Regional Transport of PM_2.5 from Coal-Fired Power Plants in the Fenwei Plain, China

The Fenwei Plain (FWP) remains one of the worst PM_2.5-polluted regions in China, although its air quality has improved in recent years. To evaluate the regional transport characteristics of PM_2.5 emitted by coal-fired power plants in the FWP in wintertime, the primary PM_2.5, SO₂, and NOx emissions from coal-fired power plants with large units (≥300 MW) in 11 cities of the area in January 2019 were collected based on the Continuous Emission Monitoring System (CEMS). The spatial distribution and source contribution of primary and secondary PM_2.5 concentrations were investigated using the Weather Research and Forecast (WRF) model and the California Puff (CALPUFF) model. The results showed that secondary PM_2.5 was transported over a larger range than primary PM_2.5 and that secondary nitrate was the main component of the total PM_2.5 concentration, accounting for more than 70%. High concentrations of primary, secondary, and total PM_2.5 mainly occurred in the Shaanxi region of the FWP, especially in Xianyang, where the PM_2.5 concentrations were the highest among the 11 cities, even though its pollutant emissions were at moderate levels. The PM_2.5 concentrations in Sanmenxia and Yuncheng primarily came from regional transport, accounting for 64% and 68%, respectively, while those in other cities were dominated by local emissions, accounting for more than 63%. The results may help to understand the regional transport characteristics of pollutants emitted from elevated point sources over a complex terrain.