Abstract
To gain a better understanding of the day-night variation characteristics of water-soluble ions, PM2.5 samples were continuously collected for two months in the Nanjing Jiangbei New Area during winter. The diurnal variation and sources of water-soluble ions were studied. Results showed that the mass concentration of water-soluble ions ranged from 17.07 μg·m-3 to 168.43 μg·m-3 with a mean value of (59.01±30.75) μg·m-3. The average mass concentration of water-soluble ions in daytime was higher than that in the nighttime. The concentration ratio of NO3- and NH4+ to total ion concentrations was higher at night, while SO42- and Cl- were higher during daytime. SO42-, NO3-, and NH4+ (SNA) were the dominant species of water-soluble ions in PM2.5 in Nanjing. The mass concentration of SNA on polluted days was higher than that on clean days. The ratio of the anion-cation balance (AE/CE) was larger than 1, indicating that the PM2.5 was acidic. There was a significant linear correlation between NH4+ with NO3- and SO42-, indicating that it occurred mainly in the form of NH4NO3 and (NH4)2SO4 in PM2.5. The PMF source apportionment indicated that water-soluble ions of PM2.5 were mainly derived from motor vehicle emissions, fossil fuel combustion, biomass burning, and dust in the Nanjing Jiangbei New Area.
Published Version
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