatment. To overcome distribution issues and to more aggressively remediate the source, a new remediation approach is being implemented for the unit. The new approach involves the injection of Modified Fenton's Reagent directly into the source area using temporary direct push injection points. This new approach provides the ability to overcome limitations imposed by heterogeneities in the subsurface by injecting relatively small quantities of reagent into a large number of temporary injection points across the source area. These injections are then repeated, as necessary, on a grid pattern until performance goals are achieved. The remediation is being implemented in four phases under a work plan approved by the Ohio Environmental Protection Agency. Phase I, the pilot test, was conducted over a small portion of the source area. Phase II currently involves full-scale treatment of the source area. In Phase III, the source area will be monitored for TCE rebound. Phase IV will involve limited treatment for the down-gradient portion of the plume. (authors)

Thompson, S.L.; Cross, P.E. [CDM, Piketon, OH (United States)

2008-07-01

183

Fingerprinting TCE in a bedrock aquifer using compound-specific isotope analysis.  

PubMed

A dual isotope approach based on compound-specific isotope analysis (CSIA) of carbon (C) and chlorine (Cl) was used to identify sources of persistent trichloroethylene (TCE) that caused the shut-down in 1994 of a municipal well in an extensive fractured dolostone aquifer beneath Guelph, Ontario. Several nearby industrial properties have known subsurface TCE contamination; however, only one has created a comprehensive monitoring network in the bedrock. The impacted municipal well and many monitoring wells were sampled for volatile organic compounds (VOCs), inorganic parameters, and CSIA. A wide range in isotope values was observed at the study site. The TCE varies between -35.6‰ and -21.8‰ and from 1.6‰ to 3.2‰ for ?(13) C and ?(37) Cl, respectively. In case of cis-1,2-dichloroethene, the isotope values range between -36.3‰ and -18.9‰ and from 2.4‰ to 4.7‰ for ?(13) C and ?(37) Cl, respectively. The dual isotope approach represented by a plot of ?(13) C vs. ?(37) Cl shows the municipal well samples grouped in a domain clearly separate from all other samples from the property with the comprehensive well network. The CSIA results collected under non-pumping and short-term pumping conditions thus indicate that this particular property, which has been studied intensively for several years, is not a substantial contributor of the TCE presently in the municipal well under non-pumping conditions. This case study demonstrates that CSIA signatures would have been useful much earlier in the quest to examine sources of the TCE in the municipal well if bedrock monitoring wells had been located at several depths beneath each of the potential TCE-contributing properties. Moreover, the CSIA results show that microbial reductive dechlorination of TCE occurs in some parts of the bedrock aquifer. At this site, the use of CSIA for C and Cl in combination with analyses of VOC and redox parameters proved to be important due to the complexity introduced by biodegradation in the complex fractured rock aquifer. It is highly recommended to revisit the study when the municipal well is back into full operation. PMID:22220911

Lojkasek-Lima, Paulo; Aravena, Ramon; Parker, Beth L; Cherry, John A

2012-01-01

184

Preliminary technology report for Southern Sector bioremediation  

SciTech Connect

This project was designed to demonstrate the potential of intrinsic bioremediation and phytoremediation in the Southern Sector of the A/M-Area at the Savannah River Site. A subsurface plume of trichloroethylene (TCE) and perchloroethylene (PCE) is present in the Lost Lake aquifer upgradient of the study site and is predicted to impact the area at some point in the future. The surface area along the Lost lake aquifer seep line where the plume is estimated to emerge was identified. Ten sites along the seep line were selected for biological, chemical, and contaminant treatability analyses. A survey was undertaken in this area to to quantify the microbial and plant population known to be capable of remediating TCE and PCE. The current groundwater quality upgradient and downgradient of the zone of influence was determined. No TCE or PCE was found in the soils or surface water from the area tested at this time. A TCE biodegradation treatability test was done on soil from the 10 selected locations. From an initial exposure of 25 ppm of TCE, eight of the samples biodegraded up to 99.9 percent of all the compound within 6 weeks. This biodegradation of TCE appears to be combination of aerobic and anaerobic microbial activity as intermediates that were detected in the treatability test include vinyl chloride (VC) and the dichloroethenes (DCE) 1,2-cis-dichloroethylene and 1,1-dichloroethylene. The TCE biological treatability studies were combines with microbiological and chemical analyses. The soils were found through immunological analysis with direct fluorescent antibodies (DFA) and microbiological analysis with direct fluorescent antibodies (DFA) and microbiological analysis to have a microbial population of methanotrophic bacteria that utilize the enzyme methane monooxygenase (MMO) and cometabolize TCE.

Brigmon, R.L.; White, R.; Hazen, T.C.; Jones, D.; Berry, C.

1997-06-01

185

Change of pH and Iron Ion Concentration During Photodegradation of TCE with Ferrioxalate/UVvis Process  

SciTech Connect

Recently, some studies show various organic compounds such as pesticides and dyes degraded with the irradiation of ultraviolet light and visible light in the presence of oxalic acid and ferric ion (ferrioxalate/UVvis process). The process has much advance than other technologies because it can utilize the wavelength of 300{approx}450nm and also under the condition of neutral pH. Chlorinated organic compounds such as trichloroethene (TCE), which have caused ground water pollution on a lot of sites, have never been applied by photodegradation with this process. In this study, we showed the degradation of TCE in the presence of oxalic acid and iron ion and the change of pH, ferric and ferrous ion concentration during the photodegradation of TCE with ferrioxalate/UV-vis process. TCE was degraded in the presence of oxalic acid and iron ion. In the reactions, the equilibrium of oxalate ion and iron ion is important since it determines the amount of ferrioxalate complex which absorbs light and induces the reactions of the degradation of TCE. Thus, the pH value and iron ion concentration are the important factors which determine the amount of ferrioxalate complex. The pH is nearly constant during the photodegradation of TCE. The ferrous ion concentration was decreased as soon as beginning photodegradation of TCE, and then the ferrous ion concentration and ferric ion concentration became constant.

Hareyama, Wataru; Suto, Koichi; Inoue, Chihiro; Chida, Tadashi [Graduate School of Environmental Studies, Tohoku University, Sendai (Japan); Nakazawa, Hiroshi [Graduate School of Engineering, Iwate University, Morioka (Japan)

2006-05-15

186

Evaluation of the effects of nanoscale zero-valent iron (nZVI) dispersants on intrinsic biodegradation of trichloroethylene (TCE).  

PubMed

In this study, the biodegradability of nanoscale zero-valent iron (nZVI) dispersants and their effects on the intrinsic biodegradation of trichloroethylene (TCE) were evaluated. Results of a microcosm study show that the biodegradability of three dispersants followed the sequence of: polyvinyl alcohol-co-vinyl acetate-co-itaconic acid (PV3A) > polyoxyethylene (20) sorbitan monolaurate (Tween 20) > polyacrylic acid (PAA) under aerobic conditions, and PV3A > Tween 20 > PAA under anaerobic conditions. Natural biodegradation of TCE was observed under both aerobic and anaerobic conditions. No significant effects were observed on the intrinsic biodegradation of TCE under aerobic conditions with the presence of the dispersants. The addition of PAA seemed to have a slightly adverse impact on anaerobic TCE biodegradation. Higher accumulation of the byproducts of anaerobic TCE biodegradation was detected with the addition of PV3A and Tween 20. The diversity of the microbial community was enhanced under aerobic conditions with the presence of more biodegradable PV3A and Tween 20. The results of this study indicate that it is necessary to select an appropriate dispersant for nZVI to prevent a residual of the dispersant in the subsurface. Additionally, the effects of the dispersant on TCE biodegradation and the accumulation of TCE biodegrading byproducts should also be considered. PMID:24901632

Chang, Y C; Huang, S C; Chen, K F

2014-01-01

187

Methanogenic community development in anaerobic granular bioreactors treating trichloroethylene (TCE)-contaminated wastewater at 37 °C and 15 °C.  

PubMed

Four expanded granular sludge bed (EGSB) bioreactors were seeded with a mesophilically-grown granular sludge and operated in duplicate for mesophilic (37 °C; R1 & R2) and low- (15°; R3 & R4) temperature treatment of a synthetic volatile fatty acid (VFA) based wastewater (3 kg COD m(-3) d(-1)) with one of each pair (R1 & R3) supplemented with increasing concentrations of trichloroethylene (TCE; 10, 20, 40, 60 mg l(-1)) and one acting as a control. Bioreactor performance was evaluated by % COD removal efficiency and % biogas methane (CH(4)) content. Quantitative Polymerase Chain Reaction (qPCR) was used to investigate the methanogenic community composition and dynamics in the bioreactors during the trial, while specific methanogenic activity (SMA) and toxicity assays were utilized to investigate the activity and TCE/dichloroethylene (DCE) toxicity thresholds of key trophic groups, respectively. At both 37 °C and 15 °C, TCE levels of 60 mg l(-1) resulted in the decline of % COD removal efficiencies to 29% (Day 235) and 37% (Day 238), respectively, and in % biogas CH(4) to 54% (Day 235) and 5% (Day 238), respectively. Despite the inhibitory effect of TCE on the anaerobic digestion process, the main drivers influencing methanogenic community development, as determined by qPCR and Non-metric multidimensional scaling analysis, were (i) wastewater composition and (ii) operating temperature. At the apical TCE concentration both SMA and qPCR of methanogenic archaea suggested that acetoclastic methanogens were somewhat inhibited by the presence of TCE and/or its degradation derivatives, while competition by dechlorinating organisms may have limited the availability of H(2) for hydrogenotrophic methanogenesis. In addition, there appeared to be an inverse correlation between SMA levels and TCE tolerance, a finding that was supported by the analysis of the inhibitory effect of TCE on two additional biomass sources. The results indicate that low-temperature anaerobic digestion is a feasible approach for the treatment of TCE-containing wastewater. PMID:21396675

Siggins, Alma; Enright, Anne-Marie; O'Flaherty, Vincent

2011-04-01

188

Retaining and recovering enzyme activity during degradation of TCE by methanotrophs  

SciTech Connect

To determine if compounds added during trichloroethylene (TCE) degradation could reduce the loss of enzyme activity or increase enzyme recovery, different compounds serving as energy and carbon sources, pH buffers, or free radical scavengers were tested. Formate and formic acid (reducing power and a carbon source), as well as ascorbic acid and citric acid (free radical scavengers) were added during TCE degradation at a concentration of 2 mM. A saturated solution of calcium carbonate was also tested to address pH concerns. In the presence of formate and methane, only calcium carbonate and formic acid had a beneficial effect on enzyme recovery. The calcium carbonate and formic acid both reduced the loss of enzyme activity and resulted in the highest levels of enzyme activity after recovery. 19 refs., 3 figs.

Palumbo, A.V.; Strong-Gunderson, J.M.; Carroll, S. [Oak Ridge National Lab., TN (United States)

1997-12-31

189

Optimizing binary phase and amplitude filters for PCE, SNR, and discrimination  

NASA Technical Reports Server (NTRS)

Binary phase-only filters (BPOFs) have generated much study because of their implementation on currently available spatial light modulator devices. On polarization-rotating devices such as the magneto-optic spatial light modulator (SLM), it is also possible to encode binary amplitude information into two SLM transmission states, in addition to the binary phase information. This is done by varying the rotation angle of the polarization analyzer following the SLM in the optical train. Through this parameter, a continuum of filters may be designed that span the space of binary phase and amplitude filters (BPAFs) between BPOFs and binary amplitude filters. In this study, we investigate the design of optimal BPAFs for the key correlation characteristics of peak sharpness (through the peak-to-correlation energy (PCE) metric), signal-to-noise ratio (SNR), and discrimination between in-class and out-of-class images. We present simulation results illustrating improvements obtained over conventional BPOFs, and trade-offs between the different performance criteria in terms of the filter design parameter.

Downie, John D.

1992-01-01

190

Application of electrolysis to stimulate microbial reductive PCE dechlorination and oxidative VC biodegradation.  

PubMed

A novel approach was applied to stimulate biodegradation of chloroethenes bya coupled bioelectro-process. In a flow-through column system, microbial dechlorination of tetrachloroethene to cis-dichloroethene, vinyl chloride, and ethene was stimulated by hydrogen produced by water electrolysis. Dechlorinating bacteria (Dehalococcoides spp. and Desulfitobacterium spp.) and also methanogens and homoacetogens were detected in the anaerobic column. Simultaneously, oxidative biodegradation of lower chlorinated metabolites (vinyl chloride) was stimulated by electrolytic oxygen formation in the corresponding aerobic column. The process was stable for more than 100 days and an average removal of approximately 23 micromol/d PCE and 72 micromo/d vinyl chloride was obtained with a current density of 0.05 mA/cm2. Abiotic electrochemical degradation of the contaminants was not observed. Microbial dechlorination correlated with the current densities in the applied range of 0.01-0.05 mA/cm2. The results are promising for environmental applications, since with electrolysis hydrogen and oxygen can be supplied continuously to chloroethene degrading microorganisms, and the supply rates can be easily controlled by adjusting the electric current. PMID:19806748

Lohner, Svenja T; Tiehm, Andreas

2009-09-15

191

Degradation of DCE and TCE by Fe–Ni nanoparticles immobilised polysulphone matrix  

Microsoft Academic Search

The reduction of dichloroethane (DCE) and trichloroethylene (TCE) by bimetallic iron–nickel (Fe–Ni) nanoparticles has been studied in this study. The reduction mechanism involves hydrodechlorination at the iron–nickel interface. The Fe–Ni nanoparticles have been synthesised by the chemical reduction method and immobilised on to a polysulphone matrix. The as-synthesised nanoparticles and Fe–Ni immobilied polysulphone support have been characterised to establish the

N. Satya Vijayakumar; N. Angeline Little Flower; B. Brabu; C. Gopalakrishnan; S. V. Kasmir Raja

2012-01-01

192

Characterization and Performance of Granular Iron as Reactive Media for TCE degradation by Permeable Reactive Barriers  

Microsoft Academic Search

The application of Permeable Reactive Barriers (PRBs), an innovative clean-up technology for in-situ groundwater remediation, represents an effective alternative to traditional pump-and-treat systems and has raised strong interest during recent years. From recent statistics of the Italian Water Research Institute (IRSA), trichloroethylene (TCE) from industrial activities is the most widespread contaminant in groundwater. The goal of the research was to

Renato Baciocchi; Maria Rosaria Boni; Laura D'Aprile

2003-01-01

193

Retaining and recovering enzyme activity during degradation of TCE by methanotrophs  

Microsoft Academic Search

To determine if compounds added during trichloroethylene (TCE) degradation could reduce the loss of enzyme activity or increase\\u000a enzyme recovery, different compounds serving as energy and carbon sources, pH buffers, or free radical scavengers were tested.\\u000a Formate and formic acid (reducing power and a carbon source), as well as ascorbic acid and citric acid (free radical scavengers)\\u000a were added during

A. V. Palumbo; J. M. Strong-Gunderson; S. Carroll

1997-01-01

194

Influence of pH on persulfate oxidation of TCE at ambient temperatures  

Microsoft Academic Search

In situ chemical oxidation (ISCO) is a technology used for groundwater remediation. This laboratory study investigated the use of the oxidant sodium persulfate for the chemical oxidation of trichloroethylene (TCE) at near ambient temperatures (10, 20 and 30°C) to determine the influence of pH (pH=4, 7 and 9) on the reaction rate (i.e., pseudo-first-order rate constants) over the range of

Chenju Liang; Zih-Sin Wang; Clifford J. Bruell

2007-01-01

195

Electrochemically induced dual reactive barriers for transformation of TCE and mixture of contaminants in groundwater  

PubMed Central

A novel reactive electrochemical flow system consisting of iron anode and porous cathode is proposed for the remediation of mixture of contaminants in groundwater. The system consists of a series of sequentially arranged electrodes, a perforated iron anode, a porous copper cathode followed by a mesh-type mixed metal oxide anode. The iron anode generates ferrous species and a chemically reducing environment, the porous cathode provides a reactive electrochemically reducing barrier, and the inert anode provides proton and oxygen to neutralize the system. The redox conditions of the electrolyte flowing through this system can be regulated by controlling the distribution of the electric current. Column experiments are conducted to evaluate the process and study the variables. The electrochemical reduction on a copper foam cathode produced an electrode-based reductive potential capable of reducing TCE and nitrate. Rational electrodes arrangement, longer residence time of electrolytes and higher surface area of foam electrode improve the reductive transformation of TCE. More than 82.2% TCE removal efficiency is achieved for the case of low influent concentration (< 7.5 mg/L) and high current (> 45 mA). The ferrous species produced from the iron anode not only enhance the transformation of TCE on the cathode, but also facilitates transformation of other contaminants including dichromate, selenate and arsenite. Removal efficiencies greater than 80% are achieved for these contaminants from flowing contaminated water. The overall system, comprising the electrode-based and electrolyte-based barriers, can be engineered as a versatile and integrated remedial method for a relatively wide spectrum of contaminants and their mixtures.

Mao, Xuhui; Yuan, Songhu; Fallahpour, Noushin; Ciblak, Ali; Howard, Joniqua; Padilla, Ingrid; Loch-Caruso, Rita; Alshawabkeh, Akram N.

2012-01-01

196

A Biotic\\/Abiotic Three-Phase In Situ Barrier System to Treat TCE in Groundwater  

Microsoft Academic Search

A groundwater remediation pilot test (PT) consisting of three (3) in series, in situ reactive barriers was designed to evaluate treatment of dissolved phase tri- chloroethene (TCE) at concentrations up to 650 µg\\/L and cis-1,2-dichloroethene (cis- DCE) concentrations up to 350 µg\\/L at the Canadian Department of National Defense (DND) site in Valcartier, Quebec, Canada. The layout of the pilot

Robert W. Tossell; Blair Greenly; Brian Whiffin

197

Surfactant foam\\/bioaugmentation technology for in situ treatment of TCE-DNAPLs  

Microsoft Academic Search

Chlorinated solvents such as trichloroethylene (TCE) are prevalent aquifer contaminants. Depending on the degree of contamination, their physical properties may cause them to occur as dense nonaqueous-phase liquids (DNAPLs) making them difficult to remediate by pump-and-treat methods. Successful in situ bioremediation requires mobilization and dispersion of DNAPLs in order to reduce sediment concentrations to levels nontoxic to degradative bacteria. A

Randi K. Rothmel; Robert W. Peters; Edward St. Martin; Mary F. DeFlaun

1998-01-01

198

A general TCE model of international business institutions: Market failure and reciprocity  

Microsoft Academic Search

In this study I propose a general transaction-cost economics (TCE) model of international business institutions, in which cross-border transactions can be conducted at multiple market levels (e.g., output, asset, and equity), and the buyer–seller relationship can go both ways (A sells to B, and B sells to A). This general model addresses two major gaps in the literature. First, although

Shih-Fen S Chen

199

A general TCE model of international business institutions: Market failure and reciprocity  

Microsoft Academic Search

In this study I propose a general transaction-cost economics (TCE) model of international business institutions, in which cross-border transactions can be conducted at multiple market levels (e.g., output, asset, and equity), and the buyer–seller relationship can go both ways (A sells to B, and B sells to A). This general model addresses two major gaps in the literature. First, although

Shih-Fen S Chen

2010-01-01

200

Long Term Remote Monitoring of TCE Contaminated Groundwater at Savannah River Site  

SciTech Connect

The purpose of this study was to develop a mobile self powered remote monitoring system enhanced for field deployment at Savannah River Site (SRS). The system used a localized power source with solar recharging and has wireless data collection, analysis, transmission, and data management capabilities. The prototype was equipped with a Hydrolab's DataSonde 4a multi-sensor array package managed by a Supervisory Control and Data Acquisition (SCADA) system, with an adequate pumping capacity of water samples for sampling and analysis of Trichloroethylene (TCE) in contaminated groundwater wells at SRS. This paper focuses on a study and technology development efforts conducted at the Hemispheric Center for Environmental Technology (HCET) at Florida International University (FIU) to automate the sampling of contaminated wells with a multi-sensor array package developed using COTS (Commercial Off The shelf) parts. Bladder pumps will pump water from different wells to the sensors array, water quality TCE indicator parameters are measured (i.e. pH, redox, ORP, DO, NO3 -, Cl-). In order to increase user access and data management, the system was designed to be accessible over the Internet. Remote users can take sample readings and collect data remotely over a web. Results obtained at Florida International University in-house testing and at a field deployment at the Savannah River Site indicate that this long term monitoring technique can be a feasible solution for the sampling of TCE indicator parameters at remote contaminated sites.

Duran, C.; Gudavalli, R.; Lagos, L.; Tansel, B.; Varona, J.; Allen, M.

2004-10-06

201

Evaluation of areas of contribution and water quality at receptors related to TCE plumes in a valley fill aquifer system  

NASA Astrophysics Data System (ADS)

The Val-Belair sector is located within Quebec City, about 20 km from downtown. Potential source zones and TCE plumes in groundwater are found at the western limit of the sector. At the center of the sector, four municipal water supply wells pump groundwater from an aquifer in surficial sediments where dissolved TCE is found. Private residential wells are also found in the sector. The Nelson River and its tributaries drain the sector and flows from west to east. New characterization results and available data were used to develop a numerical model of groundwater flow and mass transport to 1) define geological and hydrogeological contexts, 2) delineate the distribution of TCE and identify its migration paths and 3) evaluate the effect of TCE on the water quality of receptors (Nelson River, municipal and residential wells). In the sector, 30 to 40 m of sediments filling a buried valley form two aquifers separated by an aquitard: an unconfined deltaic aquifer at surface, an underlying silty prodeltaic aquitard and a semi-confined aquifer of deltaic sands and diamictons. Groundwater exchanges between the aquifers are generally downward through the aquitard, but near the Nelson River there is upward flow. Monitoring has led to sparse TCE detections in the Nelson River, regular detections at a mean value of 0.62 ?g/L at one municipal well, occasional detections at another well and no detection at the other two wells. No TCE was detected in private wells, which are located outside the migration paths of TCE plumes. The context and numerical modeling with particle tracking and mass transport show the relationships between the two source zones, three TCE plumes and three receptors. Municipal wells pump in the semi-confined aquifer at a level appearing sustainable, but use most of the recharge in the sub-watershed. Areas of contribution to the wells thus cover almost all the study area with a complex pattern. These wells compete with the effect of the Nelson River to drain groundwater flow. Mass transport shows that most of the TCE mass flux from the TCE plumes ends up in the Nelson River, but at low concentrations, thus restricting TCE concentrations in the municipal wells at levels much lower than the maximum concentration limit.

Lefebvre, R.; Ouellon, T.; Blais, V.; Ballard, J.; Brunet, P.

2009-05-01

202

Remediation of TCE-contaminated groundwater using zero valent iron and direct current: experimental results and electron competition model  

Microsoft Academic Search

The objectives of this study are to design an optimal electro-enhanced permeable reactive barrier (E2PRB) system for the remediation\\u000a of trichloroethylene (TCE)-contaminated water using zero valent iron (ZVI) and direct current (DC) and to investigate the\\u000a mechanisms responsible for TCE degradation in different ZVI-DC configurations. A series of column experiments was conducted\\u000a to evaluate the effect of different arrangements of

Ji-Won Moon; Hi-Soo Moon; Heonki Kim; Yul Roh

2005-01-01

203

Electro-enhanced Permeable Reactive Barrier : Optimal Design of PRB System With External Current for Effective TCE Removal From Groundwater  

Microsoft Academic Search

The objective of this study was to design an optimal electro-enhanced permeable reactive barrier (E2PRB) system for remediation of trichloroethylene (TCE)-contaminated water using zero valent iron (ZVI) and direct current (DC). A series of column experiments were conducted to evaluate the location of Fe0 permeable reactive barrier (PRB) and the effects of electrode arrangement in the column on the TCE

J. Moon; H. Moon; Y. Roh; H. Kim; Y. Song

2002-01-01

204

RNA elements directing in vivo assembly of the 7SK/MePCE/Larp7 transcriptional regulatory snRNP  

PubMed Central

Through controlling the nuclear level of active positive transcription elongation factor b (P-TEFb), the 7SK small nuclear RNA (snRNA) functions as a key regulator of RNA polymerase II transcription. Together with hexamethylene bisacetamide-inducible proteins 1/2 (HEXIM1/2), the 7SK snRNA sequesters P-TEFb into transcriptionally inactive ribonucleoprotein (RNP). In response to transcriptional stimulation, the 7SK/HEXIM/P-TEFb RNP releases P-TEFb to promote polymerase II-mediated messenger RNA synthesis. Besides transiently associating with HEXIM1/2 and P-TEFb, the 7SK snRNA stably interacts with the La-related protein 7 (Larp7) and the methylphosphate capping enzyme (MePCE). In this study, we used in vivo RNA–protein interaction assays to determine the sequence and structural elements of human 7SK snRNA directing assembly of the 7SK/MePCE/Larp7 core snRNP. MePCE interacts with the short 5?-terminal G1-U4/U106-G111 helix-tail motif and Larp7 binds to the 3?-terminal hairpin and the following U-rich tail of 7SK. The overall RNA structure and some particular nucleotides provide the information for specific binding of MePCE and Larp7. We also demonstrate that binding of Larp7 to 7SK is a prerequisite for in vivo recruitment of P-TEFb, indicating that besides providing stability for 7SK, Larp7 directly participates in P-TEFb regulation. Our results provide further explanation for the frequently observed link between Larp7 mutations and cancer development.

Muniz, Lisa; Egloff, Sylvain; Kiss, Tamas

2013-01-01

205

PCE dissolution and simultaneous dechlorination by nanoscale zero-valent iron particles in a DNAPL source zone  

NASA Astrophysics Data System (ADS)

While the capability of nanoscale zero-valent iron (NZVI) to dechlorinate organic compounds in aqueous solutions has been demonstrated, the ability of NZVI to remove dense non-aqueous phase liquid (DNAPL) from source zones under flow-through conditions similar to a field scale application has not yet been thoroughly investigated. To gain insight on simultaneous DNAPL dissolution and NZVI-mediated dechlorination reactions after direct placement of NZVI into a DNAPL source zone, a combined experimental and modeling study was performed. First, a DNAPL tetrachloroethene (PCE) source zone with emplaced NZVI was built inside a small custom-made flow cell and the effluent PCE and dechlorination byproducts were monitored over time. Second, a model for rate-limited DNAPL dissolution and NZVI-mediated dechlorination of PCE to its three main reaction byproducts with a possibility for partitioning of these byproducts back into the DNAPL was formulated. The coupled processes occurring in the flow cell were simulated and analyzed using a detailed three-dimensional numerical model. It was found that subsurface emplacement of NZVI did not markedly accelerate DNAPL dissolution or the DNAPL mass-depletion rate, when NZVI at a particle concentration of 10 g/L was directly emplaced in the DNAPL source zone. To react with NZVI the DNAPL PCE must first dissolve into the groundwater and the rate of dissolution controls the longevity of the DNAPL source. The modeling study further indicated that faster reacting particles would decrease aqueous contaminant concentrations but there is a limit to how much the mass removal rate can be increased by increasing the dechlorination reaction rate. To ensure reduction of aqueous contaminant concentrations, remediation of DNAPL contaminants with NZVI should include emplacement in a capture zone down-gradient of the DNAPL source.

Fagerlund, F.; Illangasekare, T. H.; Phenrat, T.; Kim, H.-J.; Lowry, G. V.

2012-04-01

206

PCE dissolution and simultaneous dechlorination by nanoscale zero-valent iron particles in a DNAPL source zone.  

PubMed

While the capability of nanoscale zero-valent iron (NZVI) to dechlorinate organic compounds in aqueous solutions has been demonstrated, the ability of NZVI to remove dense non-aqueous phase liquid (DNAPL) from source zones under flow-through conditions similar to a field scale application has not yet been thoroughly investigated. To gain insight on simultaneous DNAPL dissolution and NZVI-mediated dechlorination reactions after direct placement of NZVI into a DNAPL source zone, a combined experimental and modeling study was performed. First, a DNAPL tetrachloroethene (PCE) source zone with emplaced NZVI was built inside a small custom-made flow cell and the effluent PCE and dechlorination byproducts were monitored over time. Second, a model for rate-limited DNAPL dissolution and NZVI-mediated dechlorination of PCE to its three main reaction byproducts with a possibility for partitioning of these byproducts back into the DNAPL was formulated. The coupled processes occurring in the flow cell were simulated and analyzed using a detailed three-dimensional numerical model. It was found that subsurface emplacement of NZVI did not markedly accelerate DNAPL dissolution or the DNAPL mass-depletion rate, when NZVI at a particle concentration of 10g/L was directly emplaced in the DNAPL source zone. To react with NZVI the DNAPL PCE must first dissolve into the groundwater and the rate of dissolution controls the longevity of the DNAPL source. The modeling study further indicated that faster reacting particles would decrease aqueous contaminant concentrations but there is a limit to how much the mass removal rate can be increased by increasing the dechlorination reaction rate. To ensure reduction of aqueous contaminant concentrations, remediation of DNAPL contaminants with NZVI should include emplacement in a capture zone down-gradient of the DNAPL source. PMID:22326687

Fagerlund, F; Illangasekare, T H; Phenrat, T; Kim, H-J; Lowry, G V

2012-04-01

207

Analysis of TCE Fate and Transport in Karst Groundwater Systems Using Statistical Mixed Models  

NASA Astrophysics Data System (ADS)

Karst groundwater systems are highly productive and provide an important fresh water resource for human development and ecological integrity. Their high productivity is often associated with conduit flow and high matrix permeability. The same characteristics that make these aquifers productive also make them highly vulnerable to contamination and a likely for contaminant exposure. Of particular interest are trichloroethylene, (TCE) and Di-(2-Ethylhexyl) phthalate (DEHP). These chemicals have been identified as potential precursors of pre-term birth, a leading cause of neonatal complications with a significant health and societal cost. Both of these contaminants have been found in the karst groundwater formations in this area of the island. The general objectives of this work are to: (1) develop fundamental knowledge and determine the processes controlling the release, mobility, persistence, and possible pathways of contaminants in karst groundwater systems, and (2) characterize transport processes in conduit and diffusion-dominated flow under base flow and storm flow conditions. The work presented herein focuses on the use of geo-hydro statistical tools to characterize flow and transport processes under different flow regimes, and their application in the analysis of fate and transport of TCE. Multidimensional, laboratory-scale Geo-Hydrobed models (GHM) were used for this purpose. The models consist of stainless-steel tanks containing karstified limestone blocks collected from the karst aquifer formation of northern Puerto Rico. The models integrates a network of sampling wells to monitor flow, pressure, and solute concentrations temporally and spatially. Experimental work entails injecting dissolved CaCl2 tracers and TCE in the upstream boundary of the GHM while monitoring TCE and tracer concentrations spatially and temporally in the limestone under different groundwater flow regimes. Analysis of the temporal and spatial concentration distributions of solutes indicates a highly heterogeneous system resulting in large preferential flow components. The distributions are highly correlated with statistically-developed spatial flow models. High degree of tailing in breakthrough curves indicate significant amount of mass limitations, particularly in diffuse flow regions. Higher flow rates in the system result in increasing preferential flow region volumes, but lower mass transfer limitations. Future work will involve experiments with non-aqueous phase liquid TCE, DEHP, and a mixture of these, and geo-temporal statistical modeling. This work is supported by the U.S. Department of Energy, Savannah River (Grant Award No. DE-FG09-07SR22571), and the National Institute of Environmental Health Sciences (NIEHS, Grant Award No. P42ES017198).

Anaya, A. A.; Padilla, I. Y.

2012-12-01

208

Toward Distributed Translucent Wavelength Switched Optical Networks under GMPLS/PCE Architecture  

NASA Astrophysics Data System (ADS)

Recently, the GMPLS controlled WSON has emerged as a promising optical transport network. In order to guarantee the optical signal transmission feature without deformation, the optoelectronic 3R regenerators still need to be sparsely placed in the network, termed as translucent networks. The growing size and complexity of the translucent network requires a transition of control plane to move from the traditional centralized model to a fully distributed architecture in the future. However, centrally designed routing, wavelength assignment, and 3R regenerator allocation approaches become unfeasible under the distributed paradigm due to the outdated and inconsistent network state information. A common solution is to accelerate the update frequency of network state, but the fundamental problem remains that the inaccurate state information is still inevitable. Furthermore, it adds a significant increase to the control traffic volume which adversely degrades the performance and scalability of the network control system. In order to mitigate the impact of having inaccurate state information on network performance in the distributed systems, a novel RWA approach is proposed in this paper, termed as routing and distributed wavelength assignment with top ranked probing wavelength set computation. In our proposal, the wavelength assignment is performed by signalling process with a set of carefully preselected probing wavelengths. This set is dynamically computed based on the resource utilization each time the network state is refreshed. The PCE module is adopted in WSON control plane to be responsible for the computation of RWA and 3R allocation. The performance of the proposed approach is studied by extensive simulations. The experiment results reveal that by employing the proposed scheme, without loss on the blocking performance the inaccuracy of the wavelength availability information can be well tolerated, and the set-up delay in lightpath provisioning can be kept at a low level.

Wang, Xin; Chap, Tithra; Xu, Sugang; Tanaka, Yoshiaki

209

Development and evaluation of a harmonized physiologically based pharmacokinetic (PBPK) model for perchloroethylene toxicokinetics in mice, rats, and humans  

SciTech Connect

This article reports on the development of a 'harmonized' PBPK model for the toxicokinetics of perchloroethylene (tetrachloroethylene or perc) in mice, rats, and humans that includes both oxidation and glutathione (GSH) conjugation of perc, the internal kinetics of the oxidative metabolite trichloroacetic acid (TCA), and the urinary excretion kinetics of the GSH conjugation metabolites N-Acetylated trichlorovinyl cysteine and dichloroacetic acid. The model utilizes a wider range of in vitro and in vivo data than any previous analysis alone, with in vitro data used for initial, or 'baseline,' parameter estimates, and in vivo datasets separated into those used for 'calibration' and those used for 'evaluation.' Parameter calibration utilizes a limited Bayesian analysis involving flat priors and making inferences only using posterior modes obtained via Markov chain Monte Carlo (MCMC). As expected, the major route of elimination of absorbed perc is predicted to be exhalation as parent compound, with metabolism accounting for less than 20% of intake except in the case of mice exposed orally, in which metabolism is predicted to be slightly over 50% at lower exposures. In all three species, the concentration of perc in blood, the extent of perc oxidation, and the amount of TCA production is well-estimated, with residual uncertainties of {approx} 2-fold. However, the resulting range of estimates for the amount of GSH conjugation is quite wide in humans ({approx} 3000-fold) and mice ({approx} 60-fold). While even high-end estimates of GSH conjugation in mice are lower than estimates of oxidation, in humans the estimated rates range from much lower to much higher than rates for perc oxidation. It is unclear to what extent this range reflects uncertainty, variability, or a combination. Importantly, by separating total perc metabolism into separate oxidative and conjugative pathways, an approach also recommended in a recent National Research Council review, this analysis reconciles the disparity between those previously published PBPK models that concluded low perc metabolism in humans and those that predicted high perc metabolism in humans. In essence, both conclusions are consistent with the data if augmented with some additional qualifications: in humans, oxidative metabolism is low, while GSH conjugation metabolism may be high or low, with uncertainty and/or interindividual variability spanning three orders of magnitude. More direct data on the internal kinetics of perc GSH conjugation, such as trichlorovinyl glutathione or tricholorvinyl cysteine in blood and/or tissues, would be needed to better characterize the uncertainty and variability in GSH conjugation in humans. - Research Highlights: >We analyze perchloroethylene (perc) toxicokinetics with a physiological model. >Results from previous analyses lumping metabolic pathways are inconsistent. >Separately tracking oxidation and conjugation pathways reconciles these results. >Available data are adequate for predicting perc blood levels and oxidation by P450. >High uncertainty remains for human conjugation of perc with glutathione.

Chiu, Weihsueh A., E-mail: chiu.weihsueh@epa.gov [National Center for Environmental Assessment, U.S. Environmental Protection Agency, Washington, DC 20460 (United States); Ginsberg, Gary L., E-mail: gary.ginsberg@ct.gov [Connecticut Department of Public Health, Hartford, CT 06106 (United States)

2011-06-15

210

A PCE groundwater plume discharging to a river: influence of the streambed and near-river zone on contaminant distributions.  

PubMed

An investigation of a tetrachloroethene (PCE) groundwater plume originating at a dry cleaning facility on a sand aquifer and discharging to a river showed that the near-river zone strongly modified the distribution, concentration, and composition of the plume prior to discharging into the surface water. The plume, streambed concentration, and hydrogeology were extensively characterized using the Waterloo profiler, mini-profiler, conventional and driveable multilevel samplers (MLS), Ground Penetrating Radar (GPR) surveys, streambed temperature mapping (to identify discharge zones), drivepoint piezometers, and soil coring and testing. The plume observed in the shallow streambed deposits was significantly different from what would have been predicted based on the characteristics of the upgradient plume. Spatial and temporal variations in the plume entering the near-river zone contributed to the complex contaminant distribution observed in the streambed where concentrations varied by factors of 100 to 5000 over lateral distances of less than 1 to 3.5 m. Low hydraulic conductivity semi-confining deposits and geological heterogeneities at depth below the streambed controlled the pattern of groundwater discharge through the streambed and influenced where the plume discharged into the river (even causing the plume to spread out over the full width of the streambed at some locations). The most important effect of the near-river zone on the plume was the extensive anaerobic biodegradation that occurred in the top 2.5 m of the streambed, even though essentially no biodegradation of the PCE plume was observed in the upgradient aquifer. Approximately 54% of the area of the plume in the streambed consisted solely of PCE transformation products, primarily cis-1,2-dichloroethene (cDCE) and vinyl chloride (VC). High concentrations in the interstitial water of the streambed did not correspond to high groundwater-discharge zones, but instead occurred in low discharge zones and are likely sorbed or retarded remnants of past high-concentration plume discharges. The high-concentration areas (up to 5529 microg/l of total volatile organics) in the streambed are of ecological concern and represent potential adverse exposure locations for benthic and hyporheic zone aquatic life, but the effect of these exposures on the overall health of the river has yet to be determined. Even if the upgradient source of PCE is remediated and additional PCE is prevented from reaching the streambed, the high-concentration deposits in the streambed will likely take decades to hundreds of years to flush completely clean under natural conditions because these areas have low vertical groundwater flow velocities and high retardation factors. Despite high concentrations of contaminants in the streambed, PCE was detected in the surface water only rarely due to rapid dilution in the river and no cDCE or VC was detected. Neither the sampling of surface water nor the sampling of the groundwater from the aquifer immediately adjacent to the river gave an accurate indication of the high concentrations of PCE biodegradation products present in the streambed. Sampling of the interstitial water of the shallow streambed deposits is necessary to accurately characterize the nature of plumes discharging to rivers. PMID:15336797

Conant, Brewster; Cherry, John A; Gillham, Robert W

2004-09-01

211

Stable Isotope Fractionation of Tetrachloroethene during Reductive Dechlorination by Sulfurospirillum multivorans and Desulfitobacterium sp. Strain PCE-S and Abiotic Reactions with Cyanocobalamin  

PubMed Central

Carbon stable isotope fractionation of tetrachloroethene (PCE) during reductive dechlorination by whole cells and crude extracts of Sulfurospirillum multivorans and Desulfitobacterium sp. strain PCE-S and the abiotic reaction with cyanocobalamin (vitamin B12) was studied. Fractionation was largest during the reaction with cyanocobalamin with ?C = 1.0132. Stable isotope fractionation was lower but still in a similar order of magnitude for Desulfitobacterium sp. PCE-S (?C = 1.0052 to 1.0098). The isotope fractionation of PCE during dehalogenation by S. multivorans was lower by 1 order of magnitude (?C = 1.00042 to 1.0017). Additionally, an increase in isotope fractionation was observed with a decrease in cell integrity for both strains. For Desulfitobacterium sp. strain PCE-S, the carbon stable isotope fractionation factors were 1.0052 and 1.0089 for growing cells and crude extracts, respectively. For S. multivorans, ?C values were 1.00042, 1.00097, and 1.0017 for growing cells, crude extracts, and the purified PCE reductive dehalogenase, respectively. For the field application of stable isotope fractionation, care is needed as fractionation may vary by more than an order of magnitude depending on the bacteria present, responsible for degradation.

Nijenhuis, Ivonne; Andert, Janet; Beck, Kirsten; Kastner, Matthias; Diekert, Gabriele; Richnow, Hans-Hermann

2005-01-01

212

Reactivity of Fe(II)/cement systems in dechlorinating chlorinated ethylenes.  

PubMed

Ferrous iron (Fe(II)) in combination with Portland cement is effective in reductively dechlorinating chlorinated organics and can be used to achieve immobilization and degradation of contaminants simultaneously. Reactivities of chlorinated ethylenes (perchloroethylene (PCE), trichloroethylene (TCE), 1,1-dichloroethylene (1,1-DCE), vinyl chloride (VC)) in Fe(II)/cement systems were characterized using batch slurry reactors. Reduction kinetics of the chlorinated ethylenes were sufficiently fast to be utilized for the proposed treatment scheme, and were described by a pseudo-first-order rate law. The order of reactivity of the chlorinated ethylenes was TCE>1,1-DCE>PCE>VC. Reduction of TCE and PCE mainly yielded acetylene, implying that the transformation of the two compounds occurred principally via reductive beta-elimination pathways. Transformation of 1,1-DCE and VC gave rise to primarily ethylene, implying that major degradation pathways were a reductive alpha-elimination for the former and a hydrogenolysis for the latter. The reactivity of the Fe(II)/cement systems in dechlorinating TCE was proportional to Fe(II) dose when the Fe(II)/cement mass ratio varied between 5.6 and 22.3%. The Fe(II)/cement systems with a higher Fe(II) loading were less extensively affected by pH in reductive reactions for TCE than in the previous experiments with PCE or chlorinated methanes. Amendment of Fe(II)/cement systems with Fe(III) addition was found effective in increasing the reactivity in the previous study, but the current findings indicated that the extent to which the reaction rate increased by the amendment might be dependent on the source of the cement and/or the compounds tested. PMID:15721534

Hwang, Inseong; Park, Hyun-Jin; Kang, Wan-Hyup; Park, Joo-Yang

2005-02-14

213

Remediation of TCE-contaminated groundwater using zero valent iron and direct current: experimental results and electron competition model  

NASA Astrophysics Data System (ADS)

The objectives of this study are to design an optimal electro-enhanced permeable reactive barrier (E2PRB) system for the remediation of trichloroethylene (TCE)-contaminated water using zero valent iron (ZVI) and direct current (DC) and to investigate the mechanisms responsible for TCE degradation in different ZVI-DC configurations. A series of column experiments was conducted to evaluate the effect of different arrangements of electrodes and ZVI barriers in the column on the TCE removal capacity (RC). In twelve different combinations of ZVI and/or DC application in the test columns, the rate of reductive dechlorination of TCE was improved up to six times with simultaneous application of ZVI and DC compared to that using ZVI only. The most effective arrangement of electrode and ZVI for TCE removal was the column set with ZVI and a cathode installed at the down gradient. Based on the electrokinetic study for the column systems with only DC input, single acid front movement could explain different RCs. An enhanced dechlorination rate of TCE using E2PRB systems, compared to a conventional PRB system, was observed, and is considered to be attributed to more electron sources: (1) external DC, (2) electrolysis of water, (3) oxidation of ZVI, (4) oxidation of dissolved Fe2+, (5) oxidation of molecular hydrogen at the cathode, and (6) oxidation of Fe2+ in mineral precipitates. Each of these electron sources was evaluated for their potential influencing the TCE RC through the electron competition model and energy consumption. A strong correlation between the quantity of electrons generated, RC, and the energy-effectiveness was found.

Moon, Ji-Won; Moon, Hi-Soo; Kim, Heonki; Roh, Yul

2005-09-01

214

Public health assessment for Newton County Wells (a/k/a Silver Creek TCE), Joplin, Jasper County, Missouri, Region 7: CERCLIS number MOD985798339. Final report  

SciTech Connect

The Newton County TCE site contains an uncontrolled groundwater plume of trichloroethylene (TCE) contamination. The source of contamination is believed to be FAG Bearings. From 1973 to 1982, FAG Bearings produced ball bearings using TCE as a commercial degreaser. It is alleged that improper disposal and leaks of an alleged closed system of TCE led to the contamination of soil at the industrial site, the groundwater aquifer, and subsequently, 82 private water wells. Exposure pathways at the site consist of inhalation of, ingestion of, and dermal contact with TCE-contaminated groundwater and surface water. Because completed and potential exposure pathways exist, the Newton County TCE site has been classified as a Public Health Hazard.

NONE

1999-07-19

215

Simulating the fate and transport of TCE from groundwater to indoor air  

NASA Astrophysics Data System (ADS)

This work provides an exploratory analysis on the relative importance of various factors controlling the fate and transport of volatile organic contaminants (in this case, TCE) from a DNAPL source zone located below the water table and into the indoor air. The analysis is conducted using the multi-phase compositional model CompFlow Bio, with the base scenario problem geometry reminiscent of a field experiment conducted by Rivett [Rivett, M.O., (1995), Soil-gas signatures from volatile chlorinated solvents: Borden field experiments. Groundwater, 33(1), 84-98.] at the Borden aquifer where groundwater was observed to transport a contaminant plume a substantial distance without vertical mass transport of the contaminant across the capillary fringe and into the vadose zone. Results for the base scenario model indicate that the structure of the permeability field was largely responsible for deflecting the groundwater plume upward towards the capillary fringe, permitting aqueous phase diffusion to transport the TCE into the vadose zone. Alternative permeability realizations, generated as part of a Monte Carlo simulation process, at times deflected the groundwater plume downwards causing the extended thickness of the saturated zone to insulate the vadose zone from exposure to the TCE by upward diffusive transport. Comparison of attenuation coefficients calculated using the CompFlow Bio and Johnson and Ettinger [Johnson, P.C. and Ettinger, R.A., (1991), Heuristic model for predicting the intrusion rate of contaminant vapors into buildings. Environmental Science and Technology, 25, 1445-1452.] heuristic model exhibited fortuitous agreement for the base scenario problem geometry, with this agreement diverging for the alternative permeability realizations as well as when parameters such as the foundation slab fracture aperture, the indoor air pressure drop, the capillary fringe thickness, and the infiltration rate were varied over typical ranges.

Yu, Soonyoung; Unger, Andre J. A.; Parker, Beth

2009-07-01

216

Simulating the fate and transport of TCE from groundwater to indoor air.  

PubMed

This work provides an exploratory analysis on the relative importance of various factors controlling the fate and transport of volatile organic contaminants (in this case, TCE) from a DNAPL source zone located below the water table and into the indoor air. The analysis is conducted using the multi-phase compositional model CompFlow Bio, with the base scenario problem geometry reminiscent of a field experiment conducted by Rivett [Rivett, M.O., (1995), Soil-gas signatures from volatile chlorinated solvents: Borden field experiments. Groundwater, 33(1), 84-98.] at the Borden aquifer where groundwater was observed to transport a contaminant plume a substantial distance without vertical mass transport of the contaminant across the capillary fringe and into the vadose zone. Results for the base scenario model indicate that the structure of the permeability field was largely responsible for deflecting the groundwater plume upward towards the capillary fringe, permitting aqueous phase diffusion to transport the TCE into the vadose zone. Alternative permeability realizations, generated as part of a Monte Carlo simulation process, at times deflected the groundwater plume downwards causing the extended thickness of the saturated zone to insulate the vadose zone from exposure to the TCE by upward diffusive transport. Comparison of attenuation coefficients calculated using the CompFlow Bio and Johnson and Ettinger [Johnson, P.C. and Ettinger, R.A., (1991), Heuristic model for predicting the intrusion rate of contaminant vapors into buildings. Environmental Science and Technology, 25, 1445-1452.] heuristic model exhibited fortuitous agreement for the base scenario problem geometry, with this agreement diverging for the alternative permeability realizations as well as when parameters such as the foundation slab fracture aperture, the indoor air pressure drop, the capillary fringe thickness, and the infiltration rate were varied over typical ranges. PMID:19525028

Yu, Soonyoung; Unger, Andre J A; Parker, Beth

2009-07-21

217

The influence of different geotechnically relevant amendments on the reductive degradation of TCE by nZVI  

NASA Astrophysics Data System (ADS)

Trichloroethylene (TCE) was widely used as a cleaning and degreasing agent. Companies needing these agents were often situated in or close to built up areas, so spillage led to contaminated sites which now can only be remediated using in situ techniques. The situation is compounded by the fact that TCE tends to seep through ground water bodies forming pools at the bottom of the aquifer. When reacting with TCE, nanoscale zero valent iron (nZVI) is known to reduce it into non-toxic substances. The difficulty is to bring it in contact with the pollutant. Attempts using passive insertion into the groundwater via wells yielded mixed results. Reasons for this are that ZVI tends to coagulate, to sediment and to adsorb on the matrix of the aquifer. Also, in inhomogeneous aquifers a passive application of nZVI can be difficult and might not bring the desired results, due to existence of preferential flow paths. A possible solution to this problem is the physical in situ mixing of ZVI into the contaminant source. This can, in principle, be done by adapting jet grouting - a method that uses a high pressure slurry jet, consisting of water and geotechnical additives ("binders"), to mix and compact zones ("columns") in soil. These columns are commonly used to solve foundation problems but can also be used to solve the problem of delivering nZVI to TCE source zones. This paper examines the influence binders have on the degradation reaction between TCE and nZVI. The necessity of these binders is explained by the fact that the subsoil structure is rearranged during the jetting process leading to subsidence on the surface. These subsidences could result in damage to neighbouring structures. A series of batch experiments was conducted in this study. Contaminated groundwater was brought into contact with samples of slurries commonly used in geotechnical applications. We tested the effects of concresole, bentonite, zeolithe, fly ash, slag sand and cement on the kinetics of TCE degradation by nZVI. The degradation of TCE was measured using GC Headspace samples. Furthermore, additional experiments were conducted to investigate the interaction between binders and TCE as well as binders and nZVI. The results of these experiments led to the conclusion that jet grouting could be well suited for the delivery of nZVI to TCE contaminated source zones. Currently, soil column experiments and large-scale experiments in test facilities are performed to confirm the batch testing results.

Freitag, Peter; Schöftner, Philipp; Waldner, Georg; Reichenauer, Thomas G.; Nickel, Claudia; Spitz, Marcus; Dietzel, Martin

2014-05-01

218

Application of H2O2 lifetime as an indicator of TCE Fenton-like oxidation in soils.  

PubMed

Hydrogen peroxide decomposition and trichloroethylene (TCE) oxidation kinetics were studied through batch slurry experiments, performed on two TCE contaminated soils (a sandy soil and a clay soil), characterized by different texture and organic fraction; besides, experiments were also performed on sandy soil columns, in order to more closely reproduce the typical conditions of an in situ treatment. The results of the batch tests indicated that hydrogen peroxide lifetime was correlated to the oxidation efficiency; namely, complete TCE oxidation was achieved only for the conditions characterized by longer hydrogen peroxide lifetime, that was obtained by addition of a proper stabilizer (KH(2)PO(4)). The soil properties were also observed to influence both hydrogen peroxide decomposition and TCE oxidation kinetics, probably as a consequence of the different TOC content. The soil column experiments, performed on 10, 20, and 30 cm long columns, indicated that hydrogen peroxide decomposition, which was almost complete at 30 cm depth, was on the contrary negligible when the stabilizer was added. In agreement with this observation, the performance of TCE oxidation were greatly improved in the latter case. Based upon the collected results, it can be concluded that hydrogen peroxide experiments may be useful, at least in the first screening phase of the design activity, for selecting, among the different operating conditions, those that may be potentially more effective for the oxidation treatment. PMID:15072817

Baciocchi, Renato; Boni, Maria Rosaria; D'Aprile, Laura

2004-03-19

219

Pilot-scale demonstration of surfactant-enhanced PCE solubilization at the Bachman Road site. 1. Site characterization and test design.  

PubMed

A pilot-scale demonstration of surfactant-enhanced aquifer remediation (SEAR) was conducted to recover dense nonaqueous phase liquid (DNAPL) tetrachloroethene (PCE) from a sandy glacial outwash aquifer underlying a former dry cleaning facility at the Bachman Road site in Oscoda, MI. Part one of this two-part paper describes site characterization efforts and a comprehensive approach to SEAR test design, effectively integrating laboratory and modeling studies. Aquifer coring and drive point sampling suggested the presence of PCE-DNAPL in a zone beneath an occupied building. A narrow PCE plume emanating from the vicinity of this building discharges into Lake Huron. The shallow unconfined aquifer, characterized by relatively homogeneous fine-medium sand deposits, an underlying clay layer, and the absence of significant PCE transformation products, was judged suitable for the demonstration of SEAR. Tween 80 was selected for application based upon its favorable solubilization performance in batch and two-dimensional sand tank treatability studies, biodegradation potential, and regulatory acceptance. Three-dimensional flow and transport models were employed to develop a robust design for surfactant delivery and recovery. Physical and fiscal constraints led to an unusual hydraulic design, in which surfactant was flushed across the regional groundwater gradient, facilitating the delivery of concentrations of Tween 80 exceeding 1% (wt) throughout the treatment zone. The potential influence of small-scale heterogeneity on PCE-DNAPL distribution and SEAR performance was assessed through numerical simulations incorporating geostatistical permeability fields based upon available core data. For the examined conditions simulated PCE recoveries ranged from 94to 99%. The effluent treatment system design consisted of low-profile air strippers coupled with carbon adsorption to trap off-gas PCE and discharge of treated aqueous effluent to a local wastewater treatment plant. The systematic and comprehensive design methodology described herein may serve as a template for application at other DNAPL sites. PMID:15819238

Abriola, Linda M; Drummond, Chad D; Hahn, Ernest J; Hayes, Kim F; Kibbey, Tohren C G; Lemke, Lawrence D; Pennell, Kurt D; Petrovskis, Erik A; Ramsburg, C Andrew; Rathfelder, Klaus M

2005-03-15

220

Risk of Learning and Behavioral Disorders Following Prenatal and Early Postnatal Exposure to Tetrachloroethylene (PCE)-contaminated Drinking Water  

PubMed Central

This population-based retrospective cohort study examined the association between developmental disorders of learning, attention and behavior and prenatal and early postnatal drinking water exposure to tetrachloroethylene (PCE) on Cape Cod, Massachusetts. Subjects were identified through birth records from 1969 through 1983. Exposure was modeled using information from town water departments, a PCE leaching and transport algorithm, EPANet water flow modeling software, and a Geographic Information System (GIS). Mothers completed a questionnaire on disorders of attention, learning and behavior in their children and on potential confounding variables. The final cohort consisted of 2,086 children. Results of crude and multivariate analyses showed no association between prenatal exposure and receiving tutoring for reading or math, being placed on an Individual Education Plan, or repeating a school grade (adjusted Odds Ratios (OR)=1.0–1.2). There was also no consistent pattern of increased risk for receiving a diagnosis of Attention Deficit Disorder (ADD) or Hyperactive Disorder (HD), special class placement for academic or behavioral problems, or lower educational attainment. Modest associations were observed for the latter outcomes only in the low exposure group (e.g., adjusted ORs for ADD were 1.4 and 1.0 for low and high exposure, respectively). (All ORs are based on an unexposed referent group.) Results for postnatal exposure through age five years were similar to those for prenatal exposure. We conclude that prenatal and early postnatal PCE exposure is not associated with disorders of attention, learning and behavior identified on the basis of questionnaire responses and at the exposure levels experienced by this population.

Janulewicz, Patricia A; White, Roberta F; Winter, Michael R; Weinberg, Janice M; Gallagher, Lisa E; Vieira, Veronica; Webster, Thomas F; Aschengrau, Ann

2008-01-01

221

Risk of learning and behavioral disorders following prenatal and early postnatal exposure to tetrachloroethylene (PCE)-contaminated drinking water.  

PubMed

This population-based retrospective cohort study examined the association between developmental disorders of learning, attention and behavior and prenatal and early postnatal drinking water exposure to tetrachloroethylene (PCE) on Cape Cod, Massachusetts. Subjects were identified through birth records from 1969 through 1983. Exposure was modeled using information from town water departments, a PCE leaching and transport algorithm, EPANet water flow modeling software, and a Geographic Information System (GIS). Mothers completed a questionnaire on disorders of attention, learning and behavior in their children and on potential confounding variables. The final cohort consisted of 2086 children. Results of crude and multivariate analyses showed no association between prenatal exposure and receiving tutoring for reading or math, being placed on an Individual Education Plan, or repeating a school grade (adjusted Odds Ratios (OR)=1.0-1.2). There was also no consistent pattern of increased risk for receiving a diagnosis of Attention Deficit Disorder (ADD) or Hyperactive Disorder (HD), special class placement for academic or behavioral problems, or lower educational attainment. Modest associations were observed for the latter outcomes only in the low exposure group (e.g., adjusted ORs for ADD were 1.4 and 1.0 for low and high exposure, respectively). (All ORs are based on an unexposed referent group.) Results for postnatal exposure through age five years were similar to those for prenatal exposure. We conclude that prenatal and early postnatal PCE exposure is not associated with disorders of attention, learning and behavior identified on the basis of questionnaire responses and at the exposure levels experienced by this population. PMID:18353612

Janulewicz, Patricia A; White, Roberta F; Winter, Michael R; Weinberg, Janice M; Gallagher, Lisa E; Vieira, Veronica; Webster, Thomas F; Aschengrau, Ann

2008-01-01

222

Biodegradation of TCE Improved with Lactate Injection in Deep, Fractured Rock  

SciTech Connect

After a recent one-year field evaluation, in situ biodegradation enhanced with the injection of lactate was selected by U.S. Environmental Protection Agency’s (EPA) Region 10, Idaho Department of Environmental Quality, and U.S. Department of Energy for use in a deep, fractured rock aquifer at the Idaho National Engineering and Environmental Laboratory’s (INEEL) Test Area North (TAN). The enhanced biodegradation will replace the default pump-and-treat remedy for the residual source area of a large trichloroethylene (TCE) plume. The field evaluation was conducted as part of an innovative technology evaluation process specified in the site Record of Decision. Five innovative technologies–enhanced in situ biodegradation, in situ chemical oxidation, metal enhanced reductive dechlorination, monolithic confinement, and natural attenuation–were evaluated in this process. Based on initial evaluation and bench-scale testing, biodegradation was selected for evaluation in the residual source area, where nonaqueous TCE is present in a sludge mixture due to the historical injection of waste into the basalt aquifer.

Sorenson, Kent Soren

2000-12-01

223

Preliminary study of propyl bromide exposure among New Jersey dry cleaners as a result of a pending ban on perchloroethylene.  

PubMed

Many states are considering, and some states have actively pursued, banning the use of perchloroethylene (PERC) in dry cleaning establishments. Proposed legislation has led many dry cleaners to consider the use of products that contain greater than 90% n-propyl bromide (n-PB; also called 1-bromopropane or 1-BP). Very little information is known about toxicity and exposure to n-PB. Some n-PB-containing products are marketed as nonhazardous and "green" or "organic." This has resulted in some users perceiving the solvent as nontoxic and has resulted in at least one significant poisoning incident in New Jersey. In addition, many dry cleaning operators may not realize that the machine components and settings must be changed when converting from PERC to n-PB containing products. Not performing these modifications may result in overheating and significant leaks in the dry cleaning equipment. A preliminary investigation was conducted of the potential exposures to n-PB and isopropyl bromide (iso-PB; also called 2-bromopropane or 2-BP) among dry cleaners in New Jersey who have converted their machines from PERC to these new solvent products. Personal breathing zone and area samples were collected using the National Institute for Occupational Safety and Health Sampling and Analytical Method 1025, with a slight modification to gas chromatography conditions to facilitate better separation of n-PB from iso-PB. During the preliminary investigation, exposures to n-PB among some workers in two of three shops were measured that were greater than the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) for n-PB. The highest exposure measured among a dry cleaning machine operator was 54 parts per million (ppm) as an 8-hr time-weighted average, which is more than 5 times the ACGIH TLV of 10 ppm. The preliminary investigation also found that the work tasks most likely to result in the highest short-term exposures included the introduction of solvent to the machine, maintenance of the machine, unloading and handling of recently cleaned clothes, and interrupting the wash cycle of the machine. In addition, this assessment suggested that leaks may have contributed to exposure and may have resulted from normal machine wear over time, ineffective maintenance, and from the incompatibility of n-PB with gasket materials. PMID:20863050

Blando, James D; Schill, Donald P; De La Cruz, Mary Pauline; Zhang, Lin; Zhang, Junfeng

2010-09-01

224

Changes in concentrations of a TCE plume in near- stream zones of a DNAPL contaminated area adjacent to a stream  

NASA Astrophysics Data System (ADS)

A field investigation of a trichloroethylene (TCE) groundwater plume originating at an industrial complex and its discharges to a stream nearby showed that apparent plume attenuation occurred in the near-stream zone of a DNAPL contaminated area adjacent to a stream prior to discharging to the stream. The concentrations of TCE and cis-1,2-dichloroethene (cis-DCE) in groundwater, hyporheic water, stream water and streambed, and hydrogeology were characterized using mini-piezometers, monitoring wells, Ground Penetrating Radar (GPR) surveys, and soil coring. In the near stream zones temporal and spatial TCE plume concentration changes and mass fluxes were investigated along the flowpath of groundwater discharging to the stream. It is evident that observed concentrations of contaminants (TCE and cis-DCE) were reduced in the near-stream zone, resulting that TCE and cis-DCE were not detected in the streambed and stream water. Ground GPR surveys done in the near stream zone found that wire and water treatment pipe conduits were buried under the ground next to the stream, which could lead groundwater flow field distortion in this zone. At streambed, the GPR survey and soil coring indicated the presence of low permeable zones consisting of rotten material deposits at the top of 0.3 m ~ 0.8 m underlain by silty sands. These hydrogeological features can also attribute to no detection of contaminants in the streambed and stream water because low permeable zone is an obstacle to effective interactions between groundwater and stream water. More investigations will be carried out for comprehensive understanding of hydrological and biogeochemical processes associated with TCE plume attenuation in near stream zones and streambed in the site.

Lee, S.; Hyun, Y.; Lee, K.

2012-12-01

225

Use of gene probes to assess the impact and effectiveness of aerobic In situ bioremediation of TCE.  

SciTech Connect

Gene probe hybridization was used to determine distribution and expression of co-metabolic genes at a contaminated site as it underwent in situ methanotrophic bioremediation of trichloroethylene (TCE). The bioremediation strategies tested consisted of a series of air, air:methane, and air:methane:nutrient pulses using a horizontal injection well. Sediment core samples (n=367) taken from 0 (surface)-43m depth were probed for genes coding for soluble methane monooxygenase (sMMO) and toluene dioxygenase (TOD), which are known to cometabolize TCE. The same samples were also probed for genes coding for methanol dehydrogenase (MDH) to access changes in methylotrophic bacterial populations. Hybridization results showed that the frequency of detection of sMMO genes were stimulated approximately 250% following 1% methane:air (v/v) injection. Subsequent 4% methane:air (v/v) injection resulted in an 85% decline probably due to nutrient limitations, since subsequent addition of nutrients (gaseous nitrogen and phosphorus) caused an increase in the frequency of detection of sMMO genes. Detection of TOD genes declined during the process becoming non-detectable by the final treatment. These patterns indicate methanotrophs displaced heterotrophs containing TOD genes. Active transcription of sMMO and TOD was evidenced by hybridization to mRNA. These analyses combined with studies showing the concomitant decline in TCE concentrations, increases in methanotroph viable counts, increased mineralization rates of TCE, and increases in chloride inventories provide multiple lines of evidence that TCE remediation was caused specifically by methanotrophs. This work suggests that sMMO genes are responsible for most, if not all, of the biodegradation of TCE observed. This study demonstrated that the use of nucleic acid analytical methods provided a gene specific assessment of the effects of in situ treatment technologies.

Hazen, Terry C.; Chakraborty, Romy; Fleming, James M.; Gregory, Ingrid R.; Bowman, John P.; Jimenez, Luis; Zhang, Dai; Pfiffner, Susan M.; Brockman, Fred J.; Sayler, Gary S.

2009-03-01

226

The in-situ decontamination of sand and gravel aquifers by chemically enhanced solubilization of multiple-compound DNAPLs with surfactant solutions: Phase 1 -- Laboratory and pilot field-scale testing and Phase 2 -- Solubilization test and partitioning and interwell tracer tests. Final report  

SciTech Connect

Laboratory, numerical simulation, and field studies have been conducted to assess the potential use of micellar-surfactant solutions to solubilize chlorinated solvents contaminating sand and gravel aquifers. Ninety-nine surfactants were screened for their ability to solubilize trichloroethene (TCE), perchloroethylene (PCE), and carbon tetrachloride (CTET). The field test was conducted in the alluvial aquifer which is located 20 to 30 meters beneath a vapor degreasing operation at Paducah Gaseous Diffusion Plant. This aquifer has become contaminated with TCE due to leakage of perhaps 40,000 liters of TCE, which has generated a plume of dissolved TCE extending throughout an area of approximately 3 km{sup 2} in the aquifer. Most of the TCE is believed to be present in the overlying lacustrine deposits and in the aquifer itself as a dense, non-aqueous phase liquid, or DNAPL. The objective of the field test was to assess the efficacy of the surfactant for in situ TCE solubilization. Although the test demonstrated that sorbitan monooleate was unsuitable as a solubilizer in this aquifer, the single-well test was demonstrated to be a viable method for the in situ testing of surfactants or cosolvents prior to proceeding to full-scale remediation.

NONE

1997-10-24

227

Transformation capacities of chlorinated organics by mixed cultures enriched on methane, propane, toluene, or phenol  

SciTech Connect

The degradation of trichloroethylene (TCE), chloroform (CF), and 1,2-dichloroethane (1,2-DCA) by four aerobic mixed cultures (methane, propane, toluene, and phenol oxidizers) growth under similar chemostat conditions was measured. Methane and propane oxidizers were capable of degrading both saturated and unsaturated chlorinated organics (TCE, CF, and 1,2-DCA). Toluene and phenol oxidizers degraded TCE but were not able to degrade CF, 1,2-DCA, or other saturated organics. None of the cultures tested were able to degrade perchloroethylene (PCE) or carbon tetrachloride (CCl[sub 4]). For the four cultures tested, degradation of each of the chlorinated organics resulted in cell inactivation due to product toxicity. In all cases, the toxic products were rapidly depleted, leaving no toxic residues in solution. Among the four tested cultures, the resting cells of methane oxidizers exhibited the highest transformation capacities (T[sub c]) for TCE, CF, and 1,2-DCA. The T[sub c] for each chlorinated organic was observed to be inversely proportional to the chlorine carbon ratio (Cl/C). The addition of low concentrations of growth substrate or some catabolic intermediates enhanced TCE transformation capacities and degradation rates, presumably due to the regeneration of reducing energy (NADH); however, addition of higher concentrations of most amendments reduced TCE transformation capacities and degradation rates. Reducing energy limitations and amendment toxicity may significantly affect T[sub c] measurements, causing a masking of the toxicity associated with chlorinated organic degradation.

Chang, H.L.; Alvarez-Cohen, L. (Univ. of California, Berkeley, CA (United States). Dept. of Civil Engineering)

1995-03-05

228

Methods for environmental monitoring of DOE waste disposal and storage sites. Semiannual progress report, April 1, 1988--September 30, 1988.  

National Technical Information Service (NTIS)

Perchloroethylene (PCE) is a persistent environmental contaminant whose chemical stability and hydrophobicity have made it difficult to remove from contaminated groundwater. PCE is also toxic and has been implicated as a carcinogen. This study was aimed a...

C. T. Hadden S. B. Benson T. R. Osborne N. W. Revis

1988-01-01

229

Acute Exposure to Perchlorethylene alters Rat Visual Evoked Potentials in Relation to Brain Concentration  

EPA Science Inventory

These experiments sought to establish a dose-effect relationship between the concentration of perchloroethylene (PCE) in brain tissue and concurrent changes in visual function. A physiologically-based pharmacokinetic (PBPK) model was implemented to predict concentrations of PCE ...

230

DCA Dosimetry: Interpreting DCA-Induced Liver Cancer Dose Response and the Potential for DCA to Contribute to TCE-Induced Liver Cancer.  

National Technical Information Service (NTIS)

The contribution of TCE-derived DCA to the induction of hepatocellular carcinoma in the mouse liver bioassay has been a pivotal issue in assessing the risk associated with oral exposure to TCE. The goal of this study was to investigate the biological plau...

M. E. Andersen H. A. Barton R. Bull I. Schultz

1998-01-01

231

Application of fluorescent antibody and enzyme-linked immunosorbent assays for TCE and PAH degrading bacteria  

SciTech Connect

Historically, methods used to identify methanotrophic and polyaromatic hydrocarbon-degrading (PAH) bacteria in environmental samples have been inadequate because isolation and identification procedures are time-consuming and often fail to separate specific bacteria from other environmental microorganisms. Methanotrophic bacteria have been isolated and characterized from TCE-contaminated soils (Bowman et al. 1993; Fliermans et al., 1988). Fliermans et al., (1988) and others demonstrated that cultures enriched with methane and propane could cometabolically degrade a wide variety of chlorinated aliphatic hydrocarbons including ethylene; 1,2-cisdichloroethylene (c-DCE); 1,2-trans-dichloroethylene (t-DCE); vinyl chloride (VC); toluene; phenol and cresol. Characterization of select microorganisms in the natural setting is important for the evaluation of bioremediation potential and its effectiveness. This realization has necessitated techniques that are selective, sensitive and easily applicable to soils, sediments, and groundwater (Fliermans, et al., 1994). Additionally these techniques can identify and quantify microbial types in situ in real time

Brigmon, R.L.; Franck, M.; Brey, J.; Scott, D.; Lanclos, K.; Fliermans, C.

1996-07-01

232

Abiotic Removal of TCE and cis-DCE by Magnetite under Aerobic Conditions in Ground Water (Maryland)  

EPA Science Inventory

The former Twin Cities Army Ammunition Plant (TCAAP) is located just north of St. Paul, Minnesota. Disposal of chlorinated solvents at the Building102 site on the TCAAP contaminated groundwater in the shallow, unconsolidated sand aquifer with TCE and cis-DCE. Concentrations of ...

233

Abiotic and Biotic Transformation of TCE under Sulfate Reducing Conditions: the Role of Spatial Heterogeneity (Monterey, CA)  

EPA Science Inventory

At a number of sites in the USA, passive reactive barriers built with shredded plant mulch have been constructed to treat ground water contaminated with TCE. These barriers are called biowalls because anaerobic biodegradation of the plant mulch is expected to provide substrates ...

234

Efficient Bayesian updating with PCE-based particle filters based on polynomial chaos expansion and CO2 storage  

NASA Astrophysics Data System (ADS)

Underground flow systems, such as oil or gas reservoirs and CO2 storage sites, are an important and challenging class of complex dynamic systems. Lacking information about distributed systems properties (such as porosity, permeability,...) leads to model uncertainties up to a level where quantification of uncertainties may become the dominant question in application tasks. History matching to past production data becomes an extremely important issue in order to improve the confidence of prediction. The accuracy of history matching depends on the quality of the established physical model (including, e.g. seismic, geological and hydrodynamic characteristics, fluid properties etc). The history matching procedure itself is very time consuming from the computational point of view. Even one single forward deterministic simulation may require parallel high-performance computing. This fact makes a brute-force non-linear optimization approach not feasible, especially for large-scale simulations. We present a novel framework for history matching which takes into consideration the nonlinearity of the model and of inversion, and provides a cheap but highly accurate tool for reducing prediction uncertainty. We propose an advanced framework for history matching based on the polynomial chaos expansion (PCE). Our framework reduces complex reservoir models and consists of two main steps. In step one, the original model is projected onto a so-called integrative response surface via very recent PCE technique. This projection is totally non-intrusive (following a probabilistic collocation method) and optimally constructed for available reservoir data at the prior stage of Bayesian updating. The integrative response surface keeps the nonlinearity of the initial model at high order and incorporates all suitable parameters, such as uncertain parameters (porosity, permeability etc.) and design or control variables (injection rate, depth etc.). Technically, the computational costs for constructing the response surface depend on the number of parameters and the expansion degree. Step two consists of Bayesian updating in order to match the reduced model to available measurements of state variables or other past or real-time observations of system behavior (e.g. past production data or pressure at monitoring wells during a certain time period). In step 2 we apply particle filtering on the integrative response surface constructed at step one. Particle filtering is a strong technique for Bayesian updating which takes into consideration the nonlinearity of inverse problem in history matching more accurately than Ensemble Kalman filter do. Thanks to the computational efficiency of PCE and integrative response surface, Bayesian updating for history matching becomes an interactive task and can incorporate real time measurements.

Oladyshkin, S.; Class, H.; Helmig, R.; Nowak, W.

2011-12-01

235

Electro-enhanced Permeable Reactive Barrier : Optimal Design of PRB System With External Current for Effective TCE Removal From Groundwater  

NASA Astrophysics Data System (ADS)

The objective of this study was to design an optimal electro-enhanced permeable reactive barrier (E2PRB) system for remediation of trichloroethylene (TCE)-contaminated water using zero valent iron (ZVI) and direct current (DC). A series of column experiments were conducted to evaluate the location of Fe0 permeable reactive barrier (PRB) and the effects of electrode arrangement in the column on the TCE removal efficiency and iron corrosion processes. In twelve different combinations of ZVI and/or DC application in the test columns, the rate of reductive dechlorination of TCE was improved with simultaneous application of both ZVI and DC compared to that used ZVI only to evaluate the synergistic effect (SE). The most effective arrangement of electrode and ZVI for TCE removal from simulated groundwater was a column set with ZVI and cathode installed at the down gradient (outlet side). Based on the electrochemical study in the E2PRB system, application of direct current provided external electrons to the system so that the system did not depend entirely on the oxidation of the medium for the reductive dechlorination of TCE. The enhanced dechlorination rate of TCE in ZVI-DC systems is considered to attributed to more generation and fast formation kinetic of electron by following reactions: (1) direct supply of electrons from external DC source (2) the electrolysis of water generating additional electrons at the vicinity of the anode (3) the electro-reduction of the compound by released electrons on the ZVI surfaces by oxidation (4) released electron through oxidation of dissolved ferrous iron, and (5) oxidation of atomic hydrogen at the cathode. The competition between five different electron sources generated from five sources evidently influenced on the TCE removal efficiency, valid lifetime of E2PRB system, and reduction of energy expenditure in both of electrochemical and electrokinetic aspects. The results from a series of experiments with twelve columns showed a trend that removal efficiency was more related to the electrode arrangement, but longevity of ZVI PRB and reduction of energy expenditure to location of ZVI installation.

Moon, J.; Moon, H.; Roh, Y.; Kim, H.; Song, Y.

2002-12-01

236

Development of an updated PBPK model for trichloroethylene and metabolites in mice, and its application to discern the role of oxidative metabolism in TCE-induced hepatomegaly  

SciTech Connect

Trichloroethylene (TCE) is a lipophilic solvent rapidly absorbed and metabolized via oxidation and conjugation to a variety of metabolites that cause toxicity to several internal targets. Increases in liver weight (hepatomegaly) have been reported to occur quickly in rodents after TCE exposure, with liver tumor induction reported in mice after long-term exposure. An integrated dataset for gavage and inhalation TCE exposure and oral data for exposure to two of its oxidative metabolites (TCA and DCA) was used, in combination with an updated and more accurate physiologically-based pharmacokinetic (PBPK) model, to examine the question as to whether the presence of TCA in the liver is responsible for TCE-induced hepatomegaly in mice. The updated PBPK model was used to help discern the quantitative contribution of metabolites to this effect. The update of the model was based on a detailed evaluation of predictions from previously published models and additional preliminary analyses based on gas uptake inhalation data in mice. The parameters of the updated model were calibrated using Bayesian methods with an expanded pharmacokinetic database consisting of oral, inhalation, and iv studies of TCE administration as well as studies of TCE metabolites in mice. The dose-response relationships for hepatomegaly derived from the multi-study database showed that the proportionality of dose to response for TCE- and DCA-induced hepatomegaly is not observed for administered doses of TCA in the studied range. The updated PBPK model was used to make a quantitative comparison of internal dose of metabolized and administered TCA. While the internal dose of TCA predicted by modeling of TCE exposure (i.e., mg TCA/kg-d) showed a linear relationship with hepatomegaly, the slope of the relationship was much greater than that for directly administered TCA. Thus, the degree of hepatomegaly induced per unit of TCA produced through TCE oxidation is greater than that expected per unit of TCA administered directly, which is inconsistent with the hypothesis that TCA alone accounts for TCE-induced hepatomegaly. In addition, TCE-induced hepatomegaly showed a much more consistent relationship with PBPK model predictions of total oxidative metabolism than with predictions of TCE area-under-the-curve in blood, consistent with toxicity being induced by oxidative metabolites rather than the parent compound. Therefore, these results strongly suggest that oxidative metabolites in addition to TCA are necessary contributors to TCE-induced liver weight changes in mice.

Evans, M.V. [National Center for Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Washington DC, 20460 (United States)], E-mail: evans.marina@epa.gov; Chiu, W.A. [National Center for Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Washington DC, 20460 (United States); Okino, M.S. [National Exposure Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Las Vegas, NV 89193 (United States); Caldwell, J.C. [National Center for Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Washington DC, 20460 (United States)

2009-05-01

237

Translating the IHE Teaching File and Clinical Trial Export (TCE) Profile Document Templates into Functional DICOM Structured Report Objects  

Microsoft Academic Search

The Integrating the Healthcare Enterprise (IHE) Teaching File and Clinical Trial Export (TCE) integration profile describes\\u000a a standard workflow for exporting key images from an image manager\\/archive to a teaching file, clinical trial, or electronic\\u000a publication application. Two specific digital imaging and communication in medicine (DICOM) structured reports (SR) reference\\u000a the key images and contain associated case information. This paper

Aaron W. C. Kamauu; Scott L. Duvall; Andrew P. Liimatta; Richard H. Wiggins III; David E. Avrin

2008-01-01

238

Structural effects on the electronic properties of (BEDT-TTF) 2BF 4TCE 0.5  

Microsoft Academic Search

(BEDT-TTF)2BF4X0.5 (X=1,1,2-trichloroethane(TCE)) is a two-dimensional metal, whose low temperature behavior is strongly modified depending on cooling rates. We investigate the electronic properties of this complex and its isostructural systems with X=dichloroethane (DCE) and dibromoethane (DBE) in relation to the structural degree of freedom in the ethylene groups of BEDT-TTF.

Toshiaki Enoki; Isao Ichikawa; Akira Miyazaki; Gunzi Saito

1997-01-01

239

Thermally Activated Persulfate Oxidation of Trichloroethylene (TCE) and 1,1,1Trichloroethane (TCA) in Aqueous Systems and Soil Slurries  

Microsoft Academic Search

Under thermally activated conditions (i.e., temperature of 40?99°C), there is considerable evidence that the persulfate anion () can be converted to a powerful oxidant known as the sulfate free radical (), which could be used in situ to destroy groundwater contaminants. In this laboratory study only limited trichloroethylene (TCE) degradation and no 1,1,1-trichloroethane (TCA) degradation was observed at 20°C. However,

Chen Ju Liang; Clifford J. Bruell; Michael C. Marley; Kenneth L. Sperry

2003-01-01

240

Microbially enhanced dissolution and reductive dechlorination of PCE by a mixed culture: Model validation and sensitivity analysis  

NASA Astrophysics Data System (ADS)

Reductive dechlorination catalyzed by organohalide-respiring bacteria is often considered for remediation of non-aqueous phase liquid (NAPL) source zones due to cost savings, ease of implementation, regulatory acceptance, and sustainability. Despite knowledge of the key dechlorinators, an understanding of the processes and factors that control NAPL dissolution rates and detoxification (i.e., ethene formation) is lacking. A recent column study demonstrated a 5-fold cumulative enhancement in tetrachloroethene (PCE) dissolution and ethene formation (Amos et al., 2009). Spatial and temporal monitoring of key geochemical and microbial (i.e., Geobacter lovleyi and Dehalococcoides mccartyi strains) parameters in the column generated a data set used herein as the basis for refinement and testing of a multiphase, compositional transport model. The refined model is capable of simulating the reactive transport of multiple chemical constituents produced and consumed by organohalide-respiring bacteria and accounts for substrate limitations and competitive inhibition. Parameter estimation techniques were used to optimize the values of sensitive microbial kinetic parameters, including maximum utilization rates, biomass yield coefficients, and endogenous decay rates. Comparison and calibration of model simulations with the experimental data demonstrate that the model is able to accurately reproduce measured effluent concentrations, while delineating trends in dechlorinator growth and reductive dechlorination kinetics along the column. Sensitivity analyses performed on the optimized model parameters indicate that the rates of PCE and cis-1,2-dichloroethene (cis-DCE) transformation and Dehalococcoides growth govern bioenhanced dissolution, as long as electron donor (i.e., hydrogen flux) is not limiting. Dissolution enhancements were shown to be independent of cis-DCE accumulation; however, accumulation of cis-DCE, as well as column length and flow rate (i.e., column residence time), strongly influenced the extent of reductive dechlorination. When cis-DCE inhibition was neglected, the model over-predicted ethene production ten-fold, while reductions in residence time (i.e., a two-fold decrease in column length or two-fold increase in flow rate) resulted in a more than 70% decline in ethene production. These results suggest that spatial and temporal variations in microbial community composition and activity must be understood to model, predict, and manage bioenhanced NAPL dissolution.

Chen, Mingjie; Abriola, Linda M.; Amos, Benjamin K.; Suchomel, Eric J.; Pennell, Kurt D.; Löffler, Frank E.; Christ, John A.

2013-08-01

241

Balance measured by head (and trunk) tracking and a force platform in chemically (PCB and TCE) exposed and referent subjects.  

PubMed Central

To determine comparability of methods, postural sway was measured simultaneously with a force platform and a device that registers head (and trunk) movements (head tracking). The effects of age, sex, height, weight, shoe area, and grip strength on both measurements were examined in 162 subjects. To determine whether either method had advantages in detecting abnormal balance 46 reference subjects were compared with 116 people randomly selected from 500 residents whose well water was contaminated with polychlorinated biphenyls (PCBs) and trichloroethylene (TCE) from a metal casting plant. Speed, mean radius, and distance of sway were equally reproducible with both methods. Correlation coefficients were 0.672 with the eyes closed and 0.588 with the eyes open. The balance of those exposed to PCBs and TCE was significantly worse than that of unexposed subjects by both head tracking (1.50 + 71 cm/s v 1.27 + 0.36 cm/s; p < 0.034) and the force platform (4.93 + 1.56 N (kg force) v 4.29 + 1.14 N; p < 0.013) with the eyes closed and differences were also significant with the eyes open. Head tracking and the force platform produced equivalent results. Measurement by head tracking is recommended for field studies because the device is more portable and is less influenced by weight and height. Both methods showed impaired balance associated with years of exposure to PCBs and TCE.

Kilburn, K H; Warshaw, R H; Hanscom, B

1994-01-01

242

Development and characterization of DehaloR^2, a novel anaerobic microbial consortium performing rapid dechlorination of TCE to ethene.  

PubMed

A novel anaerobic consortium, named DehaloR^2, that performs rapid and complete reductive dechlorination of trichloroethene (TCE) to ethene is described. DehaloR^2 was developed from estuarine sediment from the Back River of the Chesapeake Bay and has been stably maintained in the laboratory for over 2 years. Initial sediment microcosms showed incomplete reduction of TCE to DCE with a ratio of trans- to cis- isomers of 1.67. However, complete reduction to ethene was achieved within 10 days after transfer of the consortium to sediment-free media and was accompanied by a shift to cis-DCE as the prevailing intermediate metabolite. The microbial community shifted from dominance of the Proteobacterial phylum in the sediment to Firmicutes and Chloroflexi in DehaloR^2, containing the genera Acetobacterium, Clostridium, and the dechlorinators Dehalococcoides. Also present were Spirochaetes, possible acetogens, and Geobacter which encompass previously described dechlorinators. Rates of TCE to ethene reductive dechlorination reached 2.83 mM Cl- d(-1) in batch bottles with a Dehalococcoides sp. density of 1.54E+11 gene copies per liter, comparing favorably to other enrichment cultures described in the literature and identifying DehaloR^2 as a promising consortium for use in bioremediation of chlorinated ethene-impacted environments. PMID:21667274

Ziv-El, Michal; Delgado, Anca G; Yao, Ying; Kang, Dae-Wook; Nelson, Katherine G; Halden, Rolf U; Krajmalnik-Brown, Rosa

2011-12-01

243

Structural Magnetic Resonance Imaging in an adult cohort following prenatal and early postnatal exposure to tetrachloroethylene (PCE)-contaminated drinking water.  

PubMed

This population-based retrospective cohort study examined Structural Magnetic Resonance Imaging (MRI) of the brain in relation to prenatal and early postnatal exposure to tetrachloroethylene (PCE)-contaminated drinking water on Cape Cod, Massachusetts. Subjects were identified through birth records from 1969 through 1983. Exposure was modeled using pipe network information from town water departments, a PCE leaching and transport algorithm, EPANet water flow modeling software, and Geographic Information System (GIS) methodology. Brain imaging was performed on 26 exposed and 16 unexposed subjects. Scans were acquired on a Philips 3T whole body scanner using the ADNI T1-weighted MP-RAGE scan. The scans were processed by FreeSurfer version 4.3.1 software to obtain measurements of specific brain regions. There were no statistically significant differences between exposed and unexposed subjects on the measures of white matter hypointensities (?: 127.5mm(3), 95% CI: -259.1, 1514.0), white matter volumes (e.g. total cerebral white matter: ?: 21230.0mm(3), 95% CI: -4512.6, 46971.7) or gray matter volumes (e.g. total cerebral gray matter: ?: 11976.0mm(3), 95% CI: -13657.2, 37609.3). The results of this study suggest that exposure to PCE during gestation and early childhood, at the levels observed in this population, is not associated with alterations in the brain structures studied. PMID:23571160

Janulewicz, Patricia A; Killiany, Ronald J; White, Roberta F; Martin, Brett M; Winter, Michael R; Weinberg, Janice M; Aschengrau, Ann

2013-01-01

244

Structural Magnetic Resonance Imaging in an Adult Cohort Following Prenatal and Early Postnatal Exposure to Tetrachloroethylene (PCE)-contaminated Drinking Water  

PubMed Central

This population-based retrospective cohort study examined Structural Magnetic Resonance Imaging (MRI) of the brain in relation to prenatal and early postnatal exposure to tetrachloroethylene (PCE)-contaminated drinking water on Cape Cod, Massachusetts. Subjects were identified through birth records from 1969 through 1983. Exposure was modeled using pipe network information from town water departments, a PCE leaching and transport algorithm, EPANet water flow modeling software, and Geographic Information System (GIS) methodology. Brain imaging was performed on 26 exposed and 16 unexposed subjects. Scans were acquired on a Philips 3T whole body scanner using the ADNI T1-weighted MP-RAGE scan. The scans were processed by FreeSurfer version 4.3.1 software to obtain measurements of specific brain regions. There were no statistically significant differences between exposed and unexposed subjects on measures of white matter hypointensities (?: 127.5 mm3, 95% CI: ?259.1, 1514.0), white matter volumes (e.g. total cerebral white matter: ?: 21230.0 mm3, 95% CI: ?4512.6, 46971.7) or gray matter volumes (e.g. total cerebral gray matter: ?: 11976.0 mm3, 95% CI: ?13657.2, 37609.3). The results of this study suggest that exposure to PCE during gestation and early childhood, at the levels observed in this population, is not associated with alterations in the brain structures studied.

Janulewicz, Patricia A; Killiany, Ronald J; White, Roberta F; Martin, Brett M; Winter, Michael R; Weinberg, Janice M; Aschengrau, Ann

2013-01-01

245

Improved Dechlorinating Performance of Upflow Anaerobic Sludge Blanket Reactors by Incorporation of Dehalospirillum multivorans into Granular Sludge  

PubMed Central

Dechlorination of tetrachloroethene, also known as perchloroethylene (PCE), was investigated in an upflow anaerobic sludge blanket (UASB) reactor after incorporation of the strictly anaerobic, reductively dechlorinating bacterium Dehalospirillum multivorans into granular sludge. This reactor was compared to the reference 1 (R1) reactor, where the granules were autoclaved to remove all dechlorinating abilities before inoculation, and to the reference 2 (R2) reactor, containing only living granular sludge. All three reactors were fed mineral medium containing 3 to 57 ?M PCE, 2 mM formate, and 0.5 mM acetate and were operated under sterile conditions. In the test reactor, an average of 93% (mole/mole) of the effluent chloroethenes was dichloroethene (DCE), compared to 99% (mole/mole) in the R1 reactor. The R2 reactor, with no inoculation, produced only trichloroethene (TCE), averaging 43% (mole/mole) of the effluent chloroethenes. No dechlorination of PCE was observed in an abiotic control consisting of sterile granules without inoculum. During continuous operation with stepwise-reduced hydraulic retention times (HRTs), both the test reactor and the R1 reactor showed conversion of PCE to DCE, even at HRTs much lower than the reciprocal maximum specific growth rate of D. multivorans, indicating that this bacterium was immobilized in the living and autoclaved granular sludge. In contrast, the R2 reactor, with no inoculation of D. multivorans, only converted PCE to TCE under the same conditions. Immobilization could be confirmed by using fluorescein-labeled antibody probes raised against D. multivorans. In granules obtained from the R1 reactor, D. multivorans grew mainly in microcolonies located in the centers of the granules, while in the test reactor, the bacterium mainly covered the surfaces of granules.

Horber, Christine; Christiansen, Nina; Arvin, Erik; Ahring, Birgitte K.

1998-01-01

246

Assessment of potential positive effects of nZVI surface modification and concentration levels on TCE dechlorination in the presence of competing strong oxidants, using an experimental design.  

PubMed

Nanoscale zero-valent iron (nZVI) particles are efficient for the remediation of aquifers polluted by trichloroethylene (TCE). But for on-site applications, their reactivity can be affected by the presence of common inorganic co-pollutants, which are equally reduced by nZVI particles. The aim of this study was to assess the potential positive effects of nZVI surface modification and concentration level on TCE removal in the concomitant presence of two strong oxidants, i.e., Cr(VI) and NO3(-). A design of experiments, testing four factors (i.e. nZVI concentration, nZVI surface modification, Cr(VI) concentration and NO3(-) concentration), was used to select the best trials for the identification of the main effects of the factors and of the factors interactions. The effects of these factors were studied by measuring the following responses: TCE removal rates at different times, degradation kinetic rates, and the transformation products formed. As expected, TCE degradation was delayed or inhibited in most of the experiments, due to the presence of inorganics. The negative effects of co-pollutants can be palliated by combining surface modification with a slight increase in nZVI concentration. Encouragingly, complete TCE removal was achieved for some given experimental conditions. Noteworthily, nZVI surface modification was found to promote the efficient degradation of TCE. When degradation occurred, TCE was mainly transformed into innocuous non-chlorinated transformation products, while hazardous chlorinated transformation products accounted for a small percentage of the mass-balance. PMID:24607397

Kaifas, Delphine; Malleret, Laure; Kumar, Naresh; Fétimi, Wafa; Claeys-Bruno, Magalie; Sergent, Michelle; Doumenq, Pierre

2014-05-15

247

Global gene expression of Dehalococcoides within a robust dynamic TCE-dechlorinating community under conditions of periodic substrate supply.  

PubMed

A microarray targeting four sequenced strains in the Dehalococcoides (Dhc) genus was used to analyze gene expression in a robust long-term trichloroethene (TCE)-degrading microbial community (designated ANAS) during feeding cycles that involve conditions of periodic substrate supply. The Dhc transcriptome was examined at three time-points throughout a batch feeding cycle: T1 (27 h) when TCE, dichloroethene (DCE), and vinyl chloride (VC) were present; T2 (54 h) when only VC remained; and T3 (13 days) when Dhc had been starved of substrate for 9 days. Ninety percent of the Dhc open reading frames (ORFs) that were detected in the ANAS DNA were found to be expressed as RNA sometime during the time course, demonstrating extraordinary utilization of the streamlined genome. Ninety-seven percent of these transcripts were differentially expressed during the time course indicating efficiency of transcription through regulation in Dhc. Most Dhc genes were significantly down-regulated at T3 , responding to a lack of substrate as would be expected. The tceA and vcrA genes, which code for proteins with known chlorinated ethene reduction functions, were highly expressed at both T1 and T2 , whereas two other putative reductive dehalogenase genes (DET0173 and DET1545) were most highly expressed at T2 , likely in response to the presence of VC. Hydrogenases were most highly expressed at T1 , reflecting their important role in accumulating electrons used to initiate reductive dechlorination and other biosynthesis pathways. Cobalamin transport genes were preferentially expressed at T2 , reflecting an increase in corrinoid transport as chloroethenes were degraded and a decrease in activity of the transport system after dehalogenation was complete. This is the first application of a microarray targeting a known genus, including both core genomes and identified strain-specific genes, to improve our understanding of transcriptional dynamics within an undefined microbial community. PMID:23280440

West, Kimberlee A; Lee, Patrick K H; Johnson, David R; Zinder, Stephen H; Alvarez-Cohen, Lisa

2013-05-01

248

Fingerprinting TCE Sources and Natural Attenuation Capacity of a Sedimentary Bedrock Aquifer using Compound Specific Isotope Analysis - A Case Study in the City of Guelph, Ontario.  

NASA Astrophysics Data System (ADS)

Chlorinated volatile organic compounds were detected in an industrial facility (site) in the upper part of the underlying dolomite bedrock aquifer. The primary chlorinated solvent detected at the site is trichloroethene (TCE), and associated daughter products, such as cis-1,2- dichloroethene (cis-1,2-DCE) and vinyl chloride (VC), are also present. Several conventional monitoring wells installed at the site were recently sampled for VOCs analysis, inorganic sensitive REDOX parameters and Compound Specific Isotope Analyses (CSIA) of 13C and 37Cl in order to evaluate the natural attenuation capacity of the local upper bedrock aquifer. A municipal well was also included in this study. The municipal well is located approximately 500 meters southwest from the investigated site and consists of anuncased bedrock well completed to 102 meters below ground surface (mbgs). Chlorinated volatile organic compounds were detected in this well during the evaluation of municipal groundwater resources performed in the early 1990s by the City of Guelph. Neither the City nor the Ministry of the Environment of the Province of Ontario (MOE) have been able to satisfactorily determine the origin of these compounds. Groundwater for VOCs analysis and CSIA were therefore collected in the municipal well in order to evaluate the relationship between the TCE detected in the municipal well and the TCE plume detected in the nearby industrial facility. The inorganic data indicated that the local upper aquifer is under sulfate-reducing conditions in some areas where typical VOC's daughter products and highly enriched ?13C and ? 37Cl values of TCE and cis-1,2-DCE were observed. These findings indicated that microbial reductive dechlorination of TCE is occurring in some areas of the local aquifer. The ? 13C values of TCE obtained in groundwater from the conventional wells were approximately 10 ‰ more depleted than ? 13C values obtained for the deep municipal production well. These data indicate that there is no relationship between the TCE plume at the site and the TCE present in the water of the municipal well, suggesting that other potential regional TCE sources are likely to be present in the area.

Lima, P. L.; Aravena, R.; Parker, B. L.; Cherry, J. A.

2009-05-01

249

In situ redox manipulation of subsurface sediments from Fort Lewis, Washington: Iron reduction and TCE dechlorination mechanisms  

SciTech Connect

Pacific Northwest National Laboratory (PNNL) conducted a bench-scale study to determine how effective chemically treated Ft. Lewis sediments can degrade trichloroethylene (TCE). The objectives of this experimental study were to quantify: (1) sediment reduction and oxidation reactions, (2) TCE degradation reactions, and (3) other significant geochemical changes that occurred. Sediment reduction and oxidation were investigated to determine the mass of reducible iron in the Ft. Lewis sediments and the rate of this reduction and subsequent oxidation at different temperatures. The temperature dependence was needed to be able to predict field-scale reduction in the relatively cold ({approximately}11 C) Ft. Lewis aquifer. Results of these experiments were used in conjunction with other geochemical and hydraulic characterization to design the field-scale injection experiment and predict barrier longevity. For example, the sediment reduction rate controls the amount of time required for the dithionite solution to fully react with sediments. Sediment oxidation experiments were additionally conducted to determine the oxidation rate and provide a separate measure of the mass of reduced iron. Laboratory experiments that were used to meet these objectives included: (1) sediment reduction in batch (static) systems, (2) sediment reduction in 1-D columns, and (3) sediment oxidation in 1-D columns. Multiple reaction modeling was conducted to quantify the reactant masses and reaction rates.

JE Szecsody; JS Fruchter; DS Sklarew; JC Evans

2000-03-21

250

Influence of humidity and of the electric and magnetic microwave radiation fields on the remediation of TCE-contaminated natural sandy soils.  

PubMed

The influence of moisture content (15% w/w) on the remediation (vaporization) of trichloroethylene (TCE) present in natural sands, chosen as a TCE-polluted model system for soils, was investigated with regard to applied microwave power levels, the depth of the sand sample, and the dielectric factors. The heating process occurring in the sand samples arises through the microwave conduction loss heating and dielectric loss heating mechanisms. The characteristic relevance of the electric and magnetic microwave radiation fields to the heating mechanisms was also examined. Heating by the magnetic microwave radiation field was considerable when magnetite was added to the dry and wet sand samples as the microwave absorber. Optimal microwave conditions are reported for a single-mode microwave applicator. Near-quantitative elimination of the TCE contaminant was achieved for sandy soils within a very short time. PMID:21701102

Horikoshi, Satoshi; Muratani, Masaru; Miyabe, Kouta; Ohmura, Keisuke; Hirowatari, Tomoaki; Serpone, Nick; Abe, Masahiko

2011-01-01

251

Occurrence of mental illness following prenatal and early childhood exposure to tetrachloroethylene (PCE)-contaminated drinking water: a retrospective cohort study  

PubMed Central

Background While many studies of adults with solvent exposure have shown increased risks of anxiety and depressive disorders, there is little information on the impact of prenatal and early childhood exposure on the subsequent risk of mental illness. This retrospective cohort study examined whether early life exposure to tetrachloroethylene (PCE)-contaminated drinking water influenced the occurrence of depression, bipolar disorder, post-traumatic stress disorder, and schizophrenia among adults from Cape Cod, Massachusetts. Methods A total of 1,512 subjects born between 1969 and 1983 were studied, including 831 subjects with both prenatal and early childhood PCE exposure and 547 unexposed subjects. Participants completed questionnaires to gather information on mental illnesses, demographic and medical characteristics, other sources of solvent exposure, and residences from birth through 1990. PCE exposure originating from the vinyl-liner of water distribution pipes was assessed using water distribution system modeling software that incorporated a leaching and transport algorithm. Results No meaningful increases in risk ratios (RR) for depression were observed among subjects with prenatal and early childhood exposure (RR: 1.1, 95% CI: 0.9-1.4). However, subjects with prenatal and early childhood exposure had a 1.8-fold increased risk of bipolar disorder (N = 36 exposed cases, 95% CI: 0.9-1.4), a 1.5-fold increased risk post-traumatic stress disorder (N = 47 exposed cases, 95% CI: 0.9-2.5), and a 2.1-fold increased risk of schizophrenia (N = 3 exposed cases, 95% CI: 0.2-20.0). Further increases in the risk ratio were observed for bipolar disorder (N = 18 exposed cases, RR; 2.7, 95% CI: 1.3-5.6) and post-traumatic stress disorder (N = 18 exposed cases, RR: 1.7, 95% CI: 0.9-3.2) among subjects with the highest exposure levels. Conclusions The results of this study provide evidence against an impact of early life exposure to PCE on the risk of depression. In contrast, the results provide support for an impact of early life exposure on the risk of bipolar disorder and post-traumatic stress disorder. The number of schizophrenia cases was too small to draw reliable conclusions. These findings should be confirmed in investigations of other similarly exposed populations.

2012-01-01

252

Biological exposure assessment to tetrachloroethylene for workers in the dry cleaning industry  

Microsoft Academic Search

BACKGROUND: The purpose of this study was to assess the feasibility of conducting biological tetrachloroethylene (perchloroethylene, PCE) exposure assessments of dry cleaning employees in conjunction with evaluation of possible PCE health effects. METHODS: Eighteen women from four dry cleaning facilities in southwestern Ohio were monitored in a pilot study of workers with PCE exposure. Personal breathing zone samples were collected

Lauralynn T McKernan; Avima M Ruder; Martin R Petersen; Misty J Hein; Christy L Forrester; Wayne T Sanderson; David L Ashley; Mary A Butler

2008-01-01

253

Time series geophysical monitoring of permanganate injections and in situ chemical oxidation of PCE, OU1 area, Savage Superfund Site, Milford, NH, USA.  

PubMed

In situ chemical oxidation (ISCO) treatment with sodium permanganate, an electrically conductive oxidant, provides a strong electrical signal for tracking of injectate transport using time series geophysical surveys including direct current (DC) resistivity and electromagnetic (EM) methods. Effective remediation is dependent upon placing the oxidant in close contact with the contaminated aquifer. Therefore, monitoring tools that provide enhanced tracking capability of the injectate offer considerable benefit to guide subsequent ISCO injections. Time-series geophysical surveys were performed at a superfund site in New Hampshire, USA over a one-year period to identify temporal changes in the bulk electrical conductivity of a tetrachloroethylene (PCE; also called tetrachloroethene) contaminated, glacially deposited aquifer due to the injection of sodium permanganate. The ISCO treatment involved a series of pulse injections of sodium permanganate from multiple injection wells within a contained area of the aquifer. After the initial injection, the permanganate was allowed to disperse under ambient groundwater velocities. Time series geophysical surveys identified the downward sinking and pooling of the sodium permanganate atop of the underlying till or bedrock surface caused by density-driven flow, and the limited horizontal spread of the sodium permanganate in the shallow parts of the aquifer during this injection period. When coupled with conventional monitoring, the surveys allowed for an assessment of ISCO treatment effectiveness in targeting the PCE plume and helped target areas for subsequent treatment. PMID:22459605

Harte, Philip T; Smith, Thor E; Williams, John H; Degnan, James R

2012-05-01

254

Time series geophysical monitoring of permanganate injections and in situ chemical oxidation of PCE, OU1 area, Savage Superfund Site, Milford, NH, USA  

NASA Astrophysics Data System (ADS)

In situ chemical oxidation (ISCO) treatment with sodium permanganate, an electrically conductive oxidant, provides a strong electrical signal for tracking of injectate transport using time series geophysical surveys including direct current (DC) resistivity and electromagnetic (EM) methods. Effective remediation is dependent upon placing the oxidant in close contact with the contaminated aquifer. Therefore, monitoring tools that provide enhanced tracking capability of the injectate offer considerable benefit to guide subsequent ISCO injections. Time-series geophysical surveys were performed at a superfund site in New Hampshire, USA over a one-year period to identify temporal changes in the bulk electrical conductivity of a tetrachloroethylene (PCE; also called tetrachloroethene) contaminated, glacially deposited aquifer due to the injection of sodium permanganate. The ISCO treatment involved a series of pulse injections of sodium permanganate from multiple injection wells within a contained area of the aquifer. After the initial injection, the permanganate was allowed to disperse under ambient groundwater velocities. Time series geophysical surveys identified the downward sinking and pooling of the sodium permanganate atop of the underlying till or bedrock surface caused by density-driven flow, and the limited horizontal spread of the sodium permanganate in the shallow parts of the aquifer during this injection period. When coupled with conventional monitoring, the surveys allowed for an assessment of ISCO treatment effectiveness in targeting the PCE plume and helped target areas for subsequent treatment.

Harte, Philip T.; Smith, Thor E.; Williams, John H.; Degnan, James R.

2012-05-01

255

Six-phase soil heating for enhanced removal of contaminants: Volatile organic compounds in non-arid soils integrated demonstration, Savannah River Site  

SciTech Connect

In November 1993, Pacific Northwest Laboratory (PNL) and Savannah River Site (SRS) personnel conducted a demonstration of six-phase soil heating (SPSH) at the Savannah River Site (SRS) in Aiken, South Carolina. The demonstration was part of the Volatile Organic Compounds in Non-Arid Soils Integrated Demonstration being conducted near the M-Area operations at the SRS, along a corridor that once contained a process sewer leading to the M-Area seepage basin. In the early 1980s, this sewer line was discovered to be leaking process wastes into the subsurface and contributing to groundwater contamination in the vicinity of M-Area seepage basin. Although use of the sewer line has been discontinued, the slow release of chlorinated solvents such as trichloroethylene (TCE) and perchloroethylene (PCE) from the heterogeneous vadose zone soil continues to be a source of potential groundwater contamination. A significant portion of the VOCs at the demonstration site are retained in low-permeability clay zones. Previous studies have shown that the rate of conventional SVE remediation of the SRS clays is quite slow. The permeability of the clay is of order 10{sup {minus}12} cm{sup 2}, which makes this a particularly difficult interval to remediate. Thus, the challenge for SPSH is to effectively remediate this clay zone by accelerating the removal of TCE and PCE.

Gauglitz, P.A.; Bergsman, T.M.; Caley, S.M. [and others

1994-10-01

256

Investigation of the potential source area, contamination pathway, and probable release history of chlorinated-solvent-contaminated groundwater at the Capital City Plume Site, Montgomery, Alabama, 2008-2010  

USGS Publications Warehouse

Detection of the organic solvent perchloroethylene (PCE) in a shallow public-supply well in 1991 and exposure of workers in 1993 to solvent vapors during excavation activities to depths near the water table provided evidence that the shallow aquifer beneath the capital city of Montgomery, Alabama, was contaminated. Investigations conducted from 1993 to 1999 by State and Federal agencies confirmed the detection of PCE in the shallow aquifer, as well as the detection of the organic solvent trichloroethylene (TCE) and various inorganic compounds, but the source of the groundwater contamination was not determined. In May 2000 the U.S. Environmental Protection Agency proposed that the site, called the Capital City Plume (CCP) Site, be a candidate for the National Priorities List. Between 2000 and 2007, numerous site-investigation activities also did not determine the source of the groundwater contamination. In 2008, additional assessments were conducted at the CCP Site to investigate the potential source area, contamination pathway, and the probable release history of the chlorinated-solvent-contaminated groundwater. The assessments included the collection of (1) pore water in 2008 from the hyporheic zone of a creek using passive-diffusion bag samplers; (2) tissue samples in 2008 and 2009 from trees growing in areas of downtown Montgomery characterized by groundwater contamination and from trees growing in riparian zones along the Alabama River and Cypress Creek; and (3) groundwater samples in 2009 and 2010. The data collected were used to investigate the potential source area of contaminants detected in groundwater, the pathway of groundwater contamination, and constraints on the probable contaminant-release history. The data collected between 2008 and 2010 indicate that the PCE and TCE contamination of the shallow aquifer beneath the CCP Site most likely resulted from the past use and disposal of industrial wastewater from printing operations containing chlorinated solvents into the sanitary sewer and (or) stormwater systems of Montgomery. Moreover, chlorinated-solvent use and disposal occurred at least between the 1940s and 1970s at several locations occupied by printing operations. The data also indicate that PCE and TCE contamination continues to occur in the shallow subsurface near potential release areas and that PCE and TCE have been transported to the intermediate part of the shallow aquifer.

Landmeyer, James E.; Miller, Scott; Campbell, Bruce G.; Vroblesky, Don A.; Gill, Amy C.; Clark, Athena P.

2011-01-01

257

Design of Zero-Valent Iron Fracture Reactive Barriers for Remediating a TCE Plume in a Chalk Aquifer  

NASA Astrophysics Data System (ADS)

A novel concept, the Fe0 fracture reactive barrier (Fe0 FRB), is proposed to clean up chlorinated solvent pollution of groundwater in a chalk aquifer. A Fe0 FRB is an extended reactive zone where the fractures are partly filled with iron. It can be created by injecting a viscous, biodegradable gel suspended with iron particles into selected fractures via boreholes. To evaluate the feasibility of Fe0 FRB as a remediation strategy, we conducted numerical modelling simulations to assess the treatment performance of a Fe0 FRB in a hypothetical chalk aquifer. The assessment was carried out using a numerical model for flow and solute transport in a discretely-fractured porous medium coupled with an analytical expression representing degradation by iron. The hypothetical chalk aquifer was represented by a 3-D discrete fracture network model which was developed using data from a number of chalk sites. TCE reactive transport in the Fe0 FRB and mass exchange of solute between fractures and the porous matrix were fully accounted for in the model. The model revealed that the success of the remediation technology lies in how to create a highly reactive Fe0 FRB without plugging fractures and reducing flow through it. A parametric study of various design parameters for the Fe0 FRB suggested that a high treatment efficiency was likely to be achieved, by employing highly reactive nanoscale iron or by using a high proportion of microscale iron fill and fracture enlargement. The model study also provided some preliminary conclusions on the optimal design of a Fe0 FRB. A preliminary analysis of the longevity of a Fe0 FRB, which contains a small amount of highly reactive nanoscale iron, showed that its lifetime is between 5 and 50 years dependant on the TCE mass flux through the barrier.

Cai, Z.; Lerner, D. N.; McLaren, R. G.; Wilson, R. D.

2005-12-01

258

Evaluation of the Fourier transform infrared (FTIR) spectrophotometer for analysis of trichloroethylene (TCE) in the presence of freon-113 in carbon disulfide eluates of charcoal air sampling tubes  

SciTech Connect

Results obtained using Fourier transform infrared spectrophotometry (FTIR) for the analysis of samples of carbon disulfide (CS2) eluates containing trichloroethylene (TCE) and freon from charcoal air sampling tubes were evaluated by comparison with results obtained when using gas chromatography (GC). The FTIR yielded accurate results without regard to the presence of freon.

Xiao, H.K.; Levine, S.P.; Kinnes, G.; Almaguer, D. (Univ. of Michigan, Ann Arbor (USA))

1990-07-01

259

Geochemistry of a Tetrachloroethene and Trichloroethene Plume at the Borden Aquifer  

Microsoft Academic Search

Under favourable redox conditions biodegradation is one of the processes that controls PCE and TCE attenuation at the Borden sand aquifer. This paper presents geochemistry data obtained in a study which main aim is to evaluate the fate of a PCE and TCE plume in the Borden forested area. Selected multilevel piezometers for five transects in a Tetrachloroethene (PCE) and

I. Vargas; R. Aravena; B. Parker; L. Wassenaar

2004-01-01

260

The in-situ decontamination of sand and gravel aquifers by chemically enhanced solubilization of multiple-component DNAPLS with surfactant solutions. Topical report  

SciTech Connect

Laboratory, numerical simulation, and field studies have been conducted to assess the potential use of micellar-surfactant solutions to solubilize chlorinated solvents contaminating sand and gravel aquifers. Laboratory studies were conducted at the State University of New York at Buffalo (SUNY) while numerical simulation and field work were undertaken by INTERA Inc. in collaboration with Martin Marietta Energy Systems Inc. at the Paducah Gaseous Diffusion Plant (PGDP) in Kentucky. Ninety-nine surfactants were screened for their ability to solubilize trichloroethene (TCE), perchloroethylene (PCE), and carbon tetrachloride (CTET). Ten of these were capable of solubilizing TCE to concentrations greater than 15,000 mg/L, compared to its aqueous solubility of 1,100 mg/L. Four surfactants were identified as good solubilizers of all three chlorinated solvents. Of these, a secondary alcohol ethoxylate was the first choice for in situ testing because of its excellent solubilizing ability and its low propensity to sorb. However, this surfactant did not meet the Commonwealth of Kentucky`s acceptance criteria. Consequently, it was decided to use a surfactant approved for use by the Food and Drug Administration as a food-grade additive. As a 1% micellar-surfactant solution, this sorbitan monooleate has a solubilization capacity of 16,000 mg TCE/L, but has a higher propensity to sorb to clays than has the alcohol ethoxylate.

NONE

1995-01-01

261

Relative importance of gas-phase diffusive and advective tichloroethene (TCE) fluxes in the unsaturated zone under natural conditions.  

PubMed

It was hypothesized that atmospheric pressure changes can induce gas flow in the unsaturated zone to such an extent that the advective flux of organic vapors in unsaturated-zone soil gas can be significant relative to the gas-phase diffusion flux of these organic vapors. To test this hypothesis, a series of field measurements and computer simulations were conducted to simulate and compare diffusion and advection fluxes at a trichloroethene-contaminated field site at Picatinny Arsenal in north-central New Jersey. Moisture content temperature, and soil-gas pressure were measured at multiple depths (including at land surface) and times for three distinct sampling events in August 1996, October 1996, and August 1998. Gas pressures in the unsaturated zone changed significantly over time and followed changes measured in the atmosphere. Gas permeability of the unsaturated zone was estimated using data from a variety of sources, including laboratory gas permeability measurements made on intact soil cores from the site, a field air pump test, and calibration of a gas-flow model to the transient, one-dimensional gas pressure data. The final gas-flow model reproduced small pressure gradients as observed in the field during the three distinct sampling events. The velocities calculated from the gas-flow model were used in transient, one-dimensional transport simulations to quantify advective and diffusive fluxes of TCE vapor from the subsurface to the atmosphere as a function of time for each sampling event. Effective diffusion coefficients used for these simulations were determined from independent laboratory measurements made on intact soil cores collected from the field site. For two of the three sampling events (August 1996 and August 1998), the TCE gas-phase diffusion flux at land surface was significantly greater than the advection flux over the entire sampling period. For the second sampling event (October 1996), the advection flux was frequently larger than the diffusion flux. When averaged over the second sampling event, the advection and diffusion fluxes were comparable in magnitude. Sensitivity analyses indicate that diffusion fluxes increase significantly with increases in air-filled porosity near land surface, whereas advection fluxes do not. For October 1996, the comparable advection and diffusion fluxes were caused by high moisture content near land surface and a subsequent reduction in the diffusion flux relative to the advection flux. These results indicate that under certain environmental conditions, the organic vapor advection flux from the unsaturated zone to the atmosphere may be equal to or greater than the diffusion flux. PMID:12141498

Choi, Jee-Won; Tillman, Fred D; Smith, James A

2002-07-15

262

Cleaner Technologies Substitutes Assessment: Professional Fabricare Processes.  

National Technical Information Service (NTIS)

Chemical solvents have been used for cleaning clothes since the mid-19th century. Perchloroethylene (PCE) has been the solvent of choice for commercial clothes cleaning applications since the 1960s, although the volume used by drycleaners has declined sig...

1998-01-01

263

MICROSCOPIC OBSERVATION AND QUANTIFICATION OF ENHANCED DNAPL REMOVAL BY COSOLVENT-AIR FLOODING  

EPA Science Inventory

The simultaneous injection of cosolvent and air has been suggested to improve sweep efficiency of cosolvent flooding for dense nonaqueous phase liquid (DNAPL) remediation. Glass micromodel experiments were conducted to investigate the factors that influence perchloroethylene (PCE...

264

Fermi Surface of the Dual-Layered Organic Superconductor ??\\prime2-(BEDT-TTF)2Ag(CF3)4(TCE) with Acentric Charge-Ordered Layers  

NASA Astrophysics Data System (ADS)

The band filling and Fermi surface in the dual-layered organic superconductor ??\\prime2-(BEDT-TTF)2Ag(CF3)4(TCE) with a charge-ordered ?\\prime-layer have been investigated, where BEDT-TTF stands for bis(ethylenedithio)tetrathiafulvalene and TCE stands for 1,1,2-trichloroethane. The de Haas--van Alphen (dHvA) oscillation indicates that the conducting layer is the ?-layer with a half-filled band; this is in agreement with the charge-ordered ?\\prime-layer due to the quarter-filled band. The effective cyclotron mass observed in the dHvA oscillation is larger than the calculated bare cyclotron mass. The BEDT-TTF superconductors including a ?-layer show the following trend: the higher the superconducting transition temperature of the material, the larger the mass enhancement.

Kawamoto, Tadashi; Mori, Takehiko; Terashima, Taichi; Uji, Shinya; Schlueter, John A.

2013-02-01

265

Fingerprinting TCE Sources and Natural Attenuation Capacity of a Sedimentary Bedrock Aquifer using Compound Specific Isotope Analysis - A Case Study in the City of Guelph, Ontario  

Microsoft Academic Search

Chlorinated volatile organic compounds were detected in an industrial facility (site) in the upper part of the underlying dolomite bedrock aquifer. The primary chlorinated solvent detected at the site is trichloroethene (TCE), and associated daughter products, such as cis-1,2- dichloroethene (cis-1,2-DCE) and vinyl chloride (VC), are also present. Several conventional monitoring wells installed at the site were recently sampled for

P. L. Lima; R. Aravena; B. L. Parker; J. A. Cherry

2009-01-01

266

Persulfate oxidation for in situ remediation of TCE. I. Activated by ferrous ion with and without a persulfate–thiosulfate redox couple  

Microsoft Academic Search

The objective of the laboratory study is to examine the conditions under which transition metal ions (e.g., ferrous ion, Fe2+) could activate the persulfate anion (S2O82?) to produce a powerful oxidant known as the sulfate free radical (SO4?) with a standard redox potential of 2.6 V. The SO4? is capable of destroying groundwater contaminants in situ such as trichloroethylene (TCE).

Chenju Liang; Clifford J. Bruell; Michael C. Marley; Kenneth L. Sperry

2004-01-01

267

Tc of 11 K Identified for the Third Polymorph of the (BEDT-TTF)2Ag(CF3)4(TCE) Organic Superconductor  

NASA Astrophysics Data System (ADS)

The crystal structure of the third polymorph of the organic superconductor (BEDT-TTF)2Ag(CF3)4(TCE), where BEDT-TTF is bis(ethylenedithio)tetrathiafulvalene and TCE is 1,1,2-trichloroethane, has been investigated. The crystal consists of alternating stacks of two types of donor sheets, ?- and ?\\prime-types. Although this structure is similar to the previously solved two-layered high-Tc phase of (BEDT-TTF)2Ag(CF3)4(TCE), the axis perpendicular to the conducting layer of the unit cell of the new phase is twice as large as that of the two-layered phase; thus, four layers form the repeating unit. Superconductivity is attributed to the ?-type conducting layer, because the ?\\prime-type conducting layer is in an acentric charge-ordered state. The onset superconducting transition temperatures are approximately 11.0 and 9.5 K for the four-layered and two-layered phases, respectively.

Kawamoto, Tadashi; Mori, Takehiko; Nakao, Akiko; Murakami, Youichi; Schlueter, John A.

2012-02-01

268

Tc of 11K Identified for the Third Polymorph of the (BEDT-TTF)(BEDT-TTF){<_2}Ag(CF{<_3}){<_4}(TCE) Organic Superconductor.  

SciTech Connect

The crystal structure of the third polymorph of the organic superconductor (BEDT-TTF){sub 2}Ag(CF{sub 3}){sub 4}(TCE), where BEDT-TTF is bis(ethylenedithio)tetrathiafulvalene and TCE is 1,1,2-trichloroethane, has been investigated. The crystal consists of alternating stacks of two types of donor sheets, {Kappa}- and {alpha}-types. Although this structure is similar to the previously solved two-layered high-T{sub c} phase of (BEDT-TTF){sub 2}Ag(CF{sub 3}){sub 4}(TCE), the axis perpendicular to the conducting layer of the unit cell of the new phase is twice as large as that of the two-layered phase; thus, four layers form the repeating unit. Superconductivity is attributed to the {Kappa}-type conducting layer, because the {alpha}-type conducting layer is in an acentric charge-ordered state. The onset superconducting transition temperatures are approximately 11.0 and 9.5 K for the four-layered and two-layered phases, respectively.

Kawamoto, T.; Mori, T.; Nakao, A.; Murakami, Y.; Schlueter, J. A. (Materials Science Division); (Tokyo Inst. Tech.); (High Energy Accl. Res. Org.)

2012-01-01

269

Phased implementation of in situ chemical oxidation for a large TCE DNAPL source Area at the Portsmouth gaseous diffusion plant  

SciTech Connect

This paper describes the In Situ Chemical Oxidation (ISCO) remediation being implemented for the the X-701B groundwater plume at the Department of Energy (DOE) Portsmouth Gaseous Diffusion Plant (PORTS). Modified Fenton's reagent is the principal oxidant for the remedy, and Direct Push Technology (DPT) is being used for delivery of the oxidant. Trichloroethene (TCE) is the primary contaminant of concern and is present within the unit as a dense nonaqueous phase liquid (DNAPL). A phased approach is being implemented to optimize the type, location, and mass of the oxidant injections. During Phase I, a unique near-real time monitoring approach was utilized to observe the transient effects of the oxidant injections on the formation. As a result of the positive results from Phase I, Ohio EPA has approved the final work plan for the remedy, and the approach is now being applied to the source area of the plume. The results from Phase I and the layout for the first series of Phase II injections are presented in this paper. Previous testing at the site has shown that the shallow, water-bearing formation is primarily composed of silty gravel and clay, and is both heterogeneous and anisotropic. These factors have significantly compromised earlier attempts to remediate the unit. A patented ISCO process from In-Situ Oxidative Technologies, Inc. (ISOTEC) was selected for the remediation of the plume. Phase I results indicate that oxidant delivery via DPT is feasible for the unit. Contaminant reduction to date has been minimal due to the small quantity of oxidant injected during Phase I. Contaminant rebound in the aqueous phase remains a concern and will be monitored closely during the remedy. (authors)

Cross, P.E.; Thompson, S.L. [CDM, Piketon, OH (United States); Haskins, S. [In Situ Oxidative Technologies, Inc., Greenwood Village, CO (United States)

2007-07-01

270

Efficient degradation of TCE in groundwater using Pd and electro-generated H2 and O2: a shift in pathway from hydrodechlorination to oxidation in the presence of ferrous ions.  

PubMed

Degradation of trichloroethylene (TCE) in simulated groundwater by Pd and electro-generated H(2) and O(2) is investigated in the absence and presence of Fe(II). In the absence of Fe(II), hydrodechlorination dominates TCE degradation, with accumulation of H(2)O(2) up to 17 mg/L. Under weak acidity, low concentrations of oxidizing •OH radicals are detected due to decomposition of H(2)O(2), slightly contributing to TCE degradation via oxidation. In the presence of Fe(II), the degradation efficiency of TCE at 396 ?M improves to 94.9% within 80 min. The product distribution proves that the degradation pathway shifts from 79% hydrodechlorination in the absence of Fe(II) to 84% •OH oxidation in the presence of Fe(II). TCE degradation follows zeroth-order kinetics with rate constants increasing from 2.0 to 4.6 ?M/min with increasing initial Fe(II) concentration from 0 to 27.3 mg/L at pH 4. A good correlation between TCE degradation rate constants and •OH generation rate constants confirms that •OH is the predominant reactive species for TCE oxidation. Presence of 10 mM Na(2)SO(4), NaCl, NaNO(3), NaHCO(3), K(2)SO(4), CaSO(4), and MgSO(4) does not significantly influence degradation, but sulfite and sulfide greatly enhance and slightly suppress degradation, respectively. A novel Pd-based electrochemical process is proposed for groundwater remediation. PMID:22315993

Yuan, Songhu; Mao, Xuhui; Alshawabkeh, Akram N

2012-03-20

271

Plume persistence caused by back diffusion from thin clay layers in a sand aquifer following TCE source-zone hydraulic isolation.  

PubMed

This paper concludes that back diffusion from one or a few thin clayey beds in a sand aquifer can cause contaminant persistence above MCLs in a sand aquifer long after the source zone initially causing the plume is isolated or removed. This conclusion is based on an intensive case study of a TCE contaminated site in Florida, with the processes evaluated using numerical modeling. At this site, the TCE DNAPL zone formed decades ago, and was hydraulically isolated by means of an innovative system performing groundwater extraction, treatment and re-injection. Treated water is re-injected in a row of injection wells situated a short distance downgradient of the extraction wells, creating a clean-water displacement front to efficiently flush the downgradient plume. This scheme avoids the creation of stagnation zones typical of most groundwater pump-and-treat systems, thereby minimizing the time for aquifer flushing and therefore downgradient cleanup. The system began operation in August 2002 and although the performance monitoring shows substantial declines in concentrations, detectable levels of TCE and degradation products persist downgradient of the re-injection wells, long after the TCE should have disappeared based on calculations assuming a nearly homogenous sand aquifer. Three hypotheses were assessed for this plume persistence: 1) incomplete source-zone capture, 2) DNAPL occurrence downgradient of the re-injection wells, and 3) back diffusion from one or more thin clay beds in the aquifer. After careful consideration, the first two hypotheses were eliminated, leaving back diffusion as the only plausible hypothesis, supported by detailed measurements of VOC concentrations within and near the clay beds and also by numerical model simulations that closely represent the field site hydrogeologic conditions. The model was also used to simulate a more generalized, hypothetical situation where more thin clayey beds occur in a sand aquifer with an underlying aquitard. While there is no doubt that DNAPL source mass reduction can eventually improve downgradient groundwater quality, the magnitude and time scale over which the improvement occurs is the major uncertainty given current characterization approaches. This study shows that even one thin clay bed, less than 0.2 m thick, can cause plume persistence due to back diffusion for several years or even decades after the flux from the source is completely isolated. Thin clay beds, which have a large storage capacity for dissolved and sorbed contaminant mass, are common in many types of sandy aquifers. However, without careful inspection of continuous cores and sampling, such thin clay beds, and their potential for causing long-term back-diffusion effects, can easily go unnoticed during site characterization. PMID:18775583

Parker, Beth L; Chapman, Steven W; Guilbeault, Martin A

2008-11-14

272

On the preparation of TiO2-sepiolite hybrid materials for the photocatalytic degradation of TCE: influence of TiO2 distribution in the mineralization.  

PubMed

Hybrid structured photocatalysts based on sepiolite, an adsorbent, and TiO2 were prepared by extrusion of ceramic dough and conformed as plates. The influence of the photocatalyst configuration was studied either by including TiO2 in the extrusion process (incorporated materials) or by coating the sepiolite plates with a TiO2 film (coated materials). The influence of the OH- surface concentration in the photocatalytic performance was studied by treating the ceramic plates at different temperatures. The samples were characterized by N2 adsorption-desorption, MIP, SEM, XRD, and UV-vis-NIR spectroscopy and tested in the photocatalytic degradation of trichloroethylene (TCE) as a target VOC molecule. Most of the catalysts presented high photoactivity, but considerable differences were observed when the CO2 selectivity was analyzed. The results demonstrate that there is a significant effect of the catalyst configuration on the selectivity of the process. An intimate contact between the sepiolite fibers and TiO2 particles for incorporated materials with a corncob-like structure favored the migration of nondesirable reaction products such as COCl2 and dichloroacetyl chloride (DCAC) to the adsorbent, reacting with OH- groups of the adsorbent and favoring the TCE mimeralization. PMID:18767641

Suárez, Silvia; Coronado, Juan M; Portela, Raquel; Martín, Juan Carlos; Yates, Malcolm; Avila, Pedro; Sánchez, Benigno

2008-08-15

273

Airlift recirculation well test results -- Southern sector  

SciTech Connect

Chlorinated solvents used in the A and M-Areas at the Savannah River Site (SRS) from 1952--1982 have contaminated the groundwater under the site. A plume of groundwater contaminated with trichloroethylene (TCE) and perchloroethylene (PCE) in the Lost Lake aquifer is moving generally southward with the natural flow of groundwater. To comply with the requirements of the current SCDHEC Part B Permit, a series of wells is being installed to contain and treat the plume. Airlift Recirculation Wells (ARW) are a new and innovative technology with potential for more cost effective implementation than conventional pump and treat systems. Two Airlift Recirculation Wells have been installed and tested to quantify performance parameters needed to locate a line of these wells along the leading edge of the contaminant plume. The wells proved to be very sensitive to proper development, but after this requirement was met, performance was very good. The Zone of Capture has been estimated to be within a radius of 130--160 ft. around the wells. Thus a line of wells spaced at 250 ft. intervals could intercept the contaminant plume. At SSR-012, TCE was stripped from the groundwater at approximately 1.2 lb./day. The longer term effect of the recirculation wells upon the plume and the degree of recirculation within the aquifer itself will require additional data over a longer time period for an accurate review. Data collection is ongoing.

White, R.M.; Hiergesell, R.A.

1997-08-01

274

Assessing in situ mineralization of recalcitrant organic compounds in vadose zone sediments using delta13C and 14C measurements.  

PubMed

Few techniques exist to measure the biodegradation of recalcitrant organic compounds such as chlorinated hydrocarbons (CHC) in situ, yet predictions of biodegradation rates are needed for assessing monitored natural attenuation. Traditional techniques measuring O2, CO2, or chemical concentrations (in situ respiration, metabolite and soil air monitoring) may not be sufficiently sensitive to estimate biodegradation rates for these compounds. This study combined isotopic measurements (14C and delta13C of CO2 and delta13C of CHCs) in conjunction with traditional methods to assess in situ biodegradation of perchloroethylene (PCE) and its metabolites in PCE-contaminated vadose zone sediments. CHC, ethene, ethane, methane, O2, and CO2 concentrations were measured over 56 days using gas chromatography (GC). delta13C of PCE, trichloroethylene (TCE) and cis-1,2-dichloroethylene (DCE), delta13C and 14C of vadose zone CO2 and sediment organic matter, and delta13C, 14C, and deltaD of methane were measured using a GC-isotope ratio mass spectrometer or accelerator mass spectrometer. PCE metabolites accounted for 0.2% to 18% of CHC concentration suggesting limited reductive dechlorination. Metabolites TCE and DCE were significantly enriched in (13)C with respect to PCE indicating metabolite biodegradation. Average delta13C-CO2 in source area wells (-23.5 per thousand) was significantly lower compared to background wells (-18.4 per thousand) indicating CHC mineralization. Calculated CHC mineralization rates were 0.003 to 0.01 mg DCE/kg soil/day based on lower 14C values of CO2 in the contaminated wells (63% to 107% modern carbon (pMC)) relative to the control well (117 pMC). Approximately 74% of the methane was calculated to be derived from in situ CHC biodegradation based on the 14C measurement of methane (29 pMC). 14C-CO2 analyses was a sensitive measurement for quantifying in situ recalcitrant organic compound mineralization in vadose zone sediments for which limited methodological tools exist. PMID:15588571

Kirtland, Brian C; Aelion, C Marjorie; Stone, Peter A

2005-01-01

275

Carbon isotope fractionation during degradation of benzene, trichloroethene, and tetrachloroethene under ultraviolet light  

Microsoft Academic Search

Stable carbon isotope fractionation factors associated with the degradation of benzene, trichloroethene (TCE), and tetrachloroethene (PCE) under ultraviolet light (254 nm) have been measured experimentally using simple and inexpen- sive quartz reaction vessels equipped with a syringe valve and septum. Carbon isotope enrichment factors of ?benzene = -6.2 ± 0.3‰, ?TCE = -6.8 ± 0.2‰, and ?PCE = -4.1 ±

SIMON R. POULSON; HIROSHI NARAOKA

2006-01-01

276

CROWTM PROCESS APPLICATION FOR SITES CONTAMINATED WITH LIGHT NON-AQUEOUS PHASE LIQUIDS AND CHLORINATED HYDROCARBONS  

SciTech Connect

Western Research Institute (WRI) has successfully applied the CROWTM (Contained Recovery of Oily Wastes) process at two former manufactured gas plants (MGPs), and a large wood treatment site. The three CROW process applications have all occurred at sites contaminated with coal tars or fuel oil and pentachlorophenol (PCP) mixtures, which are generally denser than water and are classified as dense non-aqueous phase liquids (DNAPLs). While these types of sites are abundant, there are also many sites contaminated with gasoline, diesel fuel, or fuel oil, which are lighter than water and lie on top of an aquifer. A third site type occurs where chlorinated hydrocarbons have contaminated the aquifer. Unlike the DNAPLs found at MGP and wood treatment sites, chlorinated hydrocarbons are approximately one and a half times more dense than water and have fairly low viscosities. These contaminants tend to accumulate very rapidly at the bottom of an aquifer. Trichloroethylene (TCE) and perchloroethylene, or tetrachloroethylene (PCE), are the major industrial chlorinated solvents that have been found contaminating soils and aquifers. The objective of this program was to demonstrate the effectiveness of applying the CROW process to sites contaminated with light non-aqueous phase liquids (LNAPLs) and chlorinated hydrocarbons. Individual objectives were to determine a range of operating conditions necessary to optimize LNAPL and chlorinated hydrocarbon recovery, to conduct numerical simulations to match the laboratory experiments and determine field-scale recoveries, and determine if chemical addition will increase the process efficiency for LNAPLs. The testing consisted of twelve TCE tests; eight tests with PCE, diesel, and wood treatment waste; and four tests with a fuel oil-diesel blend. Testing was conducted with both vertical and horizontal orientations and with ambient to 211 F (99 C) water or steam. Residual saturations for the horizontal tests ranged from 23.6% PV to 0.3% PV. Also conducted was screening of 13 chemicals to determine their relative effectiveness and the selection of three chemicals for further testing.

L.A. Johnson, Jr.

2003-06-30

277

Competitive Sorption and Desorption of Chlorinated Organic Solvents (DNAPLs) in Engineered Natural Organic Matter  

SciTech Connect

The effects of artificially accelerated geochemical condensation and maturation of natural organic matter on the sorption and desorption of trichloroethylene (TCE) and tetrachloroethylene (PCE) were studied. The sorption and desorption of TCE in the presence and absence of the competing PCE and 1,2-dichlorobenzene (DCB) were also examined. A sphagnum peat comprising geologically young organic matter was artificially ''aged'' using superheated water, thus increasing the aromaticity and the degree of condensation of its associated organic matter. The sorption of all solutes tested were increased remarkably and their respective desorptions reduced, by the aged peat. The sorption capacities and isotherm nonlinearities of the peat for both TCE and PCE were found to increase as treatment temperature increased. In the competitive sorption studies, both PCE and DCB were found to depress TCE sorption, with PCE having greater effects than DCB, presumably because the molecular structure o f the former is more similar to that of TCE.

Tang, Jixin; Weber, Walter J., Jr.

2004-03-31

278

Comparison of the Fourier transform infrared (FTIR) spectrophotometer and the Miniature Infrared Analyzer (MIRAN) for the determination of trichloroethylene (TCE) in the presence of Freon-113 in workplace air  

SciTech Connect

Results obtained using the Fourier transform infrared spectrophotometer (FTIR) and the Miniature Infrared Analyzer (MIRAN) for samples of workplace air containing trichloroethylene (TCE) were evaluated through comparison with results obtained when using a gas chromatography (GC). The effects of instrument resolution, relative humidity, and sample storage stability were studied. Relative humidity was found to have no effect on the performance of the FTIR over the range studied. The effect of changing resolution is complex but is explained. The linear range of the FTIR is more than adequate for the concentrations encountered in the samples reported in this study. Interference from Freon caused the TCE values to be high when the MIRAN was operated in the single-wavelength mode.

Xiao, H.K.; Levine, S.P.; D'Arcy, J.B.; Kinnes, G.; Almaguer, D. (Univ. of Michigan, Ann Arbor (USA))

1990-07-01

279

Development of an integrated in-situ remediation technology. Topical report for task No. 11 entitled: Evaluation of TCE contamination before and after the field experiment, September 26, 1994--May 25, 1996  

SciTech Connect

Contamination in low permeability soils poses a significant technical challenge to in-situ remediation efforts. Poor accessibility to the contaminants and difficulty in delivery of treatment reagents have rendered existing in-situ treatments such as bioremediation, vapor extraction, pump and treat rather ineffective when applied to low permeability soils present at many contaminated sites. The technology is an integrated in-situ treatment in which established geotechnical methods are used to install degradation zones directly in the contaminated soil and electro-osmosis is utilized to move the contaminants back and forth through those zones until the treatment is completed. The present Topical Report for Task No. 11 summarizes the results of TCE analysis in soil and carbon before and after conducting the field experiment. In addition, a discussion of the TCE material balance demonstrates that the Lasagna{trademark} process is effective in moving TCE from the contaminated soil into carbon treatment zones in the field experiment at DOE`s Gaseous Diffusion Plant in Paducah, Kentucky.

Hughes, B.M.; Athmer, C.J.; Sheridan, P.W. [and others

1997-04-01

280

HEALTH ASSESSMENT DOCUMENT FOR TETRACHLOROETHYLENE (PERCHLOROETHYLENE)  

EPA Science Inventory

Tetrachloroethylene (PERC) is believed to exert its adverse effects upon humans via metabolism by the liver. Concern that PERC is likely to be a human carcinogen is based upon the evidence of the National Cancer Institute bioassay, in which PERC induced a statistically significan...

281

Phased Implementation of In Situ Chemical Oxidation for a Large TCE DNAPL Source Area at the Portsmouth Gaseous Diffusion Plant, USA  

SciTech Connect

This paper describes the In Situ Chemical Oxidation (ISCO) remediation being implemented for the X-701B groundwater plume at the Department of Energy (DOE) Portsmouth Gaseous Diffusion Plant (PORTS). Modified Fenton's reagent is the principal oxidant for the remedy, and Direct Push Technology (DPT) is being used for delivery of the oxidant. Trichloroethene (TCE) is the primary contaminant of concern and is present within the unit as a dense non - aqueous phase liquid (DNAPL). A phased approach is being implemented to optimize the type, location, and mass of the oxidant injections. During Phase I, a unique near-real time monitoring approach was utilized to observe the transient effects of the oxidant injections on the formation. As a result of the positive results from Phase I, Ohio EPA has approved the final work plan for the remedy, and the approach is now being applied to the source area of the plume. The results from Phase I and the layout for the first series of Phase II injections are presented in this paper. Previous testing at the site has shown that the shallow, water-bearing formation is primarily composed of silty gravel and clay, and is both heterogeneous and anisotropic. These factors have significantly compromised earlier attempts to remediate the unit. A patented ISCO process from In-Situ Oxidative Technologies, Inc. (ISOTEC) was selected for the remediation of the plume. Phase I results indicate that oxidant delivery via DPT is feasible for the unit. Contaminant reduction to date has been minimal due to the small quantity of oxidant injected during Phase I. Contaminant rebound in the aqueous phase remains a concern and will be monitored closely during the remedy. (author)

Cross, Paul E. [Del Baird CDM, 3930 US Rt. 23, Piketon, OH 45661-2465 (United States)

2007-07-01

282

Desorption Behavior of Trichloroethene and Tetrachloroethene in U.S. Department of Energy Savannah River Site Unconfined Aquifer Sediments  

SciTech Connect

The DOE Savannah River Site (SRS) is evaluating the potential applicability of the monitored natural attenuation (MNA) process as a contributor to the understanding of the restoration of its unconfined groundwater aquifer known to be contaminated with the chlorinated hydrocarbon compounds trichloroethylene (TCE) and tetrachloroethylene (PCE). This report discusses the results from aqueous desorption experiments on SRS aquifer sediments from two different locations at the SRS (A/M Area; P-Area) with the objective of providing technically defensible TCE/PCE distribution coefficient (Kd) data and data on TCE/PCE reversible and irreversible sorption behavior needed for further MNA evaluation.

Riley, Robert G.; Szecsody, Jim E.; Mitroshkov, Alexandre V.; Brown, Christopher F.

2006-06-21

283

Retentive Memory of Bacteria: Long-Term Regulation of Dehalorespiration in Sulfurospirillum multivorans?  

PubMed Central

The gram-negative, strictly anaerobic epsilonproteobacterium Sulfurospirillum multivorans is able to gain energy from dehalorespiration with tetrachloroethene (perchloroethylene [PCE]) as a terminal electron acceptor. The organism can also utilize fumarate as an electron acceptor. Prolonged subcultivation of S. multivorans in the absence of PCE with pyruvate as an electron donor and fumarate as an electron acceptor resulted in a decrease of PCE dehalogenase (PceA) activity. Concomitantly, the pceA transcript level equally decreased as shown by reverse transcriptase PCR. After 35 subcultivations (approximately 105 generations), a pceA transcript was not detectable and the PceA protein and activity were completely absent. In such long-term subcultivated S. multivorans cells, the biosynthesis of catalytically active PceA was restored to the initial level within about 50 h (approximately three generations) by the addition of PCE or trichloroethene. Single colonies obtained from PceA-depleted cultures were able to induce PCE dechlorination, indicating that long-term subcultured cells still contained the functional pceA gene. The results point to a novel type of long-term regulation of PCE dehalogenase gene expression in S. multivorans.

John, Markus; Rubick, Raffael; Schmitz, Roland P. H.; Rakoczy, Jana; Schubert, Torsten; Diekert, Gabriele

2009-01-01

284

Retentive memory of bacteria: Long-term regulation of dehalorespiration in Sulfurospirillum multivorans.  

PubMed

The gram-negative, strictly anaerobic epsilonproteobacterium Sulfurospirillum multivorans is able to gain energy from dehalorespiration with tetrachloroethene (perchloroethylene [PCE]) as a terminal electron acceptor. The organism can also utilize fumarate as an electron acceptor. Prolonged subcultivation of S. multivorans in the absence of PCE with pyruvate as an electron donor and fumarate as an electron acceptor resulted in a decrease of PCE dehalogenase (PceA) activity. Concomitantly, the pceA transcript level equally decreased as shown by reverse transcriptase PCR. After 35 subcultivations (approximately 105 generations), a pceA transcript was not detectable and the PceA protein and activity were completely absent. In such long-term subcultivated S. multivorans cells, the biosynthesis of catalytically active PceA was restored to the initial level within about 50 h (approximately three generations) by the addition of PCE or trichloroethene. Single colonies obtained from PceA-depleted cultures were able to induce PCE dechlorination, indicating that long-term subcultured cells still contained the functional pceA gene. The results point to a novel type of long-term regulation of PCE dehalogenase gene expression in S. multivorans. PMID:19103925

John, Markus; Rubick, Raffael; Schmitz, Roland P H; Rakoczy, Jana; Schubert, Torsten; Diekert, Gabriele

2009-03-01

285

Interim report on testing of off-gas treatment technologies for abatement of atmospheric emissions of chlorinated volatile organic compounds  

SciTech Connect

The purpose of this report is to briefly summarize the results to date of the off-gas treatment program for atmospheric emissions of chlorinated volatile organic compounds (CVOCs), in particular trichloroethylene (TCE) and perchloroethylene (PCE). This program is part of the Department of Energy`s Office of Technology Development`s Integrated Demonstration for Treatment of Organics in Soil and Water at a Non-Arid Site. The off-gas treatment program was initiated after testing of in-situ air stripping with horizontal wells was completed. That successful test expectedly produced atmospheric emissions of CVOCs that were unabated. It was decided after that test that an off-gas treatment program would complement the Integrated Demonstration not only because off-gas treatment is an integral portion of remediation of CVOC contamination in groundwater and soil but also because several technologies were being developed across the US to mitigate CVOC emissions. A single platform for testing off-gas treatment technologies would facilitate systematic and unbiased evaluation of the emerging technologies.

Haselow, J.S.; Jarosch, T.R.; Rossabi, J.; Burdick, S.; Lombard, K.

1993-12-01

286

Initial field test of High-Energy Corona process for treating a contaminated soil-offgas stream  

SciTech Connect

The High-Energy Corona (HEC) technology for treating process offgases has been under development at Pacific Northwest Laboratory (PNL) since 1991. The HEC process uses high-voltage electrical discharges in air to ionize the air, forming a low-temperature plasma that would be expected to destroy a wide variety of organic compounds in air. The plasma contains strong oxidants, possibly including hydroxyl radicals, hydroperoxy radicals, superoxide radicals, various excited as well as ionized forms of oxygen, high-energy electrons, and ultraviolet (UV) light. Because the high-voltage plasma is produced near ambient temperatures and pressures, yet exhibits extremely rapid destruction kinetics with relatively low power requirements, the HEC technique appears promising as a low-cost treatment technique (Virden et al. 1992). As part of the Volatile Organic Compound (VOC) Nonarid Integrated Demonstration (ID) at the DOE Savannah River Site, research activities were initiated in December 1991 to develop a prototype HEC process for a small-scale field demonstration to treat a soil-offgas stream contaminated with trichloroethylene (TCE) and perchloroethylene (PCE) at varying concentrations. Over an 18-month period, the HEC technology was developed on a fast track, through bench and pilot scales into a trailer-mounted system that was tested at the Nonarid ID. Other national laboratories, universities, and private companies have also participated at the Nonarid ID to demonstrate a number of conventional, emerging and innovative approaches for treating the same soil-offgas stream.

Shah, R R; Garcia, R E; Jeffs, J T; Virden, J W; Heath, W O

1995-04-01

287

Decontamination systems information and research program  

SciTech Connect

It is estimated that over 3700 hazardous waste sites are under the jurisdiction of the Department of Energy (DOE). These sites were primarily generated from 45 years worth of environmental pollution from the design and manufacture of nuclear materials and weapons, and contain numerous types of wastes including: (1) volatile, low-volatile and nonvolatile organics, (2) radionuclides (e.g., uranium, plutonium and cesium), (3) nonradioactive heavy metals (e.g., chromium, nickel, and lead), and (4) toxic chemicals. These contaminants affect several media including soils (saturated and unsaturated), groundwater, vegetation, and air. Numerous and diverse DOE hazardous waste sites can be enumerated from soils contaminated by organics such as trichloroethylene (TCE) and perchloroethylene (PCE) at the Savannah River site to biota and vegetation contaminated by radionuclides such as radiocesium and radiostrontium at the Oak Ridge site. Over the next 30 years, the Department of Energy (DOE) is committed to bringing all its facilities into compliance with applicable Federal, State, and local environmental laws and regulations. This clean-up task is quite complex involving numerous sites containing various radioactive, organic and inorganic contaminants. To perform this clean-up effort in the most efficient manner at each site will require that DOE managers have access to all available information on pertinent technologies; i.e., to aid in maximum technology transfer. The purpose of this effort is to systematically develop a databast of those currently available and emerging clean-up technologies.

Not Available

1993-01-01

288

Decontamination systems information and research program. Quarterly technical progress report, October 1--December 31, 1992  

SciTech Connect

It is estimated that over 3700 hazardous waste sites are under the jurisdiction of the Department of Energy (DOE). These sites were primarily generated from 45 years worth of environmental pollution from the design and manufacture of nuclear materials and weapons, and contain numerous types of wastes including: (1) volatile, low-volatile and nonvolatile organics, (2) radionuclides (e.g., uranium, plutonium and cesium), (3) nonradioactive heavy metals (e.g., chromium, nickel, and lead), and (4) toxic chemicals. These contaminants affect several media including soils (saturated and unsaturated), groundwater, vegetation, and air. Numerous and diverse DOE hazardous waste sites can be enumerated from soils contaminated by organics such as trichloroethylene (TCE) and perchloroethylene (PCE) at the Savannah River site to biota and vegetation contaminated by radionuclides such as radiocesium and radiostrontium at the Oak Ridge site. Over the next 30 years, the Department of Energy (DOE) is committed to bringing all its facilities into compliance with applicable Federal, State, and local environmental laws and regulations. This clean-up task is quite complex involving numerous sites containing various radioactive, organic and inorganic contaminants. To perform this clean-up effort in the most efficient manner at each site will require that DOE managers have access to all available information on pertinent technologies; i.e., to aid in maximum technology transfer. The purpose of this effort is to systematically develop a databast of those currently available and emerging clean-up technologies.

Not Available

1993-01-01

289

Mortality among aircraft manufacturing workers  

PubMed Central

OBJECTIVES: To evaluate the risk of cancer and other diseases among workers engaged in aircraft manufacturing and potentially exposed to compounds containing chromate, trichloroethylene (TCE), perchloroethylene (PCE), and mixed solvents. METHODS: A retrospective cohort mortality study was conducted of workers employed for at least 1 year at a large aircraft manufacturing facility in California on or after 1 January 1960. The mortality experience of these workers was determined by examination of national, state, and company records to the end of 1996. Standardised mortality ratios (SMRs) were evaluated comparing the observed numbers of deaths among workers with those expected in the general population adjusting for age, sex, race, and calendar year. The SMRs for 40 cause of death categories were computed for the total cohort and for subgroups defined by sex, race, position in the factory, work duration, year of first employment, latency, and broad occupational groups. Factory job titles were classified as to likely use of chemicals, and internal Poisson regression analyses were used to compute mortality risk ratios for categories of years of exposure to chromate, TCE, PCE, and mixed solvents, with unexposed factory workers serving as referents. RESULTS: The study cohort comprised 77,965 workers who accrued nearly 1.9 million person-years of follow up (mean 24.2 years). Mortality follow up, estimated as 99% complete, showed that 20,236 workers had died by 31 December 1996, with cause of death obtained for 98%. Workers experienced low overall mortality (all causes of death SMR 0.83) and low cancer mortality (SMR 0.90). No significant increases in risk were found for any of the 40 specific cause of death categories, whereas for several causes the numbers of deaths were significantly below expectation. Analyses by occupational group and specific job titles showed no remarkable mortality patterns. Factory workers estimated to have been routinely exposed to chromate were not at increased risk of total cancer (SMR 0.93) or of lung cancer (SMR 1.02). Workers routinely exposed to TCE, PCE, or a mixture of solvents also were not at increased risk of total cancer (SMRs 0.86, 1.07, and 0.89, respectively), and the numbers of deaths for specific cancer sites were close to expected values. Slight to moderately increased rates of non-Hodgkin's lymphoma were found among workers exposed to TCE or PCE, but none was significant. A significant increase in testicular cancer was found among those with exposure to mixed solvents, but the excess was based on only six deaths and could not be linked to any particular solvent or job activity. Internal cohort analyses showed no significant trends of increased risk for any cancer with increasing years of exposure to chromate or solvents. CONCLUSIONS: The results from this large scale cohort study of workers followed up for over 3 decades provide no clear evidence that occupational exposures at the aircraft manufacturing factory resulted in increases in the risk of death from cancer or other diseases. Our findings support previous studies of aircraft workers in which cancer risks were generally at or below expected levels.  

Boice, J. D.; Marano, D. E.; Fryzek, J. P.; Sadler, C. J.; McLaughlin, J. K.

1999-01-01

290

Controlled release, blind test of DNAPL remediation by ethanol flushing  

Microsoft Academic Search

A dense nonaqueous phase liquid (DNAPL) source zone was established within a sheet-pile isolated cell through a controlled release of perchloroethylene (PCE) to evaluate DNAPL remediation by in-situ cosolvent flushing. Ethanol was used as the cosolvent, and the main remedial mechanism was enhanced dissolution based on the phase behavior of the water–ethanol–PCE system. Based on the knowledge of the actual

Michael C. Brooks; Michael D. Annable; P. Suresh C. Rao; Kirk Hatfield; James W. Jawitz; William R. Wise; A. Lynn Wood; Carl G. Enfield

2004-01-01

291

Applications of Monitored Natural Attenuation in the USA (Abstract)  

EPA Science Inventory

Monitored Natural Attenuation (MNA) is widely applied in the USA to control the risk associated with ground water contamination from chlorinated solvents such a tetrachloroethylene (PCE) and trichloroethylene (TCE). MNA relies on the natural processes of degradation, sorption an...

292

Applications of Monitored Natural Attenuation in the USA (Presentation)  

EPA Science Inventory

Monitored Natural Attenuation (MNA) is widely applied in the USA to control the risk associated with ground water contamination from chlorinated solvents such a tetrachloroethylene (PCE) and trichloroethylene (TCE). MNA relies on the natural processes of degradation, sorption an...

293

BIODEGRADATION OF CHLORINATED SOLVENTS: REACTIONS NEAR DNAPL AND ENZYME FUNCTION  

EPA Science Inventory

Chlorinated solvents are among the most common organic chemical groundwater contaminants at DOE sites, as well as at DOD and industrial facilities. Included are the solvents trichloroethene (TCE), tetrachloroethene (PCE), and carbon tetrachloride (CT). Commonly these contaminan...

294

DETERMINATION OF CHLOROETHENES IN ENVIRONMENTAL BIOLOGICAL SAMPLES USING GAS CHROMATOGRAPHY COUPLED WITH SOLID PHASE MICRO EXTRACTION  

EPA Science Inventory

An analytical method has been developed to determine the chloroethene series, tetrachloroethene (PCE), trichloroethene (TCE),cisdichloroethene (cis-DCE) andtransdichloroethene (trans-DCE) in environmental biotreatment studies using gas chromatography coupled with a solid phase mi...

295

Promising Emerging Mechanisms  

EPA Science Inventory

Most applications of enhanced in situ bioremediation are based on biological reductive dechlorination. Anaerobic metabolism can also produce reactive minerals that allow for in situ biogeochemical transformation of chlorinated organic contaminants such as PCE, TCE, and cis-DCE. ...

296

BIOTRANSFORMATION OF TRICHLOROETHYLENE IN SOIL  

EPA Science Inventory

The organic contaminants that are most commonly detected in groundwater are low-molecular-weight, chlorinated aliphatic hydrocarbons such as trichloroethylene (TCE), tetrachloroethylene (PCE), 1,1,1-trichloroethane, carbon tetrachloride, and chloroform. The authors exposed unsatu...

297

Use of Compound-Specific Stable Isotope Analysis to Distinguish Between Vapor Intrusion and Indoor Sources of VOCs.  

National Technical Information Service (NTIS)

The objective of the present study is an empirical validation of selected adsorbents for preconcentration of TCE, PCE and benzene in air samples containing low concentrations of these VOCs. For validation of adsorbent tube performance, we sought to: 1) us...

M. Klisch R. P. Philp T. Kuder T. McHugh

2012-01-01

298

Use of Compound Specific Stable Isotope Analysis to Distinguish Between Vapor Intrusion and Indoor Sources of VOCs.  

National Technical Information Service (NTIS)

The objective of the present study is an empirical validation of selected adsorbents for preconcentration of TCE, PCE and benzene in air samples containing low concentrations of these VOCs. For validation of adsorbent tube performance, we sought to: 1) us...

M. Klisch R. P. Philp T. Kuder T. McHugh

2012-01-01

299

RELATIONSHIP BETWEEN GEOCHEMICAL PARAMETERS AND THE OCCURRENCE OF DEHALOCOCCOIDES DNA IN CONTAMINATED AQUIFERS  

EPA Science Inventory

Stains of Dehalococcoides are the only microbes known that can completely dechlorinate PCE, TCE, cis-DCE and vinyl chloride to ethylene. Either naturally-occurring strains or bioaugmentation cultures of Dehalococcoides are widely used for in situ bioremediation ...

300

MICROBIAL UTILIZATION OF VADOSE ZONE ORGANIC CARBON FOR REDUCTIVE DECHLORINATION OF TETRACHLOROETHENE  

EPA Science Inventory

Aqueous extracts from a calcareous spodosol were used as the primary substrate to study the reductive dechlorination of tetrachloroethene (PCE). A comparison was made between extracts obtained using pure water and water saturated with trichloroethene (TCE). The latter solutions w...

301

Characterization of Chlorinated Ethene Degradation in a Vertical Flow Constructed Wetland.  

National Technical Information Service (NTIS)

Chlorinated solvents, including perchloroethene (PCE) and trichlorethene (TCE), are among the most common groundwater contaminants found in the United States. The use of constructed wetlands has shown promise as an effective and less costly alternative fo...

J. M. Waldron

2007-01-01

302

Mechanisms, Chemistry, and Kinetics of Anaerobic Biodegradation of cis-Dichloroethene and Vinyl Chloride.  

National Technical Information Service (NTIS)

Anaerobic biological processes can result in PCE and TCE destruction through conversion to cis-dichloroethene (cDCE) then to vinyl chloride (VC), and finally to ethene. Here, the chlorinated aliphatic hydrocarbons (CAHs) serve as electron acceptors in ene...

P. L. McCarty A. M. Spormann

2000-01-01

303

Modeling competitive adsorption of chlorinated volatile organic compounds with the Dubinin–Radushkevich equation  

Microsoft Academic Search

A recent paper showed that the breakthrough curves of volatile organic compound (VOC) mixtures on zeolite replaced the adsorbates in order of decreasing boiling points (PCE>TCE>DCA>DCM) and could be predicted by the boiling point of the compounds (similar to distillation). A previous study by the authors found a similar result on granulated activated carbon (PCE>TCE>CTC>TCA>t-12DCE>CHL>DCE), but used another thermodynamic property,

Thomas P O'Connor; James Mueller

2001-01-01

304

EFFECTS OF FOUR TRIHALOMETHANES ON DNA STRAND BREAKS, RENAL HYALINE DROPLET FORMATION AND SERUM TESTOSTERONE IN MALE F-344 RATS  

EPA Science Inventory

All four possible trihalomethanes (THMs) containing bromine and chlorine, as well as perchloroethylene (PCE), were evaluated for their ability to produce DNA strand breaks, a2u-globulin rich renal deposits, and testosterone changes in male F-344 rats. Rats received daily equimola...

305

Improved Dechlorinating Performance of Upflow Anaerobic Sludge Blanket Reactors by Incorporation of Dehalospirillum multivorans into Granular Sludge  

Microsoft Academic Search

Dechlorination of tetrachloroethene, also known as perchloroethylene (PCE), was investigated in an upflow anaerobic sludge blanket (UASB) reactor after incorporation of the strictly anaerobic, reductively dechlori- nating bacterium Dehalospirillum multivorans into granular sludge. This reactor was compared to the reference 1 (R1) reactor, where the granules were autoclaved to remove all dechlorinating abilities before inoculation, and to the reference 2

CHRISTINE HORBER; NINA CHRISTIANSEN; ERIK ARVIN; BIRGITTE K. AHRING

1998-01-01

306

CONTROLLED RELEASE, BLIND TEST OF DNAPL REMEDIATION BY ETHANOL FLUSHING  

EPA Science Inventory

A dense nonaqueous phase liquid (DNAPL) source zone was established within a sheet-pile isolated cell through a controlled release of perchloroethylene (PCE) to evaluate DNAPL remediation by in-situ cosolvent flushing. Ethanol was used as the cosolvent, and the main remedia...

307

Measuring economic losses from ground water contamination: An investigation of household avoidance costs  

Microsoft Academic Search

Economic losses from ground water contamination were estimated in a central Pennsylvania community. The averting expenditures method was applied via a mail survey of households in which water contained the unregulated volatile organic chemical, perchloroethylene (PCE). Expenditures were estimated at $148,900 (1987 dollars) over the six-month contamination period or approximately $252 per household annually. These costs underestimate the lower bound

Charles W. Abdalla

1990-01-01

308

Controlled release, blind tests of DNAPL characterization using partitioning tracers  

Microsoft Academic Search

The partitioning tracer technique for dense nonaqueous phase liquid (DNAPL) characterization was evaluated in an isolated test cell, in which controlled releases of perchloroethylene (PCE) had occurred. Four partitioning tracer tests were conducted, two using an inverted, double five-spot pumping pattern, and two using vertical circulation wells. Two of the four tests were conducted prior to remedial activities, and two

Michael C Brooks; Michael D Annable; P. Suresh C Rao; Kirk Hatfield; James W Jawitz; William R Wise; A. Lynn Wood; Carl G Enfield

2002-01-01

309

Methods for environmental monitoring of DOE waste disposal and storage sites. Semiannual progress report, April 1, 1988--September 30, 1988  

SciTech Connect

Perchloroethylene (PCE) is a persistent environmental contaminant whose chemical stability and hydrophobicity have made it difficult to remove from contaminated groundwater. PCE is also toxic and has been implicated as a carcinogen. This study was aimed at assessing methods for biological degradation of PCE. As a part of the study, the authors have characterized possible products of the degradation of PCE, and have determined the effects of detergents and solvents on the water solubility of PCE and on the toxic effects of PCE on bacteria. The authors have also isolated PCE-resistant microorganisms from monitoring wells at Y-12. To date all of the PCE-resistant bacteria isolated from the monitoring wells have been of the genus Bacillus. One of these isolates appears to be able to degrade PCE, as indicated by the disappearance of PCE from cultures of growing cells. The organism does not grow on PCE as the sole carbon source, so degradation of the solvent must occur by cometabolism.

Hadden, C.T.; Benson, S.B.; Osborne, T.R.; Revis, N.W.

1988-12-31

310

Reductive dechlorination of chlorinated ethenes and 1,2-dichloroethane by Dehalococcoides ethenogenes'' 195  

SciTech Connect

Dehalococcoides ethenogenes'' 195 can reductively dechlorinate tetrachloroethene (PCE) completely to ethene (ETH). When PCE-grown strain 195 was transferred (2% [vol/vol] inoculum) into growth medium amended with trichloroethene (TCE), cis-dichloroethene (DCE), 1,1-DCE, or 1,2-dichloroethane (DCA) as an electron acceptor, these chlorinated compounds were consumed at increasing rates over time, which indicated that growth occurred. Moreover, the number of cells increased when TCE, 1,1-DCE, or DCA was present. PCE, TCE, 1,1-DCE, and cis-DCE were converted mainly to vinyl chloride (VC) and then to ETH, while DCA was converted to ca. 99% ETH and 1% VC. cis-DCE was used at lower rates than PCE, TCE, 1,1-DCE, or DCA was used. When PCE-grown cultures were transferred to media containing VC or trans-DCE, products accumulated slowly, and there was no increase in the rate, which indicated that these two compounds did not support growth. When the intermediates in PCE dechlorination by strain 195 were monitored, TCE was detected first, followed by cis-DCE. After a lag, VC, 1,1-DCE, and trans-DCE accumulated, which is consistent with the hypothesis that cis-DCE is the precursor of these compounds. Both cis-DCE and 1,1-DCE were eventually consumed, and both of these compounds could be considered intermediates in PCE dechlorination, whereas the small amount of trans-DCE that was produced persisted. Cultures grown on TCE, 1,1-DCE, or DCA could immediately dechlorinate PCE, which indicated that PCE reductive dehalogenase activity was constitutive when these electron acceptors were used.

Maymo-Gatell, X.; Anguish, T.; Zinder, S.H. (Cornell Univ., Ithaca, NY (United States). Section of Microbiology)

1999-07-01

311

Demonstration and evaluation of the pulsed ultraviolet-irradiation gas-treatment system, Savannah River Site  

SciTech Connect

Argonne National Laboratory was asked to demonstrate and evaluate a pulsed ultraviolet-irradiation system developed by Purus, Inc., at the Volatile Organic Compounds Non-Arid Integrated Demonstration at the Savannah River Site near aiken, South Carolina. The Purus system consists of four reactor chambers, each containing a xenon flash lamp. During the two weeks of testing, samples were taken and analyzed from the inlet and outlet sides of the Purus system. The contaminants of concern on the inlet were tetrachloroethylene (PCE), trichloroethylene (TCE), and 1,1,1-trichloroethane (TCA); the contaminants of concern on the outlet were PCE, TCE, TCA, carbon tetrachloride (CT), and chloroform. The evaluation of the Purus system included an examination of the reduction of both TCE and PCE and a search for any change in the concentrations. (Operating conditions included flow rates, ranging from 25 to 100 standard cubic feet per minute; inlet concentration of PCE, ranging from 360 to 10,700 parts per million volume; and flash lamp rates, ranging from 1 to 30 hertz.) The Purus system was quite efficient at reducing the concentrations of both PCE and TCE. The potential by-products, TCA, CT, and chloroform, showed no significant increases throughout the range of the various operating parameters. Overall, the Purus system appears to be a cost-efficient means of reducing the concentrations of PCE and TCE, while the removal of the initial photo-oxidation products and TCA is slower and needs further evaluation.

Schneider, J.; Wilkey, M.; Peters, R.; Tomczyk, N.; Friedlund, J.; Farber, P. [Argonne National Lab., IL (United States). Energy Systems Div.; Mass, B.; Haag, W. [Purus, Inc., San Jose, CA (United States)

1994-10-01

312

Geochemistry of a Tetrachloroethene and Trichloroethene Plume at the Borden Aquifer  

NASA Astrophysics Data System (ADS)

Under favourable redox conditions biodegradation is one of the processes that controls PCE and TCE attenuation at the Borden sand aquifer. This paper presents geochemistry data obtained in a study which main aim is to evaluate the fate of a PCE and TCE plume in the Borden forested area. Selected multilevel piezometers for five transects in a Tetrachloroethene (PCE) and Trichloroethene (TCE) plume were sampled for analysis of VOC concentrations, 13C-VOC and ? 18O in dissolved oxygen, as well as DIC, DOC, DO, cations and anions concentrations. Field parameters such as, temperature, pH, conductivity, ORP, and alkalinity were measured as part of the study. The results showed a decrease in DO and an increase in iron concentration along the groundwater flow system indicating a pattern toward anoxic conditions. DIC and DOC increase along the flow. A significant change is observed in PCE concentration in the first 45m down gradient from the source. The increase in TCE concentration and the occurrence of cis-DCE, methane and ethane in the downgradient areas indicated that biodegradation is one the processes controlling PCE concentration along the groundwater flow system. Part of the plume in the downgradient areas is discharging into a creek and it is postulated that a change in sediments in the riparian zone explain the occurrence of methanogenic conditions that facilitated the biodegradation of PCE. Carbon isotope data in VOC will confirm the role of PCE biodegradation in the plume.

Vargas, I.; Aravena, R.; Parker, B.; Wassenaar, L.

2004-05-01

313

Compound-specific isotope analysis: Questioning the origins of a trichloroethene plume  

USGS Publications Warehouse

Stable carbon isotope ratios of trichloroethene (TCE), cis-1,2- dichloroethene, and trans-1,2-dichloroethene were determined by use of gas chromatography-combustion-isotope ratio mass spectroscopy to determine whether compound-specific stable carbon isotopes could be used to help understand the origin and history of a TCE groundwater plume in Fort Worth, TX. Calculated ??13C values for total chlorinated ethenes in groundwater samples, which can approximate the ??13C of a spilled solvent if all degradation products are accounted for, were useful for determining whether separate lobes of the plume resulted from different sources. Most notably, values for one lobe, where tetrachloroethene (PCE) has been detected periodically, were outside the range for manufactured TCE but within the range for manufactured PCE, whereas values for a separate lobe, which is downgradient of reported TCE spills, were within the range for manufactured TCE. Copyright ?? Taylor & Francis Group, LLC.

Eberts, S. M.; Braun, C.; Jones, S.

2008-01-01

314

Removing hexavalent chromium from subsurface waters with anion-exchange resin  

SciTech Connect

Some subsurface waters at Lawrence Livermore National Laboratory (LLNL) are contaminated with volatile organic compounds (VOCs). Hexavalent chromium, Cr(VI), is also present in the ground water; however, the source of the Cr(VI) may be natural. The Cr(VI) still must be treated if brought to the surface because its concentration exceeds discharge standards. We are planning facilities for removing the VOCs and Cr(VI) to a level below the discharge standards. The planned treatment includes the following steps: (1) Pumping the water to the surface facility. (2) Purging the VOCs with air and absorbing them on activated carbon. The VOCs in LLNL`s subsurface waters are primarily chlorinated organic solvents, such as dichloroethylene (DCE), trichloroethylene (TCE), perchloroethylene (PCE), and chloroform (CHCl{sub 3}). Contamination levels range from tens to thousands of parts per billion. (3) Filtering the water. (4) Passing the water through anion-exchange resin to remove the Cr. The Cr in LLNL subsurface waters occurs almost entirely as Cr(VI), which exists as the chromate anion, CrO{sub 4}{sup 2-}, at environmental pH. Cr levels range from tens to hundreds of parts per billion. (5) Discharging the treated water into the local arroyos. The relevant discharge criteria are 5 ppb total VOCs, 11 ppb Cr(VI), and pH between 6.5 and 8.5, inclusive. This report describes laboratory experiments undertaken to learn how the proposed treatment facility can be expected to operate. The laboratory results are expected to supply vendors with the detailed performance specifications needed to prepare bids on the Cr removal portion of the treatment facility. The treatment facility is expected to process 60 gallons per minute (gpm) of water by stripping VOCs with 720 standard cubic feet per minute (scfm) of air and removing Cr(VI) with 60 ft{sup 3} of resin.

Torres, R.A.

1995-06-01

315

A theoretical model of air and steam co-injection to prevent the downward migration of DNAPLs during steam-enhanced extraction.  

PubMed

When steam is injected into soil containing a dense volatile non-aqueous phase liquid contaminant the DNAPL vaporized within the heated soil region condenses and accumulates ahead of the steam condensation front. If enough DNAPL accumulates, gravitational forces can overcome trapping forces allowing the liquid contaminant to flow downward. By injecting air with steam, a portion of the DNAPL vapor remains suspended in equilibrium with the air, decreasing liquid contaminant accumulation ahead of the steam condensation front, and thus reducing the possibility of downward migration. In this work, a one-dimensional theoretical model is developed to predict the injection ratio of air to steam that will prevent the accumulation of volatile DNAPLs. The contaminated region is modeled as a one-dimensional homogeneous porous medium with an initially uniform distribution of a single component contaminant. Mass and energy balances are combined to determine the injection ratio of air to steam that eliminates accumulation of the contaminant ahead of the steam condensation front, and hence reduces the possibility of downward migration. The minimum injection ratio that eliminates accumulation is defined as the optimum injection ratio. Example calculations are presented for three DNAPLs, carbon tetrachloride (CCl4), trichloroethylene (TCE), and perchloroethylene (PCE). The optimum injection ratio of air to steam is shown to depend on the initial saturation and the volatility of the liquid contaminant. Numerical simulation results are presented to validate the model, and to illustrate downward migration for ratios less than optimum. Optimum injection ratios determined from numerical simulations are shown to be in good agreement with the theoretical model. PMID:11999630

Kaslusky, Scott F; Udell, Kent S

2002-04-01

316

Dechlorination of TCE with palladized iron  

DOEpatents

The present invention relates to various methods, such as an above-ground method and an in-ground method, of using a palladized iron bimetallic system for the dechlorination of chlorinated organic compounds from effluents containing the same. The use of palladized iron bimetallic system results in the dechlorination of the chlorinated organic compound into environmentally safe reaction products. The present invention also provides kits, devices, and other instruments that use the above-mentioned palladized iron bimetallic system for the dechlorination of chlorinated organic compounds.

Fernando, Quintus (Tucson, AZ); Muftikian, Rosy (Tucson, AZ); Korte, Nic (Grand Junction, CO)

1997-01-01

317

Dechlorination of TCE with palladized iron  

DOEpatents

The present invention relates to various methods, such as an above-ground method and an in-ground method, of using a palladized iron bimetallic system for the dechlorination of chlorinated organic compounds from effluents containing the same. The use of palladized iron bimetallic system results in the dechlorination of the chlorinated organic compound into environmentally safe reaction products. The present invention also provides kits, devices, and other instruments that use the above-mentioned palladized iron bimetallic system for the dechlorination of chlorinated organic compounds. 10 figs.

Fernando, Q.; Muftikian, R.; Korte, N.

1998-06-02

318

Dechlorination of TCE with palladized iron  

DOEpatents

The present invention relates to various methods, such as an above-ground method and an in-ground method, of using a palladized iron bimetallic system for the dechlorination of chlorinated organic compounds from various effluents or contaminated soil containing the same. The use of palladized iron bimetallic system results in the dechlorination of the chlorinated organic compound into environmentally safe reaction products. 10 figs.

Fernando, Q.; Muftikian, R.; Korte, N.

1997-04-01

319

Dechlorination of TCE with palladized iron  

DOEpatents

The present invention relates to various methods, such as an above-ground method and an in-ground method, of using a palladized iron bimetallic system for the dechlorination of chlorinated organic compounds from effluents containing the same. The use of palladized iron bimetallic system results in the dechlorination of the chlorinated organic compound into environmentally safe reaction products. The present invention also provides kits, devices, and other instruments that use the above-mentioned palladized iron bimetallic system for the dechlorination of chlorinated organic compounds. 10 figs.

Fernando, Q.; Muftikian, R.; Korte, N.

1997-03-18

320

IRIS Toxicological Review of Tetrachloroethylene (Perchloroethylene) (External Review Draft)  

EPA Science Inventory

EPA conducted a peer review of the scientific basis supporting the human health hazard and dose-response assessment of tetrachloroethylene that will appear on the Integrated Risk Information System (IRIS) database. Peer review is meant to ensure that science is used credibly and ...

321

CHARGE TO THE TETRACHLOROETHYLENE (PERCHLOROETHYLENE) NEUROTOXICITY EXPERT PANEL  

EPA Science Inventory

Today NCEA is posting the charge which will be discussed at the expert panel meeting on neurotoxicity issues associated with exposure to tetrachlroroethylene. This charge is to be the main agenda topic for the meeting. The time and place of the meeting will be announced in a fu...

322

Biological exposure assessment to tetrachloroethylene for workers in the dry cleaning industry  

PubMed Central

Background The purpose of this study was to assess the feasibility of conducting biological tetrachloroethylene (perchloroethylene, PCE) exposure assessments of dry cleaning employees in conjunction with evaluation of possible PCE health effects. Methods Eighteen women from four dry cleaning facilities in southwestern Ohio were monitored in a pilot study of workers with PCE exposure. Personal breathing zone samples were collected from each employee on two consecutive work days. Biological monitoring included a single measurement of PCE in blood and multiple measurements of pre- and post-shift PCE in exhaled breath and trichloroacetic acid (TCA) in urine. Results Post-shift PCE in exhaled breath gradually increased throughout the work week. Statistically significant correlations were observed among the exposure indices. Decreases in PCE in exhaled breath and TCA in urine were observed after two days without exposure to PCE. A mixed-effects model identified statistically significant associations between PCE in exhaled breath and airborne PCE time weighted average (TWA) after adjusting for a random participant effect and fixed effects of time and body mass index. Conclusion Although comprehensive, our sampling strategy was challenging to implement due to fluctuating work schedules and the number (pre- and post-shift on three consecutive days) and multiplicity (air, blood, exhaled breath, and urine) of samples collected. PCE in blood is the preferred biological index to monitor exposures, but may make recruitment difficult. PCE TWA sampling is an appropriate surrogate, although more field intensive. Repeated measures of exposure and mixed-effects modeling may be required for future studies due to high within-subject variability. Workers should be monitored over a long enough period of time to allow the use of a lag term.

McKernan, Lauralynn T; Ruder, Avima M; Petersen, Martin R; Hein, Misty J; Forrester, Christy L; Sanderson, Wayne T; Ashley, David L; Butler, Mary A

2008-01-01

323

Complete biological reductive transformation of tetrachloroethene to ethane  

SciTech Connect

Reductive dechlorination of tetrachloroethene (perchloroethylene; PCE) was observed at 20 C in a fixed-bed column, filled with a mixture of anaerobic sediment from the Rhine river and anaerobic granular sludge. In the presence of lactate as an electron donor, 9 [mu]M PCE was dechlorinated to ethene. Ethene was further reduced to ethane. Mass balances demonstrated an almost complete conversion, with no chlorinated compounds remaining. When the temperature was lowered to 10 C, an adaptation of 2 weeks was necessary to obtain the same performance as at 20 C. Dechlorination by column material to ethene, followed by a slow ethane production, could also be achieved in batch cultures. Ethane was not formed in the presence of bromoethanesulfonic acid, an inhibitor of methanogenesis. The high dechlorination rate, even at low temperatures and considerable PCE concentrations, together with the absence of chlorinated end products, makes reductive dechlorination an attractive method for removal of PCE in bioremediation processes.

Bruin, W.P. de; Kotterman, M.J.J.; Posthumus, M.A.; Schraa, G.; Zehnder, A.J.B. (Wageningen Agricultural Univ. (Netherlands))

1992-06-01

324

Investigation of the potential relationship between chlorinated volatile organic compounds in a perched aquifer and a regional aquifer  

SciTech Connect

Beneath an industrial site in Los Angeles County, CA, chlorinated volatile organic compounds (VOCs) have been discovered in a shallow perched and a regional aquifer. VOCs detected in the perched aquifer include tetrachloroethene (PCE), trichloroethene (TCE), 1,2-dichloroethane (1,2-DCA), and cis-1,2-dichloroethene (cis-1,2-DCE), and vinyl chloride. The aromatics benzene, toluene, and xylene have also been detected. Comparison of analytical results collected between 1986 and 1993 indicate the concentrations of VOCs in the perched aquifer have steadily decreased over time, with the exception of PCE and TCE. VOCs in the regional aquifer include PCE, TCE, cis-1,2-DCE, and chloroform. Analytical results from 1987 through 1993 indicate the concentrations of VOCs in the Exposition-Gage Aquifer beneath the site have steadily increased. However, upgradient ground-water quality analysis indicates only a trace level (2 ppb) of toluene present.

Patton, K.; Stellar, J.R.; Sohn, M.D. (McLaren/Hart Environmental Engineering Corp., Burbank, CA (United States))

1993-10-01

325

Human Health Effects of Tetrachloroethylene: Key Findings and Scientific Issues  

PubMed Central

Background: The U.S. Environmental Protection Agency (EPA) completed a toxicological review of tetrachloroethylene (perchloroethylene, PCE) in February 2012 in support of the Integrated Risk Information System (IRIS). Objectives: We reviewed key findings and scientific issues regarding the human health effects of PCE described in the U.S. EPA’s Toxicological Review of Tetrachloroethylene (Perchloroethylene). Methods: The updated assessment of PCE synthesized and characterized a substantial database of epidemiological, experimental animal, and mechanistic studies. Key scientific issues were addressed through modeling of PCE toxicokinetics, synthesis of evidence from neurological studies, and analyses of toxicokinetic, mechanistic, and other factors (tumor latency, severity, and background rate) in interpreting experimental animal cancer findings. Considerations in evaluating epidemiological studies included the quality (e.g., specificity) of the exposure assessment methods and other essential design features, and the potential for alternative explanations for observed associations (e.g., bias or confounding). Discussion: Toxicokinetic modeling aided in characterizing the complex metabolism and multiple metabolites that contribute to PCE toxicity. The exposure assessment approach—a key evaluation factor for epidemiological studies of bladder cancer, non-Hodgkin lymphoma, and multiple myeloma—provided suggestive evidence of carcinogenicity. Bioassay data provided conclusive evidence of carcinogenicity in experimental animals. Neurotoxicity was identified as a sensitive noncancer health effect, occurring at low exposures: a conclusion supported by multiple studies. Evidence was integrated from human, experimental animal, and mechanistic data sets in assessing adverse health effects of PCE. Conclusions: PCE is likely to be carcinogenic to humans. Neurotoxicity is a sensitive adverse health effect of PCE. Citation: Guyton KZ, Hogan KA, Scott CS, Cooper GS, Bale AS, Kopylev L, Barone S Jr, Makris SL, Glenn B, Subramaniam RP, Gwinn MR, Dzubow RC, Chiu WA. 2014. Human health effects of tetrachloroethylene: key findings and scientific issues. Environ Health Perspect 122:325–334;?http://dx.doi.org/10.1289/ehp.1307359

Hogan, Karen A.; Scott, Cheryl Siegel; Cooper, Glinda S.; Bale, Ambuja S.; Kopylev, Leonid; Barone, Stanley; Makris, Susan L.; Glenn, Barbara; Subramaniam, Ravi P.; Gwinn, Maureen R.; Dzubow, Rebecca C.; Chiu, Weihsueh A.

2014-01-01

326

Identification of a reductive tetrachloroethene dehalogenase in Shewanella sediminis  

PubMed Central

The genome sequence of psychrophilic Shewanella sediminis revealed the presence of five putative reductive dehalogenases (Rdhs). We found that cell extracts of pyruvate/fumarate-grown S. sediminis cells catalysed reduced methyl viologen-dependent reductive dechlorination of tetrachloroethene (PCE) to trichloroethene (TCE) at a specific activity of approximately 1 nmol TCE min?1 (mg protein)?1. Dechlorination of PCE followed Michaelis–Menten kinetics with an apparent Km of 120 ?M PCE. No PCE dechlorination was observed with heat-denatured extract or when cyanocobalamin was omitted from the growth medium; however, the presence of PCE in the growth medium increased PCE transformation rates. Analysis of mutants carrying in-frame deletions of all five Rdhs encoding genes showed that only deletion of Ssed_3769 resulted in the loss of PCE dechlorination activity suggesting that Ssed_3769 is a functional Rdh. This is the first study to show reductive dechlorination activity of PCE in a sediment-dwelling Shewanella species that may be important for linking the flux of organohalogens to organic carbon via reductive dehalogenation in marine sediments.

Lohner, Svenja T.; Spormann, Alfred M.

2013-01-01

327

Identification of a reductive tetrachloroethene dehalogenase in Shewanella sediminis.  

PubMed

The genome sequence of psychrophilic Shewanella sediminis revealed the presence of five putative reductive dehalogenases (Rdhs). We found that cell extracts of pyruvate/fumarate-grown S. sediminis cells catalysed reduced methyl viologen-dependent reductive dechlorination of tetrachloroethene (PCE) to trichloroethene (TCE) at a specific activity of approximately 1 nmol TCE min(-1) (mg protein)(-1). Dechlorination of PCE followed Michaelis-Menten kinetics with an apparent Km of 120 ?M PCE. No PCE dechlorination was observed with heat-denatured extract or when cyanocobalamin was omitted from the growth medium; however, the presence of PCE in the growth medium increased PCE transformation rates. Analysis of mutants carrying in-frame deletions of all five Rdhs encoding genes showed that only deletion of Ssed_3769 resulted in the loss of PCE dechlorination activity suggesting that Ssed_3769 is a functional Rdh. This is the first study to show reductive dechlorination activity of PCE in a sediment-dwelling Shewanella species that may be important for linking the flux of organohalogens to organic carbon via reductive dehalogenation in marine sediments. PMID:23479755

Lohner, Svenja T; Spormann, Alfred M

2013-04-19

328

Comparison of Chlorinated Ethenes DNAPL Reductive Dechlorination by Indigenous and Evanite culture with Surfactant Tween-80  

NASA Astrophysics Data System (ADS)

Although many innovative technologies have been developed to enhance remediation of chlorinated ethenes(e.g. tetrachloroethene[PCE], trichloroethene[TCE])DNAPL source zones, they have been ineffective in reducing contaminant concentration to regulatory end points. Thus, combination of surfactant flushing process that removes significant contaminant mass with microbial reductive dechlorination, posttreatment "polishing step" to control the remaining DNAPL that may serve as a source of reducing equivalents and stimulate the dechlorinating bacterial communities may be an attractive remediation process alternatively. Microcosm studies were conducted to explore chlorinated ethenes, PCE/TCE of 3 ~ 30 mg/L dechlorination by indigenous microbial communities from TCE DNAPL source zones of Korea and Evanite culture in the presence of Tween-80 of 10 ~ 5,000 mg/L. In the microcosms for indigenous microbial communities, by-products(e.g. c-DCE, vinyl chloride) of reductive dechlorination of PCE/TCE were not detected. This results suggest dechlorinating bacteria might be not exist or high concentration of chlorinated ethenes inhibit activity of dechlorinating bacteria in indigenous microbial communities. But VFAs like acetate, methane and hydrogen gas from fermentation of Tween-80 were detected. So Tween-80 might estimated to serve as a source of reducing equivalents. To evaluate the dechlorinating ability of Evanite-culture, we added Evanite-culture to the microcosms for indigenous bacteria and monitored by-products of reductive dechlorination of PCE/TCE and VFAs and hydrogen gas.

Kwon, S.; Hong, S.; Kim, R.; Kim, N.; Ahn, H.; Lee, S.; Kim, Y.

2010-12-01

329

Bio-reduction of tetrachloroethen using a H2-based membrane biofilm reactor and community fingerprinting.  

PubMed

Chlorinated ethenes in drinking water could be reductively dechlorinated to non-toxic ethene by using a hydrogen based membrane biofilm reactor (H2-MBfR) under denitrifying conditions as it provides an appropriate environment for dechlorinating bacteria in biofilm communities. This study evaluates the reductive dechlorination of perchloroethene (PCE) to non-toxic ethene (ETH) and comparative community analysis of the biofilm grown on the gas permeable membrane fibers. For these purposes, three H2-MBfRs receiving three different chlorinated ethenes (PCE, TCE and DCE) were operated under different hydraulic retention times (HRTs) and H2 pressures. Among these reactors, the H2-MBfR fed with PCE (H2-MBfR 1) accomplished a complete dechlorination, whereas cis-DCE accumulated in the TCE receiving H2-MBfR 2 and no dechlorination was detected in the DCE receiving H2-MBfR 3. The results showed that 95% of PCE dechlorinated to ETH together with over 99.8% dechlorination efficiency. Nitrate was the preferred electron acceptor as the most of electrons generated from H2 oxidation used for denitrification and dechlorination started under nitrate deficient conditions at increased H2 pressures. PCR-DGGE analysis showed that Dehalococcoides were present in autotrophic biofilm community dechlorinating PCE to ethene, and RDase genes analysis revealed that pceA, tceA, bvcA and vcrA, responsible for complete dechlorination step, were available in Dehalococcoides strains. PMID:24731873

Karata?, Serdar; Hasar, Halil; Ta?kan, Ergin; Ozkaya, Bestamin; Sahinkaya, Erkan

2014-07-01

330

PCE/K-10 Activities for Career Education.  

ERIC Educational Resources Information Center

Intended for use by Marshall High School faculty as they integrate career education into their curriculum, the project notebook is based on the (Portland, Oregon) overall Area 2 program goals for career education which proposes that all children completing school should have sufficient knowledge and competencies to enter into a field of employment…

Portland Public Schools, OR. Area II Office.

331

Comparative simulation studies of plasma cathode electron (PCE) gun  

Microsoft Academic Search

Pseudospark discharge based plasma cathode has capability to provide high current density electron beam during discharge process. In this paper an effort has been made to simulate the breakdown processes in the pseudospark discharge based plasma cathode electron gun. The two-dimensional plasma simulation codes VORPAL and OOPIC-Pro have been used and results are compared. The peak discharge current in the

Jitendra Prajapati; U N Pal; Niraj Kumar; D K Verma; Ram Prakash; V Srivastava

2012-01-01

332

Comparative simulation studies of plasma cathode electron (PCE) gun  

NASA Astrophysics Data System (ADS)

Pseudospark discharge based plasma cathode has capability to provide high current density electron beam during discharge process. In this paper an effort has been made to simulate the breakdown processes in the pseudospark discharge based plasma cathode electron gun. The two-dimensional plasma simulation codes VORPAL and OOPIC-Pro have been used and results are compared. The peak discharge current in the plasma cathode electron gun is found to be dependent on aperture size, hollow cathode dimensions, anode voltage and seed electrons energy. The effect of these design parameters on the peak anode current has been analysed by both the codes and results matches well within 10% variation. For the seed electron generation an electron beam trigger source is used to control the discharge process in the hollow cathode cavity. The time span of trigger source has been varied from 1-100 ns to analyze the effect on the peak anode current.

Prajapati, Jitendra; Pal, U. N.; Kumar, Niraj; Verma, D. K.; Prakash, Ram; Srivastava, V.

2012-05-01

333

Bioenhanced Dissolution of PCE from DNAPL Pools: Large Tank Experiments  

Microsoft Academic Search

Long-term persistence of chlorinated DNAPL has driven interest in source-depletion technologies. Recent flow- cell experiments demonstrated that microbial reductive dehalogenation can significantly enhance dissolution of high saturation pools of DNAPL. Modeling of these experiments showed that bioenhanced mass transfer can be simulated by linking abiotic DNAPL dissolution with aqueous-phase biodegradation and solute transport. For many technologies, the scale of application

K. C. Glover; T. H. Illangasekare; J. Munakata Marr; P. Philippe

2006-01-01

334

Evaluating the Relationship Between Source Zone Metrics and Down-Gradient Plume Response as a Function of Mixed DNAPL Mass Removal  

NASA Astrophysics Data System (ADS)

The influence of source zone architecture on down-gradient plume and flux-averaged effluent concentrations as a function of source depletion was evaluated through a series of 2-D aquifer cell experiments contaminated with a mixed dense non-aqueous phase liquid (DNAPL) consisting of a 1:1 molar ratio of trichloroethene (TCE) and tetrachloroethene (PCE). The aquifer cells (1.0 m length x 48 cm height x 1.4 cm internal thickness) were packed with different size fractions of quartz sands, and low permeability lens configurations were varied to achieve alternative varied source zone saturation distributions. DNAPL saturation distributions were quantified using a light transmission system and characterized by the ganglia-to-pool ratio (GTP, 0 to infinity) and pool fraction (0 to 1), where saturations less than 0.13 represent discrete ganglia and saturations equal to or greater than 0.13 are considered to represent "pools". Flux-averaged effluent dissolved-phase TCE and PCE concentrations were monitored continuously, while down-gradient plume samples were collected periodically from 25 side-ports. Results from these studies indicated that TCE was preferentially depleted during aqueous phase dissolution from the mixed DNAPL source zone, while PCE was preferentially depleted during surfactant flooding with a 4% (w/w) solution of polyoxyethylene (20) sorbitan monooleate (Tween 80, a nonionic, food-grade surfactant). Batch experiments were conducted to investigate this competitive solubilization of PCE and TCE from the DNAPL mixture in the presence of surfactant. Results indicate that PCE is preferentially solubilized relative to TCE in micellar solutions of Tween 80 and Aerosol MA-80I, demonstrating that a Raoult’s Law convention is not applicable to these systems. In contrast to the PCE and TCE data, results obtained using a 1:1 molar mixture of decane and dodecane in the same micellar solutions indicate that the amount of decane or dodecane solubilized in the aqueous phase was proportional to the mole fraction in the NAPL, consistent with a Raoult’s Law. It is hypothesized that the deviations from Raoult’s Law observed for PCE and TCE were caused by preferential solubilization of PCE within the hydrophobic core of the micelles. Work is on-going to quantify the preferential solubilization observed in the batch experiments, which will facilitate the incorporation of this relationship into multiphase compositional simulators. These simulators will then be used to improve the understanding of the inter-relationships between the initial source zone architecture, mass removal, reductions in mass flux and plume evolution in multi-component contaminated subsurface systems.

Cápiro, N. L.; Granbery, E. K.; Christ, J.; Pennell, K. D.

2009-12-01

335

SORPTION OF NONIONIC SURFACTANT OLIGOMERS TO SEDIMENT AND PCE DNAPL: EFFECTS ON PCE DISTRIBUTION BETWEEN WATER AND SEDIMENT. (R826650)  

EPA Science Inventory

Introduction of surfactant mixtures to the subsurface for the purpose of surfactant-enhanced aquifer remediation requires consideration of the effects of surfactant sorption to sediment and nonaqueous phase liquids. These effects include alteration of the solubiliz...

336

Electrical impedance tomography of the 1995 OGI perchloroethelyne release  

SciTech Connect

Goal is to determine if electrical impedance tomography (EIT) might be useful to map free product DNAPL (dense nonaqueous phase liquids) contamination. EIT was used to image the plume resulting from a release of 189 liters (50 gallons) of perchloroethylene (PCE) into a saturated aquifer constructed of sand with two layers of bentonite. Images were made in 4 planes, before, during, and after the release, to generate a detailed picture of the spatial and temporal development of the plume. Information of the EI (both in phase and out of phase voltages) was used at several different frequencies to produce images. Some frequency dispersion was observed in the images before and after the PCE release. Laboratory measurements of organic contamination in soil indicate detectable dispersion. A search for this effect in EIT images reveals weak evidence, the signal appearing just above the measurement uncertainty, of a change in the reactance in the soil because of the PCE.

Dailey, W.; Ramirez, A.

1996-10-01

337

Degradation of Perchloroethene by zero-valent iron evaluated by carbon isotope fractionation  

NASA Astrophysics Data System (ADS)

Perchloroethene (PCE) is a widely spread groundwater contaminant in formally used industrial sites. Zero valent iron (ZVI) is used for in situ chemical reduction (ISCR) of PCE contaminants in the groundwater. A key factor in the application of in situ remediation technologies is a proper monitoring of contaminant reduction. The measurement of the stable isotope ratio is a promising method that is already used for quantifying microbial degradation of chlorinated contaminants. The carbon isotope ratio of PCE, measured by - isotope ratio mass spectrometry coupled to a gas chromatograph via a combustion interface (GC-C-IRMS), increases during degradation of PCE and can be directly related to the degree of degradation. It can be used to directly quantify chemical degradation and thus serves as a useful monitoring tool for groundwater remediation. An experiment to determine the carbon isotopic fractionation factor was performed as a lab experiment using Nanofer Star (NANOIRON). Two different PCE concentrations (c1: 220mgL-1, c2: 110mgL-1) mixed with 0.5 g of ZVI were sealed under deoxygenated conditions in 250 ml glas bottles locked with mininert caps. The bottles were incubated on a shaker for 865 h. Samples were taken weekly to measure the change in the carbon isotopic ratio of PCE as well as its concentration. Results showed a strong increase in the carbon isotope ratio (?-value) of PCE (start: -27 o end: -4 ), which indicates a significant dechlorination process of PCE. Beside PCE also one degradation product (Trichloroethylene - TCE) was measured. TCE was further dechlorinated as indicated by the ?-value change of TCE from -26 o to -4 oȦn unexpected intermediate value of -45 o for TCE was observed in the experiment. This fluctuation could be induced by the time depending concentration due to degradation and conversation processes. Furthermore, it seems that the progress of the ?-value is affected by the starting concentration of PCE (?-value of c1 < c2) as there is a higher ratio of PCE to ZVI.

Leitner, Simon; Watzinger, Andrea; Reichenauer, Thomas G.

2014-05-01

338

Treatment of a Vadose Zone Plume Using Barometric Pumping: A Passive Soil Vapor Extraction Study at the Miscellaneous Chemicals Basin, Savannah River Site, S.C  

Microsoft Academic Search

A passive soil vapor extraction (PSVE) treatability study at the Miscellaneous Chemical Basin (MCB) of the Savannah River Site (SRS) has been progressing since September 1996. During this time more than 243 pounds of chlorinated organic contaminants (183 lbs of TCE and 61 lbs of PCE) have been removed by natural barometric pumping of wells fitted with BaroBall TM valves

S. L. Bosze; B. Riha; J. Rossabi; K. Hyde

2001-01-01

339

Dechlorination of chlorinated hydrocarbons by bimetallic Ni\\/Fe immobilized on polyethylene glycol-grafted microfiltration membranes under anoxic conditions  

Microsoft Academic Search

In this study, the dechlorination of chlorinated hydrocarbons including trichloroethylene (TCE), tetrachloroethylene (PCE) and carbon tetrachloride (CT) by bimetallic Ni\\/Fe nanoparticles immobilized on four different membranes was investigated under anoxic conditions. Effects of several parameters including the nature of membrane, initial concentration, pH value, and reaction temperature on the dechlorination efficiency were examined. The scanning electron microscopic images showed that

Ganesh K. Parshetti; Ruey-an Doong

340

Modeling cis-Dichloroethene Partitioning in Tetrachloroethene-NAPL Using Intra-aggregate Diffusion Sorption Models  

Microsoft Academic Search

Microbial facilitated dechlorination is being employed for treatment and polishing of source zones containing chlorinated ethenes. Metabolic reductive dechlorination converts tetrachloroethene (PCE) and trichloroethene (TCE) to lesser chlorinated ethenes and ultimately ethene. Where metabolic reductive dechlorination occurs in proximity to nonaqueous phase liquid (NAPL), the process may enhance the rate of NAPL dissolution by increasing the concentration driving force. Accumulation

J. K. Adams; S. R. Douglas; C. A. Ramsburg; J. A. Christ

2007-01-01

341

SIMULATING THE IN-SITU OXIDATIVE TREATMENT OF CHLORINATED ETHYLENES BY POTASSIUM PERMANGANATE  

EPA Science Inventory

In recent years, MnO{sub}4 oxidation of chlorinated ethylenes (PCE, TCE, and DCE) has emerged as a potentially useful approach for destroying these componds in water. Recently, more applied studies have looked at whether KMnO{sub}4 could be used in remediating sites contaminated ...

342

Natural Attenuation of Chlorinated Solvents and Fuel Components (BTEX and MTBE) in Ground Water  

EPA Science Inventory

Monitored Natural Attenuation is widely used in the USA to deal with ground water contamination from fuel components such as the BTEX compounds or MTBE or TBA and from chlorinated solvents such as PCE, TCE, and TCA. This presentation reviews the theory and practice of MNA in the...

343

Estimating DNAPL composition and VOC dilution from extraction well data  

Microsoft Academic Search

Field data from a large-scale ground-water extraction system at the Savannah River Site in South Carolina indicate that considerable dilution of volatile organic compounds (VOCs) occurs at extraction wells when compared with the effective solubilities of the VOC components (TCE and PCE) in the dense, nonaqueous phase liquid (DNAPL) source zone. This dilution is believed to be due to the

R. E. Jackson; P. E. Mariner

1995-01-01

344

Biomonitoring study of dry cleaning workers using cytogenetic tests and the comet assay.  

PubMed

Perchloroethylene (PCE) is the main solvent used in the dry cleaning industry worldwide. The aim of the present work was to evaluate the genotoxic potential of occupational exposure to PCE in dry cleaning workers. The study was carried out in 59 volunteers (30 workers, 29 controls). The genotoxic effect was evaluated by analyzing chromosome aberrations (CAs), and micronuclei (MN) and DNA damage (assessed by the comet assay) in peripheral blood lymphocytes. Environmental monitoring of exposure was carried out on personal breathing zone air samples collected during two consecutive working days by measuring the concentration of PCE air levels. The mean PCE concentration in workplace air of dry cleaning workers was 31.40 mg/m(3). There were no significant differences in CA frequency between dry cleaning workers and the controls, but analysis showed a significant association of CA frequency with employment duration and frequency of exposure to PCE. The MN frequency and DNA damage detected by alkaline comet assay were significantly increased in dry cleaning workers compared to the controls. The results suggest that (a) chronic occupational exposure to dry cleaning solvents below permissible occupational exposure limit of 70 mg/m(3) (i.e., ~10.3 ppm) may lead to an increased risk of genetic damage among dry cleaning workers, and (b) CA, MN tests, and comet assay are useful to monitor populations exposed to low doses of PCE. PMID:24116666

Everatt, R?ta; Slapšyt?, Gražina; Mierauskien?, J?rat?; Dedonyt?, Veronika; Bakien?, Liuda

2013-01-01

345

Partition behavior of surfactants, butanol, and salt during application of density-modified displacement of dense non-aqueous phase liquids.  

PubMed

Density-modified displacement (DMD) is a recent approach for removal of trapped dense NAPL (DNAPL). In this study, butanol and surfactant are contacted with the DNAPL to both reduce the density as well as release the trapped DNAPL (perchloroethylene: PCE). The objective of the study was to determine the distribution of each component (e.g., butanol, surfactant, water, PCE) between the original aqueous and PCE phases during the application of DMD. The results indicated that the presence of the surfactant increased the amount of n-butanol required to make the NAPL phase reach its desired density. In addition, water and anionic surfactant were found to partition along with the BuOH into the PCE phase. The water also found partitioned to reverse micelles in the modified phase. Addition of salt was seen to increase partitioning of surfactant to BuOH containing PCE phase. Subsequently, a large amount of water was solubilized into reverse micelles which lead to significantly increase in volume of the PCE phase. This work thus demonstrates the role of each component and the implications for the operation design of an aquifer treatment using the DMD technique. PMID:23385206

Damrongsiri, S; Tongcumpou, C; Sabatini, D A

2013-03-15

346

Dehalorespiration model that incorporates the self-inhibition and biomass inactivation effects of high tetrachloroethene concentrations.  

PubMed

In the vicinity of dense nonaqueous phase liquid (DNAPL) contaminant source zones, aqueous concentrations of tetrachloroethene (PCE) in groundwater may approach saturation levels. In this study, the ability of two PCE-respiring strains (Desulfuromonas michiganensis and Desulfitobacterium strain PCE1) to dechlorinate high concentrations of PCE was experimentally evaluated and depended on the initial biomass concentration. This suggests high PCE concentrations permanently inactivated a fraction of biomass, which, if sufficiently large, prevented dechlorination from proceeding. The toxic effects of PCE were incorporated into a model of dehalorespirer growth by adapting the transformation capacity concept previously applied to describe biomass inactivation by products of cometabolic TCE oxidation. The inactivation growth model was coupled to the Andrews substrate utilization model, which accounts for the self-inhibitory effects of PCE on dechlorination rates, and fit to the experimental data. The importance of incorporating biomass inactivation and self-inhibition effects when modeling reductive dechlorination of high PCE concentrations was demonstrated by comparing the goodness-of-fit of the Andrews biomass inactivation and three alternate models that do capture these factors. The new dehalorespiration model should improve our ability to predict contaminant removal in DNAPL source zones and determine the inoculum size needed to successfully implement bioaugmentation of DNAPL source zones. PMID:21182287

Huang, Deyang; Becker, Jennifer G

2011-02-01

347

Prenatal and Early Childhood Exposure to Tetrachloroethylene and Adult Vision  

PubMed Central

Background: Tetrachloroethylene (PCE; or perchloroethylene) has been implicated in visual impairments among adults with occupational and environmental exposures as well as children born to women with occupational exposure during pregnancy. Objectives: Using a population-based retrospective cohort study, we examined the association between prenatal and early childhood exposure to PCE-contaminated drinking water on Cape Cod, Massachusetts, and deficits in adult color vision and contrast sensitivity. Methods: We estimated the amount of PCE that was delivered to the family residence from participants’ gestation through 5 years of age. We administered to this now adult study population vision tests to assess acuity, contrast sensitivity, and color discrimination. Results: Participants exposed to higher PCE levels exhibited lower contrast sensitivity at intermediate and high spatial frequencies compared with unexposed participants, although the differences were generally not statistically significant. Exposed participants also exhibited poorer color discrimination than unexposed participants. The difference in mean color confusion indices (CCI) was statistically significant for the Farnsworth test but not Lanthony’s D-15d test [Farnsworth CCI mean difference = 0.05, 95% confidence interval (CI): 0.003, 0.10; Lanthony CCI mean difference = 0.07, 95% CI: –0.02, 0.15]. Conclusions: Prenatal and early childhood exposure to PCE-contaminated drinking water may be associated with long-term subclinical visual dysfunction in adulthood, particularly with respect to color discrimination. Further investigation of this association in similarly exposed populations is necessary.

Getz, Kelly D.; Janulewicz, Patricia A.; Rowe, Susannah; Weinberg, Janice M.; Winter, Michael R.; Martin, Brett R.; Vieira, Veronica M.; White, Roberta F.

2012-01-01

348

Experimental and numerical investigation of DNAPL infiltration and spreading in a 2-D sandbox by means of light transmission method  

NASA Astrophysics Data System (ADS)

Chlorinated solvents such as trichloroethene (TCE) and tetrachloroethene (PCE) are widespread groundwater contaminants often referred to as dense non-aqueous phase liquids (DNAPLs). Accuracy description of the spreading behavior and configuration for subsurface DNAPL migration is important, especially favourable for design effective remediation strategies. In this study, a 2-D experiment was conducted to investigate the infiltration behavior and spatial distribution of PCE in saturated porous media. Accusand 20/30 mesh sand (Unimin, Le Sueur, MN) was used as the background medium with two 70/80 and 60/70 mesh lenses embedded to simulate heterogeneous conditions. Dyed PCE of 100 ml was released into the flow cell at a constant rate of 2ml/min using a Harvard Apparatus syringe pump with a 50 ml glass syringe for two times, and 5 ml/min water was continuously injected through the inlet at the left side of the sandbox, while kept the same effluent rate at right side to create hydrodynamic condition. A light transmission (LT) system was used to record the migration of PCE and determine the saturation distribution of PCE in the sandbox experiment with a thermoelectrically air-cooled charged-coupled device (CCD) camera. All images were processed using MATLAB to calculate thickness-averaged PCE saturation for each pixel. Mass balance was checked through comparing injected known mounts of PCE with that calculated from LT analysis. Results showed that LT method is effective to delineate PCE migration pathways and quantify the saturation distribution. The relative errors of total PCE volumes calculated by LT analysis at different times were within 15% of the injected PCE volumes. The simulation are conducted using the multiphase modeling software T2VOC, which calibrated by the LT analysis results of three recorded time steps to fit with the complete spatial-temporal distribution of the PCE saturation. Model verification was then performed using the other eight recorded time steps. Simulated results showed that the model could successfully reproduce the migration pathways and distribution configuration observed from the laboratory experiment and LT analysis, excepted for a smaller pool height on the lenses, and a lower saturation values in PCE accumulation area due to local heterogeneities. Due to the influence of water flow, the PCE distribution was asymmetrical, and the PCE distribution area, pool height as well as PCE saturation in the accumulation region at right side was much greater. Acknowledge: This work is financially supported by the National Nature Science Foundation of China grants No. 41030746 and 41172206.

Zheng, F.; Shi, X.; Wu, J.; Gao, Y. W.

2013-12-01

349

Characterization of Two Tetrachloroethene-Reducing, Acetate-Oxidizing Anaerobic Bacteria and Their Description as Desulfuromonas michiganensis sp. nov.  

PubMed Central

Two tetrachlorethene (PCE)-dechlorinating populations, designated strains BB1 and BRS1, were isolated from pristine river sediment and chloroethene-contaminated aquifer material, respectively. PCE-to-cis-1,2-dichloroethene-dechlorinating activity could be transferred in defined basal salts medium with acetate as the electron donor and PCE as the electron acceptor. Taxonomic analysis based on 16S rRNA gene sequencing placed both isolates within the Desulfuromonas cluster in the ? subdivision of the Proteobacteria. PCE was dechlorinated at rates of at least 139 nmol min?1 mg of protein?1 at pH values between 7.0 and 7.5 and temperatures between 25 and 30°C. Dechlorination also occurred at 10°C. The electron donors that supported dechlorination included acetate, lactate, pyruvate, succinate, malate, and fumarate but not hydrogen, formate, ethanol, propionate, or sulfide. Growth occurred with malate or fumarate alone, whereas oxidation of the other electron donors depended strictly on the presence of fumarate, malate, ferric iron, sulfur, PCE, or TCE as an electron acceptor. Nitrate, sulfate, sulfite, thiosulfate, and other chlorinated compounds were not used as electron acceptors. Sulfite had a strong inhibitory effect on growth and dechlorination. Alternate electron acceptors (e.g., fumarate or ferric iron) did not inhibit PCE dechlorination and were consumed concomitantly. The putative fumarate, PCE, and ferric iron reductases were induced by their respective substrates and were not constitutively present. Sulfide was required for growth. Both strains tolerated high concentrations of PCE, and dechlorination occurred in the presence of free-phase PCE (dense non-aqueous-phase liquids). Repeated growth with acetate and fumarate as substrates yielded a BB1 variant that had lost the ability to dechlorinate PCE. Due to the 16S rRNA gene sequence differences with the closest relatives and the unique phenotypic characteristics, we propose that the new isolates are members of a new species, Desulfuromonas michiganensis, within the Desulfuromonas cluster of the Geobacteraceae.

Sung, Youlboong; Ritalahti, Kirsti M.; Sanford, Robert A.; Urbance, John W.; Flynn, Shannon J.; Tiedje, James M.; Loffler, Frank E.

2003-01-01

350

TRANSPORT OF TRICHLOROETHYLENE (TCE) IN NATURAL SOIL BY ELECTROOSMOSIS  

EPA Science Inventory

Contamination in low permeability soils poses a significant technical challenge to in-situ remediation, primarily due to low mobilization of the contaminants and difficulty in uniform delivery of treatment reagents. An alternative approach using electroosmosis (EO) is used to mob...

351

The TCE Corporate Technical Memory: groupware on the cheap  

Microsoft Academic Search

The Thomson Consumer Electronics Corporate Technical Memory is an electronic reference document repository used to store locally developed technical know-how as a set of files that can be browsed as well as searched. Implemented as a World Wide Web application, the Corporate Technical Memory is not constrained to a limited set of accepted file formats or restricted in its indexing

Mark Leighton Fisher

1997-01-01

352

IS INNOVATION APPROPRIATE? A CASE STUDY OF TCE SOURCE REMEDIATION  

Microsoft Academic Search

The Paint and Oil Locker (POL) facility is located in the industrial area at the National Aeronautics and Space Administration (NASA) Kennedy Space Center, Florida. Assessment activities at the site defined a dissolved plume that covers an area of approximately 10 acres (4.0 ha) and extends from a depth of approximately 6 ft. to 80 ft. below land surface (bls)

Todd P. Swingle; Michael A. Orcino; Mayra Castellanos; Jill Whitmer; Thomas A. Peel; Rosaly Santos-Ebaugh

353

Transaction Cost Economics (TCE) and Cost Estimation Methodology.  

National Technical Information Service (NTIS)

Hypothesis is that cost drivers are more complex than current methodology considers. Can a more complete view of costs improve cost estimation methodology. This briefing looks at methods of measuring transaction costs.

C. Franck D. Angelis F. Melese J. Dillard

2008-01-01

354

Characterization of the Corrinoid Iron-Sulfur Protein Tetrachloroethene Reductive Dehalogenase of Dehalobacter restrictus  

PubMed Central

The membrane-bound tetrachloroethene reductive dehalogenase (PCE-RDase) (PceA; EC 1.97.1.8), the terminal component of the respiratory chain of Dehalobacter restrictus, was purified 25-fold to apparent electrophoretic homogeneity. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a single band with an apparent molecular mass of 60 ± 1 kDa, whereas the native molecular mass was 71 ± 8 kDa according to size exclusion chromatography in the presence of the detergent octyl-?-d-glucopyranoside. The monomeric enzyme contained (per mol of the 60-kDa subunit) 1.0 ± 0.1 mol of cobalamin, 0.6 ± 0.02 mol of cobalt, 7.1 ± 0.6 mol of iron, and 5.8 ± 0.5 mol of acid-labile sulfur. Purified PceA catalyzed the reductive dechlorination of tetrachloroethene and trichloroethene to cis-1,2-dichloroethene with a specific activity of 250 ± 12 nkat/mg of protein. In addition, several chloroethanes and tetrachloromethane caused methyl viologen oxidation in the presence of PceA. The Km values for tetrachloroethene, trichloroethene, and methyl viologen were 20.4 ± 3.2, 23.7 ± 5.2, and 47 ± 10 ?M, respectively. The PceA exhibited the highest activity at pH 8.1 and was oxygen sensitive, with a half-life of activity of 280 min upon exposure to air. Based on the almost identical N-terminal amino acid sequences of PceA of Dehalobacter restrictus, Desulfitobacterium hafniense strain TCE1 (formerly Desulfitobacterium frappieri strain TCE1), and Desulfitobacterium hafniense strain PCE-S (formerly Desulfitobacterium frappieri strain PCE-S), the pceA genes of the first two organisms were cloned and sequenced. Together with the pceA genes of Desulfitobacterium hafniense strains PCE-S and Y51, the pceA genes of Desulfitobacterium hafniense strain TCE1 and Dehalobacter restrictus form a coherent group of reductive dehalogenases with almost 100% sequence identity. Also, the pceB genes, which may code for a membrane anchor protein of PceA, and the intergenic regions of Dehalobacter restrictus and the three desulfitobacteria had identical sequences. Whereas the cprB (chlorophenol reductive dehalogenase) genes of chlorophenol-dehalorespiring bacteria are always located upstream of cprA, all pceB genes known so far are located downstream of pceA. The possible consequences of this feature for the annotation of putative reductive dehalogenase genes are discussed, as are the sequence around the iron-sulfur cluster binding motifs and the type of iron-sulfur clusters of the reductive dehalogenases of Dehalobacter restrictus and Desulfitobacterium dehalogenans identified by electron paramagnetic resonance spectroscopy.

Maillard, Julien; Schumacher, Wolfram; Vazquez, Francisco; Regeard, Christophe; Hagen, Wilfred R.; Holliger, Christof

2003-01-01

355

A review of potential neurotoxic mechanisms among three chlorinated organic solvents  

SciTech Connect

The potential for central nervous system depressant effects from three widely used chlorinated solvents, trichloroethylene (TCE), perchloroethylene (PERC), and dichloromethane (DCM), has been shown in human and animal studies. Commonalities of neurobehavioral and neurophysiological changes for the chlorinated solvents in in vivo studies suggest that there is a common mechanism(s) of action in producing resultant neurotoxicological consequences. The purpose of this review is to examine the mechanistic studies conducted with these chlorinated solvents and to propose potential mechanisms of action for the different neurological effects observed. Mechanistic studies indicate that this solvent class has several molecular targets in the brain. Additionally, there are several pieces of evidence from animal studies indicating this solvent class alters neurochemical functions in the brain. Although earlier evidence indicated that these three chlorinated solvents perturb the lipid bilayer, more recent data suggest an interaction between several specific neuronal receptors produces the resultant neurobehavioral effects. Collectively, TCE, PERC, and DCM have been reported to interact directly with several different classes of neuronal receptors by generally inhibiting excitatory receptors/channels and potentiating the function of inhibitory receptors/channels. Given this mechanistic information and available studies for TCE, DCM, and PERC, we provide hypotheses on primary targets (e.g. ion channel targets) that appear to be most influential in producing the resultant neurological effects. - Research Highlights: > Comparison of neurological effects among TCE, PERC, and DCM. > Correlation of mechanistic findings to neurological effects. > Data support that TCE, PERC, and DCM interact with several ion channels to produce neurological changes.

Bale, Ambuja S., E-mail: bale.ambuja@epa.gov; Barone, Stan; Scott, Cheryl Siegel; Cooper, Glinda S.

2011-08-15

356

Spatial distributions of perchloroethylene reactive transport parameters in the Borden Aquifer  

NASA Astrophysics Data System (ADS)

We determined the descriptive statistical and spatial geostatistical properties of the perchloroethene ln Kd and the ln k of a 1.5 m thick by 10 m horizontal transect of the Borden aquifer near the location of the Stanford-Waterloo (SW) tracer experiment. The ln Kd distribution is not normal and is right skewed because of a few high values that occur localized in two regions of the transect. In contrast, the ln k data can be characterized by a normal distribution. A linear regression of ln Kd on ln k yields a statistically significant positive correlation, also shown at small lags in the cross correlogram. No significant vertical or horizontal trend in the ln Kd data was detected. The semivariogram ranges of ln k and ln Kd differ from one another in the vertical direction (0.33 ± 0.06 m and 0.20 ± 0.04 m, respectively) and are much less than the horizontal ranges (a few meters). Despite significant effort the horizontal range of ln Kd remains poorly characterized because of limitations of the sample locations. Many of the characteristics described above do not match those assumed in prior theoretical studies that examined the importance of various aquifer characteristics on SW tracer transport. We suggest that there is knowledge to be gained by revisiting the conclusions of these prior studies in light of the new information presented here.

Allen-King, Richelle M.; Divine, Dana Packard; Robin, Michel J. L.; Alldredge, J. Richard; Gaylord, David R.

2006-01-01

357

CATALYTIC STEAM REFORMING OF CHLOROCARBONS: TRICHLOROETHANE, TRICHLOROETHYLENE AND PERCHLOROETHYLENE. (R822721C633)  

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

358

SUBCHRONIC TOXICITY OF TETRACHLOROETHYLENE (PERCHLOROETHYLENE) ADMINISTERED IN THE DRINKING WATER OF RATS  

EPA Science Inventory

The study provides data on the effects of tetrachloroethylene in drinking solutions. The acute oral LD(50) was determined in male and female Charles River rats and found to be 3835 mg/kg for males and 3005 mg/kg for females. Male and female rats received theoretical daily doses o...

359

70 FR 75884 - National Perchloroethylene Air Emission Standards for Dry Cleaning Facilities  

Federal Register 2010, 2011, 2012, 2013

...implications. It will not have substantial direct effects on the States, on the relationship...Order 13175. It will not have substantial direct effects on tribal governments, on the...volume (50 parts per million by volume as methane) as indicated by a halogenated...

2005-12-21

360

Survey of subsurface treatment technologies for environmental restoration sites at Sandia National Laboratories, New Mexico.  

SciTech Connect

This report provides a survey of remediation and treatment technologies for contaminants of concern at environmental restoration (ER) sites at Sandia National Laboratories, New Mexico. The sites that were evaluated include the Tijeras Arroyo Groundwater, Technical Area V, and Canyons sites. The primary contaminants of concern at these sites include trichloroethylene (TCE), tetrachloroethylene (PCE), and nitrate in groundwater. Due to the low contaminant concentrations (close to regulatory limits) and significant depths to groundwater ({approx}500 feet) at these sites, few in-situ remediation technologies are applicable. The most applicable treatment technologies include monitored natural attenuation and enhanced bioremediation/denitrification to reduce the concentrations of TCE, PCE, and nitrate in the groundwater. Stripping technologies to remove chlorinated solvents and other volatile organic compounds from the vadose zone can also be implemented, if needed.

McGrath, Lucas K.; Ho, Clifford Kuofei; Wright, Jerome L.

2003-08-01

361

Passive and active soil gas sampling at the Mixed Waste Landfill, Technical Area III, Sandia National Laboratories/New Mexico  

SciTech Connect

The Environmental Restoration Project at Sandia National Laboratories, New Mexico is tasked with assessing and remediating the Mixed Waste Landfill in Technical Area III. The Mixed Waste Landfill is a 2.6 acre, inactive radioactive and mixed waste disposal site. In 1993 and 1994, an extensive passive and active soil gas sampling program was undertaken to identify and quantify volatile organic compounds in the subsurface at the landfill. Passive soil gas surveys identified levels of PCE, TCE, 1,1, 1-TCA, toluene, 1,1,2-trichlorotrifluoroethane, dichloroethyne, and acetone above background. Verification by active soil gas sampling confirmed concentrations of PCE, TCE, 1,1,1-TCA, and 1,1,2-trichloro-1,2,2-trifluoroethane at depths of 10 and 30 feet below ground surface. In addition, dichlorodifluoroethane and trichlorofluoromethane were detected during active soil gas sampling. All of the volatile organic compounds detected during the active soil gas survey were present in the low ppb range.

McVey, M.D.; Goering, T.J. [GRAM, Inc., Albuquerque, NM (United States); Peace, J.L. [Sandia National Labs., Albuquerque, NM (United States)

1996-02-01

362

Gas phase photocatalytic degradation on TiO{sub 2} pellets of volatile chlorinated organic compounds from a soil vapor extraction well  

SciTech Connect

The mineralization of trichloroethylene (TCE) and tetrachloroethylene (PCE) in gas stream from a soil vapor extraction (SVE) well was demonstrated with an annular photocatalytic reactor packed with porous TiO{sub 2} pellets in field trials at the Savannah River Site in Aiken, SC. The TiO{sub 2} pellets were prepared using a sol-gel method. The experiments were performed at 55 to 60{degree}C using space times of 10{sup 8} to 10{sup 10} g s/mol for TCE and PCE. Chloroform (CHCl{sub 3}) and carbon tetrachloride (CCl{sub 4}) were detected as minor products from side reactions. On a molar basis, CCl{sub 4} and CHCl{sub 3} produced were about 2% and 0.2 % of the reactants.

Yamazaki-Nishida, S.; Read, H.W.; Nagano, J.K.; Anderson, M.A. [Wisconsin Univ., Madison, WI (United States). Water Chemistry Program; Cervera-March, S. [Barcelona Univ., (Spain). Department of Chemical Engineering; Jarosch, T.R.; Eddy-Dilek, C.A. [Westinghouse Savannah River Co., Aiken, SC (United States)

1993-05-20

363

Anaerobic reductive dechlorination of tetrachloroethene: how can dual Carbon-Chlorine isotopic measurements help elucidating the underlying reaction mechanism?  

NASA Astrophysics Data System (ADS)

Chlorinated ethenes (CEs) such as tetrachloroethene (PCE) are common persistent groundwater contaminants. Among clean-up strategies applied to sites affected by such pollution, bioremediation has been considered with a growing interest as it represents a cost-effective, environmental friendly approach. This technique however sometimes leads to an incomplete and slow biodegradation of CEs resulting in an accumulation of toxic metabolites. Understanding the reaction mechanisms underlying anaerobic reductive dechlorination would thus help assessing PCE biodegradation in polluted sites. Stable isotope analysis can provide insight into reaction mechanisms. For chlorinated hydrocarbons, carbon (C) and chlorine (Cl) isotope data (?13C and ?37Cl) tend to show a linear correlation with a slope (m ? ?C/?Cl) characteristic of the reaction mechanism [1]. This study hence aims at exploring the potential of a dual C-Cl isotope approach in the determination of the reaction mechanisms involved in PCE reductive dechlorination. C and Cl isotope fractionation were investigated during anaerobic PCE dechlorination by two bacterial consortia containing members of the Sulfurospirillum genus. The specificity in these consortia resides in the fact that they each conduct PCE reductive dechlorination catalysed by one different reductive dehalogenase, i.e. PceADCE which yields trichloroethene (TCE) and cis-dichloroethene (cDCE), and PceATCE which yields TCE only. The bulk C isotope enrichment factors were -3.6±0.3 o for PceATCE and -0.7±0.1o for PceADCE. The bulk Cl isotope enrichment factors were -1.3±0.2 o for PceATCE and -0.9±0.1 o for PceADCE. When applying the dual isotope approach, two m values of 2.7±0.1 and 0.7±0.2 were obtained for the reductive dehalogenases PceATCE and PceADCE, respectively. These results suggest that PCE can be degraded according to two different mechanisms. Furthermore, despite their highly similar protein sequences, each reductive dehalogenase seems to catalyse PCE reductive dechlorination according to a different mechanism. In another study, an m value of 2.5±0.8 was found for PCE anaerobic dechlorination by a bacterial consortium dominated by species closely related to Desulfitobacterium aromaticivorans strain UKTL (consortia A) [2]. This value is indistinguishable from the one found for PceATCE within a 95% confidence interval although the reductive dehalogenase protein sequence of consortia A is distinctly different from the sequences of our two cultures. This suggests that the reaction mechanism is not related to the similarities between reductive dehalogenases. References 1. Abe, Y., et al., Carbon and Chlorine Isotope Fractionation during Aerobic Oxidation and Reductive Dechlorination of Vinyl Chloride and cis-1,2-Dichloroethene. Environmental Science & Technology, 2009. 43(1): p. 101-107. 2. Wiegert, C., et al., Carbon and Chlorine Isotope Fractionation During Microbial Degradation of Tetra- and Trichloroethene. Environmental Science & Technology, 2013. 47(12): p. 6449-6456.

Badin, Alice; Buttet, Géraldine; Maillard, Julien; Holliger, Christof; Hunkeler, Daniel

2014-05-01

364

Validation and application of pharmacokinetic models for interspecies extrapolations in toxicity-risk assessments of volatile organics. Final report, 1 Jul 87-30 Apr 91  

SciTech Connect

Direct measurements of perchloroethylene (PER), trichloroethylene (TCE), trichloroethane (TRI) and dichloroethylene (DCE) were made in the blood and exhaled breath of rats during and following inhalation exposures. The pharmacokinetics of these four halocarbons were also investigated following oral administration. An accurate assay for measuring volatile halogenated hydrocarbons in a variety of body tissues was developed and demonstrated for PER, TCE, TRI, and tetrachloroethane (TET). The tissue concentration-time profiles and bioavailability for PER and TET were determined in liver, kidney, brain, fat, lung, heart, and muscle tissues following oral and intraarterial administrations in rats. Interspecies comparisons of the pharmacokinetics of PER and TET were made following oral and intraarterial administrations in two species: Sprague-Dawley rats and Beagle dogs. Neurobehavioral determinations were conducted in rats following inhalation exposures, single oral bolus administration, and gastric infusion of PER.

Dallas, C.E.

1991-07-23

365

Phytoscreening for chlorinated solvents using rapid in vitro SPME sampling: Application to urban plume in Verl, Germany  

USGS Publications Warehouse

Rapid detection and delineation of contaminants in urban settings is critically important in protecting human health. Cores from trees growing above a plume of contaminated groundwater in Verl, Germany, were collected in 1 day, with subsequent analysis and plume mapping completed over several days. Solid-phase microextraction (SPME) analysis was applied to detect tetrachloroethene (PCE) and trichloroethene (TCE) to below nanogram/liter levels in the transpiration stream of the trees. The tree core concentrations showed a clear areal correlation to the distribution of PCE and TCE in the groundwater. Concentrations in tree cores were lower than the underlying groundwater, as anticipated; however, the tree core water retained the PCE:TCE signature of the underlying groundwater in the urban, populated area. The PCE:TCE ratio can indicate areas of differing degradation activity. Therefore, the phytoscreening analysis was capable not only of mapping the spatial distribution of groundwater contamination but also of delineating zones of potentially differing contaminant sources and degradation. The simplicity of tree coring and the ability to collect a large number of samples in a day with minimal disruption or property damage in the urban setting demonstrates that phytoscreening can be a powerful tool for gaining reconnaissance-level information on groundwater contaminated by chlorinated solvents. The use of SPME decreases the detection level considerably and increases the sensitivity of phytoscreening as an assessment, monitoring, and phytoforensic tool. With rapid, inexpensive, and noninvasive methods of detecting and delineating contaminants underlying homes, as in this case, human health can be better protected through screening of broader areas and with far faster response times. ?? 2011 American Chemical Society.

Limmer, M. A.; Balouet, J. -C.; Karg, F.; Vroblesky, D. A.; Burken, J. G.

2011-01-01

366

Microbial based chlorinated ethene destruction  

DOEpatents

A mixed culture of Dehalococcoides species is provided that has an ability to catalyze the complete dechlorination of polychlorinated ethenes such as PCE, TCE, cDCE, 1,1-DCE and vinyl chloride as well as halogenated ethanes such as 1,2-DCA and EDB. The mixed culture demonstrates the ability to achieve dechlorination even in the presence of high source concentrations of chlorinated ethenes.

Bagwell, Christopher E. (Aiken, SC); Freedman, David L. (Clemson, SC); Brigmon, Robin L. (North Augusta, SC); Bratt, William B. (Atlanta, GA); Wood, Elizabeth A. (Marietta, GA)

2009-11-10

367

Sustainable remediation: electrochemically assisted microbial dechlorination of tetrachloroethene-contaminated groundwater  

PubMed Central

Microbial electric systems (MESs) hold significant promise for the sustainable remediation of chlorinated solvents such as tetrachlorethene (perchloroethylene, PCE). Although the bio-electrochemical potential of some specific bacterial species such as Dehalcoccoides and Geobacteraceae have been exploited, this ability in other undefined microorganisms has not been extensively assessed. Hence, the focus of this study was to investigate indigenous and potentially bio-electrochemically active microorganisms in PCE-contaminated groundwater. Lab-scale MESs were fed with acetate and carbon electrode/PCE as electron donors and acceptors, respectively, under biostimulation (BS) and BS-bioaugmentation (BS-BA) regimes. Molecular analysis of the indigenous groundwater community identified mainly Spirochaetes, Firmicutes, Bacteroidetes, and ? and ?-Proteobacteria. Environmental scanning electron photomicrographs of the anode surfaces showed extensive indigenous microbial colonization under both regimes. This colonization and BS resulted in 100% dechlorination in both treatments with complete dechlorination occurring 4 weeks earlier in BS-BA samples and up to 11.5 ?A of current being generated. The indigenous non-Dehalococcoides community was found to contribute significantly to electron transfer with ?61% of the current generated due to their activities. This study therefore shows the potential of the indigenous non-Dehalococcoides bacterial community in bio-electrochemically reducing PCE that could prove to be a cost-effective and sustainable bioremediation practice.

Patil, Sayali S; Adetutu, Eric M; Rochow, Jacqueline; Mitchell, James G; Ball, Andrew S

2014-01-01

368

Effects of capillary pressure and use of polymer solutions on dense, non-aqueous-phase liquid retention and mobilization in a rough-walled fracture  

SciTech Connect

In this laboratory study, perchloroethylene (PCE) was permitted to migrate through a horizontal rough-walled limestone fracture under controlled conditions to assess fracture retention capacity. Retention of immiscible-phase PCE in the absence of an applied wetting-phase hydraulic gradient varied between 11% and 26% of the fracture volume. A portion of this residual could be removed through water flooding; however, even at the maximum applied hydraulic gradient of 1.0, residual PCE remained in the fracture. The observed correlation of reduced residual saturation with capillary number (N[sub c]) demonstrated that this rough-walled fracture exhibited behavior similar to that of a porous medium under water-flooding conditions. For a given hydraulic gradient, polymer-enhanced floods (using xanthan gum) were not as successful as conventional water flooding at removing residual from the fracture. The traditional form of the capillary number became an increasingly poor predictor of mobilization behavior as the viscosity of the displacing phase was increased. Incorporation of ([mu][sub w]/[mu][sub nw])[sup [minus]0.5] into the traditional capillary number provided a more appropriate dimensionless group with which to correlate residual PCE saturation in the fracture as [mu][sub w] increased.

Longino, B.L.; Kueper, B.H. (Queen's Univ., Kingston, Ontario (Canada). Dept. of Civil Engineering)

1999-07-15

369

DNAPL Extraction/Oleofilter Test Report  

SciTech Connect

A short term, low flow DNAPL extraction test was performed from May 29 - 30, 1997, to gather additional information about the possibility of using monitoring well MSB-3D to recover source contamination from the M-Area Aquifer. Although no visible, free phase material was recovered, the groundwater did contain perchloroethylene (PCE) at and above aqueous solubility. Improvements in the pumping configuration were identified for future trials. Prior to final treatment in the M1 air stripper, the groundwater was passed through an Oleofiltration system to evaluate its capability as a treatment technology. The Oleofilter uses a combination of conventional gravity assisted separation with coalescing plates and a final polishing filter using proprietary coated granules to remove hydrocarbons. Although free phase DNAPL was not processed through the Oleofilter, the groundwater containing high levels of dissolved PCE was treated efficiently. Initially the Oleofilter removed 99 percent of the PCE. As the test progressed, this removal rate decreased to 83 percent as the granules became loaded with PCE. Longer term testing, perhaps with periodic backflushing, is required to determine the effective granule capacity.

White, R.M. [Westinghouse Savannah River Company, AIKEN, SC (United States); Hazel, C.

1997-11-03

370

Insights into the use of time-lapse GPR data as observations for inverse multiphase flow simulations of DNAPL migration.  

PubMed

Perchloroethylene (PCE) saturations determined from GPR surveys were used as observations for inversion of multiphase flow simulations of a PCE injection experiment (Borden 9 m cell), allowing for the estimation of optimal bulk intrinsic permeability values. The resulting fit statistics and analysis of residuals (observed minus simulated PCE saturations) were used to improve the conceptual model. These improvements included adjustment of the elevation of a permeability contrast, use of the van Genuchten versus Brooks-Corey capillary pressure-saturation curve, and a weighting scheme to account for greater measurement error with larger saturation values. A limitation in determining PCE saturations through one-dimensional GPR modeling is non-uniqueness when multiple GPR parameters are unknown (i.e., permittivity, depth, and gain function). Site knowledge, fixing the gain function, and multiphase flow simulations assisted in evaluating non-unique conceptual models of PCE saturation, where depth and layering were reinterpreted to provide alternate conceptual models. Remaining bias in the residuals is attributed to the violation of assumptions in the one-dimensional GPR interpretation (which assumes flat, infinite, horizontal layering) resulting from multidimensional influences that were not included in the conceptual model. While the limitations and errors in using GPR data as observations for inverse multiphase flow simulations are frustrating and difficult to quantify, simulation results indicate that the error and bias in the PCE saturation values are small enough to still provide reasonable optimal permeability values. The effort to improve model fit and reduce residual bias decreases simulation error even for an inversion based on biased observations and provides insight into alternate GPR data interpretations. Thus, this effort is warranted and provides information on bias in the observation data when this bias is otherwise difficult to assess. PMID:17050034

Johnson, Raymond H; Poeter, Eileen P

2007-01-01

371

Insights into the use of time-lapse GPR data as observations for inverse multiphase flow simulations of DNAPL migration  

USGS Publications Warehouse

Perchloroethylene (PCE) saturations determined from GPR surveys were used as observations for inversion of multiphase flow simulations of a PCE injection experiment (Borden 9??m cell), allowing for the estimation of optimal bulk intrinsic permeability values. The resulting fit statistics and analysis of residuals (observed minus simulated PCE saturations) were used to improve the conceptual model. These improvements included adjustment of the elevation of a permeability contrast, use of the van Genuchten versus Brooks-Corey capillary pressure-saturation curve, and a weighting scheme to account for greater measurement error with larger saturation values. A limitation in determining PCE saturations through one-dimensional GPR modeling is non-uniqueness when multiple GPR parameters are unknown (i.e., permittivity, depth, and gain function). Site knowledge, fixing the gain function, and multiphase flow simulations assisted in evaluating non-unique conceptual models of PCE saturation, where depth and layering were reinterpreted to provide alternate conceptual models. Remaining bias in the residuals is attributed to the violation of assumptions in the one-dimensional GPR interpretation (which assumes flat, infinite, horizontal layering) resulting from multidimensional influences that were not included in the conceptual model. While the limitations and errors in using GPR data as observations for inverse multiphase flow simulations are frustrating and difficult to quantify, simulation results indicate that the error and bias in the PCE saturation values are small enough to still provide reasonable optimal permeability values. The effort to improve model fit and reduce residual bias decreases simulation error even for an inversion based on biased observations and provides insight into alternate GPR data interpretations. Thus, this effort is warranted and provides information on bias in the observation data when this bias is otherwise difficult to assess. ?? 2006 Elsevier B.V. All rights reserved.

Johnson, R. H.; Poeter, E. P.

2007-01-01

372

Microbial degradation of chloroethenes in groundwater systems  

USGS Publications Warehouse

The chloroethenes, tetrachloroethene (PCE) and trichloroethene (TCE) are among the most common contaminants detected in groundwater systems. As recently as 1980, the consensus was that chloroethene compounds were not significantly biodegradable in groundwater. Consequently, efforts to remediate chloroethene-contaminated groundwater were limited to largely unsuccessful pump-and-treat attempts. Subsequent investigation revealed that under reducing conditions, aquifer microorganisms can reductively dechlorinate PCE and TCE to the less chlorinated daughter products dichloroethene (DCE) and vinyl chloride (VC). Although recent laboratory studies conducted with halorespiring microorganisms suggest that complete reduction to ethene is possible, in the majority of groundwater systems reductive dechlorination apparently stops at DCE or VC. However, recent investigations conducted with aquifer and stream-bed sediments have demonstrated that microbial oxidation of these reduced daughter products can be significant under anaerobic redox conditions. The combination of reductive dechlorination of PCE and TCE under anaerobic conditions followed by anaerobic microbial oxidation of DCE and VC provides a possible microbial pathway for complete degradation of chloroethene contaminants in groundwater systems.

Bradley, P. M.

2000-01-01

373

Natural attenuation of chlorinated solvents at Area 6, Dover Air Force Base: groundwater biogeochemistry.  

PubMed

Monitored natural attenuation (MNA) has recently emerged as a viable groundwater remediation technology in the United States. Area 6 at Dover Air Force Base (Dover, DE) was chosen as a test site to examine the potential for MNA of tetrachloroethene (PCE) and trichloroethene (TCE) in groundwater and aquifer sediments. A "lines of evidence" approach was used to document the occurrence of natural attenuation. Chlorinated hydrocarbon and biogeochemical data were used to develop a site-specific conceptual model where both anaerobic and aerobic biological processes are responsible for the destruction of PCE, TCE, and daughter metabolites. An examination of groundwater biogeochemical data showed a region of depleted dissolved oxygen with elevated dissolved methane and hydrogen concentrations. Reductive dechlorination likely dominated in the anaerobic portion of the aquifer where PCE and TCE levels were observed to decrease with a simultaneous increase in cis-1,2-dichloroethene (cis-DCE), vinyl chloride (VC), ethene, and dissolved chloride. Near the anaerobic/ aerobic interface, concentrations of cis-DCE and VC decreased to below detection limits, presumably due to aerobic biotransformation processes. Therefore, the contaminant and daughter product plumes present at the site appear to have been naturally atteuated by a combination of active anaerobic and aerobic biotransformation processes. PMID:12143993

Witt, Michael E; Klecka, Gary M; Lutz, Edward J; Ei, Tom A; Grosso, Nancy R; Chapelle, Francis H

2002-07-01

374

Permeable Adsorptive Barrier (PAB) for the remediation of groundwater simultaneously contaminated by some chlorinated organic compounds.  

PubMed

In this paper, a Permeable Reactive Barrier (PRB) made with activated carbon, namely a Permeable Adsorptive Barrier (PAB), is put forward as an effective technique for the remediation of aquifers simultaneously contaminated by some chlorinated organic compounds. A design procedure, based on a computer code and including different routines, is presented as a tool to accurately describe mass transport within the aquifer and adsorption/desorption phenomena occurring inside the barrier. The remediation of a contaminated aquifer near a solid waste landfill in the district of Napoli (Italy), where Tetrachloroethylene (PCE) and Trichloroethylene (TCE) are simultaneously present, is considered as a case study. A complete hydrological and geotechnical site characterization, as well as a number of dedicated adsorption laboratory tests for the determination of activated carbon PCE/TCE adsorption capacity in binary systems, are carried out to support the barrier design. By means of a series of numerical simulations it is possible to determine the optimal barrier location, orientation and dimensions. PABs appear to be an effective remediation tool for the in-situ treatment of an aquifer contaminated by PCE and TCE simultaneously, as the concentration of both compounds flowing out of the barrier is everywhere lower than the regulatory limits on groundwater quality. PMID:24747934

Erto, A; Bortone, I; Di Nardo, A; Di Natale, M; Musmarra, D

2014-07-01

375

Estimating DNAPL composition and VOC dilution from extraction well data  

SciTech Connect

Field data from a large-scale ground-water extraction system at the Savannah River Site in South Carolina indicate that considerable dilution of volatile organic compounds (VOCs) occurs at extraction wells when compared with the effective solubilities of the VOC components (TCE and PCE) in the dense, nonaqueous phase liquid (DNAPL) source zone. This dilution is believed to be due to the convergence of both contaminated and uncontaminated streamtubes on the extraction wells studied. Thus, the measured concentrations of dissolved VOCs in extraction wells appear to be principally functions of (1) the effective solubilities of the DNAPL components, and (2) the dilution due to streamtube convergence on the extraction wells. A simple method for computing DNAPL composition and the dilution factor from extraction well data is presented for the case when dilution is the dominant mechanism that causes the measured ground-water concentrations of dissolved VOC components to be significantly less than their respective effect solubilities relative to the DNAPL mixture. This method successfully computes the molar composition of a PCE/TCE DNAPL, bailed from a pair of monitor wells at the Savannah River Site, using the measured concentrations of PCE and TCE in ground waters from the same pair of wells. The method is then used to predict the variation of DNAPL composition within the aquifer from VOC data sampled at all 11 extraction wells. Such information is of considerable use in choosing solvent-specific surfactants for enhanced remediation operations.

Jackson, R.E.; Mariner, P.E. [INTERA Inc., Austin, TX (United States)

1995-05-01

376

Slow desorption mechanisms of volatile organic chemical mixtures in soil and sediment micropores.  

PubMed

Desorption profiles of trichloroethylene (TCE), tetrachloroethylene (PCE), and a TCE-PCE mixture were measured for three natural solids and four zeolites. Initial sorbed mass (Mi) in slow desorbing sites of natural solids and in micropores of zeolites were obtained from desorption profiles. In natural solids, Mi increases with recalcitrant organic matter content. In zeolites, Mi generally increases with decreasing micropore width and increasing micropore hydrophobicity, but the effect of hydrophobicity is stronger. In both natural solids and zeolites, competition between TCE and PCE causes Mi for each sorbate in the mixture to be less than or similar to that for each sorbate alone. Zeolite results indicate that micropore width affects this competition more than micropore hydrophobicity for the solids examined. Desorption in all solids was simulated with the radial diffusion model, either alone or coupled with the advection-dispersion equation when necessary; diffusion rate constants (D/R2) were obtained. In natural solids, mean values of D/R2 increase with decreasing recalcitrant organic matter content. In zeolites, values of D/R2 generally increase with increasing micropore width, while they are a weak function of hydrophobicity. In both natural solids and zeolites, competition between TCE and PCE causes D/R2 for each sorbate in the mixture to generally be larger than that for each sorbate alone. Zeolite results indicate that the effects of competition on D/R2 generally decrease with decreasing micropore width for the solids examined; a trend with micropore hydrophobicity is not apparent. For the three natural solids and four zeolites examined in this study, the similar effects of competition between TCE and PCE on values of Mi and D/R2 and the overlapping range of D/R2 values support the hypothesis that diffusion through hydrophobic micropores affects and may control slow mass transfer processes in the recalcitrant organic matter of natural solids. These results contribute to the fundamental understanding of slow mass transfer processes in natural solids, and they indicate that characterization of micropore width and polarity may be necessary to predict organic chemical transport and fate. PMID:14750718

Li, Jun; Werth, Charles J

2004-01-15

377

Comparison of Reductive Dechlorination of Chlorinated Ethylene in Batch and Continuous-Flow Reactor  

NASA Astrophysics Data System (ADS)

A 1.28 L-Batch reactor and continuous-flow stirred tank reactor (CFSTR) fed with formate and trichloriethene (TCE) were operated for 120 days and 72 days, respectively, to study the effect of formate as electron donor on reductive dechlorination of TCE to cis-1,2-dichloroethylene (c-DCE), vinyl chloride (VC), and ethylene (ETH). In batch reactor, injected 60 ?mol TCE was completely degraded in presence of 20% hydrogen gas (H2) in less than 8 days by Evanite culture (300 mg-soluble protein) with ability to completely degrade tetrachloroethene (PCE) and TCE to ETH under anaerobic conditions. To determine the effect of formate as electron donor instead of H2, about 3 or 11 mmol of formate injected into batch-reactor every 15 days was enough to support H2 for dechlorination of c-DCE to VC and ETH. Soluble protein concentration of Evanite culture during the batch test increased from 300 mg to 688 mg for 120 days. In CFSTR test, TCE was fed continuously at 9.9 ppm (75.38 ?mol/L) and the influent formate feed concentration increased stepwise from 1.3 mmol/L to 14.3 mmol/L. Injected TCE was accumulated at HRT 18 days for 13 days, but TCE was completed degraded at HRT 36 days without accumulation during left of experiment period, getting H2 from fermentative hydrogen production of injected formate. Although c-DCE was also accumulated for 23 days after CFSTR operation, it reached steady-state without accumulation in presence of excessive formate. However, since c-DCE in CFSTR was not completely dechlorinated, we will determine the transcriptional level of enzyme involved in reductive dechlorination of TCE, c-DCE, and VC in our future work.

Park, S.; Jonghwan, L.; Hong, U.; Kim, N.; Ahn, H.; Lee, S.; Kim, Y.

2010-12-01

378

Risk-based economic decision analysis of remediation options at a PCE-contaminated site.  

PubMed

Remediation methods for contaminated sites cover a wide range of technical solutions with different remedial efficiencies and costs. Additionally, they may vary in their secondary impacts on the environment i.e. the potential impacts generated due to emissions and resource use caused by the remediation activities. More attention is increasingly being given to these secondary environmental impacts when evaluating remediation options. This paper presents a methodology for an integrated economic decision analysis which combines assessments of remediation costs, health risk costs and potential environmental costs. The health risks costs are associated with the residual contamination left at the site and its migration to groundwater used for drinking water. A probabilistic exposure model using first- and second-order reliability methods (FORM/SORM) is used to estimate the contaminant concentrations at a downstream groundwater well. Potential environmental impacts on the local, regional and global scales due to the site remediation activities are evaluated using life cycle assessments (LCA). The potential impacts on health and environment are converted to monetary units using a simplified cost model. A case study based upon the developed methodology is presented in which the following remediation scenarios are analyzed and compared: (a) no action, (b) excavation and off-site treatment of soil, (c) soil vapor extraction and (d) thermally enhanced soil vapor extraction by electrical heating of the soil. Ultimately, the developed methodology facilitates societal cost estimations of remediation scenarios which can be used for internal ranking of the analyzed options. Despite the inherent uncertainties of placing a value on health and environmental impacts, the presented methodology is believed to be valuable in supporting decisions on remedial interventions. PMID:20117877

Lemming, Gitte; Friis-Hansen, Peter; Bjerg, Poul L

2010-05-01

379

Risk-based economic decision analysis of remediation options at a PCE-contaminated site  

Microsoft Academic Search

Remediation methods for contaminated sites cover a wide range of technical solutions with different remedial efficiencies and costs. Additionally, they may vary in their secondary impacts on the environment i.e. the potential impacts generated due to emissions and resource use caused by the remediation activities. More attention is increasingly being given to these secondary environmental impacts when evaluating remediation options.

Gitte Lemming; Peter Friis-Hansen; Poul L. Bjerg

2010-01-01

380

REDUCTIVE DECHLORINATION OF TETRACHLORIDE (PCE) CATALYZED BY CYANOCOBALAMIN. (R825689C060)  

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

381

COMPARISON OF DONOR SUBSTRATES FOR BIOLOGICALLY ENHANCED TETRACHLOROETHENE (PCE) DNAPL DISSOLUTION. (R828772)  

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

382

VAPOR PHASE TREATMENT OF PCE IN A SOIL COLUMN BY LAB-SCALE ANAEROBIC BIOVENTING  

EPA Science Inventory

Microbial destruction of highly chlorinated organic compounds must be initiated by anaerobic followed by aerobic dechlorination. In-situ dechlorination of vadose zone soil contaminated with these compounds requires, among other factors, the establishment of highly reductive anaer...

383

Carbon and chlorine isotope fractionation during microbial degradation of tetra- and trichloroethene.  

PubMed

Two-dimensional compound-specific isotope analysis (2D-CSIA), combining stable carbon and chlorine isotopes, holds potential for monitoring of natural attenuation of chlorinated ethenes (CEs) in contaminated soil and groundwater. However, interpretation of 2D-CSIA data sets is challenged by a shortage of experimental Cl isotope enrichment factors. Here, isotope enrichments factors for C and Cl (i.e., ?C and ?Cl) were determined for biodegradation of tetrachloroethene (PCE) and trichloroethene (TCE) using microbial enrichment cultures from a heavily CE-contaminated aquifer. The obtained values were ?C = -5.6 ± 0.7‰ (95% CI) and ?Cl = -2.0 ± 0.5‰ for PCE degradation and ?C = -8.8 ± 0.2‰ and ?Cl = -3.5 ± 0.5‰ for TCE degradation. Combining the values for both ?C and ?Cl yielded mechanism-diagnostic ?Cl/?C ratios of 0.35 ± 0.11 and 0.37 ± 0.11 for the degradation of PCE and TCE, respectively. Application of the obtained ?C and ?Cl values to a previously investigated field site gave similar estimates for the fraction of degraded contaminant as in the previous study, but with a reduced uncertainty in assessment of the natural attenuation. Furthermore, 16S rRNA gene clone library analyses were performed on three samples from the PCE degradation experiments. A species closely related to Desulfitobacterium aromaticivorans UKTL dominated the reductive dechlorination process. This study contributes to the development of 2D-CSIA as a tool for evaluating remediation strategies of CEs at contaminated sites. PMID:23668287

Wiegert, Charline; Mandalakis, Manolis; Knowles, Tim; Polymenakou, Paraskevi N; Aeppli, Christoph; Machá?ková, Ji?ina; Holmstrand, Henry; Evershed, Richard P; Pancost, Richard D; Gustafsson, Orjan

2013-06-18

384

Enhanced utilization of oxidants for in situ chemical oxidation of chlorinated and aromatic hydrocarbons  

NASA Astrophysics Data System (ADS)

Potentially viable strategies were sought for enhanced utilization of potassium permanganate (KMnO4) and Fenton's reagent during in situ chemical oxidation (ISCO). An innovative concept of controlled release of oxidant was introduced and organic-coated, completely or partially microencapsulated KMnO4 (MEPP) particles (874 +/- 377 mum) were created to serve a material that can be specifically targeted to a contaminant source zone. Paraffin wax was employed as the coating material because it is biodegradable, inert to KMnO4, insoluble in water and yet soluble in hydrophobic contaminants such as perchloroethylene (PCE). KMnO4 was released very slowly into water, but the oxidant was rapidly released into PCE. The estimated times for 90% release of the oxidant were 1.6 months, 19.3 years, and 472 years for paraffin wax to KMnO4 mass ratios of 1:1, 2:1 and 5:1, respectively. The MEPP particles preferentially accumulated at the PCE-water interface, and the KMnO4 was rapidly released into PCE (<3 min) as the paraffin wax completely dissolved. These findings suggest that enhanced contact between the target contaminant and the locally high concentrations of KMnO 4 could be achieved at the interfacial region between PCE and water. Fenton's oxidative destruction was investigated for aromatic hydrocarbons (benzene, toluene, ethylbenzene, and o-xylene; BTEX) present as dissolved and adsorbed phases, and chlorinated hydrocarbon (PCE) present mostly as dense non-aqueous phase liquid (DNAPL) (>93% of total PCE mass) in batch reactors (soil: solution = 1 g/L). An enhanced mass removal was observed by combining 300 mM H2O2, 2 mM Fe(III) and 2 mM N-(2-hydroxyethyl)iminodiacetic acid (HEIDA) at near-neutral pH. The PCE degradation was maximal at 600 mM H2O2, 5 mM Fe(III) and 5 mM HEIDA at pH 3. The observed BTEX mass removal rate constants (3.6--7.8 x 10-4 s-1) were compared to the estimated ones (4.1--10.1 x 10-3 s-1) using a semi-quantitative kinetic model. The model sensitivity analyses indicate that iron oxides and soil organic matter could play important roles in the non-specific losses of both H 2O2 and ·OH. These findings suggest that system design could be optimized with respect to process variables in remediation of contaminated soils and groundwater with Fenton's reagent.

Kang, Namgoo

385

Probabilistic Health Risk Assessment of Chemical Mixtures: Importance of Travel Times and Connectivity  

NASA Astrophysics Data System (ADS)

Subsurface contamination cases giving rise to groundwater pollutions are extensively found in all industrialized countries. Under this pressure, risk assessment methods play an important role in population protection by (1) quantifying the potential impact on human health of an aquifer contamination and (2) helping and driving decisions of groundwater-resource managers. Many reactive components such as chlorinated solvents or nitrates potentially experience attenuation processes under common geochemical conditions. This represents an attractive and extensively used remediation solution but leads often to the production of by-products before to reach a harmless chemical form. This renders mixtures of contaminants a common issue for groundwater resources managers. In this case, the threat posed by these contaminants to human health at a given sensitive location greatly depends on the competition between reactive and advective-dispersive characteristic times. However, hydraulic properties of the aquifer are known to be spatially variable, which can lead to the formation of preferential flow channels and fast contamination pathways. Therefore, the uncertainty on the spatial distribution of the aquifer properties controlling the plume travel time may then play a particular role in the human health risk assessment of chemical mixtures. We investigate here the risk related to a multispecies system in response to different degrees of heterogeneity of the hydraulic conductivity (K or Y =ln(K)). This work focuses on a Perchloroethylene (PCE) contamination problem followed by the sequential first-order production/biodegradation of its daughter species Trichloroethylene (TCE), Dichloroethylene (DCE) and Vinyl Chlorine (VC). For this specific case, VC is known to be a highly toxic contaminant. By performing numerical experiments, we evaluate transport through three-dimensional mildly (?Y 2=1.0) and highly (?Y 2=4.0) heterogeneous aquifers. Uncertainty on the hydraulic conductivity field is considered through a Monte Carlo scheme, and statistics of the total risk for human health (RT) related to the mixtures of the four carcinogenic plumes are evaluated. Results show two distinct spatiotemporal behavior of the RT estimation. Simulations in highly heterogeneous aquifers display a lower mean of RT close to the injection and higher further away. We explain this by the distinct ranges of travel times and connectivity metrics related to the two sets of aquifers. A high ?Y 2 trends to decrease the travel time (and increase the connectivity). Early travel times, associated to channeling effects, are intuitively perceived as an indicator for high risk. However, in our case, early travel times lead a limited production of highly toxic daughter species and a lower total risk. Our results reflect then the interplay between the characteristic reactive time for each component and the characteristic travel time of the plume since the production of VC depends on these factors.

Henri, Christopher V.; Fernàndez-Garcia, Daniel; de Barros, Felipe P. J.

2014-05-01

386

Assessment of subsurface chlorinated solvent contamination using tree cores at the front street site and a former dry cleaning facility at the Riverfront Superfund site, New Haven, Missouri, 1999-2003  

USGS Publications Warehouse

Tree-core sampling has been a reliable and inexpensive tool to quickly assess the presence of shallow (less than about 30 feet deep) tetrachloroethene (PCE) and trichloroethene (TCE) contamination in soils and ground water at the Riverfront Superfund Site. This report presents the results of tree-core sampling that was successfully used to determine the presence and extent of chlorinated solvent contamination at two sites, the Front Street site (operable unit OU1) and the former dry cleaning facility, that are part of the overall Riverfront Superfund Site. Traditional soil and ground-water sampling at these two sites later confirmed the results from the tree-core sampling. Results obtained from the tree-core sampling were used to design and focus subsequent soil and ground-water investigations, resulting in substantial savings in time and site assessment costs. The Front Street site is a small (less than 1-acre) site located on the Missouri River alluvium in downtown New Haven, Missouri, about 500 feet from the south bank of the Missouri River. Tree-core sampling detected the presence of subsurface PCE contamination at the Front Street site and beneath residential property downgradient from the site. Core samples from trees at the site contained PCE concentrations as large as 3,850 mg-h/kg (micrograms in headspace per kilogram of wet core) and TCE concentrations as large as 249 mg-h/kg. Soils at the Front Street site contained PCE concentrations as large as 6,200,000 mg/kg (micrograms per kilogram) and ground-water samples contained PCE concentrations as large as 11,000 mg/L (micrograms per liter). The former dry cleaning facility is located at the base of the upland that forms the south bank of the Missouri River alluvial valley. Tree-core sampling did not indicate the presence of PCE or TCE contamination at the former dry cleaning facility, a finding that was later confirmed by the analyses of soil samples collected from the site. The lateral extent of PCE contamination in trees was in close agreement with the extent of subsurface PCE contamination determined using traditional soil and ground-water sampling methods. Trees growing in soils containing PCE concentrations of 60 to 5,700 mg/kg or larger or overlying ground water containing PCE concentrations from 5 to 11,000 mg/L generally contained detectable concentrations of PCE. The depth to contaminated ground water was about 20 to 25 feet below the land surface. Significant quantitative relations [probability (p) values of less than 0.05 and correlation coefficient (r2) values of 0.88 to 0.90] were found between PCE concentrations in trees and subsurface soils between 4 and 16 feet deep. The relation between PCE concentrations in trees and underlying ground water was less apparent (r2 value of 0.17) and the poor relation is thought to be the result of equilibrium with PCE concentrations in soil and vapor in the unsaturated zone. Based on PCE concentrations detected in trees at the Front Street site and trees growing along contaminated tributaries in other operable units, and from field hydroponic experiments using hybrid poplar cuttings, analysis of tree-core samples appears to be able to detect subsurface PCE contamination in soils at levels of several hundred micrograms per liter or less and PCE concentrations in the range of 8 to 30 mg/L in ground water in direct contact with the roots. Loss of PCE from tree trunks by diffusion resulted in an exponential decrease in PCE concentrations with increasing height above the land surface in most trees. The rate of loss also appeared to be a function of the size and growth characteristics of the tree as some trees exhibited a linear loss with increasing height. Diffusional loss of PCE in small (0.5-inch diameter) trees was observed to occur at a rate more than 10 times larger than in trees 6.5 inches in diameter. Concentrations of PCE also exhibited directional variability around the tree trunks and concentration differe

Schumacher, John G.; Struckhoff, Garrett C.; Burken, Joel G.

2004-01-01

387

Effects of bioaugmentation on enhanced reductive dechlorination of 1,1,1-trichloroethane in groundwater: a comparison of three sites.  

PubMed

Microcosm studies investigated the effects of bioaugmentation with a mixed Dehalococcoides (Dhc)/Dehalobacter (Dhb) culture on biological enhanced reductive dechlorination for treatment of 1,1,1-trichloroethane (TCA) and chloroethenes in groundwater at three Danish sites. Microcosms were amended with lactate as electron donor and monitored over 600 days. Experimental variables included bioaugmentation, TCA concentration, and presence/absence of chloroethenes. Bioaugmented microcosms received a mixture of the Dhc culture KB-1 and Dhb culture ACT-3. To investigate effects of substrate concentration, microcosms were amended with various concentrations of chloroethanes (TCA or monochloroethane [CA]) and/or chloroethenes (tetrachloroethene [PCE], trichloroethene [TCE], or 1,1-dichloroethene [1,1-DCE]). Results showed that combined electron donor addition and bioaugmentation stimulated dechlorination of TCA and 1,1-dichloroethane (1,1-DCA) to CA, and dechlorination of PCE, TCE, 1,1-DCE and cDCE to ethane. Dechlorination of CA was not observed. Bioaugmentation improved the rate and extent of TCA and 1,1-DCA dechlorination at two sites, but did not accelerate dechlorination at a third site where geochemical conditions were reducing and Dhc and Dhb were indigenous. TCA at initial concentrations of 5 mg/L inhibited (i.e., slowed the rate of) TCA dechlorination, TCE dechlorination, donor fermentation, and methanogenesis. 1 mg/L TCA did not inhibit dechlorination of TCA, TCE or cDCE. Moreover, complete dechlorination of PCE to ethene was observed in the presence of 3.2 mg/L TCA. In contrast to some prior reports, these studies indicate that low part-per million levels of TCA (< 3 mg/L) in aquifer systems do not inhibit dechlorination of PCE or TCE to ethene. In addition, the results show that co-bioaugmentation with Dhc and Dhb cultures can be an effective strategy for accelerating treatment of chloroethane/chloroethene mixtures in groundwater, with the exception that all currently known Dhc and Dhb cultures cannot treat CA. PMID:24233554

Scheutz, Charlotte; Durant, Neal D; Broholm, Mette M

2014-06-01

388

Observation of the Dissolution from Residual Phase Multicomponent Nonaqueous Phase Liquids  

NASA Astrophysics Data System (ADS)

Nonaqueous phase liquid (NAPL) subsurface contaminants (e.g., fuels, solvents) are typically complex mixtures. This work examines the impact of intra-NAPL diffusion and mixture nonideality on dissolution from multicomponent NAPL mixtures through a computational and experimental approach. Downstream concentrations are observed during the controlled dissolution of three-component residual NAPL in a three-dimensional model aquifer. These results, when compared to single-component residual NAPL results, are used to identify (1) if and when intra-NAPL interactions contribute significantly to the overall dissolution process, and (2) the role that factors, such as length scale, hydrodynamic conditions, and/or mixture ideality, play in determining (1). Model ternary mixtures were chosen to represent a range of ideality based on UNIFAC-estimated activity coefficients. In this case, tetrachloroethene (PCE), trichloroethene (TCE), and 1,1,1-trichloroethane (TCA) were selected as the ideal mixture. The mixture of PCE, TCE, and octanol was shown to exhibit significant deviations from ideality and selected to represent a nonideal mixture. Experimental results for the two mixtures are compared to each other and to analogous results from pure PCE dissolution experiments. The experimental results are further interpreted using a three-dimensional transport model subject to a boundary concentration history calculated using a ternary intra-NAPL diffusion/dissolution submodel. The combined experimental and computational findings are used to delineate conditions for which a detailed physical-chemical description of NAPL dissolution is warranted and those for which a simplified description will suffice.

Brahma, P. P.; Harmon, T. C.

2001-05-01

389

Quantitative PCR Confirms Purity of Strain GT, a Novel Trichloroethene-to-Ethene-Respiring Dehalococcoides Isolate  

PubMed Central

A novel Dehalococcoides isolate capable of metabolic trichloroethene (TCE)-to-ethene reductive dechlorination was obtained from contaminated aquifer material. Growth studies and 16S rRNA gene-targeted analyses suggested culture purity; however, the careful quantitative analysis of Dehalococcoides 16S rRNA gene and chloroethene reductive dehalogenase gene (i.e., vcrA, tceA, and bvcA) copy numbers revealed that the culture consisted of multiple, distinct Dehalococcoides organisms. Subsequent transfers, along with quantitative PCR monitoring, yielded isolate GT, possessing only vcrA. These findings suggest that commonly used qualitative 16S rRNA gene-based procedures are insufficient to verify purity of Dehalococcoides cultures. Phylogenetic analysis revealed that strain GT is affiliated with the Pinellas group of the Dehalococcoides cluster and shares 100% 16S rRNA gene sequence identity with two other Dehalococcoides isolates, strain FL2 and strain CBDB1. The new isolate is distinct, as it respires the priority pollutants TCE, cis-1,2-dichloroethene (cis-DCE), 1,1-dichloroethene (1,1-DCE), and vinyl chloride (VC), thereby producing innocuous ethene and inorganic chloride. Strain GT dechlorinated TCE, cis-DCE, 1,1-DCE, and VC to ethene at rates up to 40, 41, 62, and 127 ?mol liter?1 day?1, respectively, but failed to dechlorinate PCE. Hydrogen was the required electron donor, which was depleted to a consumption threshold concentration of 0.76 ± 0.13 nM with VC as the electron acceptor. In contrast to the known TCE dechlorinating isolates, strain GT dechlorinated TCE to ethene with very little formation of chlorinated intermediates, suggesting that this type of organism avoids the commonly observed accumulation of cis-DCE and VC during TCE-to-ethene dechlorination.

Sung, Youlboong; Ritalahti, Kirsti M.; Apkarian, Robert P.; Loffler, Frank E.

2006-01-01

390

Laboratory and controlled field experiments using potassium permanganate to remediate trichloroethylene and perchloroethylene DNAPLs in porous media  

Microsoft Academic Search

Few proven technologies exist that may be used to treat dense non-aqueous phase liquid (DNAPL) contaminants. In-situ chemical flushing is a proposed technology which consists of flushing DNAPL source zones with a reactive solution to degrade the contaminant mass below ground.A laboratory and controlled field experimental program was conducted to assess the potential of potassium permanganate (KMnO4) as a reagent

M. Schnarr; C. Truax; G. Farquhar; E. Hood; T. Gonullu; B. Stickney

1998-01-01

391

Process for removing halogenated aliphatic and aromatic compounds from petroleum products. [Polychlorinated biphenyls; methylene chloride; perchloroethylene; trichlorofluoroethane; trichloroethylene; chlorobenzene  

DOEpatents

A process for removing halogenated aliphatic and aromatic compounds, e.g., polychlorinated biphenyls, from petroleum products by solvent extraction. The halogenated aliphatic and aromatic compounds are extracted from a petroleum product into a polar solvent by contracting the petroleum product with the polar solvent. The polar solvent is characterized by a high solubility for the extracted halogenated aliphatic and aromatic compounds, a low solubility for the petroleum product and considerable solvent power for polyhydroxy compound. The preferred polar solvent is dimethylformamide. A miscible polyhydroxy compound, such as, water, is added to the polar extraction solvent to increase the polarity of the polar extraction solvent. The halogenated aliphatic and aromatic compounds are extracted from the highly-polarized mixture of polyhydroxy compound and polar extraction solvent into a low polar or nonpolar solvent by contacting the polyhydroxy compound-polar solvent mixture with the low polar or nonpolar solvent. The halogenated aliphatic and aromatic compounds in the low polar or nonpolar solvent by physical means, e.g., vacuum evaporation. The polar and nonpolar solvents are recovered for recycling. The process can easily be designed for continuous operation. Advantages of the process include that the polar solvent and a major portion of the nonpolar solvent can be recycled, the petroleum products are reclaimable and the cost for disposing of waste containing polychlorinated biphenyls is significantly reduced. 2 tables.

Googin, J.M.; Napier, J.M.; Travaglini, M.A.

1982-03-31

392

Coupling of Realistic Rate Estimates with Genomics for Assessing Contaminant Attenuation and Long-Term Plume Containment  

SciTech Connect

Natural attenuation of TCE under aerobic conditions at the INEEL Test Area North site was demonstrated largely on the basis of preferential loss of TCE relative to conservative solutes (PCE and H-3) along groundwater flow paths. First order degradation half-lives were calculated from the rate of preferential TCE loss. We are utilizing the same approach at other DOE sites that have aerobic TCE plumes to determine if aerobic natural attenuation of TCE is rapid enough at these sites to be environmentally significant, i.e. if natural attenuation can reduce concentrations to acceptable levels before groundwater reaches potential receptors. The first step in this process was to identify TCE plumes at DOE sites that have the appropriate site conditions and data needed to perform this analysis. The site conditions include the presence of TCE in groundwater at appreciable concentrations in an aerobic aquifer, a co-mingled contaminant that can be used as a conservative tracer (e.g. PCE, H-3, Tc-99), a flow path that represents at least a decade of travel time, and several monitoring wells located along this flow path. Candidate sites were identified through interviews with knowledgeable individuals in the DOE system and by screening the U.S. Dept. of Energy Groundwater Database using the keywords ''TCE'' and ''groundwater''. The initial screening yielded 25 plumes for consideration. These sites had anywhere from one to 37 individual plumes containing TCE. Of the 25 sites, 13 sites were further evaluated because they met the screening criteria or were promising. After contacting DOE personnel from the respective sites, they were divided into three groups: (1) sites that meet all the project criteria, (2) sites that could potentially be used for the project, and (3) DOE sites that did not meet the criteria. The five sites with plumes that met the criteria were: Brookhaven National Laboratory, Lawrence Livermore National Laboratory, Paducah Gaseous Diffusion Plant, Rocky Flats Environmental Technology Site, and the Savannah River Site. Detailed characterization data from the promising plumes is being entered into our database as it is received. The next step is to calculate natural attenuation half-life values for all of these plumes. We will next identify the plumes in which natural attenuation via aerobic degradation of TCE is fast enough that it may be relevant as a component of a remedy. We will then select at least one of these sites and either modify an existing groundwater transport model or, if necessary, create a new model, for this plume. This model will initially include first order decay of TCE, and degradation will be parameterized using the half-live values determined from the field data. The models will be used to simulate the evolution of the TCE plume and to predict concentrations as a function of time at property lines or other artificial boundaries, and where potential receptors are located. Ultimately rate data from th e laboratory studies being performed at INEEL will be incorporated into this model, as well as the model of the TAN site to provide a realistic prediction of degradation rates and plume longevity. Although identifying suitable TCE plumes and obtaining characterization data has taken longer than expected, this process has successfully identified the plumes needed for the detailed modeling activity without adversely impacting the project budget.

Sorenson, Kent S. Jr.

2003-06-01

393

Refinement of the density-modified displacement method for efficient treatment of tetrachloroethene source zones  

NASA Astrophysics Data System (ADS)

A novel method to remediate dense nonaqueous phase liquid (DNAPL) source zones that incorporates in situ density conversion of DNAPL via alcohol partitioning followed by displacement with a low interfacial tension (IFT) surfactant flood has been developed. Previous studies demonstrated the ability of the density-modified displacement (DMD) method to recover chlorobenzene (CB) and trichloroethene (TCE) from heterogeneous porous media without downward migration of the dissolved plume or free product. However, the extent of alcohol ( n-butanol) partitioning required for in situ density conversion of high-density NAPLs, such as tetrachloroethene (PCE), could limit the utility of the DMD method. Hence, the objective of this study was to compare the efficacy of two n-butanol delivery approaches: an aqueous solution of 6% (wt) n-butanol and a surfactant-stabilized macroemulsion containing 15% (vol) n-butanol in water, to achieve density reduction of PCE-NAPL in two-dimensional (2-D) aquifer cells. Results of liquid-liquid equilibrium studies indicated that density conversion of PCE relative to water occurred at an n-butanol mole fraction of 0.56, equivalent to approximately 5 ml n-butanol per 1 ml of PCE when in equilibrium with an aqueous solution. In 2-D aquifer cell studies, density conversion of PCE was realized using both n-butanol preflood solutions, with effluent NAPL samples exhibiting density reductions ranging from 0.51 to 0.70 g/ml. Although the overall PCE mass recoveries were similar (91% and 93%) regardless of the n-butanol delivery method, the surfactant-stabilized macroemulsion preflood removed approximately 50% of the PCE mass. In addition, only 1.2 pore volumes of the macroemulsion solution were required to achieve in situ density conversion of PCE, compared to 6.4 pore volumes of the 6% (wt) n-butanol solution. These findings demonstrate that use of the DMD method with a surfactant-stabilized macroemulsion containing n-butanol holds promise as an effective source zone remediation technology, allowing for efficient recovery of PCE-DNAPL while mitigating downward migration of the dissolved plume and free product.

Ramsburg, C. Andrew; Pennell, Kurt D.; Kibbey, Tohren C. G.; Hayes, Kim F.

2004-10-01

394

Public health assessment for north Penn-area 1, Souderton, Montgomery County, Pennsylvania, Region 3. Cerclis No. PAD096834494. Final report  

SciTech Connect

The North Penn Area 1 site, a National Priorities List (NPL) site, is located in the Borough of Souderton, Montgomery County, Pennsylvania. Gentle, Cleaners, Inc., one of the parties potentially responsible for the site contamination, has been in business since 1953 and used tetrachloroethene (PCE) from 1953 to 1983 in dry cleaning operations. At present, groundwater is the only medium that is known to be contaminated. Enviromental data for surface soil, surface water, sediment, and air do not exist. Past, present, and future completed exposure pathways for volatile organic compounds such as PCE and TCE in groundwater exist for nearby residents. The site is considered an indeterminate public health hazard because limited data are available; however, data that are available do not indicate that humans are being or have been exposed to levels of contaminants that would be expected to cause any adverse health effects.

Not Available

1994-01-12

395

A controlled field experiment on groundwater contamination by a multicomponent DNAPL: creation of the emplaced-source and overview of dissolved plume development.  

PubMed

A unique field experiment has been undertaken at the CFB Borden research site to investigate the development of dissolved chlorinated solvent plumes from a residual dense non-aqueous phase liquid (DNAPL) source. The "emplaced-source" tracer test methodology involved a controlled emplacement of a block-shaped source of sand containing chlorinated solvents below the water table. The gradual dissolution of this residual DNAPL solvent source under natural aquifer conditions caused dissolved solvent plumes of trichloromethane (TCM), trichloroethene (TCE) and perchloroethene (PCE) to continuously develop down gradient. Source dissolution and 3-D plume development were successfully monitored via 173 multilevel samplers over a 475-day tracer test period prior to site remediation research being initiated. Detailed groundwater level and hydraulic conductivity data were collected. Development of plumes with concentrations spanning 1-700,000 micrograms/1 is described and key processes controlling their migration identified. Plumes were observed to be narrow due to the weakness of transverse dispersion processes and long due to advection and significant longitudinal dispersion, very limited sorptive retardation and negligible, if any, attenuation due to biodegradation or abiotic reaction. TCM was shown to be essentially conservative, TCE very nearly conservative and PCE, consistent with its greater hydrophobicity, more retarded yet having a greater mobility than observed in previous Borden field tests. The absence of biodegradation was ascribed to the prevailing aerobic conditions and lack of any additional biodegradable carbon substrates. The transient groundwater flow regime caused significant transverse lateral plume movement, plume asymmetry and was likely responsible for most of the, albeit limited, transverse horizontal plume spreading. In agreement with the widespread incidence of extensive TCE and PCE plumes throughout the industrialized world, the experiment indicates such solvent plumes are likely to be highly mobile and persistent, at least in aquifers that are aerobic and have low sorption potential (low foc content). PMID:11351512

Rivett, M O; Feenstra, S; Cherry, J A

2001-05-01

396

A controlled field experiment on groundwater contamination by a multicomponent DNAPL: creation of the emplaced-source and overview of dissolved plume development  

NASA Astrophysics Data System (ADS)

A unique field experiment has been undertaken at the CFB Borden research site to investigate the development of dissolved chlorinated solvent plumes from a residual dense non-aqueous phase liquid (DNAPL) source. The "emplaced-source" tracer test methodology involved a controlled emplacement of a block-shaped source of sand containing chlorinated solvents below the water table. The gradual dissolution of this residual DNAPL solvent source under natural aquifer conditions caused dissolved solvent plumes of trichloromethane (TCM), trichloroethene (TCE) and perchloroethene (PCE) to continuously develop down gradient. Source dissolution and 3-D plume development were successfully monitored via 173 multilevel samplers over a 475-day tracer test period prior to site remediation research being initiated. Detailed groundwater level and hydraulic conductivity data were collected. Development of plumes with concentrations spanning 1-700,000 ?g/l is described and key processes controlling their migration identified. Plumes were observed to be narrow due to the weakness of transverse dispersion processes and long due to advection and significant longitudinal dispersion, very limited sorptive retardation and negligible, if any, attenuation due to biodegradation or abiotic reaction. TCM was shown to be essentially conservative, TCE very nearly conservative and PCE, consistent with its greater hydrophobicity, more retarded yet having a greater mobility than observed in previous Borden field tests. The absence of biodegradation was ascribed to the prevailing aerobic conditions and lack of any additional biodegradable carbon substrates. The transient groundwater flow regime caused significant transverse lateral plume movement, plume asymmetry and was likely responsible for most of the, albeit limited, transverse horizontal plume spreading. In agreement with the widespread incidence of extensive TCE and PCE plumes throughout the industrialized world, the experiment indicates such solvent plumes are likely to be highly mobile and persistent, at least in aquifers that are aerobic and have low sorption potential (low foc content).

Rivett, Michael O.; Feenstra, Stanley; Cherry, John A.

2001-05-01

397

Subsurface occurrence and potential source areas of chlorinated ethenes identified using concentrations and concentration ratios, Air Force Plant 4 and Naval Air Station-Joint Reserve Base Carswell Field, Fort Worth, Texas  

USGS Publications Warehouse

The U.S. Geological Survey, in cooperation with the U.S. Air Force Aeronautical Systems Center, Environmental Management Directorate, conducted a study during 2003-05 to characterize the subsurface occurrence and identify potential source areas of the volatile organic compounds classified as chlorinated ethenes at U.S. Air Force Plant 4 (AFP4) and adjacent Naval Air Station-Joint Reserve Base Carswell Field (NAS-JRB) at Fort Worth, Texas. The solubilized chlorinated ethenes detected in the alluvial aquifer originated as either released solvents (tetrachloroethene [PCE], trichloroethene [TCE], and trans-1,2-dichloroethene [trans-DCE]) or degradation products of the released solvents (TCE, cis-1,2-dichloroethene [cis-DCE], and trans-DCE). The combined influences of topographic- and bedrock-surface configurations result in a water table that generally slopes away from a ground-water divide approximately coincident with bedrock highs and the 1-mile-long aircraft assembly building at AFP4. Highest TCE concentrations (10,000 to 920,000 micrograms per liter) occur near Building 181, west of Building 12, and at landfill 3. Highest PCE concentrations (500 to 920 micrograms per liter) occur near Buildings 4 and 5. Highest cis-DCE concentrations (5,000 to 710,000 micrograms per liter) occur at landfill 3. Highest trans-DCE concentrations (1,000 to 1,700 micrograms per liter) occur just south of Building 181 and at landfill 3. Ratios of parent-compound to daughter-product concentrations that increase in relatively short distances (tens to 100s of feet) along downgradient ground-water flow paths can indicate a contributing source in the vicinity of the increase. Largest increases in ratio of PCE to TCE concentrations are three orders of magnitude from 0.01 to 2.7 and 7.1 between nearby wells in the northeastern part of NAS-JRB. In the northern part of NAS-JRB, the largest increases in TCE to total DCE concentration ratios relative to ratios at upgradient wells are from 17 to 240 or from 17 to 260. In the southern part of NAS-JRB, the largest ratio increases with respect to those at upgradient wells are from 22 and 24 to 130, and from 0 and 7.2 to 71. Numerous maximum historical ratios of trans-DCE to cis-DCE are greater than 1, which can indicate that trans-DCE likely was released as a solvent and does not occur only as a result of degradation of TCE. High concentrations of TCE, PCE, cis-DCE, and trans-DCE, abrupt increases in ratios of PCE to TCE and TCE to total DCE, and ratios of trans-DCE to cis-DCE greater than 1 were used to identify 16 potential source areas of chlorinated ethenes at NAS-JRB. The evidence for some of the potential source areas is stronger than for others, but each area reflects one or more of the conditions indicative of chlorinated ethenes entering the aquifer. Potential source areas supported by the strongest evidence are Building 181, between buildings 4 and 5, just west of Building 12, and landfills 1 and 3. The highest historical TCE concentration in the study area, 920,000 micrograms per liter, is near Building 181. The potential source area between Buildings 4 and 5 primarily is identified by notably high PCE concentrations (to 920 micrograms per liter). Primary evidence for the potential source are just west of Building 12 is the notably high TCE concentrations (for example, 160,000 micrograms per liter) that appear to originate in the area. Primary evidence for the potential source area at landfills 1 and (primarily) 3 is the magnitudes of TCE concentrations (for example, two in the 100,000-to-920,000-microgram-per-liter range), cis-DCE concentrations (several in the 5,000-to-710,000-microgram-per-liter range), and trans-DCE concentrations (several in the 500-to-1,700-microgram-per-liter range). The ratio of trans-DCE to cis-DCE at one well in landfill 3 (6.7) is appreciably above the threshold that can indicate likely solvent release as opposed to TCE degradation alone.

Garcia, C. Amanda

2005-01-01

398

A two and half-year-performance evaluation of a field test on treatment of source zone tetrachloroethene and its chlorinated daughter products using emulsified zero valent iron nanoparticles.  

PubMed

A field test of emulsified zero valent iron (EZVI) nanoparticles was conducted at Parris Island, SC, USA and was monitored for two and half years to assess the treatment of subsurface-source zone chlorinated volatile organic compounds (CVOCs) dominated by tetrachloroethene (PCE) and its chlorinated daughter products. Two EZVI delivery methods were used: pneumatic injection and direct injection. In the pneumatic injection plot, 2180 L of EZVI containing 225 kg of iron (Toda RNIP-10DS), 856 kg of corn oil, and 22.5 kg of surfactant were injected to remedy an estimated 38 kg of CVOCs. In the direct injection plot, 572 L of EZVI were injected to treat an estimated 0.155 kg of CVOCs. After injection of the EZVI, significant reductions in PCE and trichloroethene (TCE) concentrations were observed in downgradient wells with corresponding increases in degradation products including significant increases in ethene. In the pneumatic injection plot, there were significant reductions in the downgradient groundwater mass flux values for PCE (>85%) and TCE (>85%) and a significant increase in the mass flux of ethene. There were significant reductions in total CVOC mass (86%); an estimated reduction of 63% in the sorbed and dissolved phases and 93% reduction in the PCE DNAPL mass. There are uncertainties in these estimates because DNAPL may have been mobilized during and after injection. Following injection, significant increases in dissolved sulfide, volatile fatty acids (VFA), and total organic carbon (TOC) were observed. In contrast, dissolved sulfate and pH decreased in many wells. The apparent effective remediation seems to have been accomplished by direct abiotic dechlorination by nanoiron followed by biological reductive dechlorination stimulated by the corn oil in the emulsion. PMID:22868086

Su, Chunming; Puls, Robert W; Krug, Thomas A; Watling, Mark T; O'Hara, Suzanne K; Quinn, Jacqueline W; Ruiz, Nancy E

2012-10-15

399

Public health assessment for Butz Landfill, Jackson Township, Monroe County, Pennsylvania, Region 3. Cerclis No. PAD981034705. Final report  

SciTech Connect

The Butz Landfill in Jackson Township, Monroe County, Pennsylvania, was added to the Environmental Protection Agency`s (EPA) National Priorities List (NPL) in March 1989. Groundwater contamination downgradient of the site, with subsequent contamination of private residential wells by volatile organic compounds (VOCs), eventually led EPA to construct a potable public water supply. The major contaminants found in the private wells are 1,1-dichloroethene (1,1-DCE), 1,2-dichloroethene (1,2-DCE), trichloroethene (TCE), and tetrachloroethene (PCE). The site posed a past public health hazard because people were exposed to contaminated groundwater.

NONE

1996-03-29

400

Nonpoint sources of volatile organic compounds in urban areas - Relative importance of land surfaces and air  

USGS Publications Warehouse

Volatile organic compounds (VOCs) commonly detected in urban waters across the United States include gasoline-related compounds (e.g. toluene, xylene) and chlorinated compounds (e.g. chloroform, tetrachloroethane [PCE], trichloroethene [TCE]). Statistical analysis of observational data and results of modeling the partitioning of VOCs between air and water suggest that urban land surfaces are the primary nonpoint source of most VOCs. Urban air is a secondary nonpoint source, but could be an important source of the gasoline oxygenate methyl-tert butyl ether (MTBE). Surface waters in urban areas would most effectively be protected by controlling land-surface sources.

Lopes, T. J.; Bender, D. A.

1998-01-01

401

Evidence for existence in human tissues of monomers for plastics and rubber manufacture.  

PubMed Central

Although exposure to many industrially important monomers is controlled by law, few of these reactive chemicals have been determined in human tissues. Analogy with other fat-soluble organic substances strongly implies that these monomers may be retained in tissue, subject to the usual physiological constraints of metabolism, solubility and volatility. The storage of DDT and PCBs is discussed, as well as tetrachloro-ethylene (PCE) and trichloroethylene (TCE), which are chemically similar to many industrially used monomers. Styrene in blood and breath and its metabolites in urine have been studied in humans. Styrene and vinyl chloride have been measured in fat tissue of polymerization workers.

Wolff, M S

1976-01-01

402

Public health assessment for Tutu Wellfield, St. Thomas, St. Thomas County, Virgin Islands. Cerclis No. VID982272569. Final report  

SciTech Connect

The Tutu Wellfield National Priorities List (NPL) site is in east-central St. Thomas, U.S. Virgin Island. Twenty-two wells in the Turpentine Run Basin contain at minimum a trace of volatile organic contaminants. Volatile and chlorinated hydrocarbons including benzene; toluene; 1,2-trans-dichloroethene (DCE); trichloroethene (TCE); and tetrachloroethene (PCE) were detected in several of the wells. The Agency for Toxic Substances and Disease Registry (ATSDR) has concluded that the Tutu Wellfield National Priorities List (NPL) site, St. Thomas, U.S. Virgin Islands, poses a public health hazard for past, present, and possible future ingestion of contaminated groundwater.

NONE

1996-05-14

403

OZON\\/DEM?R OKS?T YÖNTEM? ?LE SU K?RL?L??? ARITIMI  

Microsoft Academic Search

ÖZET - Bu çali?mada, ozonlama ile birlikte katalizör olarak demir oksit partikülleri kullanilarak sudan klorlu organik kirletici giderimi ara?tirilmi?tir. Demir oksit katalizörü olarak suda çözünürlü?ü dü?ük ve do?ada yaygin olarak bulunan geotit (?-FeOOH) kullanilmi?tir. Klorlu organik kirleticilere model olarak sularda do?al bozunma reaksiyonlari yava? olarak bilinen Trikloroetilen (TCE) ve Tetrakloroetilen (PCE) seçilmi?tir. Bu kirleticilerin sudan O3\\/?-FeOOH ile aritim çali?malari laboratuar

Ahmet KILIÇ