Estimation of Gibbs free energies of formation for polychlorinated biphenyls

Holmes, D. R.; Harrison, B. Keith; Dolfing, Jan

doi:10.1021/es00041a017

Cited by 65 publications

(44 citation statements)

References 19 publications

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“…2 have been proposed previously from inference of Aroclor 1260 dechlorination products. For example, a previous report with BH Aroclor 1260 microcosms (62) predicted the ortho dechlorination pathway of PCB 151 (2356-25) to PCB 72 (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35). However, the previously predicted dechlorination pathway from PCB 170 (2345-234) to PCB 68 (24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35) was only partly consistent with our results (Fig.…”

Section: Discussionsupporting

confidence: 79%

“…For example, a previous report with BH Aroclor 1260 microcosms (62) predicted the ortho dechlorination pathway of PCB 151 (2356-25) to PCB 72 (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35). However, the previously predicted dechlorination pathway from PCB 170 (2345-234) to PCB 68 (24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35) was only partly consistent with our results (Fig. 2), as most of PCB 170 was dechlorinated to either 26 mol% PCB 47 (24-24) or 13 mol% PCB 49 (24)(25) at day 400.…”

Section: Discussionmentioning

confidence: 99%

“…Effect of congener characteristics on dehalogenation. An analysis of (i) the differences in the estimated Gibbs free energy of formation between parent and daughter congeners (29), (ii) the differences in relative retention time (17), (iii) the aqueous solubilities (29), and(iv) the number of total chlorines and the number of ortho-, meta-, and para-chlorines on the ring subjected to dechlorination, as well as on the opposite ring, showed that there were no significant relationships (P Ͻ 0.05) between these parameters and the dechlorination rates, end mol%, or the number of putative dechlorinators in BH microcosms. However, we observed weak relationships (with low R 2 values) between the dechlorination rate and the aqueous solubility of the PCB congener (r 2 ϭ 0.25), the total amount of chlorines (r 2 ϭ 0.22), as well as the number of meta-chlorines (r 2 ϭ 0.28).…”

Section: Discussionmentioning

confidence: 99%

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Microbial Reductive Dechlorination of Aroclor 1260 in Baltimore Harbor Sediment Microcosms Is Catalyzed by Three Phylotypes within the Phylum Chloroflexi

Fagervold

May

Sowers

2007

Appl Environ Microbiol

129

112

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The specific dechlorination pathways for Aroclor 1260 were determined in Baltimore Harbor sediment microcosms developed with the 11 most predominant congeners from this commercial mixture and their resulting dechlorination intermediates. Most of the polychlorinated biphenyl (PCB) congeners were dechlorinated in the meta position, and the major products were tetrachlorobiphenyls with unflanked chlorines. Using PCR primers specific for the 16S rRNA genes of known PCB-dehalogenating bacteria, we detected three phylotypes within the microbial community that had the capability to dechlorinate PCB congeners present in Aroclor 1260 and identified their selective activities. Phylotype DEH10, which has a high level of sequence identity to Dehalococcoides spp., removed the double-flanked chlorine in 234-substituted congeners and exhibited a preference for para-flanked meta-chlorines when no double-flanked chlorines were available. Phylotype SF1 had similarity to the o-17/DF-1 group of PCB-dechlorinating bacteria. Phylotype SF1 dechlorinated all of the 2345-substituted congeners, mostly in the double-flanked meta position and 2356-, 236-, and 235-substituted congeners in the ortho-flanked meta position, with a few exceptions. A phylotype with 100% sequence identity to PCB-dechlorinating bacterium o-17 was responsible for an ortho and a double-flanked meta dechlorination reaction. Most of the dechlorination pathways supported the growth of all three phylotypes based on competitive PCR enumeration assays, which indicates that PCB-impacted environments have the potential to sustain populations of these PCB-dechlorinating microorganisms. The results demonstrate that the variation in dechlorination patterns of congener mixtures typically observed at different PCB impacted sites can potentially be mediated by the synergistic activities of relatively few dechlorinating species.

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Section: Discussionsupporting

confidence: 79%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Microbial Reductive Dechlorination of Aroclor 1260 in Baltimore Harbor Sediment Microcosms Is Catalyzed by Three Phylotypes within the Phylum Chloroflexi

Fagervold

May

Sowers

2007

Appl Environ Microbiol

129

112

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“…However, this does not explain why selected activities of the indigenous population could be completely repressed in the presence of excess PCB. The free energy yield is similar for products of the alternative pathways (Holmes et al, 1993), so this selection is unlikely due to thermodynamic differences. Likewise, the similarity between rates for dechlorination of parent compound PCB 151 via alternate pathways rules out kinetic differences as a reason for selection.…”

Section: Discussionmentioning

confidence: 99%

Quantifying Enhanced Microbial Dehalogenation Impacting the Fate and Transport of Organohalide Mixtures in Contaminated Sediments

Häggblom¹,

Fennell²,

Rodenburg³

et al. 2012

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Standard Form 298 (Rev. 8/98) REPORT DOCUMENTATION PAGEPrescribed by ANSI Std. Z39.18 Form Approved OMB No. 0704-0188The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to the Department of Defense, Executive Services and Communications Directorate (0704-0188). Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ORGANIZATION. 1. REPORT DATE (DD-MM-YYYY)2. REPORT TYPE 3. DATES COVERED (From -To) 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER AUTHOR(S) PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION REPORT NUMBER SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S) SPONSOR/MONITOR'S REPORT NUMBER(S)12 SERDPThe project investigated techniques and amendments to enhance microbial dehalogenation in sediments contaminated with organohalide mixtures and developed methods and tools to monitor the effectiveness of biostimulation processes. Micro-and mesocosm studies with organohalide-contaminated sediments demonstrated that these contain diverse communities of dehalogenating microorganisms. Dechlorination of historical PCB and PCDD/F contaminant mixtures can be stimulated by addition of amendments and/or bioaugmentation with dechlorinating bacteria. The enhanced dechlorination correlates with increased numbers of dehalorespirer populations and reductive dehalogenase genes. Identification of the specific microbial members associated with PCB-and PCDD/F-dechlorinating activity should allow for better strategies to enhance dehalogenation. The results provide compelling evidence to support further testing and development of biostimulation and bioaugmentation with dehalorespiring bacteria as environmentally less invasive and lower cost alternatives for in situ treatment of PCB impacted sediments. Anacostia microcosms compared to the sum of all di-through deca-chlorinated biphenyls (homolog groups 2 through 10). Analyses of the dry matter content, the total PCB concentration, the average number and percentage of chlorines less than 4 and 6, respectively and in soil samples and commercial Aroclor mixtures. Table 6-2. Analyses of total bacteria, putative dechlorinating and PCB degrading bacteria and the number of dechlorinating bacteria in soil samples. Table 6-3. The potential dechlorination activi...

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“…Physicochemical properties of selected SVOCs certainly depend on prevailing environmental conditions. They are subject to measurement uncertainties [66], and are reported in a wide range, rather than consistent, values [67], which makes it particularly challenging to theoretically simulate the behaviors of SVOCs in the environment.…”

Section: Physicochemical Properties Of Selected Svocsmentioning

confidence: 99%

Air-sea interactions of semi-volatile organic compounds in the tropical environment of Southeast Asia

Balasubramanian

2010

EPJ Web of Conferences

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Abstract. Major urban and industrial centers increase loadings of semi-volatile organic compounds (SVOCs) to proximate sea waters through riverine transport, atmospheric deposition via dry particle deposition, wet deposition, and air-sea gas exchange. In addition to acting as sinks for SVOCs, oceans can act as sources of SVOCs to coastal atmospheres and play important roles in the global biogeochemistry of SVOCs. Particle-sorbed SVOCs can settle to the ocean surface by dry particle deposition, a uni-directional advective transport process from the atmosphere to the water, the removal rate by which is a function of the physical and chemical properties of the aerosols and bound pollutants, meteorological conditions and surface characteristics. In addition, SVOCs are removed from the atmosphere and transported to the waters by precipitation scavenging of atmospheric vapors and particles, which are incorporated into the rain within or below the clouds. After SVOCs are deposited into the bulk seawater, water-column partitioning can affect the distribution of pollutants between the dissolved aqueous and the solid phases and eventually impact the fate of these compounds in oceans. Other than the abovementioned processes, air-sea exchange can make SVOCs diffuse across the air-sea interface; however, the sea surface microlayer (SML), a unique compartment at the air-sea boundary defined operationally as the upper millimeter (1 ∼ 1000 μm) of the sea surface, has large storage capacity to delay the transport of SVOCs across the interface.This article reports the dry particle deposition and wet deposition of selected SVOCs based on an extensive set of yearly data collected in Singapore. Singapore, a representative country of Southeast Asia (SEA), is a small but highly developed island with dense industrial parks in the Southwestern part, where the terrestrial sources affect the surrounding coasts. In this study, Singapore's Southern coastline was chosen during the Northeast monsoon season to evaluate if this coastal area acts a sink or source for selected SVOCs via air-sea diffusive exchange as well as to investigate the SML enrichment effect.

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Estimation of Gibbs free energies of formation for polychlorinated biphenyls

Cited by 65 publications

References 19 publications

Microbial Reductive Dechlorination of Aroclor 1260 in Baltimore Harbor Sediment Microcosms Is Catalyzed by Three Phylotypes within the Phylum Chloroflexi

Microbial Reductive Dechlorination of Aroclor 1260 in Baltimore Harbor Sediment Microcosms Is Catalyzed by Three Phylotypes within the Phylum Chloroflexi

Quantifying Enhanced Microbial Dehalogenation Impacting the Fate and Transport of Organohalide Mixtures in Contaminated Sediments

Air-sea interactions of semi-volatile organic compounds in the tropical environment of Southeast Asia

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