Microbial reductive dehalogenation of persistent halogenated aromatic contaminants in sediments of the Hackensack River in New Jersey
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Sohn, Seo Yean.
Microbial reductive dehalogenation of persistent halogenated aromatic contaminants in sediments of the Hackensack River in New Jersey. Retrieved from
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TitleMicrobial reductive dehalogenation of persistent halogenated aromatic contaminants in sediments of the Hackensack River in New Jersey
Date Created2015
Other Date2015-10 (degree)
Extent1 online resource (xi, 142 p. : ill.)
DescriptionMicrobial reductive dechlorination of problematic halogenated aromatics was observed in aquatic sediments. Laboratory experiments demonstrated reductive dehalogenation of hexachlorobenzene (HCB) and pentachloroaniline (PCA) in anaerobic microcosms set up with sediment samples originating from different sites (H1 ~ H5) along the Hackensack River, NJ. The dehalogenation products and intermediates were detected by gas chromatography-mass spectrometry. HCB was dechlorinated via pentachlorobenzene (PeCB) and 1,3,5-trichlorobenzene (TriCB) to 1,3- and 1,4-dichlorobenzene (DCB), while PCA was dechlorinated via 2,3,5,6-tetrachloroaniline, 2,4,5- and 2,4,6-trichloroaniline, and 2,4-, 2,5-, 2,6-, and 3,5-dichloroaniline, to monochloroaniline. Debromination of hexabromobenzene (HBB) was not observed after up to 12 months incubation. However, when HCB was added as a co-substrate, reductive debromination of HBB occurred with 1,2,3,5-tetrabromobenzene (TeBB) and 1,3,5-tribromobenzene (TriBB) detected at low concentration. Chloroflexi specific 16S rRNA gene PCR-DGGE followed by sequence analysis detected members of the “Pinellas subgroup” of Dehalococcoides mccartyi in H1 sediment. H1 and H5 cultures had different reductive dehalogenase (rdh) gene profiles based on the analysis of a set of 12 rdh genes. Generally, more rdh genes were detected in H1 cultures, corresponding with higher dehalogenating activity and greater abundance of Dehalococcoides species in H1 sediment. Cultures amended with both HBB and HCB had all 12 tested rdh genes. Carbon compound specific isotope analysis (CSIA) was conducted to obtain isotope fractionation data for dehalogenation of HCB, PeCB, 1,2,3,5-TeCB, 1,2,3,5-TeBB, and 1,3,5-TriBB. Strong evidence of isotope fractionation coupled to dehalogenation was not observed, possibly due to the low solubility of the halobenzene substrates and a dilution of the isotope signal. However, we could detect a depletion of the δ13C value in the DCB product from dechlorination of HCB; isotope fractionation of TeCB and the sequential depletion and enrichment of δ13C value for TriCB in TeCB dechlorinating cultures; and the enrichment of δ13C during debromination of TriBB. From this study, we conclude that indigenous anaerobic microorganisms in the Hackensack River, NJ are capable of dehalogenating chloro- and bromobenzenes. Molecular community analyses demonstrated that there are different responsible microbial communities corresponding to the locations of the Hackensack River. A “priming” effect of HCB on HBB dehalogenation was observed. CSIA data for highly halogenated benzenes suggest that it may have application for assessing in situ microbial reductive dehalogenation.
NotePh.D.
NoteIncludes bibliographical references
Noteby Seo Yean Sohn
Genretheses, ETD doctoral
Languageeng
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.
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