Vasilakos Petros, Kim Yong-Ηa, Pierce Jeffrey R, Yiacoumi Sotira, Tsouris Costas, Nenes Athanasios
School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, 30332, GA, USA.
School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, 30332, GA, USA.
J Environ Radioact. 2018 Dec;192:150-159. doi: 10.1016/j.jenvrad.2018.06.014. Epub 2018 Jun 26.
Radioactive charging can significantly impact the way radioactive aerosols behave, and as a result their lifetime, but such effects are neglected in predictive model studies of radioactive plumes. The objective of this work is to determine the influence of radioactive charging on the vertical transport of radioactive aerosols in the atmosphere, through its effect on coagulation and deposition, as well as quantifying the impact of this charging on aerosol lifetime. The TwO-Moment Aerosol Sectional (TOMAS) microphysical model was extended to account for radioactive charging effects on coagulation in a computationally efficient way. The expanded model, TOMAS-RC (TOMAS with Radioactive Charging effects), was then used to simulate the microphysical evolution and deposition of radioactive aerosol (containing the isotopes I and Cs) in a number of idealized atmospheric transport experiments. Results indicate that radioactive charging can facilitate or suppress coagulation of radioactive aerosols, thus influencing the deposition patterns and total amount of radioactive aerosol mass available for long-range transport. Sensitivity simulations to uncertain parameters affirm the potential importance of radioactive charging effects. An important finding is that charging of neutral, coarse mode aerosol from background radiation can reduce coagulation rates and extend its lifetime in the atmosphere by up to a factor of 2.
放射性充电会显著影响放射性气溶胶的行为方式，进而影响其寿命，但在放射性羽流的预测模型研究中，此类影响被忽略了。这项工作的目的是通过研究放射性充电对凝聚和沉积的影响，来确定其对大气中放射性气溶胶垂直传输的影响，并量化这种充电对气溶胶寿命的影响。对双矩气溶胶粒谱（TOMAS）微物理模型进行了扩展，以一种计算高效的方式考虑放射性充电对凝聚的影响。然后，使用扩展后的模型TOMAS-RC（具有放射性充电效应的TOMAS），在一些理想化的大气传输实验中模拟放射性气溶胶（含有同位素碘和铯）的微物理演化和沉积。结果表明，放射性充电可以促进或抑制放射性气溶胶的凝聚，从而影响沉积模式以及可用于长距离传输的放射性气溶胶总量。对不确定参数的敏感性模拟证实了放射性充电效应的潜在重要性。一个重要发现是，背景辐射使中性粗模态气溶胶带电，可降低凝聚速率，并将其在大气中的寿命延长至两倍。
