Mass Concentration and Size-Resolved Chemical Composition of Atmospheric Aerosols Sampled at the Pescadores Islands during Asian Dust Storm Periods in the Years of 2001 and 2002

  • Author(s): Chung-Shin Yuan, Cheng-Chung Sau, Ming-Chung Chen, Ming-Ho Huang, Su-Wen Chang, Yat-Chen Lin, and Chang-Gai Lee
  • DOI:

    10.3319/TAO.2004.15.5.857(ADSE)

  • Keywords:
Abstract

This study investigated the mass concentration and size distribution of atmospheric aerosols collected at the Pescadores Islands during Asian dust storm periods in the years of 2001 and 2002. As part of an island-wide Asian dust sampling network covering Taiwan and its surrounding islands, an atmospheric aerosol sampling site was established at Xiaumen, Pescadores Islands since March 2001. Xiaumen was at the northwest tip of the Pescadores Islands located at the center of Taiwan Strait and approximately 110 kilometers from the West Coast of the Taiwan Main Island. The sampling protocol was conducted to collect sea level atmospheric aerosols for further physical and chemical analysis. This study revealed that five Asian dust storms invaded the Pescadores Islands during the sampling campaign. The mass concentration of atmospheric aerosols, particularly PM2.5-10, were 2 - 3 times higher than background levels (i.e., non-Asian dust storm periods). Comparison of hourly PM10 concentration between Xiaumen and ambient air quality monitoring stations in Taiwan indicated that Asian dust storms usually invaded from either the northeast or the northwest and could last for approximately 2 - 4 days. Moreover, Asian dusts could be preliminarily validated in situ by observing the change of their apparent colors from dark gray to light brown. Comparison of hourly PM10 concentration measured at the Pescadores Islands and Taiwan Main Island during the Asian dust storm periods showed that the Asian dust storm invaded Taiwan from either the northwest or the northeast. Increasing both PM10 concentration and coarse particle mode in the size distribution of atmospheric aerosols validated the invasion of Asian dust storms. Significant increase of SO42- , Cl- , Na+ , NH4+ , Mg2+ and Ca2+ concentration on coarse particle mode was also observed for Asian dusts. This suggested that not just natural soil dusts but also anthropogenic pollutants and oceanic spray could accompany the Asian dust storms and arrive at the Pescadores Islands.

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