Chemical Characterization of Precipitation by Air Pollutants on Jeju Island in Korea during 2015–2016

Abstract

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.