A new estimate of the CaCO3 to organic carbon export ratio

Jorge Louis Sarmiento, J. Dunne, A. Gnanadesikan, R. M. Key, K. Matsumoto, R. Slater

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Abstract

We use an ocean biogeochemical-transport box model of the top 100 m of the water column to estimate the CaCO3 to organic carbon export ratio from observations of the vertical gradients of potential alkalinity and nitrate. We find a global average molar export ratio of 0.06 ± 0.03. This is substantially smaller than earlier estimates of 0.25 on which a majority of ocean biogeochemical models had based their parameterization of CaCO3 production. Contrary to the pattern of coccolithophore blooms determined from satellite observations, which show high latitude predominance, we find maximum export ratios in the equatorial region and generally smaller ratios in the subtropical and subpolar gyres. Our results suggest a dominant contribution to global calcification by low-latitude nonbloom forming coccolithophores or other organisms such as foraminifera and pteropods.

Original languageEnglish (US)
Pages (from-to)54-1 - 54-12
JournalGlobal Biogeochemical Cycles
Volume16
Issue number4
DOIs
StatePublished - Dec 2002

All Science Journal Classification (ASJC) codes

  • Global and Planetary Change
  • Environmental Chemistry
  • Environmental Science(all)
  • Atmospheric Science

Keywords

  • Calcium carbonate
  • Export ratio
  • Ocean biogeochemistry
  • Organic carbon

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    Sarmiento, J. L., Dunne, J., Gnanadesikan, A., Key, R. M., Matsumoto, K., & Slater, R. (2002). A new estimate of the CaCO3 to organic carbon export ratio. Global Biogeochemical Cycles, 16(4), 54-1 - 54-12. https://doi.org/10.1029/2002gb001919