Characteristics and Sources Analysis of Water-Soluble Ions in PM2.5 in North China Coal Mining Area

Abstract

To analyze the characteristics and sources of water-soluble ions in PM 2.5 in north China coal mi n-ing area, this study collected atmospheric PM 2.5 samples in Fengfeng Mining District from April 2018 to February 2019 and used ion chromatography to determine the mass concentration of nine water-soluble ions (Na + , 4 NH + , K + , Mg 2+ , Ca 2+ , F − , Cl − , − 24 SO , 3 NO − ) in PM 2.5 . The result showed that the mean concentration of PM 2.5 was (134.43 ± 77.07) ug·m − 3 , which was 1.79 times than the second level criterion of Environmental Air Quality Standard , and the mean concentration of wa- ter-soluble ions was up to (58.76 ± 39.40) μg·m − 3 ; the average of SOR and NOR was 0.38 and 0.22, respectively. The proportion of − 24 SO , 3 NO − and 4 NH + in water-soluble ions was as high as 85.00%, and the degree of secondary transformation would also increase with worsened poll u-tion. The average of ρ ( 3 NO − )/ ρ ( − 24 SO ) was 1.30, which suggested that mobile sources contributed to air pollution significantly. The principal component analysis showed that the sources of w a-ter-soluble ions included secondary conversion, coal and biomass combustion mixed sources (55.88%), and dust sources (29.82%). The result of backward trajectory model indicated that the two air masses from Hebei province (71.76%) accounted for the highest proportion in the four types of air masses obtained by clustering.