HR: 14:55h
AN: A13F-05    [Abstracts]
TI: Arctic Surface Ozone Depletion Meets Nitrate Isotopes
AU: * Morin, S
EM: samuel.morin@lgge.obs.ujf-grenoble.fr
AF: Laboratoire de Glaciologie et Géophysique de l'Environnement, 54 rue Moliere, Saint Martin d'Heres, 38400 France
AU: Savarino, J
EM: joel.savarino@lgge.obs.ujf-grenoble.fr
AF: Laboratoire de Glaciologie et Géophysique de l'Environnement, 54 rue Moliere, Saint Martin d'Heres, 38400 France
AU: Gong, S
EM: sunling.gong@ec.gc.ca
AF: Meteorological Service of Canada, 4905 Dufferin St., Toronto, ON M3H 5T4 Canada
AU: Bottenheim, J W
EM: jan.bottenheim@ec.gc.ca
AF: Meteorological Service of Canada, 4905 Dufferin St., Toronto, ON M3H 5T4 Canada
AB: We report here the first measurements of the isotopic anomaly of oxygen in particulate nitrate from the Arctic. Data and aerosol samples were collected at Alert, Nunavut, Canada (N82°30', W62°19') in Springtime 2004. Focussing on the polar sunrise period, characterized by the occurence of severe Ozone Depletion Events (ODEs), our data show a significant correlation between the evolution of the mole fraction of ozone (O₃) and Δ¹⁷O in particulate nitrate (^Δp-NO₃^-, with Δ¹⁷O~eq δ¹⁷O-0.52· δ¹⁸O). ^Δp-NO₃^- (‰)= 0.15· [O₃](nmol.mol^-1)+28.6, with R²=0.70, with ^Δp-NO₃^- ranging between 29 and 34 ‰. Nitrogen oxides (NOx) cycling with O₃ and hydroxyl radicals is responsible for this coupling, hence providing information on timing and spatial localization of chemical reactions involved in these cycles. The implications of our measurements are fourfold : (1) to our knowledge they represent the first measurements of Δ¹⁷O in particulate nitrate in coastal Arctic and therefore enhance the global representation of this variable (2) due to a highly variable ozone mole fraction the links between ozone mole fraction and ^Δp-NO₃^- can be explored for the first time in natural samples. (3) the observed correlation between these two variables provides insight in ODE mechanism itself since ^Δp-NO₃^- is a unique tracer of NOx chemistry known to be affected by ODEs (4) during ODEs a clear co evolution is established between a short life oxidant species O₃ and a stable indicator (the isotopic composition of nitrate), a first step towards a paleorecord of O₃. This new isotopic approach appears promising towards a better understanding of processes involving the Ocean-Atmosphere-Sea Ice-Snowpack System in the Arctic.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0365 Troposphere: composition and chemistry
DE: 0799 General or miscellaneous
DE: 1041 Stable isotope geochemistry (0454, 4870)
DE: 9315 Arctic region (0718, 4207)
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005