CHEMICAL-COMPOSITION OF SINGLE AEROSOL-PARTICLES AT IDAHO-HILL - POSITIVE-ION MEASUREMENTS

The chemical compositions of single aerosol particles larger than 0.3 mu m optical diameter were measured at Idaho Hill using a laser ioniza tion mass spectrometer. The mass spectrometer can analyze either posit ive or negative ions; this paper covers the positive ion results. Pota ssium, iron, and organics were among the most common positive ions in the spectra of particles at Idaho Hill. Organic ions were the largest contributor to the ion current from accumulation mode particles and we re also significant in larger particles. Iron was present mostly in co arse mode particles. Potassium was bimodal, with large amounts of K in coarse mode particles and large amounts in particles near 0.3 mu m in west winds but not in east winds. Boron was observed in a number of p articles. A wide variety of metals were also observed including lead, tin, and vanadium. Lead was less common in polluted air. Silver, coppe r, zinc, nickel, molybdenum, rhenium, and thallium were also observed in a few particles. Ammonium ions and duster ions were more abundant i n upslope conditions. Amines seem to be evident in many of the spectra , especially in east winds. Elemental carbon was observed in 2 to 3% o f the particles. Almost all of the particles contained some nonvolatil e material.