[Chemical Compositions and Sources of PM2.5 in Weinan City].

ABSTRACT

Based on the PM2.5 samples from Weinan City collected from December 16, 2020 to January 14, 2021, the contamination characteristics of the carbonaceous components and inorganic ions in PM2.5 and the relationship between PM2.5 and water-soluble ions were analyzed. Meanwhile, the sources and source areas were also analyzed by using the positive matrix factorization(PMF), potential source contribution factor(PSCF), and concentration weight trajectory(CWT) methods. The results showed that the night and daytime concentrations of PM2.5, OC, EC, and TWSIIs during the winter in Weinan City were 119.08, 17.02, 6.20, and 34.30 µg·m-3and 130.66, 18.09, 6.22, and 50.65 µg·m-3, respectively. Ion concentrations followed the order of F->NO3->Ca2+>SO42->Na+>Cl->NH4+>K+>Mg2+ during the daytime and NO3->SO42->Ca2+>NH4+>F->Na+>Cl->K+>Mg2+ at night. PM2.5 was acidic during the day and alkaline at night. SOR and NOR values were 0.20 and 0.09, respectively. The R2 values of NH4+ and SO42- during the day and night were 0.04 and 0.09, respectively, and those of NH4+ and NO3- during the day and night were 0.07 and 0.65, respectively. The PMF model analysis showed that the sources of PM2.5 in Weinan City during the winter were mainly coal burning and industrial emission sources, dust sources, and secondary sources. Backward trajectory combined with the potential source analysis indicated that the PM2.5 sources in Weinan City during the winter could be divided into two categoriesthe first was northwest to the remote source transmission, mainly affected by Gansu, Southern Inner Mongolia, and the Ningxia Hui Autonomous Region; the other category was local emissions, affected by the surrounding neighboring cities of Xianyang, Xi'an, and Tongchuan.