[Characterization of water-soluble ions in PM2.5 at Dinghu Mount]

To study the characteristics and source of aerosol in the background region of the Pearl River Delta, PM2.5 samples were collected with a high volume sampler from Jan. 2007 to Dec. 2008 at Dinghu Mountain. Water-soluble ions in PM2.5 were analyzed by ion chromatography (IC). The results showed that the annual concentrations of total water-soluble ions was (36.3 +/- 16.4) microg x m(-3) The three major ions SO4(2-), NH4(+) and NO3(-), accounted for 89% of the total water-soluble ions. The correction of Na+ and Cl- was significantly enhanced in summer by the marine air mass, and the correlation coefficient R2 was 0.91. The mean value of NO3(-)/SO(2-) was 0.32, indicating that stationary sources had more contributions to Dinghu Mountain. The range of sigma cation/ sigma anion was 0.44 - 2.59, with a mean of 1.03 in PM2.5. The charge of water-soluble ions almost achieved balance in PM2.5