Thus, source V and VI had almost no potential contribution to Black Carbon at Tongyu due to few emissions and the overestimation of the PSCF calculation (in section 2.3). Black Carbon emissions in source areas I, II, and III had more effective influence on the Black Carbon in Tongyu than sources area IV because most polluted air parcels arriving at Tongyu traveled over source areas II and III in winter, spring, and fall, and traveled over source I in summer, spring, and fall.