On the speciation of iodine in marine aerosol

Juan C. Gómez Martín (Lead Author), Alfonso Saiz Lopez, Carlos A. Cuevas, Alex Baker, Rafael P. Fernandez

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We have compiled and analyzed a comprehensive data set of field observations of iodine speciation in marine aerosol. The soluble iodine content of fine aerosol (PM1) is dominated by soluble organic iodine (SOI; ∼50%) and iodide (∼30%), while the coarse fraction is dominated by iodate (∼50%), with non-negligible amounts of iodide (∼20%). The SOI fraction shows an equatorial maximum and minima coinciding with the ocean “deserts,” which suggests a link between soluble iodine speciation in aerosol and ocean productivity. Among the major aerosol ions, organic anions and non-sea-salt sulfate show positive correlations with SOI in PM1. Alkali cations are positively correlated to iodate and negatively correlated with SOI and iodide in coarse aerosol. These relationships suggest that under acidic conditions iodate is reduced to HOI, which reacts with organic matter to form SOI, a possible source of iodide. In less acidic sea-salt or dust-rich coarse aerosols, HOI oxidation to iodate and reaction with organic matter likely compete.
Original languageEnglish
Article numbere2021JD036081
Number of pages14
JournalJournal of Geophysical Research: Atmospheres
Issue number4
Early online date10 Feb 2022
Publication statusPublished - 27 Feb 2022

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