Skip to content

Modelling iodide – iodate speciation in atmospheric aerosol: Contributions of inorganic and organic iodine chemistry

by S. Pechtl, G. Schmitz, R. von Glasow
Atmospheric Chemistry and Physics ()
Get full text at journal

Abstract

The speciation of iodine in atmospheric aerosol is currently poorly understood. Models predict negligible iodide concentrations but accumulation of iodate in aerosol, both of which is not confirmed by recent measurements. We present an updated aqueous phase iodine chemistry scheme for use in atmospheric chemistry models and discuss sensitivity studies with the marine boundary layer model MISTRA. These studies show that iodate can be reduced in acidic aerosol by inorganic reactions, i.e., iodate does not necessarily accumulate in particles. Furthermore, the transformation of particulate iodide to volatile iodine species likely has been overestimated in previous model studies due to negligence of collision-induced upper limits for the reaction rates. However, inorganic reaction cycles still do not seem to be sufficient to reproduce the observed range of iodide - iodate speciation in atmospheric aerosol. Therefore, we also investigate the effects of the recently suggested reaction of HOI with dissolved organic matter to produce iodide. If this reaction is fast enough to compete with the inorganic mechanism, it would not only directly lead to enhanced iodide concentrations but, indirectly via speed-up of the inorganic iodate reduction cycles, also to a decrease in iodate concentrations. Hence, according to our model studies, organic iodine chemistry, combined with inorganic reaction cycles, is able to reproduce observations. The presented chemistry cycles are highly dependent on pH and thus offer an explanation for the large observed variability of the iodide - iodate speciation in atmospheric aerosol.

Cite this document (BETA)

Readership Statistics

41 Readers on Mendeley
by Discipline
 
32% Environmental Science
 
24% Earth and Planetary Sciences
 
24% Chemistry
by Academic Status
 
46% Researcher
 
20% Student > Ph. D. Student
 
10% Professor > Associate Professor
by Country
 
7% United States
 
2% India
 
2% United Kingdom

Sign up today - FREE

Mendeley saves you time finding and organizing research. Learn more

  • All your research in one place
  • Add and import papers easily
  • Access it anywhere, anytime

Start using Mendeley in seconds!

Sign up & Download

Already have an account? Sign in