Chlorine Isotope Fractionation during Reductive Dechlorination of Chlorinated Ethenes by Anaerobic Bacteria

In this study, wood mulch-based amendments were tested in a bench-scale microcosm experiment in order to assess the treatability of saturated soils and groundwater from an industrial site contaminated by chlorinated ethenes. Wood mulch was tested alone as the only electron donor in order to assess its potential for stimulating the biological reductive dechlorination. It was also tested in combination with millimetric iron filings in order to assess the ability of the additive to accelerate/improve the bioremediation process. The efficacy of the selected amendments was compared with that of unamended control microcosms. The results demonstrated that wood mulch is an effective natural and low-cost electron donor to stimulate the complete reductive dechlorination of chlorinated solvents to ethene. Being a side-product of the wood industry, mulch can be used in environmental remediation, an approach which perfectly fits the principles of circular economy and addresses the compelling needs of a sustainable and low environmental impact remediation. The efficacy of mulch was further improved by the co-presence of iron filings, which accelerated the conversion of vinyl chloride into the ethene by increasing the H2 availability rather than by catalyzing the direct abiotic dechlorination of contaminants. Chemical analyses were corroborated by biomolecular assays, which confirmed the stimulatory effect of the selected amendments on the abundance of Dehalococcoides mccartyi and related reductive dehalogenase genes. Overall, this paper further highlights the application potential and environmental sustainability of wood mulch-based amendments as low-cost electron donors for the biological treatment of chlorinated ethenes.

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Chlorine isotope composition in chlorofluorocarbons CFC-11, CFC-12 and CFC-113 in firn, stratospheric and tropospheric air

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-6867-2015 ◽

2015 ◽

Vol 15 (12) ◽

pp. 6867-6877 ◽

Cited By ~ 6

Author(s):

S. J. Allin ◽

J. C. Laube ◽

E. Witrant ◽

J. Kaiser ◽

E. McKenna ◽

...

Keyword(s):

Isotope Fractionation ◽

Isotope Composition ◽

Stratospheric Ozone ◽

Standard Uncertainty ◽

Gas Chromatography Mass Spectrometry ◽

Sources And Sinks ◽

Chlorine Isotope ◽

Tropospheric Measurements ◽

Single Detector

Abstract. The stratospheric degradation of chlorofluorocarbons (CFCs) releases chlorine, which is a major contributor to the destruction of stratospheric ozone (O3). A recent study reported strong chlorine isotope fractionation during the breakdown of the most abundant CFC (CFC-12, CCl2F2, Laube et al., 2010a), similar to effects seen in nitrous oxide (N2O). Using air archives to obtain a long-term record of chlorine isotope ratios in CFCs could help to identify and quantify their sources and sinks. We analyse the three most abundant CFCs and show that CFC-11 (CCl3F) and CFC-113 (CClF2CCl2F) exhibit significant stratospheric chlorine isotope fractionation, in common with CFC-12. The apparent isotope fractionation (&varepsilon;app) for mid- and high-latitude stratospheric samples are respectively −2.4 (0.5) and −2.3 (0.4) ‰ for CFC-11, −12.2 (1.6) and −6.8 (0.8) ‰ for CFC-12 and −3.5 (1.5) and −3.3 (1.2) ‰ for CFC-113, where the number in parentheses is the numerical value of the standard uncertainty expressed in per mil. Assuming a constant isotope composition of emissions, we calculate the expected trends in the tropospheric isotope signature of these gases based on their stratospheric 37Cl enrichment and stratosphere–troposphere exchange. We compare these projections to the long-term δ (37Cl) trends of all three CFCs, measured on background tropospheric samples from the Cape Grim air archive (Tasmania, 1978–2010) and tropospheric firn air samples from Greenland (North Greenland Eemian Ice Drilling (NEEM) site) and Antarctica (Fletcher Promontory site). From 1970 to the present day, projected trends agree with tropospheric measurements, suggesting that within analytical uncertainties, a constant average emission isotope delta (δ) is a compatible scenario. The measurement uncertainty is too high to determine whether the average emission isotope δ has been affected by changes in CFC manufacturing processes or not. Our study increases the suite of trace gases amenable to direct isotope ratio measurements in small air volumes (approximately 200 mL), using a single-detector gas chromatography–mass spectrometry (GC–MS) system.

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Chlorine isotope composition in chlorofluorocarbons CFC-11, CFC-12 and CFC-113 in firn, stratospheric and tropospheric air

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-14-31813-2014 ◽

2014 ◽

Vol 14 (23) ◽

pp. 31813-31841

Author(s):

S. J. Allin ◽

J. C. Laube ◽

E. Witrant ◽

J. Kaiser ◽

E. McKenna ◽

...

Keyword(s):

Isotope Fractionation ◽

Isotope Composition ◽

Stratospheric Ozone ◽

Isotope Ratios ◽

Gas Chromatography Mass Spectrometry ◽

Chlorine Isotope ◽

Site Model ◽

Tropospheric Measurements ◽

Single Detector

Abstract. The stratospheric degradation of chlorofluorocarbons (CFCs) releases chlorine, which is a major contributor to the destruction of stratospheric ozone (O3). A recent study reported strong chlorine isotope fractionation during the breakdown of the most abundant CFC (CFC-12, CCl2F2), similar to effects seen in nitrous oxide (N2O). Using air archives to obtain a long-term record of chlorine isotope ratios in CFCs could help to identify and quantify their sources and sinks. We analyse the three most abundant CFCs and show that CFC-11 (CCl3F) and CFC-113 (CClF2CCl2F) exhibit significant stratospheric chlorine isotope fractionation, in common with CFC-12. The apparent isotope fractionation (&varepsilon;app) for mid- and high-latitude stratospheric samples are (−2.4 ± 0.5) and (−2.3 ± 0.4)‰ for CFC-11, (−12.2 ± 1.6) and (−6.8 ± 0.8)‰ for CFC-12 and (−3.5 ± 1.5) and (−3.3 ± 1.2)‰ for CFC-113, respectively. Assuming a constant source isotope composition, we estimate the expected trends in the tropospheric isotope signature of these gases due to their stratospheric 37Cl enrichment and stratosphere–troposphere exchange. We compare these model results to the long-term δ(37Cl) trends of all three CFCs, measured on background tropospheric samples from the Cape Grim air archive (Tasmania, 1978–2010) and tropospheric firn air samples from Greenland (NEEM site) and Antarctica (Fletcher Promontory site). Model trends agree with tropospheric measurements within analytical uncertainties. From 1970 to the present-day, we find no evidence for variations in chlorine isotope ratios associated with changes in CFC manufacturing processes. Our study increases the suite of trace gases amenable to direct isotope ratio measurements in small air volumes, using a single-detector gas chromatography-mass spectrometry system.

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The potential of anaerobic bacteria to degrade chlorinated compounds

Water Science & Technology ◽

10.2166/wst.2001.0462 ◽

2001 ◽

Vol 44 (8) ◽

pp. 49-56 ◽

Cited By ~ 19

Author(s):

M.H.A. van Eekert ◽

G. Schraa

Keyword(s):

Anaerobic Bacteria ◽

Granular Sludge ◽

Chlorinated Ethenes ◽

Contaminated Sites ◽

Contaminated Site ◽

Anaerobic Conditions ◽

Chlorinated Aromatics ◽

Start Up ◽

Acetogenic Bacteria ◽

Uasb Reactors

Chlorinated ethenes and chlorinated aromatics are often found as pollutants in sediments, groundwater, and wastewater. These compounds were long considered to be recalcitrant under anaerobic conditions. In the past years however, dechlorination of these compounds has been found to occur under anaerobic conditions at contaminated sites and in wastewater treatment systems. This dechlorination is mainly attributed to halo-respiring bacteria, which are able to couple this dechlorination to energy conservation via electron transport coupled phosphorylation. The dechlorinating activities of the halo-respiring bacteria seem to be confined to the dechlorination of chloroethenes and chlorinated aromatic compounds. In addition, methanogenic and acetogenic bacteria are also able to reduce the chlorinated ethenes via a-specific cometabolic pathways. Although these latter reactions may not be important in the remediation of contaminated sites, they may be of substantial influence in the start-up of remediation processes and in the application of granular sludge from UASB reactors. Specific halo-respiring bacteria may be used to increase the dechlorination activities via bioaugmentation in the case that the appropriate microorganisms are not present at the contaminated site or in the sludge.

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Factors controlling the carbon isotope fractionation of tetra- and trichloroethene during reductive dechlorination by Sulfurospirillum ssp. and Desulfitobacterium sp. strain PCE-S

FEMS Microbiology Ecology ◽

10.1111/j.1574-6941.2007.00367.x ◽

2007 ◽

Vol 62 (1) ◽

pp. 98-107 ◽

Cited By ~ 52

Author(s):

Danuta Cichocka ◽

Michael Siegert ◽

GwenaÃ«l Imfeld ◽

Janet Andert ◽

Kirsten Beck ◽

...

Keyword(s):

Carbon Isotope ◽

Reductive Dechlorination ◽

Isotope Fractionation ◽

Carbon Isotope Fractionation

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Chlorine isotope fractionation associated with volcanic activity at the Kusatsu-Bandaiko hot spring in Japan

Isotopes in Environmental and Health Studies ◽

10.1080/10256010802310051 ◽

2008 ◽

Vol 44 (3) ◽

pp. 305-313 ◽

Cited By ~ 5

Author(s):

Masaaki Musashi ◽

Takao Oi ◽

Hans G.M. Eggenkamp ◽

Motoyuki Matsuo

Keyword(s):

Volcanic Activity ◽

Isotope Fractionation ◽

Hot Spring ◽

Chlorine Isotope

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

Applied and Environmental Microbiology ◽

10.1128/aem.71.7.3413-3419.2005 ◽

2005 ◽

Vol 71 (7) ◽

pp. 3413-3419 ◽

Cited By ~ 86

Author(s):

Ivonne Nijenhuis ◽

Janet Andert ◽

Kirsten Beck ◽

Matthias Kästner ◽

Gabriele Diekert ◽

...

Keyword(s):

Stable Isotope ◽

Reductive Dechlorination ◽

Isotope Fractionation ◽

Field Application ◽

Carbon Stable Isotope ◽

Cell Integrity ◽

Whole Cells ◽

Stable Isotope Fractionation ◽

Crude Extracts ◽

Order Of Magnitude

ABSTRACT 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 αC = 1.0132. Stable isotope fractionation was lower but still in a similar order of magnitude for Desulfitobacterium sp. PCE-S (αC = 1.0052 to 1.0098). The isotope fractionation of PCE during dehalogenation by S. multivorans was lower by 1 order of magnitude (αC = 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, αC 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.

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