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Variations of chemical compositions in coarse aerosols and fine aerosols in two successive episodes
Author(s) -
Kuo ChungYih,
Lin ChuanYao,
Chiang WanFu,
Ko LiChin,
Wu ChiaWen,
Shang WenLing
Publication year - 2006
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1897/05-511r.1
Subject(s) - aerosol , nitrate , particulates , environmental chemistry , ammonium , environmental science , dust storm , air quality index , chemistry , atmospheric sciences , meteorology , geography , physics , organic chemistry
Particulate matter with diameters less than 2.5 μm (PM 2.5 ) and ranging between 10 to 2.5 μm (PM 10‐2.5 ) were simultaneously collected at four air‐quality monitoring stations in the Taichung area of central Taiwan during the period of February 12 to 22, 2004. Two different types of PM 10 episodes, a nonlocal dust‐storm episode and a local episode, were observed in the present study. High concentrations of coarse aerosols occurred during the dust‐storm episode, whereas high concentrations of fine aerosols were present during the local episode. Relatively high levels of Na + , Mg 2+ , Ca 2+ , and Cl − in coarse aerosols were observed during the dust‐storm episode. Very high concentrations of secondary aerosols (NH + 4 , SO 2− 4 , and NO − 3 ) in fine aerosols were observed during the local episode. The nitrate ion demonstrated the greatest increase in the ratios of ionic species to PM 2.5 and ionic species to PM 10‐2.5 during the local episode. Significantly high ratios (0.444) of NO − 3 to NO 2 in fine aerosols were present during the local episode, indicating that the relatively high formation rate of NO − 3 was one of the important factors leading to the increase of the NO − 3 to PM 2.5 ratio during the local episode. Results also showed that an abundant quantity of fine ammonium nitrate was formed during the local episode, and chloride depletion probably was the major pathway to form coarse NaNO 3 during this episode.