Publication: Production and consumption mechanisms of N2O in the Southern Ocean revealed from its isotopomer ratios
Accepted Date
2010-10-11
Issued Date
2010
Resource Type
Language
eng
ISSN
18106277
Rights
Mahidol University.
Bibliographic Citation
Biogeosciences Discussions. (2010), 7821-7848.
Suggested Citation
N. Boontanon, S. Watanabe, T. Odate, N. Yoshida, Narin Boontanon, นรินทร์ บุญตานนท์ Production and consumption mechanisms of N2O in the Southern Ocean revealed from its isotopomer ratios. Biogeosciences Discussions. (2010), 7821-7848.. doi:10.5194/bgd-7-7821-2010 Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/48482
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Title
Production and consumption mechanisms of N2O in the Southern Ocean revealed from its isotopomer ratios
Other Contributor(s)
Mahidol University. Faculty of Environment and Resource Studies.
Japan Science and Technology Agency. 2SORST project.
Japan Marine Science and Technology Center
National Institute of Polar Research, Japan
Tokyo Institute of Technology. Interdisciplinary Graduate School of Science and Engineering. Department of Environmental Science and Technology
Japan Science and Technology Agency. 2SORST project.
Japan Marine Science and Technology Center
National Institute of Polar Research, Japan
Tokyo Institute of Technology. Interdisciplinary Graduate School of Science and Engineering. Department of Environmental Science and Technology
Abstract
The distribution of dissolved N2O in the Southern Ocean at 140 E was measured
during the austral summer (February–March 2002) in the framework of the 43rd
Japanese Antarctic Research Expedition (JARE-43). Surface-dissolved N2O was un-dersaturated (about 94% saturation), and the calculated mean sea-air flux rate was
−3.68±2.57 μmolm−2 d−1. The vertical distributions tested exhibited N2O maxima at
around 150–300m (ÉN2O, 7.90–8.51 nM) below the chlorophyll-rich layer, which coincided
with the layer of minimum oxygen. These observations strongly suggest that
N2O production and consumption are related to apparent oxygen utilization (AOU). In the deeper layer, the presence of anoxic microsites within particles, together with the
horizontal and vertical movement of cold water around Antarctica, is one of the parameters
that govern the intramolecular distribution of the isotopic composition of N2O.
The N2O isotopic compositions in the maximum layer were +7.3 to +8.2‰ for 15Nbulk
and +43.5 to +46.2‰ for 18O associated with the coupling of nitrification and denitrification production mechanisms. Site preference decreased from an average 17‰ at
the surface to the ÉN2O maximum and slightly increased with depth up to 24‰ at the
deeper region. The influence of deep Southern Ocean N2O on the global N2O budget
is estimated to be about 46.2±5.3Mg N2O-N d−1, which represents the amount
that can escape to the atmosphere and thus contribute to emissions into the world’s oceans.