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G-Cubed: Geochemistry, Geophysics, Geosystems

 

Keywords

  • carbonate geochemistry
  • ocean acidification
  • benthic CaCO3 dissolution

Index Terms

  • Biogeosciences: Benthic processes
  • Oceanography: Biological and Chemical: Biogeochemical cycles, processes, and modeling
  • Biogeosciences: Biogeochemical cycles, processes, and modeling
  • Global Change: Impacts of global change
Abstract
Cited By (0)
 

Abstract

GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS, VOL. 9, Q02012, 11 PP., 2008
doi:10.1029/2007GC001756 [Citation]

Short-term dissolution response of pelagic carbonate sediments to the invasion of anthropogenic CO2: A model study

M. Gehlen

Laboratoire des Sciences du Climat et de l'Environnement, Institut Pierre Simon Laplace, CEA-CNRS-UVSQ, Orme des Merisiers, Bât. 712, CEA/Saclay, F-91198 Gif-sur-Yvette Cedex, France

L. Bopp

Laboratoire des Sciences du Climat et de l'Environnement, Institut Pierre Simon Laplace, CEA-CNRS-UVSQ, Orme des Merisiers, Bât. 712, CEA/Saclay, F-91198 Gif-sur-Yvette Cedex, France

O. Aumont

Laboratoire d'Océanographie et du Climat: Expérimentations et Approches Numériques, Institut Pierre Simon Laplace, Centre IRD de Bretagne, BP 70, F-29280 Plouzané, France

This study addresses the potential for and the quantification of dissolution of marine calcium carbonate (CaCO3) sediments occurring on century timescales in response to the invasion of anthropogenic CO2. It presents results obtained with the global biogeochemical model PISCES interactively coupled to a global sediment model. The latter represents the principal reactions involved in early diagenesis of biogenic opal, CaCO3, and organic matter. The model reproduces observed distributions of core top CaCO3 content and bottom water carbonate chemistry (e.g., [CO3 2−]). Starting from the climatological state, a model experiment is carried out according to the standard CMIP scenario of atmospheric pCO2 increasing at a rate of 1% per year from 286 to 1144 ppm over a 140 year time period. The invasion of anthropogenic CO2 results in a strong decrease in bottom water [CO3 2−] reaching −100 μM in areas of deep water formation in the North Atlantic and mode and intermediate water formation in the Southern Hemisphere. The concomitant decrease in calcite saturation state of bottom waters drives the dissolution of CaCO3. The absolute CaCO3 content averaged over the top first centimeter decreases by up to 6%, while the change in advection calculated at the base of the bioturbated layer (10 cm) is indicative of net erosion. The predicted changes in bottom water chemistry are discussed in terms of their potential impact on benthic communities.

Received 16 July 2007; accepted 27 November 2007; published 16 February 2008.

Citation: Gehlen, M., L. Bopp, and O. Aumont (2008), Short-term dissolution response of pelagic carbonate sediments to the invasion of anthropogenic CO2: A model study, Geochem. Geophys. Geosyst., 9, Q02012, doi:10.1029/2007GC001756.

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