Field and laboratory studies of aerosol formation from halogenated precursor gases

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This project investigates secondary aerosol formation from halogenated precursor gases and its impact on halogen chemistry in the troposphere both in field and laboratory studies. Embedded into the HaloProc research unit which aims at understanding the reaction mechanisms prevailing in natural halogenation processes, the main objective is an improved understanding of iodine-initiated new particle formation. Nucleation of aerosol particles from reactive iodine species has previously been observed in coastal environments with biogenic sources of organic iodine compounds. Here, we propose to study new particle formation events in salt lake environments that may be dominated by inorganic sources of reactive iodine compounds. The temporal evolution of submicron particle size distributions will be measured, and aerosol filter samples will be collected for subsequent chemical analysis. Supplementary laboratory experiments designed to simulate the atmospheric conditions encountered at the field sites, and equipped with more sophisticated analytical methods, will help to identify the relevant iodine species and the key reaction mechanisms for iodine-initiated new particle formation. From the combination of field and laboratory work, an extensive set of experimental data is expected that will be made available to the modeling community in order to gain deeper insight into the implications of iodine nucleation on halogen chemistry in the troposphere. Thus, the proposed research agenda is designed to bridge the gap between field experiments, laboratory studies and modeling work, and contribute to the overarching objectives of the HaloProc research unit.