| Summary: | 碩士 === 國立成功大學 === 環境工程學系 === 104 === Fine particulate matters have been identified as one of the major air pollutants in urban areas, which are responsible for the deterioration of the atmospheric air quality as well as adverse effects on public health. In this study, the mass concentration, water-soluble ionic component, trace metal component, carbon component and modeling the contribution source for PM2.5 was characterized for Chiayi City which has high population density and surrounded by agricultural area. The results of this study are as following:
1.In the spring, the PM2.5 concentrations were 33-61μg/m3. The PM2.5/PM10 ratios were 45.9-58.0%, which is among the levels of normal urban area. The main wind direction were NW and N, leading to the relatively higher PM2.5 levels around the east of Chiayi City. The particulate accumulation in valley or near-mountain location occurred. The mass concentration of PM2.5 were mainly composed of 58.7% water soluble ions 14.4% carbonates, and 5.1% metals. The ion contents were majorly composed of NO3- (22.4%), SO42- (16.8%), and NH4+ (14.3%). The average OC (10.1%) mass content was higher the EC (4.9%).
2.In the summer, the PM2.5 concentrations were 9-22μg/m3. The PM2.5/PM10 ratios were 33.3-42.9%, which is significantly lower than other seasons. This could be resulted from the inhibition of primary particles and secondary gaseous precursors by temporal precipitation. The mass concentration of PM2.5 were mainly composed of 39.1% water soluble ions 18.0% carbonates, and 13.0% metals. The ion contents were majorly composed of SO42- (21.8%), NH4+ (8.8%), and NO3- (7.2%). The average OC (10.6%) mass content was higher the EC (7.4%).
3.In the autumn, the PM2.5/PM10 ratios were 34.9-59.1%. The mass concentration of PM2.5 were mainly composed of 54.2% water soluble ions 10.2% carbonates, and 7.5% metals. The ion contents were majorly composed of SO42- (21.9%), NO3- (16.6%), and NH4+ (11.0%). The average OC (6.4%) mass content was higher the EC (3.8%).
4.In the winter, the PM2.5 concentrations were 29-69μg/m3. The PM2.5/PM10 ratios were 52.9-67.9%, reporting the higher fine particle level with more potential harmful effects than other seasons. The mass concentration of PM2.5 were mainly composed of 59.2% water soluble ions 13.7% carbonates, and 4.6% metals. The ion contents were majorly composed of SO42- (20.7%), NO3- (17.5%), and NH4+ (12.6%). The average OC (9.5%) mass content was higher the EC (3.9%).
5.The main contribution for locally atmospheric PM2.5 by CMB model were as follows. Spring: secondary nitrate, traffic source, secondary sulfate, re-suspending soil particle, petrochemical industry, agricultural open burning, metallurgical industry, cement industry, and sea salt. Summer: secondary sulfate, secondary nitrate, re-suspending soil particle, traffic source, petrochemical industry, sea salt, cement industry, and metallurgical industry. Autumn: secondary sulfate, secondary nitrate, traffic source, petrochemical industry, re-suspending soil particle, agricultural open burning, sea salt, cement industry, and metallurgical industry. Winter: traffic source, secondary nitrate, secondary sulfate, agricultural open burning, petrochemical industry, re-suspending soil particle, sea salt, cement industry, and metallurgical industry.
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