Atmospheric nitrogen and sulfur containing compounds for three sites of South Korea

초록

Atmospheric concentrations of gaseous HNO<inf>3</inf>, NH<inf>3</inf> and particulates NO<inf>3</inf>- and SO<inf>4</inf>2- were analyzed at three sites, Chunchon, Seoul and Anmyon-do, on the Korean peninsula by filter pack method. The samples were collected over a period of 24h every Wednesday. At one of the sites, Chunchon, atmospheric SO<inf>2</inf> was measured by using a four-stage filter pack. The annual mean concentrations of HNO<inf>3</inf> and NH<inf>3</inf> in 1998 ranged from 1.67 to 2.94 and from 2.00 to 3.95μgm-3, respectively. The annual average of SO<inf>2</inf> at Chunchon was 7.32μgm-3. The annual averages of particulate NO<inf>3</inf>- and SO<inf>4</inf>2- were 4.83-6.10 and 4.88-7.25μgm-3, respectively. Particulate SO<inf>4</inf>2- showed no distinct seasonal variation while its primary pollutant, SO<inf>2</inf> displayed concentration peak in winter and bottomed out during summer. Consequently, the S(VI)/[S(IV)+S(VI)] ratio increased in a warm and light intensive summer and decreased in the cold and dark winter. This result suggests oxidation reactions were more efficient during the summer than in the winter. HNO<inf>3</inf> showed a summer maximum which resulted from the temperature dependence of vapor pressure and oxidation reaction rates of its related compounds. Atmospheric NH<inf>3</inf> was elevated in the warmer season, which related to an increase in source strength and vapor pressure. On the other hand, particulate NO<inf>3</inf>- and NH<inf>4</inf>+ showed either winter peaks or no seasonal variation. These seasonal trends in nitrogen related compounds can primarily be explained by the gas-particle conversion reaction of NH<inf>4</inf>NO<inf>3</inf> to NH<inf>3</inf> and HNO<inf>3</inf>. This fact is supported by an increase in the ratio of gaseous nitrogen to particulate nitrogen as the ambient temperature rose. © 2002 Elsevier Science Ltd. All rights reserved.

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