Signature of Arctic surface ozone depletion events in the isotope anomaly ( Δ 17 O) of atmospheric nitrate

• Main Authors: Morin, S., Savarino, J., Bekki, Slimane, Gong, S., Bottenheim, J. W.
• Other Authors: Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS), Service d'aéronomie (SA), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Environment and Climate Change Canada
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2007
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; Arctic; Nunavut; Canada
• Online Access: https://hal.archives-ouvertes.fr/hal-00328485; https://hal.archives-ouvertes.fr/hal-00328485/document; https://hal.archives-ouvertes.fr/hal-00328485/file/acp-7-1451-2007.pdf

International audience We report the first measurements of the oxygen isotope anomaly of atmospheric inorganic nitrate from the Arctic. Nitrate samples and complementary data were collected at Alert, Nunavut, Canada (82°30 ' N, 62°19 ' W) in spring 2004. Covering the polar sunrise period, characterized by the occurrence of severe boundary layer ozone depletion events (ODEs), our data show a significant correlation between the variations of atmospheric ozone (O 3 ) mixing ratios and Δ 17 O of nitrate (Δ 17 O(NO - 3 )). This relationship can be expressed as: Δ 17 O(NO - 3 )/‰, =(0.15±0.03)×O 3 /(nmol mol –1 )+(29.7±0.7), with R 2 =0.70(n=12), for Δ 17 O(NO - 3 ) ranging between 29 and 35 ‰. We derive mass-balance equations from chemical reactions operating in the Arctic boundary layer, that describe the evolution of Δ 17 O(NO - 3 ) as a function of the concentrations of reactive species and their isotopic characteristics. Changes in the relative importance of O 3 , RO 2 and BrO in the oxidation of NO during ODEs, and the large isotope anomalies of O 3 and BrO, are the driving force for the variability in the measured Δ 17 O(NO - 3 ) . BrONO 2 hydrolysis is found to be a dominant source of nitrate in the Arctic boundary layer, in agreement with recent modeling studies.