Regional characteristics of atmospheric sulfate formation in East Antarctica imprinted on <sup>17</sup>O-excess signature - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Journal of Geophysical Research: Atmospheres Année : 2021

Regional characteristics of atmospheric sulfate formation in East Antarctica imprinted on 17O-excess signature

Résumé

17O-excess (Δ17O = δ17O − 0.52 × δ18O) of sulfate trapped in Antarctic ice cores has been proposed as a potential tool for assessing past oxidant chemistry, while insufficient understanding of atmospheric sulfate formation around Antarctica hampers its interpretation. To probe influences of regional specific chemistry, we compared year-round observations of Δ17O of non-sea-salt sulfate in aerosols (Δ17O(SO42−)nss) at Dome C and Dumont d'Urville, inland and coastal sites in East Antarctica, throughout the year 2011. Although Δ17O(SO42−)nss at both sites showed consistent seasonality with summer minima (∼1.0‰) and winter maxima (∼2.5‰) owing to sunlight-driven changes in the relative importance of O3 oxidation to OH and H2O2 oxidation, significant intersite differences were observed in austral spring–summer and autumn. The cooccurrence of higher Δ17O(SO42−)nss at inland (2.0‰ ± 0.1‰) than the coastal site (1.2‰ ± 0.1‰) and chemical destruction of methanesulfonate (MS–) in aerosols at inland during spring–summer (October–December), combined with the first estimated Δ17O(MS–) of ∼16‰, implies that MS– destruction produces sulfate with high Δ17O(SO42−)nss of ∼12‰. If contributing to the known postdepositional decrease of MS– in snow, this process should also cause a significant postdepositional increase in Δ17O(SO42−)nss over 1‰, that can reconcile the discrepancy between Δ17O(SO42−)nss in the atmosphere and ice. The higher Δ17O(SO42−)nss at the coastal site than inland during autumn (March–May) may be associated with oxidation process involving reactive bromine and/or sea-salt particles around the coastal region.
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hal-03402190 , version 1 (25-10-2021)

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Paternité - Pas d'utilisation commerciale

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Sakiko Ishino, Shohei Hattori, Michel Legrand, Q. Chen, Becky Alexander, et al.. Regional characteristics of atmospheric sulfate formation in East Antarctica imprinted on 17O-excess signature. Journal of Geophysical Research: Atmospheres, 2021, 126 (6), pp.e2020JD033583. ⟨10.1029/2020JD033583⟩. ⟨hal-03402190⟩
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