Nitrate postdeposition processes in Svalbard surface snow

• Published in: Journal of Geophysical Research: Atmospheres
• Main Authors: Björkman, Mats, Vega, Carmen P., Kühnel, Rafael, Spataro, Francesca, Ianniello, Antonietta, Esposito, Giulio, Kaiser, Jan, Marca, Alina, Hodson, Andy, Isaksson, Elisabeth, Roberts, Tjarda J.
• Other Authors: Department of Geosciences Oslo, Faculty of Mathematics and Natural Sciences Oslo, University of Oslo (UiO)-University of Oslo (UiO), Norwegian Polar Institute, Department of Earth Sciences - Palaeobiology Uppsala, Uppsala University, Istituto sull’Inquinamento Atmosferico (CNR-IIA), Consiglio Nazionale delle Ricerche (CNR), School of Environmental Sciences Norwich, University of East Anglia Norwich (UEA), Department of Geography Sheffield, University of Sheffield Sheffield, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales Paris (CNES), Arctic Field Grant, Svalbard Science Forum, ANR-10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010), European Project: 215503,EC:FP7:PEOPLE,FP7-PEOPLE-2007-1-1-ITN,NSINK(2008)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2014
• Subjects: [SDU]Sciences of the Universe [physics]; Ny-Ålesund; Svalbard; Arctic; ice core; Ny Ålesund
• Online Access: https://hal-insu.archives-ouvertes.fr/insu-01172714; https://hal-insu.archives-ouvertes.fr/insu-01172714/document; https://hal-insu.archives-ouvertes.fr/insu-01172714/file/Bjrkman_et_al-2014-Journal_of_Geophysical_Research__Atmospheres.pdf; https://doi.org/10.1002/2013JD021234

International audience The snowpack acts as a sink for atmospheric reactive nitrogen, but several postdeposition pathways have been reported to alter the concentration and isotopic composition of snow nitrate with implications for atmospheric boundary layer chemistry, ice core records, and terrestrial ecology following snow melt. Careful daily sampling of surface snow during winter (11–15 February 2010) and springtime (9 April to 5 May 2010) near Ny-Ålesund, Svalbard reveals a complex pattern of processes within the snowpack. Dry deposition was found to dominate over postdeposition losses, with a net nitrate deposition rate of (0.6 ± 0.2) μmol m À2 d À1 to homogeneous surface snow. At Ny-Ålesund, such surface dry deposition can either solely result from long-range atmospheric transport of oxidized nitrogen or include the redeposition of photolytic/bacterial emission originating from deeper snow layers. Our data further confirm that polar basin air masses bring 15 N-depleted nitrate to Svalbard, while high nitrate δ(18 O) values only occur in connection with ozone-depleted air, and show that these signatures are reflected in the deposited nitrate. Such ozone-depleted air is attributed to active halogen chemistry in the air masses advected to the site. However, here the Ny-Ålesund surface snow was shown to have an active role in the halogen dynamics for this region, as indicated by declining bromide concentrations and increasing nitrate δ(18 O), during high BrO (low-ozone) events. The data also indicate that the snowpack BrO-NO x cycling continued in postevent periods, when ambient ozone and BrO levels recovered.