PM2.5 temporal source apportionment analysis over the Pearl River Delta region

The Pearl River Delta (PRD) region is one of the most developed city clusters in China, and it is also the area that suffers from severe air pollution. A key problem in addressing pollution is to find out where the pollutants come and how to control them. Most of the previous studies focused on the source area, and source category contribution analysis, but fewer studies paid attention to the temporal contribution, which is also an important factor in policymaking. Therefore, in this study, based on the CAMx-PSAT model, we extended the model to track the contribution of the sources emitted at different periods. The updated PSAT can reflect the temporal correlation between the source and receptor and provide scientific support to efficient control policymaking. The simulation result of a high PM_2.5 episode shows that the emission outside the PRD region is the major contributor to PM_2.5 over the PRD region. PM_2.5 mainly comes from the emission within the current two days. Under the control of the high-pressure system, low wind speed hinders the diffusion of PM_2.5 and paves the way for the accumulation of the pollutants. The emission two days ago can still have a considerable contribution during the high concentration period. The results suggest that emission control measurements should be implemented in advance when adverse meteorology condition is predicted.