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Etude du maillon atmosphérique du cycle biogéochimique du soufre aux hautes latitudes sud (station Dumont d'Urville)

Abstract : The high southern latitude atmosphere remains poorly documented. The understanding of the biogeochemical sulphur cycle is a critical aspect for climate change studies as well as to interpret the record of sulphur species in polar ice, in relation with the large oceanic emissions of dimethylsulphur (DMS). Size segregated aerosol studies at the French coastal Antarctic station Dumont d'Urville allowed us to better evaluate the fractionation processes of the sea-salt aerosol in comparison to the bulk sea-water composition. In winter, a depletion of sulphate in regard of Na+ or Cl- is observed. The timing and the intensity of this phenomena have been studied in the aim of quantify the winter nss-sulphate. A second fractionation process, linked to the remobilization of HCI and characterised by a depletion of Cl- compared to Na+ in the seasalt aerosol, appears to be weakly pronounced at this site due to the combination of many parameters, among which a local influence of alkaline ornithogenic emissions. Since late 1998, DMS and DMSO measurements complete the continuous aerosol samplings since 1991. After three years, a large interannual variability of the DMS mixing ratios, firstly driven by the variability of the summer oceanic source, is revealed. If the atmospheric DMS concentrations appear to be largely controlled by the oceanic source at a local scale, the aerosol species (MSA and nss-sulphate) are more representative in summer of a regional scale. Winter values of the later species are low (15 to 20 ng/m3 of nss-sulphate, out of volcanism influence, half of which would be of biogenic origin). Finally, photochemical case studies in summer confirmed the importance of a heterogeneous lost of DMSO that seems to have a partial photochemical behaviour and appears to be a important production pathway of particulate MSA.
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https://tel.archives-ouvertes.fr/tel-00693953
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Submitted on : Thursday, May 3, 2012 - 11:02:58 AM
Last modification on : Friday, March 25, 2022 - 11:10:21 AM
Long-term archiving on: : Thursday, December 15, 2016 - 4:20:52 AM

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  • HAL Id : tel-00693953, version 1

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Bruno Jourdain. Etude du maillon atmosphérique du cycle biogéochimique du soufre aux hautes latitudes sud (station Dumont d'Urville). Océan, Atmosphère. Université Joseph-Fourier - Grenoble I, 2001. Français. ⟨tel-00693953⟩

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