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 ± 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+ > NH4+ > nss‐SO42− > NO3− > Mg2+ > nss‐Ca2+ > H+ > K+ > HCOO– > CH3COO– > HCO3– > F− > NO2− > CH3SO3− > PO43−. Sea salt (Cl−, Na+, Mg2+) and secondary pollutants (NH4+, nss‐SO42−, NO3−) contributed to the total ionic species in the precipitation samples by 52.6% and 33.6%, respectively. The acidity contributions by inorganic (nss‐SO42−, NO3−) and organic (HCOO−, CH3COO−) 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.