Abstract

The last 10 years have seen the parallel development of active research on the budget of reactive nitrogen species in polar regions, triggered by the discovery that polar snowpacks could be a source of NOx to the overlying atmosphere, and the instigation of sensitive analytical techniques to analyze the comprehensive isotopic composition of nitrate (d15N, d17O and d18O).

In my talk, I will show the benefits of the synergetic use of stable isotopes approaches for nitrate in polar areas. Recent progresses have been made in terms of the identification of direct nitrate sources (e.g. stratospheric injections to the Antarctic atmosphere), NOx oxidation pathways (including the role of halogens during the spring) and NOx sources (in particular snowpack emissions), to unravel the seasonal variations of the budget of reactive nitrogen species in the Arctic and the Antarctic atmosphere. Recent investigations carried out in the Antarctic snowpack itself reveal the potential of coupled O and N isotopic studies to distinguish between evaporation and photolysis of nitrate in the snow.

This research has strong implications (and potential) for the understanding of the oxidative power of the atmosphere in polar regions, and for the interpretation of the message carried by nitrate buried in ice-cores.