Monitoring of air pollutants at Kosan, Cheju Island, Korea, during March-April 1994

Gaseous species and total suspended particles were measured at Kosan, Cheju Island, Korea, between 11 March and 19 April 1994. The concentrations of nonsea salt (nss) ions were higher than those measured in clean marine areas of Japan and other background marine areas of the world. In particular, the nss sulfate concentration was comparable to that measured in Seoul. The average SO₂ and NO_x concentrations were approximately 0.97 and 3.5 ppb, respectively, which were lower than those at other urban areas in Korea but higher than those of other remote areas in the world. In contrast, the average O₃ concentration was approximately 55 ppb, which is comparable to or higher than those at remote sites in Japan that were influenced by long-range transport of air pollutants. Half of the air parcels during the period were from northern China and about 30% of the air parcels from southern China. The main difference of air pollutant levels between the two areas was higher crustal species and lower nss sulfate concentrations for air parcels from northern China. The nss SO^2-₄ concentrations had a strong correlation with nss K⁺, NH⁺₄, and O₃ concentrations. In addition, the nss Ca²⁺ concentrations had a strong correlation with the nss K⁺ and nss Mg²⁺ concentrations. It was suggested that nss K⁺ had two sources: anthropogenic and crustal.