Ocean acidification, induced by the increase in anthropogenic CO2 emissions, has a profound impact on marine organisms and biogeochemical processes1. The response of marine microbial activities to ocean acidification might play a crucial role in the future evolution of air–sea fluxes of biogenic gases such as nitrous oxide (N2O), a strong GHG and the dominant stratospheric ozone-depleting substance2. Here, we examine the response of N2O production from nitrification to acidification in a series of incubation experiments conducted in subtropical and subarctic western North Pacific. The experiments show that when pH was reduced, the N2O production rate during nitrification measured at subarctic stations increased significantly while nitrification rates remained stable or decreased. Contrary to previous findings, these results suggest that the effect of ocean acidification on N2O production during nitrification and nitrification rates are probably uncoupled. Collectively, these results suggest that if seawater pH continues to decline at the same rate, ocean acidification could increase marine N2O production during nitrification in the subarctic North Pacific by 185 to 491% by the end of the century.
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The authors declare that the data supporting the findings of this study are available within the article and its Supplementary Information and at at http://www.godac.jamstec.go.jp/darwin/e.
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We thank the captain, officers, crew, scientists and technicians for their assistance during the KS-16-8 and YK16-16 cruises and M. C. Honda, PI of the MR13-04 cruise. This project was financially supported by Kakenhi grants (project nos 23224013, 15H05822, 15H05471 and 17H06105) of the Ministry of Education, Culture, Sports, Science and Technology of Japan (MEXT) and the Swiss National Science Foundation (project no. PBNEP2-142954).
The authors declare no competing interests.
Peer review information Nature Climate Change thanks Hermann Bange, Shuh-Ji Kao and Brian Popp for their contribution to the peer review of this work.
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Breider, F., Yoshikawa, C., Makabe, A. et al. Response of N2O production rate to ocean acidification in the western North Pacific. Nat. Clim. Chang. 9, 954–958 (2019). https://doi.org/10.1038/s41558-019-0605-7
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