title: Mineral dust photochemistry induces nucleation events in the presence of SO2.
abstract: Large quantities of mineral dust particles are frequently ejected into the atmosphere through the action of wind. The surface of dust particles acts as a sink for many gases, such as sulfur dioxide. It is well known that under most conditions, sulfur dioxide reacts on dust particle surfaces, leading to the production of sulfate ions. In this report, for specific atmospheric conditions, we provide evidence for an alternate pathway in which a series of reactions under solar UV light produces first gaseous sulfuric acid as an intermediate product before surface-bound sulfate. Metal oxides present in mineral dust act as atmospheric photocatalysts promoting the formation of gaseous OH radicals, which initiate the conversion of SO(2) to H(2)SO(4) in the vicinity of dust particles. Under low dust conditions, this process may lead to nucleation events in the atmosphere. The laboratory findings are supported by recent field observations near Beijing, China, and Lyon, France.
authors.affiliation: Université de Lyon 1, Lyon, Institut de Recherches sur la Catalyse et l'Environnement de Lyon, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5256, Villeurbanne F-69626, France.
authors.forename: Yoan
authors.initials: Y
authors.lastname: Dupart
authors.forename: Stephanie M
authors.initials: SM
authors.lastname: King
authors.forename: Bettina
authors.initials: B
authors.lastname: Nekat
authors.forename: Andreas
authors.initials: A
authors.lastname: Nowak
authors.forename: Alfred
authors.initials: A
authors.lastname: Wiedensohler
authors.forename: Hartmut
authors.initials: H
authors.lastname: Herrmann
authors.forename: Gregory
authors.initials: G
authors.lastname: David
authors.forename: Benjamin
authors.initials: B
authors.lastname: Thomas
authors.forename: Alain
authors.initials: A
authors.lastname: Miffre
authors.forename: Patrick
authors.initials: P
authors.lastname: Rairoux
authors.forename: Barbara
authors.initials: B
authors.lastname: D'Anna
authors.forename: Christian
authors.initials: C
authors.lastname: George
mesh_terms: D000393:Air Pollutants; D001272:Atmosphere; D002681:China; D004391:Dust; D005602:France; D007477:Ions; D008956:Models, Chemical; D055095:Optics and Photonics; D010316:Particle Size; D010777:Photochemistry / Q000379:methods*; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D013431:Sulfates / Q000737:chemistry; D013458:Sulfur Dioxide / Q000737:chemistry*; D013464:Sulfuric Acids / Q000737:chemistry; D014466:Ultraviolet Rays; D014867:Water
chemical_list: D000393:Air Pollutants; D004391:Dust; D007477:Ions; D013431:Sulfates; D013464:Sulfuric Acids; D014867:Water; D013458:Sulfur Dioxide; C033158:sulfuric acid