Measurement of submicron aerosols in the urban area of Seoul and in the national park area of Gyeongju using PIXE analysis

This study provides the physical and the chemical characteristics of submicron aerosols observed in the urban area of Seoul and in the national park area of Gyeongju. Seoul is mega city and represents a typical urban area in Korea. Gyeongju has seven contiguous sections of the national park areas. The elemental compositions of the submicron aerosols were analyzed using a PIXE (proton induced X-ray emission) method with a 3 MV Tandetron accelerator. In addition, submicron aerosols were prepared for a determination of ions using ion chromatography. Aerosol monitoring was conducted for airborne particles less than 1.0 and 2.5 micron. They were collected on nuclepore filters using PM1.0 and PM2.5 cyclone samplers. During the monitoring period, Asian Dust storm events occurred at each monitoring site. The contributions of elements to the submicron aerosols were 8 % lower in the urban area than in the national park area. However, the contributions of aged ions to submicron aerosols were relatively higher by 42 % in the urban area of Seoul. The elementals of the submicron aerosols were categorized as soil-related, anthropogenic-related, and aerosol-acidity-related species based on an enrichment factor analysis. The average mass fraction of soil-related elements was approximately 20 % for Seoul and 75 % for Gyeongju. That of the aerosol-acidity-related specie was higher in Seoul and showed a big difference among Asian Dust storm events, non-Asian Dust storm events, and clear atmospheric conditions due to precipitation. Anthropogenic-related elements accounted for 11.7 % in Seoul and 5.7 % in Gyeongju.