| Summary: | 碩士 === 國立中央大學 === 環境工程研究所 === 94 === Although PM10 air quality standard has been set up for regulating ambient aerosols by Environmental Protection Administration (EPA) in Taiwan, fine aerosol which is more related to motor vehicle emissions and photochemical reactions is not yet regulated. It is worthwhile to investigate whether the new fine aerosol standard should be either PM2.5 or PM1 in Taiwan?
This study assesses aerosol continuous monitoring characteristics from North Aerosol Supersite and the air quality data from nearby Hsin-Chuang monitoring site to analyze PM1 and PM2.5 physical, chemical, and optical properties from March 2002 to December 2005. In addition, filter-based aerosols waere collected in various days in August, September, October, and December 2005. The analysis of aerosol properties shows that major water-soluble ions like SO42-, NH4+, K+ are predominantly distributed in aerosol sizes below 1 μm. In contrast, more sea salts are found in PM2.5 from the calculation of chlorine loss. However, major sources for PM1 and PM2.5 are both from traffic activity and photochemical reactions. In aerosol carbon fractions, PM1 is predominant except for pyrolyzed carbon (OP) and low temperature evolved elemental carbon with the substraction of OP (EC1-OP) are dominated by PM2.5-1. The aerosol monitoring characteristics shows that major aerosol species are in submicron particles for high concentration events, high fine aerosol events in front of transported Yellow dusts, and high aerosol events under anticyclonic outflow after the passage of Yellow dust. This indicates PM1 is useful as a tracer in representing high aerosol events. Moreover, PM1 is better than PM2.5 in accounting for aerosol optical effects for the environment. In fact, submicron aerosols frequently reach a substantial concentration even without shooting up the US 65 μg m-3 standard. This might mislead people to underscore aerosol effects on human health and the environment.
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