A gas-to-particle conversion mechanism helps to explain atmospheric particle formation through clustering of iodine oxides.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 32908140.
- Also identified by DOI 10.1038/s41467-020-18252-8 and PMC identifier 7481236.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Emitted from the oceans, iodine-bearing molecules are ubiquitous in the atmosphere and a source of new atmospheric aerosol particles of potentially global significance. However, its inclusion in atmospheric models is hindered by a lack of understanding of the first steps of the photochemical gas-to-particle conversion mechanism. Our laboratory results show that under a high humidity and low HO<sub>x</sub> regime, the recently proposed nucleating molecule (iodic acid, HOIO<sub>2</sub>) does not form rapidly enough, and gas-to-particle conversion proceeds by clustering of iodine oxides (I<sub>x</sub>O<sub>y</sub>), albeit at slower rates than under dryer conditions. Moreover, we show experimentally that gas-phase HOIO<sub>2</sub> is not necessary for the formation of HOIO<sub>2</sub>-containing particles. These insights help to explain new particle formation in the relatively dry polar regions and, more generally, provide for the first time a thermochemically feasible molecular mechanism from ocean iodine emissions to atmospheric particles that is currently missing in model calculations of aerosol radiative forcing.