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A mechanism for biologically-induced iodine emissions from sea-ice
Earth and Space Science Division, NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109, USA
Abstract. Only recently, ground- and satellite-based measurements have reported high concentrations of IO in coastal Antarctica. The sources of such a large iodine burden in the Antarctic atmosphere remain unknown. We propose a novel mechanism for iodine release from sea-ice surfaces. The release is triggered by the biological production of iodide (I-) and hypoiodous acid (HOI) from marine algae, contained within and underneath sea-ice, and their diffusion through sea-ice brine channels to accumulate in the quasi-liquid layer on the surface of sea-ice. A multiphase chemical model of polar atmospheric chemistry has been developed to investigate the biology-ice-atmosphere coupling in the polar environment. Model simulations were conducted to interpret recent observations of elevated IO in the coastal Antarctic springtime. The results show that the levels of inorganic iodine (i.e. I2, IBr, ICl) released from sea-ice through this mechanism account for the observed IO concentrations in the Antarctic springtime environment. The model results also indicate that iodine may trigger the catalytic release of bromine from sea-ice through phase equilibration of IBr. Considering the extent of sea-ice around the Antarctic continent, we suggest that the resulting high levels of iodine may have widespread impact on catalytic ozone destruction and aerosol formation in the Antarctic lower troposphere.
Discussion Paper (PDF, 1089 KB) Supplement (115 KB) Interactive Discussion (Final Response, 10 Comments)
Citation: Saiz-Lopez, A. and Boxe, C. S.: A mechanism for biologically-induced iodine emissions from sea-ice, Atmos. Chem. Phys. Discuss., 8, 2953-2976, 2008. Bibtex EndNote Reference Manager
