Abstract
AbstractOcean–atmosphere gas exchange in the Arctic Ocean is sensitive to global warming because the decrease of sea‐ice covered area enhances the exchange. Melting sea ice affects the vertical transport of dissolved gases. Few reports of Arctic Ocean studies have described observations of dissolved N2O or temporal variation of sea‐to‐atmosphere N2O flux. Therefore, production mechanisms of this greenhouse gas and the stratospheric ozone depleting gas remain unclear. We measured dissolved N2O and its isotopic signatures in the western Arctic shelf region of the Chukchi Sea and surrounding areas during September in 2014 and 2015. In the Chukchi Sea shelf, the N2O concentration was slightly higher than the value expected under sea–air equilibrium in the surface water. It increased with depth to 23 nmol kg−1 in 2014, although it showed a vertically homogeneous distribution in 2015. Isotopocule ratios of N2O, which include 15N‐site preference in the N2O molecule as well as elemental N and O isotope ratios, indicate that N2O in the Chukchi Sea shelf is a mixture of N2O produced in the bottom water and that of atmospheric origin. The isotopic signature of excess N2O (δ15Nbulk = −3.6‰ to −1.4‰, δ18O = 61.5‰–63.0‰, SP = 38.7‰–49.0‰) suggests that it is produced by archeal or bacterial nitrification and that it is partly reduced by denitrification. Although further quantitative observations are necessary, the results confirmed that the western Arctic Ocean can act as a source of N2O to the atmosphere when sea‐ice cover retreats and the pycnocline is weakened.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.