A new marine biogenic emission: methane sulfonamide (MSAM), dimethyl sulfide (DMS), and dimethyl sulfone (DMSO<sub>2</sub>) measured in air over the Arabian Sea
oleh: A. Edtbauer, C. Stönner, E. Y. Pfannerstill, M. Berasategui, D. Walter, D. Walter, J. N. Crowley, J. Lelieveld, J. Lelieveld, J. Williams, J. Williams
| Format: | Article |
|---|---|
| Diterbitkan: | Copernicus Publications 2020-05-01 |
Deskripsi
<p>We present the first ambient measurements of a new marine emission methane sulfonamide (MSAM: <span class="inline-formula">CH<sub>5</sub>NO<sub>2</sub>S</span>), along with dimethyl sulfide (DMS) and dimethyl sulfone (<span class="inline-formula">DMSO<sub>2</sub></span>) over the Arabian Sea. Two shipborne transects (W <span class="inline-formula">→</span> E, E <span class="inline-formula">→</span> W) were made during the AQABA (Air Quality and Climate Change in the Arabian Basin) measurement campaign. Molar mixing ratios in picomole of species per mole of air (throughout this paper abbreviated as ppt) of DMS were in the range of 300–500 ppt during the first traverse of the Arabian Sea (first leg) and 100–300 ppt on the second leg. On the first leg <span class="inline-formula">DMSO<sub>2</sub></span> was always below 40 ppt and MSAM was close to the limit of detection. During the second leg <span class="inline-formula">DMSO<sub>2</sub></span> was between 40 and 120 ppt and MSAM was mostly in the range of 20–50 ppt with maximum values of 60 ppt. An analysis of HYSPLIT back trajectories combined with calculations of the exposure of these trajectories to underlying chlorophyll in the surface water revealed that most MSAM originates from the Somalia upwelling region, known for its high biological activity. MSAM emissions can be as high as one-third of DMS emissions over the upwelling region. This new marine emission is of particular interest as it contains both sulfur and nitrogen, making it potentially relevant to marine nutrient cycling and marine atmospheric particle formation.</p>