Variability of Monthly Radiocarbon During the 1760s in Corals from the Galapagos Islands
AuthorDruffel, Ellen R. M.
Beaupre, Steven R.
Druffel-Rodriguez, Kevin C.
Santos, Guaciara M.
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CitationDruffel, E. R. M., Griffin, S., Hwang, J., Komada, T., Beaupre, S. R., Druffel-Rodriguez, K. C., ... & Southon, J. (2004). Variability of monthly radiocarbon during the 1760s in corals from the Galapagos Islands. Radiocarbon, 46(2), 627-631.
DescriptionFrom the 18th International Radiocarbon Conference held in Wellington, New Zealand, September 1-5, 2003.
AbstractRadiocarbon (∆14C) measurements of monthly samples from a Galapagos surface coral are among the first data sets from the new Keck Carbon Cycle Accelerator Mass Spectrometry laboratory at the University of California, Irvine. An average ∆14C value of -62 is obtained for 144 measurements of samples from monthly coral bands that lived from about AD 1760-1771 (+/6 yr). High ∆14C values were found during January through March, when upwelling was weak or absent at the Galapagos Islands. Low ∆14C values were obtained mid-year during strong upwelling. The average seasonal variability of ∆14C was 15-25 ppm, which is greater than that at other tropical and subtropical locations in the Pacific Ocean because of intense seasonal upwelling at this site. Periods of sustained high ∆14C values were found during 1762-1763 and 1766. A spectral analysis revealed that the spectral density for the ∆14C data displays most of its variance at the 5-yr cycle, which is reflective of El Niño periodicity during the 20th century.