14 Mar 2022
14 Mar 2022
Status: this preprint is currently under review for the journal ACP.

Factors controlling atmospheric DMS and its oxidation products (MSA and nssSO42-) in the aerosol at Terra Nova Bay, Antarctica

Silvia Becagli1,2, Elena Barbaro2, Simone Bonamano3, Laura Caiazzo1, Alcide di Sarra4, Matteo Feltracco2, Paolo Grigioni4, Jost Heintzenberg5, Luigi Lazzara6, Michel Legrand7, Alice Madonia3, Marco Marcelli3, Chiara Melillo6, Daniela Meloni4, Caterina Nuccio6, Giandomenico Pace4, Ki-Tae Park8, Suzanne Preunkert7, Mirko Severi1,2, Marco Vecchiato2, Roberta Zangrando2, and Rita Traversi1,2 Silvia Becagli et al.
  • 1Department of Chemistry “Ugo Schiff”, University of Florence, Sesto (FI), 50019, Italy
  • 2Intitute of Polar Sciences, National Research Council (CNR-ISP), Venice Mestre (VE), 30172, Italy
  • 3Department of Ecologic and Biologic Science,University of Tuscia, Civitavecchia, 00053, Italy
  • 4ENEA Laboratory of Observations And Measurements for the environment and climate, Rome, Italy
  • 5Leibniz-Institute for Tropospheric Research, Leipzig, 04318, Germany
  • 6Department of Biology, University of Florence, 50121, Florence, Italy
  • 7IGE-Institute des Géosciences de l’Environment, S. Martin d'Heres, 38400, France
  • 8Korea Polar Research Institute (KOPRI), Incheon 406-840, South Korea

Abstract. This paper presents the results on simultaneous high time resolution measurements of biogenic aerosol (methane sulfonic acid-MSA, non-sea salt sulfate nssSO42-) with its gaseous precursor dimethylsulfide (DMS) performed at the Italian coastal base Mario Zucchelli Station (MZS) in Terra Nova Bay (MZS) during two summer campaigns (2018–2019 and 2019–2020). The study provides information on marine biological activity in the nearby polynya in the Ross Sea and on the influence of biogenic and atmospheric processes on biogenic aerosol formation. Data on atmospheric DMS concentration are scarce especially in Antarctica. The DMS-maximum at MZS occurs in December, one month earlier than at other Antarctic stations. The maximum of DMS concentration is connected with the phytoplanktonic senescent phase following the bloom of Phaeocystis antarctica that occurs in the polynya when sea ice opens up. The second plankton bloom occurs in January and, despite the high Dimethylsulfopropionate (DMSP) concentration in sea water, atmospheric DMS remains low probably due to its fast biological turnover in sea water in this period. The intensity and timing of the DMS evolution during the two years suggests that only the portion of the polynya close to the sampling site produces a discernible effect on the measured DMS. The closeness to the DMS source area, and the occurrence of air masses containing DMS and freshly formed oxidation products allow to study the kinetic of biogenic aerosol formation and the reliable derivation of the branch ratio between MSA and nssSO42- from DMS oxidation that is estimated to be 0.84 ± 0.06. Conversely, for aged airmasses with low DMS content, an enrichment of nssSO42- with respect to MSA, due to the presence of background concentration of nssSO42- from volcanic origin (Erebus) or from long range transport, takes place. Therefore, the aged air mass presents an MSA / nssSO42- ratio lower than in newly formed biogenic aerosol. By considering the sum of MSA and biogenic nssSO42-, we estimate that the mean contribution of biogenic particulate matter to PM10 is 17 %, with a maximum of 56 %. The high contribution of biogenic aerosol to the total PM10 mass in summer in this area highlights the dominant role of the polynya on biogenic aerosol formation. Finally, due to the regional and year-to year variability of DMS and related biogenic aerosol formation, we stress the need of long-term measurements of atmospheric DMS and biogenic aerosol along the Antarctic coast and in the Southern Ocean.

Silvia Becagli et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2022-195', albert gabric, 23 Mar 2022
    • AC1: 'Reply on RC1', Silvia Becagli, 13 May 2022
    • AC2: 'Reply on RC1', Silvia Becagli, 13 May 2022
  • RC2: 'Comment on acp-2022-195', C. A. Marandino, 26 Apr 2022
    • AC3: 'Reply on RC2', Silvia Becagli, 13 May 2022

Silvia Becagli et al.

Silvia Becagli et al.


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Short summary
The paper reports data on contemporaneous measurements of biogenic aerosol (BA) and its gaseous precursor in a coastal site of Antarctica facing the polynya of Ross Sea. A multidisciplinary approach is used to understand the mechanism of BA formation and its quantification as function of oceanic parameters such as the extent of polynya, chl-a and aerosol precursor concentration in sea water. The paper aims to understand the interaction between ocean and atmosphere in the Southern Ocean.