NATURE OF COARSE NITRATE PARTICLES IN THE ATMOSPHERE - A SINGLE, PARTICLE APPROACH

Aerosol particles were collected in Nagoya, a coastal city of Japan. Individual nitrate-containing particles were identified with a vapor-deposited thin film method by electron microscopy. Elemental composition of individual coarse nitrate-containing particles was determined with X-ray spectrometry. Nitrate was detected in the coarse particles in all the samples. It was observed that chemical modification of sea-salt particles by nitric acid occurred frequently in the coastal urban area. It is found that nitrate also existed on the surface of dust particles during the period of ''Kosa'' phenomenon, a yellow sand storm originating from East Asian deserts or loess areas observed in Japan. Nitrate formation through heterogeneous reactions on the dust particles may provide a removal mechanism for the nitrogen oxides in the atmosphere in ''Kosa'' phenomenon.