Molecular fossil evidence for anaerobic ammonium oxidation in the Arabian Sea over the last glacial cycle

Jaeschke, Andrea, Ziegler, Martin, Hopmans, Ellen C., Reichart, Gert‐Jan, Lourens, Lucas J., Schouten, Stefan and Sinninghe Damsté, Jaap S. 2009. Molecular fossil evidence for anaerobic ammonium oxidation in the Arabian Sea over the last glacial cycle. Paleoceanography 24 (2) 10.1029/2008PA001712

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Abstract

Anaerobic ammonium oxidation (anammox) has been recognized as an important process converting fixed nitrogen to N2 in many marine environments, thereby having a major impact on the present‐day marine nitrogen cycle. However, essentially nothing is known about the importance of anammox in past marine nitrogen cycles. In this study, we analyzed the distribution of fossil ladderane lipids, derived from bacteria performing anammox, in a sediment core from the northern Arabian Sea. Concentrations of ladderane lipids varied between 0.3 and 5.3 ng g−1 sediment during the past 140 ka, with high values observed during the Holocene, intervals during the last glacial, and during the penultimate interglacial. Maxima in ladderane lipid abundances correlate with high total organic carbon (4–6%) and elevated δ 15N (>8‰) values. Anammox activity, therefore, seems enhanced during periods characterized by an intense oxygen minimum zone (OMZ). Low concentrations of ladderanes (<0.5 ng g−1 sediment), indicating low‐anammox activity, coincide with periods during which the OMZ was severely diminished. Since anammox activity covaried with OMZ intensity, it may play an important role in the loss of fixed inorganic nitrogen from the global ocean on glacial‐interglacial timescales, which was so far attributed only to heterotrophic denitrification.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Earth and Environmental Sciences
Subjects:	Q Science > QE Geology
Additional Information:	Pdf uploaded in accordance with publisher's policy at http://www.sherpa.ac.uk/romeo/issn/1944-9186/ (accessed 20/02/2014).
Publisher:	American Geophysical Union
ISSN:	0883-8305
Date of First Compliant Deposit:	30 March 2016
Last Modified:	23 May 2023 14:47
URI:	https://orca.cardiff.ac.uk/id/eprint/9671

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