Characterization of atmospheric aerosols in chichi of the Ogasawara (Bonin) Islands

Atmospheric aerosols in Chichi of the Ogasawara (Bonin) Islands, which is isolated by approximately 1000km from the main island of Japan in the Pacific Ocean, were investigated by using an Andersen sampler. The ratio of Na to Cl in the aerosol was almost consistent with that in seawater. The Cl discrepancy of 3.1 % to total Cl amount on the mole basis was explained by the Cl loss from a sea salt particle through the formation of NaNO₃. Al and V were considered to be derived from soil and fuel oil burning fly ash which were distributed dominatively in the coarse and fine particle ranges, respectively. It was shown that most of the nitrate consisted of NaNO₃ which was distributed in the coarse particle range. In addition, a very small amount of NH₄NO₃ was observed with a peak in the fine particle range. The sulfate was found to be distributed in a bimodal form with a peak in the coarse particle range which was derived from seawater, and a peak in the fine particle range which would be ascribed to sulfate converted from oceanic DMS. Finally, the inventory of total suspended particulate matter was presented.