Biogeochemical applications of compound-specific radiocarbon analysis
MetadataShow full item record
LocationSanta Monica Basin
Santa Barbara Basin
KeywordCarbon; Isotopes; Biochemical markers; Biogeochemistry; Roger Revelle (Ship) Cruise Pulse-32
Compound-specific carbon isotopic (δ13C and Δ14C) data are reported for lipid biomarkers isolated from Santa Monica Basin (SMB) and Santa Barbara Basin (SBB) surface sediments. These organic compounds represent phytoplanktonic, zooplanktonic, bacterial, archaeal, terrestrial, and fossil carbon sources. The lipids include long-chain n-alkanes, fatty acids (as FAMEs), n-alcohols, C30 mid-chain ketols and diols, sterols, hopanols, and ether-linked C4o-biphytanes of Archaea. The data show that the carbon source for most of the biomarkers is marine euphotic zone primary production or subsequent heterotrophic consumption of this biomass. Two lipid classes represent exceptions to this finding. Δ14C values for the n-alkanes are consistent with mixed fossil and contemporary terrestrial plant sources. The archaeal isoprenoid data reflect chemoautotrophic growth below the euphotic zone. The biomarker class most clearly representing marine phytoplanktonic production is the sterols. It is suggested, therefore, that the sterols could serve as paleoceanographic tracers for surface-water DIC. The isotopic data are used to construct two algebraic models. The first calculates the contributions of fossil and modem vascular plant carbon to 5MB n-alkanes. This model indicates that the Δ14C of the modern component is +235% (post-bomb) or 0% (pre-bomb). The second model uses these values to determine the origin of sedimentary TOC. The results are comparable to estimates based on other approaches and suggest that ~60% of SMB TOC is of marine origin, modern terrestrial and fossil sources contribute ~10% each, and the remaining ~20% is of unknown origin.
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 October 1999
Showing items related by title, author, creator and subject.
Exchanges between hemispheres and gyres : a direct approach to the mean circulation of the equatorial Pacific Wijffels, Susan E. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1993-09)An extensive set of new high-quality hydrographic data is assembled in order to determine the mean circulation in the equatorial Pacific, and thus the pathways for cross-equatorial and cross-gyre exchange. Making up the ...
Baringer, Molly O. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1993-10)Hydrographic and expendable current profiler (XCP) data taken during the Gulf of Cadiz Expedition in September 1988 are analyzed to diagnose the mixing and dynamics of the Mediterranean outflow. The overall structure of ...
Cosmogenic ³²P and ³³P in the atmosphere and aligotrophic ocean and applications to the study of phosphorus cycling Waser, Nathalie A. D. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1992-11)Cosmogeruc P-32 (14.28 days) and P-33 (25.3 days) are powerful tracers of upper ocean P cycling, when coupled with time-series of the atmospheric sources. A method was developed to determine the low-level beta activities ...