IODINE SPECIATION IN SIZE-FRACTIONATED ATMOSPHERIC PARTICLES BY ISOTOPE-DILUTION MASS-SPECTROMETRY

An isotope dilution mass spectrometric method has been developed for t he accurate and sensitive determination of iodide and iodate in aeroso l particles of the atmosphere. The direct iodine speciation has been p ossible by the use of species specifically I-129 enriched spike soluti ons and separation of the isotope diluted species by anion exchange ch romatography after water extraction of the filters. Size fractionated collection of aerosol particles by a six stage impactor system shows d ifferent distributions of iodide and iodate for particles of different size with specific patterns for anthropogenically influenced continen tal and unpolluted marine aerosols, respectively. The detection limit for particulate iodide and iodate has been (3-5) pg/m(3) for sampling volumes of 3000 m(3). Oil, used for heating plants, could be identifie d as one but not the only anthropogenic iodine source.