FIELD TESTS YIELD DIFFUSION COEFFICIENTS AND TRICHLOROETHENE (TCE) DEGRADATION RATES FOR A FRACTURED SEDIMENTARY ROCK AQUIFER

2018 ◽  
Author(s):  
Richelle M. Allen-King ◽  
◽  
Rory Dishman ◽  
Rebecca L. Kiekhaefer
Keyword(s):  
Diffusion Coefficients ◽  
Sedimentary Rock ◽  
Field Tests ◽  
Degradation Rates ◽  
Tce Degradation

scholarly journals Carbon Isotope Fractionation during Aerobic Biodegradation of Trichloroethene by Burkholderia cepacia G4: a Tool To Map Degradation Mechanisms

2002 ◽  
Vol 68 (4) ◽  
pp. 1728-1734 ◽  
Author(s):  
Johannes A. C. Barth ◽  
Greg Slater ◽  
Christoph Schüth ◽  
Markus Bill ◽  
Angela Downey ◽  
...  
Keyword(s):  
Carbon Isotope ◽  
Burkholderia Cepacia ◽  
Isotope Fractionation ◽  
Enrichment Factors ◽  
Aerobic Biodegradation ◽  
Isotope Shifts ◽  
Time Period ◽  
Degradation Rates ◽  
Tce Degradation ◽  
Enzymatic Mechanisms

ABSTRACT The strain Burkholderia cepacia G4 aerobically mineralized trichloroethene (TCE) to CO2 over a time period of ∼20 h. Three biodegradation experiments were conducted with different bacterial optical densities at 540 nm (OD540s) in order to test whether isotope fractionation was consistent. The resulting TCE degradation was 93, 83.8, and 57.2% (i.e., 7.0, 16.2, and 42.8% TCE remaining) at OD540s of 2.0, 1.1, and 0.6, respectively. ODs also correlated linearly with zero-order degradation rates (1.99, 1.11, and 0.64 μmol h−1). While initial nonequilibrium mass losses of TCE produced only minor carbon isotope shifts (expressed in per mille δ13CVPDB), they were 57.2, 39.6, and 17.0‰ between the initial and final TCE levels for the three experiments, in decreasing order of their OD540s. Despite these strong isotope shifts, we found a largely uniform isotope fractionation. The latter is expressed with a Rayleigh enrichment factor, ε, and was −18.2 when all experiments were grouped to a common point of 42.8% TCE remaining. Although, decreases of ε to −20.7 were observed near complete degradation, our enrichment factors were significantly more negative than those reported for anaerobic dehalogenation of TCE. This indicates typical isotope fractionation for specific enzymatic mechanisms that can help to differentiate between degradation pathways.

scholarly journals Construction and Use of an ipb DNA Module To Generate Pseudomonas Strains with Constitutive Trichloroethene and Isopropylbenzene Oxidation Activity

1998 ◽  
Vol 64 (7) ◽  
pp. 2454-2462 ◽  
Author(s):  
Frank Berendes ◽  
Nicolas Sabarth ◽  
Beate Averhoff ◽  
Gerhard Gottschalk
Keyword(s):  
Dna Sequences ◽  
Promoter Region ◽  
Sequence Similarity ◽  
Regulatory Protein ◽  
Continuous Cultivation ◽  
Oxidation Activity ◽  
Translational Initiation ◽  
Degradation Rates ◽  
Tce Degradation ◽  
Arac Family

ABSTRACT Pseudomonas sp. strain JR1 exhibits trichloroethene (TCE) oxidation activity with isopropylbenzene (IPB) as the inducer substrate. We previously reported the genes encoding the first three enzymes of the IPB-degradative pathway (ipbA1,ipbA2, ipbA3, ipbA4,ipbB, and ipbC) and identified the initial IPB dioxygenase (IpbA1A2A3A4) as responsible for TCE cooxidation (U. Pflugmacher, B. Averhoff, and G. Gottschalk, Appl. Environ. Microbiol. 62:3967–3977, 1996). Primer extension analyses revealed multiple transcriptional start points located upstream of the translational initiation codon of ipbA1. The transcription from these start sites was found to be IPB dependent. Thirty-one base pairs upstream of the first transcriptional start point tandemly repeated DNA sequences overlapping the −35 region of a putative ς70 promoter were found. These repeats exhibit significant sequence similarity to the operator-promoter region of thexyl meta operon in Pseudomonas putida, which is required for the binding of XylS, a regulatory protein of the XylS (also called AraC) family. These similarities suggest that the transcription of the IPB dioxygenase genes is modulated by a regulatory protein of the XylS/AraC family. The construction of an ipbDNA module devoid of this ipb operator-promoter region and the stable insertion of this DNA module into the genomes of differentPseudomonas strains resulted in pseudomonads with constitutive IPB and TCE oxidation activities. Constitutive TCE oxidation of two such Pseudomonas hybrid strains, JR1A::ipb and CBS-3::ipb, was found to be stable for more than 120 generations in antibiotic-free medium. Evaluation of constitutive TCE degradation rates revealed that continuous cultivation of strain JR1A::ipbresulted in a significant increase in rates of TCE degradation.

A Borehole Test for Chlorinated Solvent Diffusion and Degradation Rates in Sedimentary Rock

2022 ◽  
Author(s):  
R.M. Allen‐King ◽  
R.L. Kiekhaefer ◽  
D.J. Goode ◽  
P.A. Hsieh ◽  
M.M. Lorah ◽  
...  
Keyword(s):  
Sedimentary Rock ◽  
Solvent Diffusion ◽  
Chlorinated Solvent ◽  
Degradation Rates

Aerobic TCE degradation by encapsulated toluene-oxidizing bacteria, Pseudomonas putida and Bacillus spp.

2010 ◽  
Vol 62 (9) ◽  
pp. 1991-1997 ◽  
Author(s):  
Seungjin Kim ◽  
Wookeun Bae ◽  
Jungmin Hwang ◽  
Jaewoo Park
Keyword(s):  
Pseudomonas Putida ◽  
Removal Rate ◽  
Reducing Power ◽  
Transfer Efficiency ◽  
Toluene Degradation ◽  
Degradation Rates ◽  
Bacillus Spp ◽  
Lag Period ◽  
Suspended Cultures ◽  
Tce Degradation

The degradation rates of toluene and trichloroethylene (TCE) by Pseudomonas putida and Bacillus spp. that were encapsulated in polyethylene glycol (PEG) polymers were evaluated in comparison with the results of exposure to suspended cultures. PEG monomers were polymerized together with TCE-degrading microorganisms, such that the cells were encapsulated in and protected by the matrices of the PEG polymers. TCE concentrations were varied from 0.1 to 1.5 mg/L. In the suspended cultures of P. putida, the TCE removal rate decreased as the initial TCE concentration increased, revealing TCE toxicity or a limitation of reducing power, or both. When the cells were encapsulated, an initial lag period of about 10–20 h was observed for toluene degradation. Once acclimated, the encapsulated P. putida cultures were more tolerant to TCE at an experimental range of 0.6–1.0 mg/L and gave higher transfer efficiencies (mass TCE transformed/mass toluene utilized). When the TCE concentration was low (e.g., 0.1 mg/L) the removal of TCE per unit mass of cells (specific removal) was significantly lower, probably due to a diffusion limitation into the PEG pellet. Encapsulated Bacillus spp. were able to degrade TCE cometabolically. The encapsulated Bacillus spp. gave significantly higher values than did P. putida in the specific removal and the transfer efficiency, particularly at relatively high TCE concentration of approximately 1.0±0.5 mg/L. The transfer efficiency by encapsulated Bacillus spp. in this study was 0.27 mgTCE/mgToluene, which was one to two orders of magnitude greater than the reported values.

scholarly journals Whole-Cell Kinetics of Trichloroethylene Degradation by Phenol Hydroxylase in a Ralstonia eutropha JMP134 Derivative

1998 ◽  
Vol 64 (11) ◽  
pp. 4353-4356 ◽  
Author(s):  
Patricia J. Ayoubi ◽  
Alan R. Harker
Keyword(s):  
Total Protein ◽  
Catabolite Repression ◽  
Cell Kinetics ◽  
Carbon Catabolite Repression ◽  
Ralstonia Eutropha ◽  
Whole Cells ◽  
Degradation Rates ◽  
Trichloroethylene Degradation ◽  
Tce Degradation ◽  
Kinetics Of

ABSTRACT The rate, progress, and limits of trichloroethylene (TCE) degradation by Ralstonia eutropha AEK301/pYK3021 whole cells were examined in the absence of aromatic induction. At TCE concentrations up to 800 μM, degradation rates were sustained until TCE was no longer detectable. TheKs and V max for TCE degradation by AEK301/pYK3021 whole cells were determined to be 630 μM and 22.6 nmol/min/mg of total protein, respectively. The sustained linear rates of TCE degradation by AEK301/pYK3021 up to a concentration of 800 μM TCE suggest that solvent effects are limited during the degradation of TCE and that this construct is little affected by the formation of toxic intermediates at the TCE levels and assay duration tested. TCE degradation by this strain is subject to carbon catabolite repression.

Interlayer mixing in GaAs/AlxGa1-xAs heterostructures as a result of Se+ ion implantation

1988 ◽  
Vol 46 ◽  
pp. 908-909
Author(s):  
E.G. Bithell ◽  
W.M. Stobbs
Keyword(s):  
Ion Implantation ◽  
Diffusion Coefficients ◽  
Dark Field ◽  
Atomic Mass ◽  
Composition Profile ◽  
Semiconductor Heterostructures ◽  
Transmission Electron ◽  
Microscope Images ◽  
Damage Process ◽  
Electron Energy Loss

It is well known that the microstructural consequences of the ion implantation of semiconductor heterostructures can be severe: amorphisation of the damaged region is possible, and layer intermixing can result both from the original damage process and from the enhancement of the diffusion coefficients for the constituents of the original composition profile. A very large number of variables are involved (the atomic mass of the target, the mass and energy of the implant species, the flux and the total dose, the substrate temperature etc.) so that experimental data are needed despite the existence of relatively well developed models for the implantation process. A major difficulty is that conventional techniques (e.g. electron energy loss spectroscopy) have inadequate resolution for the quantification of any changes in the composition profile of fine scale multilayers. However we have demonstrated that the measurement of 002 dark field intensities in transmission electron microscope images of GaAs / AlxGa1_xAs heterostructures can allow the measurement of the local Al / Ga ratio.

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