长江三角洲大气颗粒物生成-成长过程的研究 ——不同气团影响下的过程特征

针对大气颗粒物数浓度粒径分布的演变特征,于2005年夏季在上海下风方向站点太仓进行大约30d的观测.观测发现颗粒物生成-成长过程主要发生于混合充分、有区域代表性的气团中.应用颗粒物数浓度粒径分布数据计算了颗粒物凝结汇、可凝结性蒸气浓度、可凝结性蒸气源速率、颗粒物成长速率等过程特征量.颗粒物成长速率平均为6.0nm/h,可凝结性蒸气浓度平均为8.2′107/cm3,其源速率为3.1′106/(cm3×s).利用后向气流轨迹对影响颗粒物生成-成长过程的气团来源进行分析,并利用观测所得SO2浓度及过程特征量计算了不同气团影响下气态硫酸蒸气对颗粒物成长速率的贡献:长江三角洲城市群气团影响下硫酸贡献量最大,为59%,北方气团影响下硫酸贡献量次之,超过53.8%,受南方气团影响下硫酸贡献量最低,为30%.

Observational study on particle nucleation process in the Yangtze River Delta,China:The growth property in different air masses

The particle nucleation process was studied in summer of 2005, in a downwind site of the Yangtze River Delta.In the 29 observation days, particle formation and growth was mainly found to occur in the air masses with regional characteristic and well-developed photochemical process. Using the measured spectral evolution of aerosol particles as a function of time the formation and growth properties of nucleation mode aerosols were evaluated. The averaged growth rate of newly formed particles is 6.0nm/h. The needed concentration of condensable vapor is 8.2′107/cm3, and its source rate is 3.1′106/(cm3×s), which were higher than previous researches in similar latitude.The further calculation on the source rate of sulphuric acid vapor indicated the average participation of sulphuric acid to the particle growth rates has large variation among the events in different air masses. That is, the contribution of H2SO4 to particle growth is 59% in air masses originated in the YRD region, 53.8% in the air masses northward and 30% in southerly air masses.