A core-top study of dissolution effect on B/Ca inGlobigerinoides sacculiferfrom the tropical Atlantic: Potential bias for paleo-reconstruction of seawater carbonate chemistry

Coadic, R. and Bassinot, F. and Dissard, D. and Douville, E. and Greaves, M. J. and Michel, E. (2013) A core-top study of dissolution effect on B/Ca inGlobigerinoides sacculiferfrom the tropical Atlantic: Potential bias for paleo-reconstruction of seawater carbonate chemistry. Geochemistry, Geophysics, Geosystems, 14 (4). n/a-n/a. ISSN 15252027 DOI 10.1029/2012GC004296

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Official URL: http://dx.doi.org/10.1029/2012GC004296

Abstract

It has been recently shown that B/Ca in planktonic foraminiferal calcite can be used as a proxy for seawater pH. Based on the study of surface sediments (multi-cores) retrieved along a depth transect on the Sierra Leone Rise (Eastern Equatorial Atlantic), we document the decrease of B/Ca and Mg/Ca of Globigerinoides sacculifer shells with increasing water depth and dissolution. This effect of dissolution on B/Ca may potentially represent a severe bias for paleo-pH reconstructions using this species. Samples of G. sacculifer were analyzed independently at two laboratories for B/Ca and Mg/Ca. Both sets of results show a systematic decrease of B/Ca and Mg/Ca along the depth transect, with an overall loss of ~14 mmol/mol (~15%) for B/Ca and of ~0.7 mmol/mol (~21%) for Mg/Ca between the shallowest (2640 m) and the deepest (4950 m) sites. Because of this dissolution effect, surface water pH reconstructed from B/Ca of G. sacculifer decreases by ~0.11 units between the shallowest site and the deepest site, a magnitude similar to the expected glacial/interglacial surface water pH changes.

Item Type: Article
Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions: 01 - Climate Change and Earth-Ocean Atmosphere Systems
08 - Green Open Access
Journal or Publication Title: Geochemistry, Geophysics, Geosystems
Volume: 14
Page Range: n/a-n/a
Identification Number: 10.1029/2012GC004296
Depositing User: Sarah Humbert
Date Deposited: 03 Jul 2014 17:21
Last Modified: 03 Jul 2014 17:21
URI: http://eprints.esc.cam.ac.uk/id/eprint/3078

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