A replication technique for the collection of individual fog droplets and their chemical analysis using micro-PIXE

In order to get a better understanding of fog formation and its multiple scavenging processes, the replication technique was especially applied to the studies of individual fog droplets. Moreover, micro-particle-induced X-ray emission (PIXE) was applied to the chemical analysis of individual fog droplets. Field measurements were performed at urban site in Kyoto, Japan in April 2001. The replicas of individual fog droplets were successfully formed on the thin collodion film without bounce-off. The number size distributions of fog droplets show the bimodal shape with the maximum level around 7 and 23 μm for two fog events. Several elements including sulfur in individual fog droplets were successfully analyzed by micro-PIXE. Crustal components and sulfur are significantly distributed on the elemental maps taken on individual fog droplets collected during our sampling periods. It should be said that the proposed sampling and analysis methods for individual fog droplets in this study are helpful to obtain more detailed information on individual fog droplets.