有机种子对异戊二烯光氧化反应形成二次有机气溶胶的粒谱演化和形成速率的影响

基于室内烟雾箱实验平台，研究了在有机种子气溶胶下，来自OH启动异戊二烯光氧化反应形成的二次有机气溶胶的动力学. 探究了二次有机气溶胶的粒谱分布分别与来自室内大气中痕量碳氢化合物光氧化反应产生的种子颗粒物浓度以及前体物异戊二烯浓度的依赖关系. 研究结果表明在高浓度种子气溶胶和低浓度异戊二烯条件下(对应于典型城市大气条件)，光化学反应形成的二次有机产物凝聚到种子颗粒物表面而造成的颗粒物增长起主导作用；而在低浓度种子气溶胶和相对高浓度异戊二烯条件下(对应于典型偏远地区大气条件)，二次有机气溶胶粒谱分布出现双模式结构，分别对应于来自均相成核的新粒子生成和二次有机产物在种子颗粒物上的凝聚增长. 此外，还研究了有机种子颗粒物浓度对二次有机气溶胶形成的影响，评估了在不同种子浓度下二次有机气溶胶粒谱分布的演化和相应新粒子的形成速率.

Photo-oxidation of Isoprene with Organic Seed: Estimates of Aerosol Size Distributions Evolution and Formation Rates

ondary organic aerosol (SOA) formation from OH-initiated photo-oxidation of isoprene in the presence of organic seed aerosol. The dependence of the size distributions of SOA on both the level of pre-existing particles generated in situ from the photo-oxidation of trace hydrocarbons of indoor atmosphere and the concentration of precursor, has been investi-gated. It was shown that in the presence of high-level seed aerosol and low-level isoprene (typical urban atmospheric conditions), particle growth due to condensation of secondary organic products on pre-existing particles dominated; while in the presence of low-level seed aerosol and comparatively high-level isoprene (typical atmospheric conditions in rural re-gion), bimodal structures appeared in the size distributions of SOA, which corresponded to new particle formation resulting from homogeneous nucleation and particle growth due to condensation of secondary organic products on the per-existing particles respectively. The effects of concentrations of organic seed particles on SOA were also investigated. The particle size distributions evolutions as well as the corresponding formation rates of new particles in different conditions were also estimated.