大气气溶胶中7Be的粒径分布

利用5级大流量串级撞击器采集大气气溶胶样品，高纯锗γ谱仪系统测量放射性，分析了大气气溶胶中放射性核素⁷Be的浓度及粒径分布规律。在样品采集期间，环境大气中⁷Be浓度平均值为7.29 mBq/m³，且在春季出现较大的浓度。研究发现，在粒径＞3.0 μm的气溶胶样品中，基本测量不到⁷Be；在粒径＞0.95 μm的气溶胶样品中，⁷Be仅占总量的10%左右；⁷Be主要分布在粒径＜0.95 μm的气溶胶粒子上。

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.