2017년 제주도 한라산 1100고지 PM10, PM2.5 미세먼지의 장거리 이동 특성

Abstract

The PM10 and PM2.5 samples were collected at the Mt. Halla-1100 site in Jeju Island, which is a background site located at the atmospheric boundary layer (ABL), in 2017. Their ionic and elemental species were analyzed, in order to examine the chemical compositions and emission characteristics of particulate matters. Furthermore, their long-range transport was studied in accordance with the various airflow pathways and meteorological conditions. Mass concentration of PM10 and PM2.5 were 20.9±15.1 and 10.7±7.3 μg/m3, respectively, during the non-event days. From the comparison of ionic balance, the correlation coefficients (r) between the sums of cationic and anionic equivalent concentration were 0.976 and 0.987, respectively, for PM10 and PM2.5, indicating the good linear correlations. In coarse particles (PM10-2.5), the concentrations of secondary pollutants such as NO3 -, nss-SO4 2- and NH4 + were 1.47, 0.39 and 0.31 μg/m3, respectively. In fine particles (PM2.5), their concentrations were 3.96, 1.56 and 0.64 μg/m3, respectively, showing 95.9% of those ionic species. Meanwhile, the elemental compositions of PM10 showed 41.0% for anthropogenic (S, Zn, Pb, Ni), 41.3% for soil (Al, Fe, Ca) and 10.8% for marine (Na, Mg) sources. Based on the study of separated course and fine particle compositions, the concentration ratios of PM10-2.5/PM2.5 were 0.1 and 0.2 respectively for nss-SO4 2- and NH4 +, indicating that those species were mostly existed in fine particles. On the other hand, marine and soil species such as Na+, Cl-, nss-Ca2+, Mg2+ were rich in coarse particles. From the study of source origins by the principal component analysis, the ionic species of coarse particles were mostly originated from mixed soil-anthropogenic sources, followed next by anthropogenic and marine sources. While the compositions of fine particles were influenced mainly by anthropogenic sources, followed next by marine and soil sources. The backward trajectory analysis showed that the frequency of airflows from the China was high, and the concentrations of NO3 -, nss-SO4 2-, and NH4 + increased remarkably when the airflow moved from the China continent. During the Asian dust periods, the concentration of nss-Ca2+ were 10.1 and 10.2 times higher, respectively, in coarse and fine particle compared to non-event days. Especially, the concentrations of the crustal species in PM10 such as, Al, Fe, Ca, Mn, Ba, and Sr showed a noticeable increase during the Asian dust periods. The back trajectory analysis during Asian dust has shown that the concentration of soil components were increased when airflow moved to Mt. Halla-1100 site from China. For the haze events days, the concentration of the secondary pollutants increased 1.8∼5.0 times more in fine particles. It's likely due to the influence of its long-range transport from China continent. Also, those for the mist event days were 1.1∼1.8 times higher in fine particles, compared to non-event days. Therefore, the atmosphere of Mt. Halla-1100 site is affected by long-range transport airflows from China.