Variability of radiocarbon during the 1760s in monthly corals from the Galapagos Islands
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Variability of radiocarbon during the 1760s in monthly corals from the Galapagos Islands

  • Author(s): Druffel, ER
  • Druffel, ER
  • Griffin, S
  • Hwang, J
  • Komada, T
  • Beaupre, SR
  • Druffel-Rodriguez, KC
  • Santos, GM
  • Southon, J
  • et al.
Creative Commons Attribution 4.0 International Public License
Abstract

. Radiocarbon (∆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‰, 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.

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