Isotopic constraints on the sources and associations of organic compounds in marine sediments
White, Helen K.
MetadataShow full item record
Santa Monica Basin
New England Margin
Eel River Margin
West Falmouth, MA
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. 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.
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2006
Suggested CitationThesis: White, Helen K., "Isotopic constraints on the sources and associations of organic compounds in marine sediments", 2006-02, DOI:10.1575/1912/1512, https://hdl.handle.net/1912/1512
Showing items related by title, author, creator and subject.
Direct application of compound-specific radiocarbon analysis of leaf waxes to establish lacustrine sediment chronology Uchikawa, Joji; Popp, Brian N.; Schoonmaker, Jane E.; Xu, Li (2006-12-18)This study demonstrates use of compound-specific radiocarbon analysis (CSRA) for dating Holocene lacustrine sediments from carbonate-hosted Ordy Pond, Oahu, Hawaii. Long-chain odd-numbered normal alkanes (n-alkanes), ...
Timescales of lateral sediment transport in the Panama Basin as revealed by radiocarbon ages of alkenones, total organic carbon and foraminifera Kusch, Stephanie; Eglinton, Timothy I.; Mix, Alan C.; Mollenhauer, Gesine (2009-12)Paired radiocarbon measurements on haptophyte biomarkers (alkenones) and on cooccurring tests of planktic foraminifera (Neogloboquadrina dutertrei and Globogerinoides sacculifer) from late glacial to Holocene sediments ...
An evaluation of 14C age relationships between co-occurring foraminifera, alkenones, and total organic carbon in continental margin sediments Mollenhauer, Gesine; Kienast, Markus; Lamy, Frank; Meggers, Helge; Schneider, Ralph R.; Hayes, John M.; Eglinton, Timothy I. (American Geophysical Union, 2005-01-25)Radiocarbon age relationships between co-occurring planktic foraminifera, alkenones and total organic carbon in sediments from the continental margins of Southern Chile, Northwest Africa and the South China Sea were ...