Real-Time Numerical Source Apportionment Of Pm2.5 Concentrations Over The Yangtze River Delta Region, China

A real-time numerical source apportionment system was established based on the operational regional atmospheric environmental modelling system (RAEMS) for eastern China in order to calculate the contribution of emissions from different provincial regions over the Yangtze River Delta (YRD) region to the PM2.5 concentration. The 2019 modelling results showed good and reliable performance of the RAEMS in modelling PM2.5 concentrations over 55 cities in the YRD region. Herein, the analysis results indicated the importance of local emissions on PM2.5 concentration at both provincial and city scales, with contribution rates of 54%-65% and 62.3%-70.7%, respectively. The contribution of mutual inner-regional transport among provinces was clear, contributing varied proportions (1%-22%) among themselves and similar proportions (23%-29%) to the provincial city PM2.5 concentration. The cross-regional transport contributed from regions outside the YRD provided relatively weaker contributions of 3.3%-10.6%. However, this contribution doubled during cold air events. Note that the temporal trend of PM2.5 over Shanghai is largely dominated by the contributions from Zhejiang and Jiangsu, whereas the other provinces are highly self-dominated. In addition to controlling local emissions to decrease the PM2.5 pollution rate, varied effects were found by reducing inner-regional transport. The cross regional transport contribution found herein was relatively lower throughout the year than that in previous pollution episode studies. The results of this research provide support for both the real-time emergency PM2.5 pollution prevention and joint strategy policy making for anthropogenic emission regulation and control in the YRD region.