Oceanic nutrient rise and the late Miocene inception of Pacific oxygen-deficient zones
Oceanic nutrient rise and the late Miocene inception of Pacific oxygen-deficient zones
The modern Pacific Ocean hosts the largest oxygen-deficient zones (ODZs), where oxygen concentrations are so low that nitrate is used to respire organic matter. The history of the ODZs may offer key insights into ocean deoxygenation under future global warming. In a 12-My record from the southeastern Pacific, we observe a >10 increase in foraminifera-bound nitrogen isotopes (15N/14N) since the late Miocene (8 to 9 Mya), indicating large ODZs expansion. Coinciding with this change, we find a major increase in the nutrient content of the ocean, reconstructed from phosphorus and iron measurements of hydrothermal sediments at the same site. Whereas global warming studies cast seawater oxygen concentrations as mainly dependent on climate and ocean circulation, our findings indicate that modern ODZs are underpinned by historically high concentrations of seawater phosphate.
late Miocene, nitrogen isotopes, nutrient cycling, ocean deoxygenation
Wang, Xingchen Tony
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Wang, Yuwei
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Auderset, Alexandra
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Sigman, Daniel M.
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Ren, Haojia
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Martínez-García, Alfredo
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Haug, Gerald H.
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Su, Zhan
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Zhang, Yi Ge
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Rasmussen, Birger
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Sessions, Alex L.
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Fischer, Woodward W.
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8 November 2022
Wang, Xingchen Tony
38155a1c-775c-4f5b-a611-6328cdeab6f3
Wang, Yuwei
e53d4d17-853f-4a91-ad65-cea9c0cc527f
Auderset, Alexandra
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Sigman, Daniel M.
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Ren, Haojia
8bda3a52-50de-4e34-9a67-d8fee0994c98
Martínez-García, Alfredo
29c2896b-3a8c-4457-b640-5c3ac1b9d272
Haug, Gerald H.
b6d161a0-4bdc-44d3-8a88-8de0e3517ca8
Su, Zhan
5e72ecf8-2480-4239-88bd-9badeaceaf32
Zhang, Yi Ge
57eb90b7-b182-4203-93a1-0a0be4227c34
Rasmussen, Birger
df7a9c65-9a8c-4840-9ed4-95c1b3816730
Sessions, Alex L.
c89b4a38-bdf8-4822-bffc-98ebca5d0292
Fischer, Woodward W.
bd5bcd26-c882-4968-9af0-5619e9d66eab
Wang, Xingchen Tony, Wang, Yuwei, Auderset, Alexandra, Sigman, Daniel M., Ren, Haojia, Martínez-García, Alfredo, Haug, Gerald H., Su, Zhan, Zhang, Yi Ge, Rasmussen, Birger, Sessions, Alex L. and Fischer, Woodward W.
(2022)
Oceanic nutrient rise and the late Miocene inception of Pacific oxygen-deficient zones.
Proceedings of the National Academy of Sciences, 119 (45), [e2204986119].
(doi:10.1073/pnas.2204986119).
Abstract
The modern Pacific Ocean hosts the largest oxygen-deficient zones (ODZs), where oxygen concentrations are so low that nitrate is used to respire organic matter. The history of the ODZs may offer key insights into ocean deoxygenation under future global warming. In a 12-My record from the southeastern Pacific, we observe a >10 increase in foraminifera-bound nitrogen isotopes (15N/14N) since the late Miocene (8 to 9 Mya), indicating large ODZs expansion. Coinciding with this change, we find a major increase in the nutrient content of the ocean, reconstructed from phosphorus and iron measurements of hydrothermal sediments at the same site. Whereas global warming studies cast seawater oxygen concentrations as mainly dependent on climate and ocean circulation, our findings indicate that modern ODZs are underpinned by historically high concentrations of seawater phosphate.
Text
pnas.2204986119
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More information
Accepted/In Press date: 1 October 2022
Published date: 8 November 2022
Additional Information:
Funding Information:
We thank the International Ocean Discovery Program, the Oregon State University Core Repository, and D. C. Lund (University of Connecticut) for providing the samples used in this study. We also thank G. R. Rossman for assistance with the Fe and P content analyses. This work was funded by Boston College (to X.T.W.), the Simons Foundation (to X.T.W.), the David and Lucile Packard Foundation (to W.W.F.), the US NSF (to D.M.S.), the Australian Research Council (to B.R.), and the ACS Petroleum Research Fund (to Y.G.Z.).
Keywords:
late Miocene, nitrogen isotopes, nutrient cycling, ocean deoxygenation
Identifiers
Local EPrints ID: 473342
URI: http://eprints.soton.ac.uk/id/eprint/473342
ISSN: 0027-8424
PURE UUID: 7e0b60a7-2030-443b-ba9e-f8df7b795fed
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Date deposited: 16 Jan 2023 17:43
Last modified: 17 Mar 2024 04:18
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Contributors
Author:
Xingchen Tony Wang
Author:
Yuwei Wang
Author:
Alexandra Auderset
Author:
Daniel M. Sigman
Author:
Haojia Ren
Author:
Alfredo Martínez-García
Author:
Gerald H. Haug
Author:
Zhan Su
Author:
Yi Ge Zhang
Author:
Birger Rasmussen
Author:
Alex L. Sessions
Author:
Woodward W. Fischer
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