BROMINE, IODINE, AND CHLORINE IN SINGLE AEROSOL-PARTICLES AT CAPE GRIM

Using a laser ionization mass spectrometer, the chemical compositions of single particles larger than 0.16 mu m diameter were measured in th e marine boundary layer (MBL) at Cape Grim, Tasmania during the ACE-1 experiment. Chlorine was observed in nearly all of the particles. Brom ine was internally mixed with amounts near the sea water mole fraction in most particles. The aerosol mole fraction of iodine was similar to bromine, so iodine was highly enriched relative to sea water. Iodine was not uniformly mixed among all particles. Iodine-rich particles inc luded sea salt and metals. Iodine was also correlated with the presenc e of organics in the spectra. Chlorine, bromine and iodine were anti-c orrelated with sodium sulfate. Since particles accumulate sulfate in t he MEL, this anti-correlation suggests that the aerosols were losing a ll three halogens as they aged.