Abiotic transformation of iodine species in ice and its environmental implications

Ice is one of the most common matters on earth and regarded as active reaction media in the environment. Recently, it was reported that several chemical reactions in frozen state proceed unexpected pathway and markedly accelerated compared to those in aqueous phase. The freeze concentration of reactants, protons, and gases in ice grain boundaries between ice crystals is regarded as main driving force for the intrinsic chemical processes in ice. Iodine plays important roles on ozone depletion event, oxidation of gaseous elemental mercury (Hg⁰) to Hg(II), oxidizing capacity in atmosphere, control of HO_x and NO_x ratio in marine boundary layer, and the formation of ultrafine aerosol particles as cloud condensation nuclei(CCN). Furthermore, iodine is also proposed to be a potential proxy for past sea ice variability. However, the chemical behavior of iodine compounds during transport and after deposition is not well understood. Although the intensive investigations on chemical behavior of iodine species such as theoretical studies, laboratory experiments, and field observations, the clear pathway and mechanism of iodine formation in polar regions are still uncovered. In this presentation, I want to introduce several unique chemical processes in ice related to iodine compounds such as 1) redox reactions of iodide (I^-), iodate (IO₃^-), periodate (IO₄^-) in ice, 2) interaction between iodine and metal oxides, 3) degradation and removal of pollutants with iodine species for the better understanding of fate of iodine species in polar environment. The detailed experimental conditions and mechanism will be discussed in the presentation