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Enhanced carbon dioxide outgassing from the eastern Equatorial Atlantic during the last glacial

G. L. Foster and P. F. Sexton
Enhanced carbon dioxide outgassing from the eastern Equatorial Atlantic during the last glacial
Geology (Boulder) (November 2014) 42 (11): 1003-1006

Abstract

Biological productivity and carbon export in the equatorial Atlantic are thought to have been dramatically higher during the last glacial period than during the Holocene. Here we reconstruct the pH and CO (sub 2) content of surface waters from the eastern equatorial Atlantic Ocean over the past approximately 30 k.y. using the boron isotope composition of Globigerinoides ruber (a mixed-layer-dwelling planktic foraminifera). Our new record, combined with previously published data, indicates that during the last glacial, in contrast to today, a strong west to east gradient existed in the extent of air:sea equilibrium with respect to pCO (sub 2) (Delta pCO (sub 2) ), with the eastern equatorial Atlantic acting as a significant source of CO (sub 2) (+100 mu atm) while the western Atlantic remained close to equilibrium (+25 mu atm). This pattern suggests that a fivefold increase in the upwelling rate of deeper waters drove increased Atlantic productivity and large-scale regional cooling during the last glacial, but the higher than modern Delta pCO (sub 2) in the east indicates that export production did not keep up with enhanced upwelling of nutrients. However, the downstream decline of Delta pCO (sub 2) provides evidence that the unused nutrients from the east were eventually used for biologic carbon export, thereby effectively negating the impact of changes in upwelling on atmospheric CO (sub 2) levels. Our findings indicate that the equatorial Atlantic exerted a minimal role in contributing to lower glacial-age atmospheric CO (sub 2) .


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 42
Serial Issue: 11
Title: Enhanced carbon dioxide outgassing from the eastern Equatorial Atlantic during the last glacial
Affiliation: University of Southampton, National Oceanography Centre, Southampton, United Kingdom
Pages: 1003-1006
Published: 201411
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 36
Accession Number: 2014-105178
Categories: Quaternary geologyGeochronology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus.
N12°44'37" - N12°44'37", W78°44'22" - W78°44'22"
Secondary Affiliation: Open University, GBR, United Kingdom
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201452
Program Name: ODPOcean Drilling Program
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