This study was performed to investigate the characteristics of acid rain in Seoul in the last five years. The three sampling sites were; a residential area of Hannam-Dong, an industrial area of Kuro-Dong, and a rural area of Bangi-Dong. Source of data was the annual reports of Seoul Metropolitan Government Institute of Health and Environment from 1986-1990, which measured pH value and electroconductivity using an automatic rain monitor and concentrations of sulfate, nitrate and chloride ions using an ion chromatograph.
Acid rain below pH 5.0 was found in all of the three points with no significant difference in pH among areas over the five-year study. The acidity of rainfall by season was descending in the order of; summer, 5.17; spring, 4.90; fall, 4.73; winter, 4.59. The initial 1 mm of the 5 mm portion regarded as in early precipitation showed the highest pH value of 5.13 and it lowered as the precipitation increased. For the electroconductivity in rainfall, there were trends increasing by year and decreasing by rainfall and varying by session to session though in the latter case the marginal error was substantial. No obvious trends were observed by year and season for individual ions. The sulfate, nitrate and chloride ion concentrations showed the highest value within the single rainfall of 1 mm. The chloride ion concentration showed the highest in winter and the lowest in summer; however, the other two ion concentrations did not follow the same trend. The sulfate, nitrate and chloride ion concentrations,_ electroconductivity, and pH decreased by precipitation.
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