Activity Size Distribution of ⁷Be in Atmospheric Aerosol

The activity concentration and the size distribution of the ⁷Be in atmospheric aerosol were measured in ground-level air. Aerosol sampling was performed with a cascade impactor covering the size range from 0.49 to 7.2 μm and simultaneously with a high-volume sampler. Activity of ⁷Be was measured by gamma spectrometry. During sampling period, the concentration mean of the ⁷Be is 7.29 mBq/m³ and it is high in spring. It is found that ⁷Be almost cannot be detected on aerosols above 3.0 μm in diameter. Aerosols larger than 0.95 μm are attached by about 10% of total ⁷Be. The most ⁷Be activity is associated with aerosols smaller than 0.95 μm.