@article{oai:rakuno.repo.nii.ac.jp:00006421,
 author = {Toyoda, Sakae and 吉田, 磨 and Yamagishi, Hiroaki and Fujii, Ayako and Yoshida, Naohiro and Watanabe, Shuichi},
 journal = {Scientific Reports},
 month = {May},
 note = {Article, Nitrous oxide (N_2O) contributes to global warming and stratospheric ozone depletion. Although its major sources are regarded as bacterial or archaeal nitrification and denitrification in soil and water, the origins of ubiquitous marine N_2O maximum at depths of 100–800 m and N_2O dissolved in deeper seawater have not been identified. We examined N2O production processes in the middle and deep sea by analyzing vertical profiles of N_2O concentration and isotopocule ratios, abundance ratios of molecules substituted with rare stable isotopes ^<15>N or ^<18>O to common molecules ^<14>N^<14>N^<16>O, in the Atlantic, Pacific, Indian, and Southern oceans. Isotopocule ratios suggest that the N_2O concentration maxima is generated by in situ microbial processes rather than lateral advection or diffusion from biologically active sea areas such as the eastern tropical North Pacific. Major production process is nitrification by ammonia-oxidizing archaea (AOA) in the North Pacific although other processes such as bacterial nitrification/denitrification and nitrifier-denitrification also significantly contribute in the equatorial Pacific, eastern South Pacific, Southern Ocean/southeastern Indian Ocean, and tropical South Atlantic. Concentrations of N_2O below 2000 m show significant correlation with the water mass age, which supports an earlier report suggesting production of N_2O during deep water circulation. Furthermore, the isotopocule ratios suggest that AOA produce N2O in deep waters. These facts indicate that AOA have a more important role in marine N_2O production than bacteria and that change in global deep water circulation could affect concentration and isotopocule ratios of atmospheric N_2O in a millennium time scale.},
 pages = {7790-1--7790-9},
 title = {Identifying the origin of nitrous oxide dissolved in deep ocean by concentration and isotopocule analyses},
 volume = {9},
 year = {2019}
}