Basin-scale distribution of NH4 + and NO2 in the Pacific Ocean

Sayaka Yasunaka, Yukihiro Nojiri, Taketo Hashioka, Chisato Yoshikawa, Taketoshi Kodama, Shin ichiro Nakaoka, Sanae Chiba, Fuminori Hashihama, Masahide Wakita, Ken Furuya, Daisuke Sasano, Akihiko Murata, Hiroshi Uchida, Michio Aoyama

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)


We used more than 25,000 nutrient samples to elucidate for the first time basin-scale distributions and seasonal changes of surface ammonium (NH4 +) and nitrite (NO2 ) concentrations in the Pacific Ocean. The highest NH4 +, NO2 , and nitrate (NO3 ) concentrations were observed north of 40°N, in the coastal upwelling region off the coast of Mexico, and in the Tasman Sea. NH4 + concentrations were elevated during May–October in the western subarctic North Pacific, May–December in the eastern subarctic North Pacific, and June–September in the subtropical South Pacific. NO2 concentrations were highest in winter in both hemispheres. The seasonal cycle of NH4 + was synchronous with NO2 , NO3 , and satellite chlorophyll a concentrations in the western subtropical South Pacific, whereas it was synchronous with chlorophyll-a but out of phase with NO2 and NO3 in the subarctic regions.

Original languageEnglish
Pages (from-to)1-11
Number of pages11
JournalJournal of Oceanography
Issue number1
Publication statusPublished - 2018 Feb 1


  • Ammonium (NH )
  • Nitrate (NO )
  • Nitrite (NO )
  • Pacific Ocean
  • Satellite chlorophyll-a
  • Ship-of-opportunity


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