Possible evidence for a connection between methyl iodide emissions and saharan dust

J. Williams, V. Gros, Elliot L Atlas, K. Maciejczyk, A. Batsaikhan, H. F. Schöler, C. Forster, B. Quack, N. Yassaa, R. Sander, R. Van Dingenen

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Methyl iodide has been measured during two field campaigns in the Atlantic region in 2002. The first took place in July-August at 2300 in on the island of Tenerife, while the second was a shipborne, east-west crossing of the Tropical Atlantic at 10°N in October-November of the same year. Both campaigns were periodically impacted by dust, advected from Africa in trade winds. Unexpectedly, during these dust events, methyl iodide mixing ratios were observed to be high relative to other times. Backward calculations with the particle dispersion model FLEXPART show the origin of the dust storms as Mauritania and southern Algeria for the ground- and ship-based campaigns, respectively. The dust-laden air traveled from its source above the marine boundary layer to the measurement region. On the basis of the field data correlations and the simulations, we suggest that dust-stimulated emission of methyl iodide has occurred. To test this hypothesis, dust samples were collected from the identified source regions and added to filtered Atlantic seawater. This rapidly produced methyl iodide. Further tests established that the addition of iodide increased the yield and that iodide with H2O2 was greater still. This was found for both sterilized and nonsterilized samples. We conclude that there is an abiotic methyl iodide production mechanism that can occur via substitution, analogous to those in soil, rather than radical recombination. This may occur when dust contacts seawater containing iodide or when marine water vapor condenses on dust containing iodide. This hypothesis appears to be consistent with recent long-term methyl iodide data sets from Tasmania and may help resolve current uncertainties in the iodine cycle.

Original languageEnglish (US)
Article numberD07302
JournalJournal of Geophysical Research C: Oceans
Volume112
Issue number7
DOIs
StatePublished - Apr 16 2007

Fingerprint

iodide
iodides
Dust
dust
Iodides
Seawater
Mauritania
Stimulated emission
methyl iodide
Tasmania
Algeria
Steam
seawater
dust storms
data correlation
Iodine
trade wind
dust storm
iodine
ships

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Atmospheric Science
  • Astronomy and Astrophysics
  • Oceanography

Cite this

Williams, J., Gros, V., Atlas, E. L., Maciejczyk, K., Batsaikhan, A., Schöler, H. F., ... Van Dingenen, R. (2007). Possible evidence for a connection between methyl iodide emissions and saharan dust. Journal of Geophysical Research C: Oceans, 112(7), [D07302]. https://doi.org/10.1029/2005JD006702

Possible evidence for a connection between methyl iodide emissions and saharan dust. / Williams, J.; Gros, V.; Atlas, Elliot L; Maciejczyk, K.; Batsaikhan, A.; Schöler, H. F.; Forster, C.; Quack, B.; Yassaa, N.; Sander, R.; Van Dingenen, R.

In: Journal of Geophysical Research C: Oceans, Vol. 112, No. 7, D07302, 16.04.2007.

Research output: Contribution to journalArticle

Williams, J, Gros, V, Atlas, EL, Maciejczyk, K, Batsaikhan, A, Schöler, HF, Forster, C, Quack, B, Yassaa, N, Sander, R & Van Dingenen, R 2007, 'Possible evidence for a connection between methyl iodide emissions and saharan dust', Journal of Geophysical Research C: Oceans, vol. 112, no. 7, D07302. https://doi.org/10.1029/2005JD006702
Williams, J. ; Gros, V. ; Atlas, Elliot L ; Maciejczyk, K. ; Batsaikhan, A. ; Schöler, H. F. ; Forster, C. ; Quack, B. ; Yassaa, N. ; Sander, R. ; Van Dingenen, R. / Possible evidence for a connection between methyl iodide emissions and saharan dust. In: Journal of Geophysical Research C: Oceans. 2007 ; Vol. 112, No. 7.
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