Gas-to-Particle Conversion of Polluted Gas by Nucleation

大气中分散的亚微米细颗粒（气溶胶）造成大气污染、人类健康问题和对地球的温室效应。然而，气体到颗粒的转化过程是大气环境中细颗粒产生的重要过程，迄今尚未得到充分的评价，因为这些过程受成核现象的支配。因此，本研究通过日本、美国和欧洲的研究人员的合作，研究了大气中微量杂质气体向细颗粒的转化过程，以及细颗粒和气体的动力学行为和沉积过程，这对研究大气污染具有重要意义。在本研究的实验中，研究了NO_<x'>、SO_<x'>、H_2O等二元和三元气体体系的成核现象。在一个装有放射源和绝热膨胀室的小室中进行了研究。然后从团簇和颗粒的尺寸分布的测量中澄清了成核速率和离子对成核增强的影响。在现代成核理论的基础上，建立了离子增强成核的理论模型，探讨了离子增强成核的机理，为实验结果的解释提供了可能。推导了生成颗粒的一般动力学方程和对流扩散方程，描述了生成颗粒的生长过程以及气体和颗粒的输运和沉积过程。方程的数值计算结果可以解释化学反应生成粒子的实验结果和小空间悬浮气体和粒子的实验结果。因此，本研究的实验和理论研究结果可用于构建评估环境中细颗粒物影响的物理数学模型。少

A dispersed system of submicron, fine particles in the atmospheric air (aerosol) causes atmospheric pollution, problems on human health and the greenhouse effect to the earth. However, the processes of gas-to-particle conversion which are important as the processes of fine particle generation in the atmospheric environment have not been fully evaluated to date since these are governed by nucleation phenomena. Therefore, in this study, the conversion processes of trace impurity gas in the atmosphere into fine particles, and dynamic behavior and deposition processes of fine particles and gas, which are important especially from the viewpoint of investigating atmospheric pollution, were studied through collaboration among researchers in Japan, U.S.A.and Europe.In the experiments of this study, nucleation phenomena in binary and ternary gas systems including NO_<x'>, SO_<x'>, H_2O,etc.were investigated using a small chamber equipped with a radioactive source and an adiabatic expansion cham … More ber. The rate of nucleation and the effect of ions on the enhancement of nucleation were then clarified from the measurements of the size distributions of clusters and particles. The mechanisms of the enhancement of nucleation by ions were discussed with a theoretical model based on the modem nucleation theories, which made it possible to explain the experimental results. The general dynamic equation and convection-diffusion equation were also derived to describe the growth processes of generated particles, and the transport and deposition processes of gas and particles. The results of numerical calculation of the equations could explain the results of experiments on particle generation via chemical reaction and experiments using a small space where gas and particles are suspended. Accordingly, the results obtained through the experiments and theoretical investigation of this study are considered useful for constructing a physico-mathematical model for evaluating the effect of fine particles in the environment. Less