Ozone depletion due to dust release of iodine in the free troposphere.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 34936464.
- Also identified by DOI 10.1126/sciadv.abj6544 and PMC identifier 8694599.
- Licence recorded as CC BY-NC.
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Abstract
Iodine is an atmospheric trace element emitted from oceans that efficiently destroys ozone (O<sub>3</sub>). Low O<sub>3</sub> in airborne dust layers is frequently observed but poorly understood. We show that dust is a source of gas-phase iodine, indicated by aircraft observations of iodine monoxide (IO) radicals inside lofted dust layers from the Atacama and Sechura Deserts that are up to a factor of 10 enhanced over background. Gas-phase iodine photochemistry, commensurate with observed IO, is needed to explain the low O<sub>3</sub> inside these dust layers (below 15 ppbv; up to 75% depleted). The added dust iodine can explain decreases in O<sub>3</sub> of 8% regionally and affects surface air quality. Our data suggest that iodate reduction to form volatile iodine species is a missing process in the geochemical iodine cycle and presents an unrecognized aeolian source of iodine. Atmospheric iodine has tripled since 1950 and affects ozone layer recovery and particle formation.