Sources of organic aerosols in eastern China: a modeling study with high-resolution intermediate-volatility and semivolatile organic compound emissions

Current chemical transport models fail to reproduce both the concentrations and temporal variations of organic aerosol (OA), especially the secondary organic aerosol (SOA), hindering the identification of major contribution sources. The fact that precursors of intermediate-volatility and semivolatile organic compounds (I/SVOCs) are not included in models has a significant impact on the performance of SOA simulation. Herein, we establish a high-resolution emission inventory of I/SVOCs and by incorporating it into the CMAQ model, concentrations, temporal variations, and spatial distributions of POA and SOA originating from different sources in the Yangtze River Delta (YRD) region of China were simulated. By incorporating I/SVOC emissions into the model, the modeled average SOA concentrations in the region increased by 148 %. Significant model improvements in the simulations of different OA components were demonstrated by comparison with comprehensive observation data. Furthermore, spatial and seasonal variations of different source contributions to OA production have been identified. We found that cooking emissions are predominant sources of POA in the densely populated urban area of the region. I/SVOC emissions from industrial sources are dominant contributors to the SOA formation, followed by those from mobile sources. Our results indicate that future control measures should be specifically tailored on an intraregional scale based on the different source characteristics to achieve the national goal of continuous improvement in air quality. In addition, local source profiles and emission factors of I/SVOCs, as well as SOA formation mechanisms in the model framework must urgently be updated to further improve the model performance and thus the accuracy of source identifications.