Ozone depletion due to dust release of iodine in the free troposphere.

ABSTRACT: Iodine is an atmospheric trace element emitted from oceans that efficiently destroys ozone (O₃). Low O₃ 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 O₃ inside these dust layers (below 15 ppbv; up to 75% depleted). The added dust iodine can explain decreases in O₃ 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.

SUBMITTER: Koenig TK 

PROVIDER: S-EPMC8694599 | biostudies-literature | 2021 Dec

REPOSITORIES: biostudies-literature