Response of N2O production rate to ocean acidification in the western North Pacific

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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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Fig. 1: Experiment and sampling stations.
Fig. 2: Response of nitrification and nitrous oxide production rates to simulated ocean acidification.
Fig. 3: Nitrification and nitrifier denitrification pathways.

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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


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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).

Author information

F.B., C.Y., A.M. and S.T. conceived this study, designed and executed the experiments, analysed the results and wrote the paper. M.W. calculated pH values from DIC and total alkalinity for all cruises. Y.M. measured δ15NO3 values to estimate nitrification rates. S.K., T.F. and N.H. contributed to the organization of the sampling campaigns. All authors contributed to the interpretation of the results and the preparation of the manuscript.

Correspondence to Florian Breider.

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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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Supplementary Information

Supplementary Tables 1 and 2 and Figs. 1–4.

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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) doi:10.1038/s41558-019-0605-7

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