Parallel between the isotopic composition of coccolith calcite and carbon levels across Termination II: developing a new paleo-CO 2 probe
Beyond the pCO 2 records provided by ice core measurements, the quantification of atmospheric CO 2 concentrations and changes thereof relies on proxy data, the development of which represents a foremost challenge in paleoceanography. In the paleoceanographic toolbox, the coccolithophores occupy a no...
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ftdoajarticles:oai:doaj.org/article:84f44e74a41a4edba3e26903dfd09ecd 2023-05-15T16:39:06+02:00 Parallel between the isotopic composition of coccolith calcite and carbon levels across Termination II: developing a new paleo-CO 2 probe C. Godbillot F. Minoletti F. Bassinot M. Hermoso 2022-03-01T00:00:00Z https://doi.org/10.5194/cp-18-449-2022 https://doaj.org/article/84f44e74a41a4edba3e26903dfd09ecd EN eng Copernicus Publications https://cp.copernicus.org/articles/18/449/2022/cp-18-449-2022.pdf https://doaj.org/toc/1814-9324 https://doaj.org/toc/1814-9332 doi:10.5194/cp-18-449-2022 1814-9324 1814-9332 https://doaj.org/article/84f44e74a41a4edba3e26903dfd09ecd Climate of the Past, Vol 18, Pp 449-464 (2022) Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 article 2022 ftdoajarticles https://doi.org/10.5194/cp-18-449-2022 2022-12-31T14:44:41Z Beyond the pCO 2 records provided by ice core measurements, the quantification of atmospheric CO 2 concentrations and changes thereof relies on proxy data, the development of which represents a foremost challenge in paleoceanography. In the paleoceanographic toolbox, the coccolithophores occupy a notable place, as the magnitude of the carbon isotopic fractionation between ambient CO 2 and a type of organic compounds that these photosynthetic microalgae synthesize (the alkenones) represents a relatively robust proxy to reconstruct past atmospheric CO 2 concentrations during the Cenozoic. The isotopic composition of coeval calcite biominerals found in the sediments and also produced by the coccolithophores (the coccoliths) have been found to record an ambient CO 2 signal through culture and sediment analyses. These studies have, however, not yet formalized a transfer function that quantitatively ties the isotopic composition of coccolith calcite to the concentrations of aqueous CO 2 and, ultimately, to atmospheric CO 2 levels. Here, we make use of a microseparation protocol to compare the isotopic response of two size-restricted coccolith assemblages from the North Atlantic to changes in surface ocean CO 2 during Termination II (ca. 130–140 ka). Performing paired measurements of the isotopic composition ( δ 13 C and δ 18 O) of relatively large and small coccoliths provides an isotopic offset that can be designated as a “differential vital effect”. We find that the evolution of this offset follows that of aqueous CO 2 concentrations computed from the ice core CO 2 curve and an independent temperature signal. We interpret this biogeochemical feature to be the result of converging carbon fixation strategies between large and small cells as the degree of carbon limitation for cellular growth decreases across the deglaciation. We are therefore able to outline a first-order trend between the coccolith differential vital effects and aqueous CO 2 in the range of Quaternary CO 2 concentrations. Although this study would ... Article in Journal/Newspaper ice core North Atlantic Directory of Open Access Journals: DOAJ Articles Climate of the Past 18 3 449 464 |
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Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 |
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Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 C. Godbillot F. Minoletti F. Bassinot M. Hermoso Parallel between the isotopic composition of coccolith calcite and carbon levels across Termination II: developing a new paleo-CO 2 probe |
topic_facet |
Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 |
description |
Beyond the pCO 2 records provided by ice core measurements, the quantification of atmospheric CO 2 concentrations and changes thereof relies on proxy data, the development of which represents a foremost challenge in paleoceanography. In the paleoceanographic toolbox, the coccolithophores occupy a notable place, as the magnitude of the carbon isotopic fractionation between ambient CO 2 and a type of organic compounds that these photosynthetic microalgae synthesize (the alkenones) represents a relatively robust proxy to reconstruct past atmospheric CO 2 concentrations during the Cenozoic. The isotopic composition of coeval calcite biominerals found in the sediments and also produced by the coccolithophores (the coccoliths) have been found to record an ambient CO 2 signal through culture and sediment analyses. These studies have, however, not yet formalized a transfer function that quantitatively ties the isotopic composition of coccolith calcite to the concentrations of aqueous CO 2 and, ultimately, to atmospheric CO 2 levels. Here, we make use of a microseparation protocol to compare the isotopic response of two size-restricted coccolith assemblages from the North Atlantic to changes in surface ocean CO 2 during Termination II (ca. 130–140 ka). Performing paired measurements of the isotopic composition ( δ 13 C and δ 18 O) of relatively large and small coccoliths provides an isotopic offset that can be designated as a “differential vital effect”. We find that the evolution of this offset follows that of aqueous CO 2 concentrations computed from the ice core CO 2 curve and an independent temperature signal. We interpret this biogeochemical feature to be the result of converging carbon fixation strategies between large and small cells as the degree of carbon limitation for cellular growth decreases across the deglaciation. We are therefore able to outline a first-order trend between the coccolith differential vital effects and aqueous CO 2 in the range of Quaternary CO 2 concentrations. Although this study would ... |
format |
Article in Journal/Newspaper |
author |
C. Godbillot F. Minoletti F. Bassinot M. Hermoso |
author_facet |
C. Godbillot F. Minoletti F. Bassinot M. Hermoso |
author_sort |
C. Godbillot |
title |
Parallel between the isotopic composition of coccolith calcite and carbon levels across Termination II: developing a new paleo-CO 2 probe |
title_short |
Parallel between the isotopic composition of coccolith calcite and carbon levels across Termination II: developing a new paleo-CO 2 probe |
title_full |
Parallel between the isotopic composition of coccolith calcite and carbon levels across Termination II: developing a new paleo-CO 2 probe |
title_fullStr |
Parallel between the isotopic composition of coccolith calcite and carbon levels across Termination II: developing a new paleo-CO 2 probe |
title_full_unstemmed |
Parallel between the isotopic composition of coccolith calcite and carbon levels across Termination II: developing a new paleo-CO 2 probe |
title_sort |
parallel between the isotopic composition of coccolith calcite and carbon levels across termination ii: developing a new paleo-co 2 probe |
publisher |
Copernicus Publications |
publishDate |
2022 |
url |
https://doi.org/10.5194/cp-18-449-2022 https://doaj.org/article/84f44e74a41a4edba3e26903dfd09ecd |
genre |
ice core North Atlantic |
genre_facet |
ice core North Atlantic |
op_source |
Climate of the Past, Vol 18, Pp 449-464 (2022) |
op_relation |
https://cp.copernicus.org/articles/18/449/2022/cp-18-449-2022.pdf https://doaj.org/toc/1814-9324 https://doaj.org/toc/1814-9332 doi:10.5194/cp-18-449-2022 1814-9324 1814-9332 https://doaj.org/article/84f44e74a41a4edba3e26903dfd09ecd |
op_doi |
https://doi.org/10.5194/cp-18-449-2022 |
container_title |
Climate of the Past |
container_volume |
18 |
container_issue |
3 |
container_start_page |
449 |
op_container_end_page |
464 |
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1766029427930562560 |