Measurement report: Indirect evidence for the controlling influence of acidity on the speciation of iodine in Atlantic aerosols
<p>The speciation of soluble iodine and major-ion composition were determined in size-fractionated aerosols collected during the AMT21 cruise between Avonmouth, UK, and Punta Arenas, Chile, in September–November 2011. The proportions of iodine species (iodide, iodate and soluble organic iodine...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2021-09-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/21/13067/2021/acp-21-13067-2021.pdf |
| Summary: | <p>The speciation of soluble iodine and major-ion
composition were determined in size-fractionated aerosols collected during
the AMT21 cruise between Avonmouth, UK, and Punta Arenas, Chile, in September–November 2011. The proportions of iodine species (iodide, iodate and
soluble organic iodine (SOI)) varied markedly between size fractions and
with the extent to which the samples were influenced by pollutants. In
general, fine mode aerosols (<span class="inline-formula"><i><</i></span> 1 <span class="inline-formula">µ</span>m) contained higher
proportions of both iodide and SOI, while iodate was the dominant component
of coarse (<span class="inline-formula"><i><</i></span> 1 <span class="inline-formula">µ</span>m) aerosols. The highest proportions of
iodate were observed in aerosols that contained (alkaline) unpolluted
sea spray or mineral dust. Fine mode samples with high concentrations of
acidic species (e.g. non-sea-salt sulfate) contained very little iodate and
elevated proportions of iodide and SOI. These results are in agreement with
modelling studies that indicate that iodate can be reduced under acidic
conditions and that the resulting hypoiodous acid (HOI) can react with
organic matter to produce SOI and iodide. Further work that investigates the
link between iodine speciation and aerosol pH directly, as well as studies
on the formation and decay of organo-iodine compounds under aerosol
conditions, will be necessary before the importance of this chemistry in
regulating aerosol iodine speciation can be confirmed.</p> |
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| ISSN: | 1680-7316 1680-7324 |