Integrating Chemical Mass Balance and the Community Multiscale Air Quality models for source identification and apportionment of PM2.5

Abstract Source apportionment offers an efficient way to identify emission sources and the contributions to air pollution. It helps to deepen our understanding of the air pollution formation process and develop productive environmental policies. Accurate PM2.5 source apportionment is more essential for small-scale local air pollution control. An integrated source apportionment approach was built by combining chemical mass balance (CMB) model and the Community Multiscale Air Quality modelling system (CMAQ) model to complement individual model and apportion PM2.5 pollution into more elaborate emission sources categories. The CMAQ source apportionment results of corresponding PM2.5 precursors were applied to assign secondary components while that of PM2.5 were applied to assign non-local sources as the basic constrains. An island city with typical secondary components in PM2.5 pollution was chosen. The results showed the dominant source impacts of non-local sources ranged from 31.07% in summer to 49.60% in winter. Compared to individual model, the integrated source apportionment approach preserved the accuracy of CMB modelling for primary sources, simultaneously apportioned the secondary components to the primary sources and abstracted non-local sources from primary sources, which acquired more elaborate results. The results further helped develop more efficient air quality control policies.