Identifying the origin of nitrous oxide dissolved in deep ocean by concentration and isotopocule analyses
| Autor: | Sakae Toyoda, Shuichi Watanabe, Hiroaki Yamagishi, Ayako Fujii, Osamu Yoshida, Naohiro Yoshida |
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| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
0301 basic medicine
Marine biology Water mass Multidisciplinary Denitrification Stable isotope ratio lcsh:R Global warming lcsh:Medicine equipment and supplies Ozone depletion Deep sea Article Environmental sciences 03 medical and health sciences 030104 developmental biology 0302 clinical medicine Oceanography Element cycles Environmental science lcsh:Q Nitrification Seawater lcsh:Science 030217 neurology & neurosurgery |
| Zdroj: | Scientific Reports Scientific Reports, Vol 9, Iss 1, Pp 1-9 (2019) |
| Popis: | Nitrous oxide (N2O) 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 N2O maximum at depths of 100–800 m and N2O dissolved in deeper seawater have not been identified. We examined N2O production processes in the middle and deep sea by analyzing vertical profiles of N2O concentration and isotopocule ratios, abundance ratios of molecules substituted with rare stable isotopes 15N or 18O to common molecules 14N14N16O, in the Atlantic, Pacific, Indian, and Southern oceans. Isotopocule ratios suggest that the N2O 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 N2O below 2000 m show significant correlation with the water mass age, which supports an earlier report suggesting production of N2O 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 N2O production than bacteria and that change in global deep water circulation could affect concentration and isotopocule ratios of atmospheric N2O in a millennium time scale. |
| Databáze: | OpenAIRE |
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