Organic trace gases of oceanic origin observed at South Pole during ISCAT 2000

Aaron L. Swanson, Douglas D. Davis, Richard Arimoto, Pauline Roberts, Elliot L. Atlas, Frank Flocke, Simone Meinardi, F. Sherwood Rowland, Donald R. Blake

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


Volatile organic compounds (VOCs) were measured at the South Pole (SP) from late Austral spring to mid-summer 2000 as part of the Investigation of Sulfur Chemistry in the Antarctic Troposphere Program (ISCAT-2000). This paper focuses on VOCs that are directly emitted from the ocean, specifically dimethyl sulfide (DMS), methyl nitrate (CH3ONO2), methyl iodide (CH 3I) and bromoform (CHBr3). A partial seasonal cycle of these gases was also recorded during the year following ISCAT-2000. During the summer, the SP periodically receives relatively fresh marine air containing short-lived oceanic trace gases, such as DMS (τ≈1 day). However, DMS was not detected at the SP until January even though DMS emissions from the Southern Ocean typically start peaking in November and elevated levels of other ocean-derived VOCs, including CH3ONO2 and CHBr 3, were observed in mid-November. We speculate that in November and December most of the DMS is oxidized before it reaches the SP: a strong correlation between CH3ONO2 and methane sulfonate (MSA), an oxidation product of DMS, supports this hypothesis. Based on a limited number of samples taken over the course of one year, CH3ONO2 apparently accumulates to a quasi-steady-state level over the SP in winter, most likely due to continuing emissions of the compound coupled with a lower rate of photochemical destruction. Oceanic emissions were concluded to be the dominant source of alkyl nitrates at the SP; this is in sharp contrast to northern high latitudes where total alkyl nitrate mixing ratios are dominated by urban sources.

Original languageEnglish (US)
Pages (from-to)5463-5472
Number of pages10
JournalAtmospheric Environment
Issue number32
StatePublished - Oct 2004
Externally publishedYes


  • Alkyl nitrates
  • Bromoform
  • DMS
  • Methyl iodide
  • Oceanic emissions
  • Photochemistry
  • South pole

ASJC Scopus subject areas

  • Environmental Science(all)
  • Atmospheric Science


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