Chemical Characterization of Acid Fog and Rain of Akita in Northern Japan

Fog/cloud and rain water was collected at the mountainside of Hachiman tai range and rain water was also collected at Akita City. The various ion concentrations (H+, Cl-, SO42-, NO3-, Na+, NH4+, K+, Ca2+, Mg2+) of these sam ples were analyzed, and the droplet size and the wind direction were measured for each fog sample. The fog at Hachimantai range had a very high total ion concentration, and was considerably acidified by nss (non sea-salt)-SO42- and NO3-, in comparison with the rain at Akita and Onuma (Hachimantai range). There were some fog and rain samples whose chemical components in insoluble substance, which were analyzed by PIXE analysis, were similar to that of Kosa from China. As the fog droplet size increased, the ion concentration decreased, and the slope of plots of the concentration versus the droplet size was different from each other. From the negative slope of the plots, we can conclude that the fog samples in this work were in the size interval I (unactivated or freshly-activated) for the droplet growth.