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Christopher M. Reddy. White, Helen K Woods Hole Oceanographic Institution. Joint Program in Oceanography Woods Hole Oceanographic Institution Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences 2007-11-15T19:51:23Z 2007-11-15T19:51:23Z 2006 2006 http://hdl.handle.net/1721.1/34566 71196529 Thesis (Ph. D.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2006. Includes bibliographical references. To provide a new perspective on the fate of both natural organic matter and hydrophobic organic contaminants (HOCs) in marine sediments, we have investigated the relationship between radiocarbon (14C) age and the different modes of association in aquatic sediments and soils. Radiocarbon is a sensitive tracer of OM provenance, with variations in its natural abundance reflecting the age and origin of material. The main objective has been to determine the significance of these associations, and to assess how they affect the transport, bioavailability, preservation and residence times of organic compounds in the environment. Our results indicate that the majority of HOCs that persist in marine sediments are solvent-extractable and incorporation into insoluble sediment residues is not quantitatively significant. For pristine sediments, systematic variations in 14C content are observed between different chemically defined sedimentary organic fractions. These variations are dependent on organic matter inputs and/or the affects of diagenesis. Our observations also provide evidence for the protection of labile marine carbon by chemical binding. (cont.) Finally, the persistence of n-alkanes from biogenic sources compared to those derived from petroleum indicates that protective matrix association can play a crucial role in determining the long-term fate of a compound. Overall, it is clear that both natural organic compounds and HOCs can undergo very different fates depending on their mode of introduction to, and physical disposition in environmental matrices. by Helen K. White. Ph.D. 204 p. eng Massachusetts Institute of Technology M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 Joint Program in Oceanography. Earth, Atmospheric, and Planetary Sciences. Woods Hole Oceanographic Institution. Marine sediments Carbon compounds Isotopic constraints on the sources and associations of organic compounds in marine sediments Thesis application/pdf Publication unknown unknown <Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="aa6bbc61-2cdb-4ebf-ba20-a3fb440a89a0"> <Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type> <Language>eng</Language> <Title>Isotopic constraints on the sources and associations of organic compounds in marine sediments</Title> <PublishedIn> <Publication> </Publication> </PublishedIn> <PublicationDate>2006</PublicationDate> <Authors> <Author> <DisplayName>White, Helen K</DisplayName> <Affiliation> <OrgUnit> </OrgUnit> </Affiliation> </Author> </Authors> <Editors> </Editors> <Publishers> <Publisher> <DisplayName>Massachusetts Institute of Technology</DisplayName> <OrgUnit /> </Publisher> </Publishers> <License>http://dspace.mit.edu/handle/1721.1/7582</License> <Keyword>Joint Program in Oceanography.</Keyword> <Keyword>Earth, Atmospheric, and Planetary Sciences.</Keyword> <Keyword>Woods Hole Oceanographic Institution.</Keyword> <Abstract>To provide a new perspective on the fate of both natural organic matter and hydrophobic organic contaminants (HOCs) in marine sediments, we have investigated the relationship between radiocarbon (14C) age and the different modes of association in aquatic sediments and soils. Radiocarbon is a sensitive tracer of OM provenance, with variations in its natural abundance reflecting the age and origin of material. The main objective has been to determine the significance of these associations, and to assess how they affect the transport, bioavailability, preservation and residence times of organic compounds in the environment. Our results indicate that the majority of HOCs that persist in marine sediments are solvent-extractable and incorporation into insoluble sediment residues is not quantitatively significant. For pristine sediments, systematic variations in 14C content are observed between different chemically defined sedimentary organic fractions. These variations are dependent on organic matter inputs and/or the affects of diagenesis. Our observations also provide evidence for the protection of labile marine carbon by chemical binding.</Abstract> <Abstract>(cont.) Finally, the persistence of n-alkanes from biogenic sources compared to those derived from petroleum indicates that protective matrix association can play a crucial role in determining the long-term fate of a compound. Overall, it is clear that both natural organic compounds and HOCs can undergo very different fates depending on their mode of introduction to, and physical disposition in environmental matrices.</Abstract> <Access xmlns="http://purl.org/coar/access_right" > </Access> </Publication>