快速定量识别污染源贡献是PM2.5精细化管理的重要科学前提。已有PM2.5溯源多采用滤膜分析结合受体模型、源清单结合数值模型开展研究，存在三个科技瓶颈：（1）时间分辨率低，难以快速捕捉污染过程变化；（2）有机分子示踪物在线测量尚属空白，难以快速获得示踪物信息；（3）受体和数值模型相对独立且各有优缺点，缺乏耦合方法量化PM2.5特别是二次气溶胶的源贡献。本项目拟基于有机分子和元素示踪物在线测量，研究耦合受体和数值模型的实时溯源新方法。本项目将攻关PM2.5中有机分子示踪物的在线测量方法，建立包括有机分子及元素示踪物、水溶性离子、元素碳、有机碳在内的在线测量系统；基于在线观测数据，开展受体模型实时溯源和比对验证，确定最优实时溯源受体模式方法；开展“示踪物观测-受体模型”和“源排放-数值模式”交叉验证，发展“ROM-SOM”耦合实时溯源方法，并通过在长三角示范应用，提升对PM2.5来源的认知。

Identification of various sources and quantification of their contributions are important scientific basis for developing detailed PM2.5 pollution control strategies. The current researches related to PM2.5 source apportionment generally use filter analysis and receptor models, emissions inventory and chemical models, these methods generally meet three scientific bottlenecks: (1) low-temporal resolution, and it is hard to grasp the changes of the pollution episodes; (2) online measurement of organic molecular markers are almost blank, thus it is difficult to quickly get changes of the sources; (3) receptor models and chemical models are dependent with each other, both with merits and limits, there is no coupled methodology to quantify PM2.5 sources especially secondary aerosol. In this project, we will develop a new methodology coupled with both receptor models and chemical models based on online tracer measurement to quantify PM2.5 sources with high time resolution and source sectors. We plan to develop robust online measurement capabilities for a range of organic molecular makers, elemental tracers, ions, elemental and organic carbon. Based on the online measurement of the PM2.5 species, different receptor models will be applied and verified to identify the most suitable method to do online source apportionment. Through cross verification of the source apportionment results based on “tracer observation – receptor models” and “emissions – chemical transport models”, we plan to develop a “ROM-SOM” hybrid algorithm for online source apportionment. Through the application of the above-mentioned techniques to the Yangtze River Delta, more insights will be gained on the sources of PM2.5 in this region.