Ionic Compositions of PM10 and PM2.5 Related to Meteorological Conditions at the Gosan Site, Jeju Island from 2013 to 2015

PM10 and PM2.5 were collected at the Gosan Site on Jeju Island from 2013 to 2015, and their ionic and elemental species were analyzed to examine the variations in their chemical compositional characteristics related to different meteorological conditions. Concentrations of nss-SO42− and NH4+ were respectively 6.5 and 4.7 times higher in the fine particle mode (PM2.5) compared to the coarse particle mode (PM10-2.5), however NO3− concentrations were 2.4 times higher in the coarse mode compared to the fine particle mode. During Asian dust days, the concentrations of nss-Ca2+ and NO3− increased to 8.2 and 5.0 times higher in PM10, and 3.5 and 6.0 times higher in PM2.5, respectively. During haze days, the concentrations of secondary pollutants increased by 3.1–4.7 and 3.2–7.9 in PM10 and PM2.5, respectively, and they were, respectively, 1.2–2.1 and 0.9–2.1 times higher on mist days. The aerosols were acidified largely by sulfuric and nitric acids, and neutralized mainly by ammonia in the fine particle mode during the haze days, but neutralized by calcium carbonate in coarse particle mode during the Asian dust days. Clustered back trajectory analysis showed that concentrations of nss-SO42−, NO3−, and NH4+ were relatively high when air masses travelled from China.