深圳大气气溶胶中水溶性有机物粒径分布特征

摘要

建立了雾化器-气溶胶化学组分检测仪(ACSM)联用的分析方法,实现了对2013年春季深圳 MOUDI 多级采样膜(0.056~18µm)中WSOM 与无机离子组分的同时测定.结果表明：所测得的水溶性颗粒物总质量浓度变化范围为(17.4±2.1)µg/m3,其中有机物和硫酸盐是最主要的两种化学组分；粗、细粒子中的 WSOM 主要以二次来源为主,且大部分粗粒子中的 WSOM 可能来源于非均相反应；不同粒径范围WSOM的氧化态(以O/C计)估计值在0.46~1.4范围内,平均为0.96,对应的有机物/有机碳比(OM/OC)估计值在1.8~2.9范围内,平均为2.4,粗粒子中WSOM的O/C比细粒子更高,暗示粗粒子中WSOM可能经历了更多的老化过程.%This study established an experimental system, which combined an ultrasonic nebulizer with an Aerosol Chemical Speciation Monitor to measure the chemical composition and size distribution of inorganic ions and water-soluble organic matter of size-segregated aerosol samples collected during the spring of 2013 in Shenzhen, China. The mean water-soluble particle mass concentration was (17.4±2.1)µg/m3during the campaign, with WSOM and sulfate being the dominant species. Both the fine and coarse mode WSOM was found to be dominated by secondary organic aerosol, and the coarse mode WSOM was inferred to be produced by heterogeneous reaction. The oxidation state (based on the ratio of O/C) of size-segregated WSOM was measured to be 0.46~1.36, corresponding to an OM/OC ratio (mass ratio of organic matter to organic carbon) of 1.76~2.89. The higher oxidation state of the coarse mode WSOM implied its experience of more ageing processes.