Measurement report: Indirect evidence for the controlling influence of acidity on the speciation of iodine in Atlantic aerosols

Abstract. The speciation of soluble iodine and major-ion composition were determined in size-fractionated aerosols collected during the AMT21 cruise between Avonmouth, UK, Punta Arenas, Chile, September–November 2011. proportions species (iodide, iodate organic (SOI)) varied markedly size fractions with extent to which samples influenced by pollutants. In general, fine mode (< 1 µm) contained higher both iodide SOI, while was dominant component coarse aerosols. highest observed that (alkaline) unpolluted sea spray or mineral dust. Fine high concentrations acidic (e.g. non-sea-salt sulfate) very little elevated SOI. These results are agreement modelling studies indicate can be reduced under conditions resulting hypoiodous acid (HOI) react matter produce SOI iodide. Further work investigates link aerosol pH directly, as well on formation decay organo-iodine compounds conditions, will necessary before importance this chemistry regulating confirmed.