Characteristics of PM2.5 Water-soluble Ions and Source Identification during Springtime 2017 in Wuhan

Daily PM2.5 and water-soluble inorganic ions (NH4+, SO42-, NO3-, Cl-, Ca2+, Na+, K+, Mg2+) were collected in Hongshan Air Monitoring Station in China University of Geosciences (Wuhan) (30 degrees 31' N, 114 degrees 23' E) from March 3 to April 9 in 2017. PM2.5 was collected using medium flow membrane filter samplers. And the ions were determined by ion chromatography. Then, the Positive Matrix Factorization method (PMF) and the HYSPLIT were selected to analyze the PM2.5 pollution sources. The average mass concentration of PM2.5 was found to be 101.34 +/- 31.52 mu g/m3. And the average mass concentrations of the 8 ions was 58.88 mu g/m(3), with the order as NH4+> SO42-> NO3-> Cl-> Ca-2(+)> Na+> K+> Mg2+. Among them, NH4+, SO42- and NO3 were the major components of water-soluble ions in PM2.5 with their sum took 97% of the total ions concentrations. The PMF results showed that the following 7 PM2.5 pollution sources decreased in order of secondary nitrate (23%) > coal combustion (18%) > biomass burning (15%) > traffic source (13%) > secondary ammonium (12%) > road dust (10%) > sea salt (9%). HYSPLIT back trajectories described the four prevailing airflow directions included E, ES, S and NE directions that affect PM2.5 concentrations in a spatial scale during the observing period. Meanwhile, the wind from NW and N directions might facilitate the dispersion of the pollutant.