大气气溶胶中~7Be的粒径分布

Activity Size Distribution of ~7Be in Atmospheric Aerosol

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7 Be的浓度及粒径分布规律。在样品采集期间,环境大气中7 Be浓度平均值为7.29mBq/m3,且在春季出现较大的浓度。研究发现,在粒径>3.0μm的气溶胶样品中,基本测量不到7Be;在粒径>0.95μm的气溶胶样品中,7 Be仅占总量的10%左右;7 Be主要分布在粒径<0.95μm的气溶胶粒子上。

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.