Characteristics of PM2.5 concentration and water-soluble ions in the typical town of southern Gansu

ABSTRACT

In order to study the pollution levels of PM2.5 and water-soluble inorganic ions（WSIIs）in the towns of southern Gansu, PM2.5 samples were collected quarterly in Cheng County of Gansu from April 2019 to February 2020. Their characteristics of variation were analyzed, and the sources were apportioned using correlation and principal component analysis. The results showed that the mean annual mass concentration of PM2.5 was（57.2±26.9）μg·m-3 in Cheng County of Gansu Province. The seasonal variation of PM2.5 concentration was represented by winter>spring>autumn>summer during the sampling period, and the concentrations in winter were about 1.9 times than that in summer. The annually good air quality rate was 81%, of which 100% in summer. The ranking of WSII concentrations was SO42->NO3->Na+>NH4+>Ca2+>K+>Cl->Mg2+.SNA is the highest water-soluble ions, accounting for 70.1% of the concentration of eight main water-soluble ions. The mean ratio of ρ（NO3-）/ρ（SO42-）was 0.6, indicating that fixed sources such as industrial and agricultural production and fossil fuel combustion emissions, was the major source for particulate pollution. During the 2019 coronavirus epidemic, control measures had a significant impact on the concentration of PM2.5 and SNA in water-soluble ions, and the mean concentration of PM2.5 was reduced by 44.2%. Source apportionment showed that WSIIs in PM2.5 were mainly from fossil fuel combustion, biomass combustion, secondary formation and road construction dust, etc. © 2022 Science Press. All rights reserved.