Epipelagic nitrous oxide production offsets carbon sequestration by the biological pump

Xianhui S. Wan, Hua Xia Sheng, Minhan Dai, Karen L. Casciotti, Matthew J. Church, Wenbin Zou, Li Liu, Hui Shen, Kuanbo Zhou, Bess B. Ward, Shuh Ji Kao

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

The removal of carbon dioxide from the atmosphere by the marine biological pump is a key regulator of Earth’s climate; however, the ocean also serves as a large source of nitrous oxide, a potent greenhouse gas and ozone-depleting substance. Although biological carbon sequestration and nitrous oxide production have been individually studied in the ocean, their combined impacts on net greenhouse forcing remain uncertain. Here we show that the magnitude of nitrous oxide production in the epipelagic zone of the subtropical ocean covaries with remineralization processes and thus acts antagonistically to weaken the radiative benefit of carbon removal by the marine biological pump. Carbon and nitrogen isotope tracer incubation experiments and nitrogen isotope natural abundance data indicate enhanced biological activity promotes nitrogen recycling, leading to substantial nitrous oxide production via both oxidative and reductive pathways. These shallow-water nitrous oxide sources account for nearly half of the air–sea flux and counteract 6–27% (median 9%) of the greenhouse warming mitigation achieved by carbon export via the biological pump.

Original languageEnglish (US)
Pages (from-to)29-36
Number of pages8
JournalNature Geoscience
Volume16
Issue number1
DOIs
StatePublished - Jan 2023

All Science Journal Classification (ASJC) codes

  • General Earth and Planetary Sciences

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