Zhukovsky Michael, Rogozina Marina, Suponkina Anna
Institute of Industrial Ecology UB RAS, Sophy Kovalevskoy St. 20, Ekaterinburg 620990, Russia Ural Federal Univercity, Ekaterinburg, Russia
Institute of Industrial Ecology UB RAS, Sophy Kovalevskoy St. 20, Ekaterinburg 620990, Russia Ural Federal Univercity, Ekaterinburg, Russia.
Radiat Prot Dosimetry. 2014 Jul;160(1-3):192-5. doi: 10.1093/rpd/ncu084. Epub 2014 Apr 7.
Information about the size distribution of radioactive aerosols in nanometre range is essential for the purposes of air contamination monitoring, dose assessment to respiratory tract and planning of protective measures. The diffusion battery, which allows capturing particles in the size range of 0.1-10 nm, has developed. Interpreting data obtained from diffusion battery is very complex. The method of expectation maximisation by Maher and Laird was chosen for indirect inversion data. The experiments were performed in the box with equivalent equilibrium concentration of radon in the range of 7000-10,000 Bq m(-3). The three modes of size distribution of radon decay products aerosols were obtained: activity median thermodynamic diameter (AMTD) 0.3, 1.5 and 5 nm. These modes can be identified as: AMTD 0.3 nm--atoms of radon progeny (218Po in general); AMTD 1.5 nm--clusters of radon progeny atoms and non-radioactive atoms in the atmosphere; AMTD 5 nm--particles formed by coagulation of previous mode clusters with existing aerosol particles or nucleation of condensation nuclei containing atoms of radon progeny.
对于空气污染监测、呼吸道剂量评估以及防护措施规划而言，有关纳米级放射性气溶胶粒径分布的信息至关重要。能够捕集粒径范围在0.1 - 10纳米的粒子的扩散电池已研制出来。解读从扩散电池获得的数据非常复杂。选用了Maher和Laird提出的期望最大化方法来对数据进行间接反演。实验在氡等效平衡浓度范围为7000 - 10,000 Bq m(-3)的箱体内进行。获得了氡衰变产物气溶胶粒径分布的三种模态：活度中值热力学直径（AMTD）分别为0.3、1.5和5纳米。这些模态可被确定为：AMTD 0.3纳米——氡子体原子（一般为218Po）；AMTD 1.5纳米——大气中氡子体原子与非放射性原子的团簇；AMTD 5纳米——由前一模态的团簇与现有气溶胶粒子凝聚形成的粒子，或含有氡子体原子的凝结核的成核作用形成的粒子。
