Similar glacial and interglacial export bioproductivity in the Atlantic sector of the Southern Ocean: Multiproxy evidence and implications for atmospheric CO2.

Frank, Martin , Gersonde, R., Rutgers van der Loeff, M., Bohrmann, Gerhard, Nürnberg, Christine C., Kubik, P. W., Suter, M. and Mangini, A. (2000) Similar glacial and interglacial export bioproductivity in the Atlantic sector of the Southern Ocean: Multiproxy evidence and implications for atmospheric CO2. Open Access Paleoceanography, 15 . pp. 642-658. DOI 10.1029/2000PA000497.

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Abstract

We present time series of export productivity proxy data including 230Thex-normalized deposition rates (rain rates) of 10Be, dissolution-corrected biogenic Ba, and biogenic opal as well as authigenic U concentrations which are complemented by rain rates of total (detrital) Fe and sea ice indicating diatom abundances from five sediment cores across the Atlantic sector of the Southern Ocean covering the past 150,000 years. The results suggest that 10Be rain rates and authigenic U concentration cannot serve as quantitative paleoproductivity proxies because they have also been influenced by detrital particle fluxes in the case of 10Be and bulk sedimentation rates (sediment focussing) and deep water oxygenation in the case of U. The combined results of the remaining productivity proxies of this study (rain rates of biogenic opal and biogenic Ba in those sections without authigenic U) and other previously published proxy data from the Southern Ocean (231Pa/230Th and nitrogen isotopes) suggest that a combination of sea ice cover, shallow remineralization depth, and stratification of the glacial water column south of the present position of the Antarctic Polar Front and possibly Fe fertilization north of it have been the main controlling factors of export paleoproductivity in the Southern Ocean over the last 150,000 years. An overall glacial increase of export paleoproductivity is not supported by the data, implying that bioproductivity variations in the Southern Ocean are unlikely to have contributed to the major glacial atmospheric CO2 drawdown observed in ice cores.

Document Type: Article
Keywords: Export bioproductivity, Southern Ocean
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems
AWI
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1029/2000PA000497
ISSN: 0883-8305
Projects: SFB261
Date Deposited: 12 Sep 2008 15:05
Last Modified: 02 Jul 2019 11:26
URI: http://oceanrep.geomar.de/id/eprint/6256

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