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Origin and fluxes of nitrous oxide along a latitudinal transect in western North Pacific: Controls and regional significance
Author(s) -
Breider Florian,
Yoshikawa Chisato,
Abe Hitomi,
Toyoda Sakae,
Yoshida Naohiro
Publication year - 2015
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1002/2014gb004977
Subject(s) - subarctic climate , photic zone , ocean gyre , oceanography , transect , water column , new production , flux (metallurgy) , environmental science , atmospheric sciences , radiative forcing , atmosphere (unit) , trace gas , subtropics , geology , phytoplankton , nutrient , chemistry , climate change , ecology , physics , organic chemistry , biology , thermodynamics
Nitrous oxide (N 2 O) is an atmospheric trace gas playing an important role in both radiative forcing and stratospheric ozone depletion. The oceans are the second most important natural source of N 2 O. The magnitude of the flux of this source is poorly constrained. Moreover, the relative importance of the microbial processes leading to the formation or the consumption of N 2 O in oceans remains unclear. We present here fluxes and isotope and isotopomer signatures of N 2 O measured at three stations located along a latitudinal transect in subtropical and subarctic western North Pacific. These results indicate that about 30% to 55% of the oceanic flux of N 2 O to the atmosphere originates from the deep euphotic and shallow aphotic zones. The sea‐to‐air fluxes of N 2 O calculated using an isotope mass balance model indicate that the emission rate of N 2 O in subarctic waters is about 2 times higher than in oligotrophic subtropical waters suggesting that nutrient‐rich water coming from the western subarctic gyre stimulates the N 2 O production. Moreover, isotopomer analysis has revealed that in shallow water N 2 O originates from nitrification and nitrifier denitrification processes, and its distribution in the water column is partly controlled by the incident solar radiation. The results of this study contribute to better constrain the global N 2 O budget and provide important information to better predict the future evolution of the oceanic emissions of N 2 O.