NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Predictive isotopic biogeochemistry: hydrocarbons from anoxic marine basinsCarbon isotopic compositions were determined for individual hydrocarbons in water column and sediment samples from the Cariaco Trench and Black Sea. In order to identify hydrocarbons derived from phytoplankton, the isotopic compositions expected for biomass of autotrophic organisms living in surface waters of both localities were calculated based on the concentrations of CO2(aq) and the isotopic compositions of dissolved inorganic carbon. These calculated values are compared to measured delta values for particulate organic carbon and for individual hydrocarbon compounds. Specifically, we find that lycopane is probably derived from phytoplankton and that diploptene is derived from the lipids of chemoautotrophs living above the oxic/anoxic boundary. Three acyclic isoprenoids that have been considered markers for methanogens, pentamethyleicosane and two hydrogenated squalenes, have different delta values and apparently do not derive from a common source. Based on the concentration profiles and isotopic compositions, the C31 and C33 n-alkanes and n-alkenes have a similar source, and both may have a planktonic origin. If so, previously assigned terrestrial origins of organic matter in some Black Sea sediments may be erroneous.
Document ID
20040089710
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
Authors
Freeman, K. H.
(Pennsylvania State University, State College 16802 United States)
Wakeham, S. G.
Hayes, J. M.
Date Acquired
August 21, 2013
Publication Date
January 1, 1994
Publication Information
Publication: Organic geochemistry
Volume: 21
Issue: 7-Jun
ISSN: 0146-6380
Subject Category
Exobiology
Funding Number(s)
CONTRACT_GRANT: OCE-9101667
CONTRACT_GRANT: N0001485C0-071
CONTRACT_GRANT: NAGW-1940
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Discipline Exobiology

Available Downloads

There are no available downloads for this record.
No Preview Available