EVALUATION OF THE CHARACTERISTICS OF ACID PRECIPITATION IN TAIPEI, TAIWAN USING CLUSTER ANALYSIS

摘要

This work investigated the characteristics of acid precipitation collected in Taipei, Taiwan during l99l--l995 by performing cluster analysis. The extent to which meteorological conditions influence precipitation chemistry was also elucidated. Three potential sources of watersoluble ions in rainwater were identified f seasalt aerosols (Na+, Cl-- and Mg~2+), anthropogenic pollutants (H+ and NO~3), and mixing sources associated with sulfate (nss-SO~2-_4, NH~+_4 and Ca~2+). As the northeast flow prevailed during the northeast monsoon season, the concentrations of seasalt and sulfate ions in rainwater were significantly high. During that season, a typically high ratio of nss-SO~2-_4/NO_3 was also observed, indicating that Taipei might receive foreign pollutants via a long-range trans- port. In contrast, when the Pacific high dominated the region, nitrate concentration in rainwater was significantly elevated. Also during that period, the ratio of nss-SO~2-_4/NO_3 was substantially lower, indicating the prominence of acidic substances contributed by local sources.