Factors controlling atmospheric DMS and its oxidation products (MSA and nssSO 4 2− ) in the aerosol at Terra Nova Bay, Antarctica

• Published in: Atmospheric chemistry and physics Vol. 22; no. 14; pp. 9245 - 9263
• Main Authors: Becagli, Silvia, Barbaro, Elena, Bonamano, Simone, Caiazzo, Laura, di Sarra, Alcide, Feltracco, Matteo, Grigioni, Paolo, Heintzenberg, Jost, Lazzara, Luigi, Legrand, Michel, Madonia, Alice, Marcelli, Marco, Melillo, Chiara, Meloni, Daniela, Nuccio, Caterina, Pace, Giandomenico, Park, Ki-Tae, Preunkert, Suzanne, Severi, Mirko, Vecchiato, Marco, Zangrando, Roberta, Traversi, Rita
• Format: Journal Article
• Language: English
• Published: Katlenburg-Lindau Copernicus GmbH 18-07-2022; European Geosciences Union; Copernicus Publications
• Subjects: Aerosol formation; Aerosols; Air masses; Algae; Antarctic aerosols; Antarctic stations; Atmosphere; Atmospheric data; Chemical analysis; Climate change; Dimethyl sulfide; Gases; Methane; Oxidation; Oxidation-reduction reaction; Particulate matter; Plankton; Plankton blooms; Polar environments; Polynyas; Radiation; Sciences of the Universe; Sea ice; Seawater; Sulfates; Sulfonic acid; Sulfur; Summer; Water analysis; Wind; Antarctica; Ross Sea; Southern Ocean
• ISSN: 1680-7324; 1680-7316; 1680-7324
• DOI: 10.5194/acp-22-9245-2022

This paper presents the results of 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). 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 dimethylsufoniopropionate (DMSP) concentration in seawater, atmospheric DMS remains low, probably due to its fast biological
turnover in seawater in this period. The intensity and timing of the DMS evolution during the two years suggest 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 us 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 air masses with low
DMS content, an enrichment of nssSO42- with respect to MSA, is observed. We estimate that
the mean contribution of freshly formed biogenic aerosol 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 for long-term measurements of seawater and atmospheric DMS and biogenic aerosol along the Antarctic coast and in the Southern Ocean.