HR: 08:45h
AN: B51E-04    [Abstracts]
TI: New Observations of Regional Variability in Delta-14C of Background CO2 from the Scripps CO2 Program
AU: * Graven, H D
EM: hgraven@ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Dr, La Jolla, CA 92093-0244,
AU: Guilderson, T P
EM: tguilderson@llnl.gov
AF: Lawrence Livermore National Laboratory, 7000 East Ave. UC/LLNL L-397, Livermore, CA 94550,
AU: Guilderson, T P
EM: tguilderson@llnl.gov
AF: University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064,
AU: Keeling, R F
EM: rkeeling@ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Dr, La Jolla, CA 92093-0244,
AB: We present new records of Δ¹⁴C in CO₂ from a set of 7 sites in the Scripps CO₂ flask sampling program. The monthly records span 2 years at Palmer Station, 5 years at Mauna Loa, Kumukahi and Samoa, 7 years at Pt Barrow and South Pole, and 15 years at La Jolla. The long time series were made possible by the archiving of extracted CO₂ samples. The samples were analyzed by Accelerator Mass Spectrometry (AMS) at the Lawrence Livermore National Laboratory, where an initiative to support high precision Δ¹⁴C analysis in CO₂ with improved analytical methodology has been ongoing since 2003. The new records build on previous work by I. Levin, M. Manning, R. Nydal and others to characterize atmospheric Δ¹⁴C levels following nuclear weapons testing. Our time series reveal changes in the latitudinal profile of Δ¹⁴C that reflect shifting regional ¹⁴C fluxes. As ¹⁴C fluxes depend on the source of CO₂ to the atmosphere, atmospheric ¹⁴C measurements improve our understanding of regional oceanic, biospheric and industrial CO₂ exchanges and provide important constraints on carbon cycle models. The new records will additionally serve as a background definition for studies utilizing Δ¹⁴C measurements to identify local fossil fuel-derived CO₂.
DE: 0428 Carbon cycling (4806)
DE: 0454 Isotopic composition and chemistry (1041, 4870)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting