Antarctic Zone nutrient conditions during the last two glacial cycles

Studer, Anja, S.; Sigman, Daniel, M.; Martinez-Garcia, Alfredo; Benz, Verena; Winckler, Gisela; Kuhn, Gerhard; Esper, Oliver; Lamy, Frank; Jaccard, Samuel; Wacker, Lukas; Oleynik, Sergey; Gersonde, Rainer; Haug, Gerald, H. (2015). Antarctic Zone nutrient conditions during the last two glacial cycles. Paleoceanography, 30(7), pp. 845-862. American Geophysical Union 10.1002/2014PA002745

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In a sediment core from the Pacific sector of the Antarctic Zone (AZ) of the Southern Ocean, we report diatom-bound N isotope (δ15Ndb) records for total recoverable diatoms and two distinct diatom assemblages (pennate and centric rich). These data indicate tight coupling between the degree of nitrate consumption and Antarctic climate across the last two glacial cycles, with δ15Ndb (and thus the degree of nitrate consumption) increasing at each major Antarctic cooling event. Coupled with evidence from opal- and barium-based proxies for reduced export production during ice ages, the δ15Ndb increases point to ice age reductions in the supply of deep ocean-sourced nitrate to the AZ surface. The two diatom assemblages and species abundance data indicate that the δ15Ndb changes are not the result of changing species composition. The pennate and centric assemblage δ15Ndb records indicate similar changes but with a significant decline in their difference during peak ice ages. A tentative seasonality-based interpretation of the centric-to-pennate δ15Ndb difference suggests that late summer surface waters became nitrate free during the peak glacials.

Item Type:

Journal Article (Original Article)

Division/Institute:

10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR)
08 Faculty of Science > Institute of Geological Sciences

UniBE Contributor:

Jaccard, Samuel

Subjects:

500 Science > 550 Earth sciences & geology

ISSN:

0883-8305

Publisher:

American Geophysical Union

Funders:

[4] Swiss National Science Foundation

Language:

English

Submitter:

Samuel Jaccard

Date Deposited:

05 Aug 2015 10:42

Last Modified:

26 Jun 2016 02:06

Publisher DOI:

10.1002/2014PA002745

BORIS DOI:

10.7892/boris.70683

URI:

https://boris.unibe.ch/id/eprint/70683

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