Iodine oxoacids enhance nucleation of sulfuric acid particles in the atmosphere.
basic_science · Level V
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- Record sourced from PubMed, PMID 38096284.
- Also identified by DOI 10.1126/science.adh2526.
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Abstract
The main nucleating vapor in the atmosphere is thought to be sulfuric acid (H<sub>2</sub>SO<sub>4</sub>), stabilized by ammonia (NH<sub>3</sub>). However, in marine and polar regions, NH<sub>3</sub> is generally low, and H<sub>2</sub>SO<sub>4</sub> is frequently found together with iodine oxoacids [HIO<i><sub>x</sub></i>, i.e., iodic acid (HIO<sub>3</sub>) and iodous acid (HIO<sub>2</sub>)]. In experiments performed with the CERN CLOUD (Cosmics Leaving OUtdoor Droplets) chamber, we investigated the interplay of H<sub>2</sub>SO<sub>4</sub> and HIO<i><sub>x</sub></i> during atmospheric particle nucleation. We found that HIO<i><sub>x</sub></i> greatly enhances H<sub>2</sub>SO<sub>4</sub>(-NH<sub>3</sub>) nucleation through two different interactions. First, HIO<sub>3</sub> strongly binds with H<sub>2</sub>SO<sub>4</sub> in charged clusters so they drive particle nucleation synergistically. Second, HIO<sub>2</sub> substitutes for NH<sub>3</sub>, forming strongly bound H<sub>2</sub>SO<sub>4</sub>-HIO<sub>2</sub> acid-base pairs in molecular clusters. Global observations imply that HIO<i><sub>x</sub></i> is enhancing H<sub>2</sub>SO<sub>4</sub>(-NH<sub>3</sub>) nucleation rates 10- to 10,000-fold in marine and polar regions.