Oceanic nutrient rise and the late Miocene inception of Pacific oxygen-deficient zones

Xingchen Tony Wang, Yuwei Wang, Alexandra Auderset, Daniel M. Sigman, Haojia Ren, Alfredo Martínez-García, Gerald H. Haug, Zhan Su, Yi Ge Zhang, Birger Rasmussen, Alex L. Sessions, Woodward W. Fischer

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

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.

Original languageEnglish (US)
Article numbere2204986119
JournalProceedings of the National Academy of Sciences of the United States of America
Volume119
Issue number45
DOIs
StatePublished - Nov 8 2022

All Science Journal Classification (ASJC) codes

  • General

Keywords

  • late Miocene
  • nitrogen isotopes
  • nutrient cycling
  • ocean deoxygenation

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