The collection of rainwater samples was made at Jeju area during 2009~2010, and the major ionic species were analyzed. In the comparison of ion balance, conductivity, and acid fraction for the validation of analytical data, the correlation coefficients showed a good linear relationship within the range of 0.966~0.990. The volume-weighted mean pH and electric conductivity were 4.9 and 17.8 μS/cm, respectively, at the Jeju area. The volume-weighted mean concentrations of ionic species in rainwater were in the order of ClThe ionic strength of rainwater was 0.26±0.21 mM during the study period. The composition ratios of ionic species were such as 50.1% for the marine sources (Na , and nss-SO 4 2-increased in winter and spring seasons, indicating a reasonable possibility of long range transport from Asia continent. Especially, the acidifying contributions by major inorganic acids (nss-SO 4 2-and NO 3 -) and organic acids (HCOO -and CH 3 COO -) were 87.6% and 12.4%, respectively. In comparison by sectional inflow pathway of air mass during the rainy sampling days, the concentrations of nss-SO 4 2-and NO 3 -were relatively high when the air mass was moved from the China continent into Jeju area.
, and followed by the order of marine (Na , soil-originated components (Al, Fe, and Ca) were consisted of 50.9 %, which was higher proportion than marine and anthropogenic elements. The acidification of the fine particulate matters was found to be influenced mostly by sulfuric and nitric acids, and these acids were mainly neutralized by calcium carbonate in PM This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons. org/licenses/ by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
In order to examine the variation characteristics of chemical compositions in accordance with the different meteorological conditions, PM 10 and PM 2.5 were collected at Gosan site of Jeju Island in 2014, and then their ionic and elemental species were analyzed. The concentrations of nss-SO 4 2-and NH 4 + were respectively 4.3 and 3.3 times higher in fine particle mode (PM 2.5 ) compared to coarse particle mode (PM 10-2.5 ), however NO 3 -concentration was 1.6 times higher in coarse mode compared to fine particle mode. During Asian dust days, the concentrations of nssCa 2+ and NO 3 -increased highly as 7.7 and 4.5 times in coarse particle mode, and 3.0 and 4.9 times higher in fine particles, respectively. Especially, the concentrations of the crustal species (Al, Fe, Ca, K, Mn, Ba, Sr, etc.) indicated a noticeable increase during the Asian dust days. For the haze days, the concentrations of secondary pollutants increased 2.2~2.7 and 2.9~6.0 times in coarse and fine particles, respectively, and they were 0.8~1.1 and 1.8~2.4 times, respectively, during the mist days. The aerosols were acidified largely by sulfuric and nitric acids, and neutralized mainly by ammonia in fine particle mode during the haze days, but neutralized by calcium carbonate in coarse particle mode during the Asian dust days. The clustered back trajectory analysis showed that the concentrations of nss-SO 4 2-, NO 3 -, and NH 4 + were relatively high when the inflow pathway of air mass was from the southern part of China.
Atmospheric total suspended particulate aerosols were collected at the Gosan site of Jeju Island during 2011-2013, and their major water-soluble ionic and elemental species were analyzed in order to examine the chemical composition change and pollution characteristics change between Asian dust (AD) and non-Asian dust (NAD) periods. The comparison of the aerosol compositions showed that the concentrations of soil-originated species such as nss-Ca 2+ , Al, Fe, Ti, Mn, Ba, and Sr increased by as much as 4.5-18.6 times during the AD periods. Meanwhile, the concentrations of nss-SO 4 2− and NO 3 − , typical secondary aerosol species, increased 1.2 and 2.5 times, respectively. On the contrary, NH 4 + concentration decreased slightly during the AD periods, probably because of the neutralization reaction of acidic ammonium ion with basic calcium carbonate. A comparison of ion balances suggested that the carbonate contents in AD are likely much larger than those of NAD. Based on a cluster back-trajectory analysis, it was found that the concentrations of anthropogenic and soil-sourced components, such as nss-SO 4 2− , NO 3 − , NH 4 + , and nss-Ca 2+ , increased when an air mass moved into Jeju Island from the China continent, but decreased when an air mass moved from the North Pacific Ocean.
Precipitation samples were collected in the Jeju Island during 2015-2016, and the ionic components of the precipitation were analyzed to investigate the chemical composition and pollution characteristics of the precipitation. In a comparison of ion balance, electrical conductivity, and acid fraction for verification of the analytical data, the correlation coefficients showed within the range of 0.953-0.991. During the study period, the volume-weighted mean pH and electrical conductivity were 5.1 and 15.9 μS/cm, respectively. The precipitation was weakly acidic, with a high frequency of precipitation (43.8%) in the range of pH 5.0-5.5. The ionic strength of the precipitation was 0.2 AE 0.2 mM, indicating that 44.5% of the total precipitation was within the pure precipitation criteria. The volume-weighted mean concentrations (μeq/L) of the ionic components in the precipitation were in order of Cl − > Na + > NH 4. Sea salt (Cl − , Na + , Mg 2+ ) and secondary pollutants (NH 4 + , nss-SO 4 2− , NO 3 − ) contributed to the total ionic species in the precipitation samples by 52.6% and 33.6%, respectively. The acidity contributions by inorganic (nss-SO 4 2− , NO 3 − ) and organic (HCOO − , CH 3 COO − ) acids were 89.3% and 10.7%, respectively. The neutralization factors by ammonium and calcium carbonate were 0.44 and 0.21, respectively. A clustered back trajectory analysis showed that the concentrations of secondary pollutants were relatively high when airflow moved to Jeju Island from the China continent.
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