Air-snow exchange of reactive nitrogen species at Ny-Ålesund, Svalbard (Arctic)

Abstract

Measurements of atmospheric concentrations and fluxes of reactive nitrogen (NO, NO2, HNO3, NO3 − fine and NO3 − coarse) above the snow surface were performed from 29 March to 30 April 2010 at Ny-Alesund, Svalbard. Determinations of chemical and physical properties of snow were also carried out. Both NO and NO2 showed clear diurnal cycles with noontime maxima and nighttime minima. Significant emission fluxes of NO and NO2 were observed, reaching noontime values up to 19.42 and 25.20 pmol/m2 s, respectively. The snow surface was the source of NO and NO2 but these observed releases were small due to almost alkaline snow environment and chemical forms of snow NO3 −. Significant deposition fluxes of HNO3, fine and coarse particulate NO3 − fluxes were also observed, reaching peak values up to −18.00, −37.80 and −12.50 pmol/m2 s, respectively, during snowfall events. Measurements of surface snow provided experimental data that the total contribution of dry deposition of these species to the NO3 − –N in the snow was about 24 %. However, wet deposition in falling snow seemed to be the major contribution to the nitrate input to the snow.