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Mass dependent stable isotope fractionation of mercury during its microbial transformations
Descriptive
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Text
TitleInfo
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Title
Mass dependent stable isotope fractionation of mercury during its microbial transformations
Identifier
ETD_859
Identifier
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http://hdl.rutgers.edu/1782.2/rucore10001600001.ETD.000051089
Language
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eng
Genre
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theses
Subject
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(authority = RUETD)
Topic
Microbiology and Molecular Genetics
Subject
(ID = SBJ-1);
(authority = ETD-LCSH)
Topic
Mercury--Isotopes
Subject
(ID = SBJ-1);
(authority = ETD-LCSH)
Topic
Microbial synthesis
Abstract
Mercury (Hg) is often cited in fish consumption advisories across the world due to the extreme neurotoxicity of its methylated forms. Given the complex biogeochemical cycling of Hg, a differentiation between local vs. global and natural vs. anthropogenic sources of Hg(0) and determination of transformations that are dominant in a given ecosystem is critical. Mercury has seven stable isotopes and Hg isotope ratios can become a novel biogeochemical tool to track sources and transformations of Hg in the environment. However, development of a stable isotope based tool requires the determination of the extent of fractionation during individual biotic and abiotic transformations that can occur in the environment. This thesis reports the extent of fractionation of Hg isotopes during two biological transformations: 1) degradation of monomethyl-Hg (MMHg) via the mercury resistance (mer) pathway in Escherichia coli JM109/pPB117 and 2) Hg(II) reduction by four Hg(II) reducing strains, including three Hg(II) resistant strains (E. coli JM109/pPB117, Bacillus cereus Strain 5 and Anoxybacillus spp. FB9) and a Hg(II) sensitive strain (Shewanella oneidensis MR-1). Using a multi-collector inductively coupled plasma mass spectrometer, it was found that MMHg and Hg(II) that remained in the reactors became progressively heavier (increasing delta202Hg) with time and underwent mass dependent Rayleigh-type fractionation with average fractionation factors (alpha 202/198 for reactant/instantaneous product) of 1.0004 and 1.0016, respectively. Mass independent fractionation (MIF) was not observed and based on the nature of microbe-Hg interactions, it is suggested that the nuclear spin dependent MIF is unlikely to occur during biological processes. A multi-step framework for understanding the extent of fractionation seen during the mer mediated MMHg degradation and Hg(II) reduction experiments is provided, and based on the biochemistry and kinetics of the steps involved in the two pathways, the steps in the process that could contribute to the observed extent of fractionation are suggested in the thesis. A clear effect of Hg(II) bioavailability on the extent of fractionation of Hg was observed and is also discussed. The framework discussed here can guide future experiments on Hg isotope fractionation during other transformations in its biogeochemical cycle, and ultimately facilitate a more rigorous development of a Hg isotope based geochemical tool.
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electronic resource
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xiv, 152 p. : ill.
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Ph.D.
Note
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Includes bibliographical references (p. 140-151)
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by Kritee
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Kritee Kritee
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Barkay
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Tamar
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chair
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Advisory Committee
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Tamar Barkay
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Blum
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Joel
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co-chair
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Advisory Committee
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Joel D. Blum
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Haggblom
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Max
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Advisory Committee
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Max Haggblom
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Falkowski
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Paul
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Advisory Committee
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Paul Falkowski
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Reinfelder
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John
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John Reinfelder
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Rutgers University
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degree grantor
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Graduate School - New Brunswick
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OriginInfo
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2008
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2008-05
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xx
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Rutgers University Electronic Theses and Dissertations
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ETD
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Graduate School - New Brunswick Electronic Theses and Dissertations
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rucore19991600001
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NjNbRU
Identifier
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doi:10.7282/T3QR4XCT
Genre
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ETD doctoral
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The author owns the copyright to this work.
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Open
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Non-exclusive ETD license
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Author Agreement License
Detail
I hereby grant to the Rutgers University Libraries and to my school the non-exclusive right to archive, reproduce and distribute my thesis or dissertation, in whole or in part, and/or my abstract, in whole or in part, in and from an electronic format, subject to the release date subsequently stipulated in this submittal form and approved by my school. I represent and stipulate that the thesis or dissertation and its abstract are my original work, that they do not infringe or violate any rights of others, and that I make these grants as the sole owner of the rights to my thesis or dissertation and its abstract. I represent that I have obtained written permissions, when necessary, from the owner(s) of each third party copyrighted matter to be included in my thesis or dissertation and will supply copies of such upon request by my school. I acknowledge that RU ETD and my school will not distribute my thesis or dissertation or its abstract if, in their reasonable judgment, they believe all such rights have not been secured. I acknowledge that I retain ownership rights to the copyright of my work. I also retain the right to use all or part of this thesis or dissertation in future works, such as articles or books.
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