Carnat, G.

Delille, B.

Deman, F.

Fripiat, F.

Kotovitch, M.

Moreau, S.

Sapart, C.

Tison, J.-L.

Van der Linden, F.

Open Marine Archive

382 
 
S13: Understanding the role of sea ice in the Southern Ocean ecosystem 
N
2
O production and cycling within Antarctic sea ice 
Kotovitch Marie1,2, Jean Louis Tison2, François Fripiat3, Florian Deman4, Célia Sapart2, Gauthier 
Carnat2, Sébastien Moreau5, Fanny Van der Linden1,2 and Bruno Delille1 
1 Unité d’Océanographie Chimique, Université de Liège, Quartier Agora, Allée du six aout 19, 4000 
Liège, Belgique 
E-mail: marie.kotovitch@gulg.ac.be  
2  Laboratoire de Glaciologie, Faculty of Sciences of the Université Libre de Bruxelles, Brussels, 
Belgium 
3  Max Planck Institute for Chemistry, Climate Geochemistry Department, Mainz, Germany 
4  Department of Chemistry, Vrije Universiteit Brussel, Bruxelles, Belgium 
5  Institute for Marine and Antarctic Studies (IMAS), University of Tasmania, Hobart, Tasmania 
 
Nitrous oxide (N2O) is a potent greenhouse gas that has a lifetime of 114 years in the atmosphere 
and a global warming potential 300 time higher than that of CO2. However there are still large 
uncertainties and gaps in the understanding of the N2O cycle in polar oceans and particularly 
associated to sea ice. Sources and sinks of N2O are therefore poorly quantified. To date, only one 
study by Randall et al. 2012 present N2O measurements in sea ice. They pointed out that sea ice 
formation and melt has the potential to generate sea-air or air-sea fluxes of N2O, respectively. The 
main processes (except the transport processes) involved in the N2O cycle within the aquatic 
environment are nitrification and denitrification. Recent observations of significant nitrification in 
Antarctic sea ice shed a new light on nitrogen cycle within sea ice. It has been suggested that 
nitrification supplies up to 70% of nitrate assimilated within Antarctic spring sea ice. Corollary, 
production of N2O, a by-product of nitrification, can potentially be significant. Our recent studies in 
Antarctic land fast ice in McMurdo Sound, confirmed this suggestion, where N2O release to the 
atmosphere was estimated to reach 4µmol.m-2.yr-1. But this assessment is probably an 
underestimation since it only accounts for dissolved N2O while a significant amount of N2O is likely 
to occur in the gaseous form like N2, O2 and Ar. We will then address the new tools to measure the 
bulk concentration of N2O (dissolved and gaseous) in sea ice, and the production of N2O by 
sympagic microorganisms - what process is dominant and how much N2O is produced - based on 
the first time series of N2O measurement in sea ice. The determination of the isotopic composition 
of N2O using cavity enhanced laser absorption spectroscopy technique (Off-axis ICOS) will allow us 
to determine the origin of these processes.  
 
Reference 
- Randall, K. et al. 2012. First measurements of nitrous oxide in Arctic sea ice. Journal of 
Geophysical Research: Oceans 117:1978–2012. 
 
  


N<sub>2</sub>O production and cycling within Antarctic sea ice

N<sub>2</sub>O production and cycling within Antarctic sea ice

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