The acceleration of oceanic denitrification during deglacial warming.

Galbraith, Eric D., Kienast, Markus, Galbraith, Eric D., Kienast, Markus, Albuquerque, Ana Luiza, Altabet, Mark A., Batista, Fabian, Bianchi, Daniele, Calvert, Stephen E., Contreras, Sergio, Crosta, Xavier, De Pol-Holz, Ricardo, Dubois, Nathalie, Etourneau, Johan, Francois, Roger, Hsu, Ting-Chang, Ivanochko, Tara, Jaccard, Samuel L., Kao, Shuh-Ji, Kiefer, Thorsten, Kienast, Stephanie, Lehmann, Moritz F., Martinez, Philippe, McCarthy, Matthew, Meckler, Anna Nele, Mix, Alan, Möbius, Jürgen, Pedersen, Tom F., Pichevin, Laetitia, Quan, Tracy M., Robinson, Rebecca S., Ryabenko, Evgeniya, Schmittner-Boesch, Andreas, Schneider, Ralph, Schneider-Mor, Aya, Shigemitsu, Masahito, Sinclair, Dan, Somes, Christopher J. , Studer, Anja S., Tesdal, Jan-Erik, Thunell, Robert and Terence Yang, Jin-Yu (2013) The acceleration of oceanic denitrification during deglacial warming. Nature Geoscience, 6 (7). pp. 579-584. DOI 10.1038/ngeo1832.

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Abstract

Over much of the ocean’s surface, productivity and growth are limited by a scarcity of bioavailable nitrogen. Sedimentary δ15N records spanning the last deglaciation suggest marked shifts in the nitrogen cycle during this time, but the quantification of these changes has been hindered by the complexity of nitrogen isotope cycling. Here we present a database of δ15N in sediments throughout the world’s oceans, including 2,329 modern seafloor samples, and 76 timeseries spanning the past 30,000 years. We show that the δ15N values of modern seafloor sediments are consistent with values predicted by our knowledge of nitrogen cycling in the water column. Despite many local deglacial changes, the globally averaged δ15N values of sinking organic matter were similar during the Last Glacial Maximum and Early Holocene. Considering the global isotopic mass balance, we explain these observations with the following deglacial history of nitrogen inventory processes. During the Last Glacial Maximum, the nitrogen cycle was near steady state. During the deglaciation, denitrification in the pelagic water column accelerated. The flooding of continental shelves subsequently increased denitrification at the seafloor, and denitrification reached near steady-state conditions again in the Early Holocene. We use a recent parameterization of seafloor denitrification to estimate a 30–120% increase in benthic denitrification between 15,000 and 8,000 years ago. Based on the similarity of globally averaged δ15N values during the Last Glacial Maximum and Early Holocene, we infer that pelagic denitrification must have increased by a similar amount between the two steady states.

Document Type: Article
Keywords: ocean denitrification
Research affiliation: OceanRep > SFB 754 > A6
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-BM Biogeochemical Modeling
Kiel University
OceanRep > SFB 754 > B1
OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > SFB 754
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1038/ngeo1832
ISSN: 1752-0894
Projects: PAGES, IMAGES, GEOTOP, SFB754, Future Ocean
Date Deposited: 08 Nov 2013 08:35
Last Modified: 20 Feb 2017 14:32
URI: http://oceanrep.geomar.de/id/eprint/22372

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