[Influence of Pollutant Transport from Both Sides of the Taihang Mountains on Cross-Valley Urban Aerosols].

Based on hourly concentration data of PM10 and PM2.5 from 2017 to 2019 and wind speed and direction data at the corresponding times in Yangquan, an urban valley of the Taihang Mountains, the characteristics of air transport in a cross-valley urban area and their influence on aerosols in Yangquan were analyzed using the HYSPLIT model, cluster analysis, and the potential source contribution factor and concentration weight trajectory methods. The pollutant transport characteristics on the east and west sides of the Taihang Mountains were evaluated. The diurnal variation of the aerosols showed a single peak and single valley, with continuous improvements in aerosol concentration from evening to the morning of the next day. The maximum aerosol concentration occurs at 10:00-11:00 in winter and at 09:00 in other seasons, whereas the minimum value occurs at 15:00-16:00. The monthly mean aerosol concentration in Yangquan was highest in January and lowest in August, and PM10 was also high in March and April. The most frequent surface wind directions in Yangquan are easterly and westerly due to the topography of the cross valley. The average concentrations of aerosols were highest in the calm wind weather. Furthermore, the dust weather caused by the westerly wind in spring and autumn and the easterly transport in winter also causes an increase in aerosol concentration in Yangquan. The backward trajectories in combination with the pollution characteristics showed that 26.2% of the pollution trajectories are in spring, 36.4% are in autumn, and 33.7% are in winter, and that these are mainly distributed in the southwest and southeast of Yangquan and also in the northeast in winter. There was significant fine particle transport on both sides of the mountains, and the trajectories originating from or passing through the west side of the Taihang Mountains also transport coarse particles. As indicated by the pollution trajectory, the westerly air transport has an impact on PM10 in excess of the standard rate. The easterly transport has larger noise and mainly affects the exceedance rate of PM2.5. The main potential source areas of aerosol pollution in Yangquan differ in different seasons. The potential source areas are to the southwest and southeast of Yangquan in spring, the southwest and south of Yangquan in autumn, and the south and east of Yangquan in winter. The areas with high PSCF and CWT in PM2.5 were in the southeast region, but those for PM10 were in the southwest region. The area southeast of Shanxi and the border area north of Henan are the main source areas. Based on the influence of aerosol pollution transmission in Yangquan, the cross-valley urban area is affected simultaneously by the areas east and west of the Taihang Mountains, especially by PM2.5 transport from east to west.