| Summary: | 碩士 === 明志科技大學 === 環境與安全衛生工程系環境工程碩士班 === 102 === This study assesses the continuous monitoring data of aerosol at Hsin-Chuang North Aerosol Supersite to analyze temporal characteristics of PM2.5、black carbon (BC) mass and particle number(ranging from 10–560 nm, N10–560) levels in the Taipei urban area from 2006 to 2010. Long-term measurement results of this study demonstrated that PM2.5 concentration in the spring, summer, autumn, and winter were 32.3 μg m-3 、24.2 μg m-3、26.9 μg m-3and 30.4 μg m-3, respectively. BC mass concentrations in the spring, summer, autumn, and winter were 3.26 μg m-3, 3.19 μg m-3, 2.39 μg m-3, and 3.08 μg m-3, respectively. Additionally, the N10–560 levels in the spring, summer, autumn, and winter were 1.46×104 particles cm-3, 1.60×104 particles cm-3, 1.07×104 particles cm-3, and 1.36×104 particles cm-3, respectively. Results suggested that the highest level of PM2.5 appeared in the spring and winter which was closely related to the influence of long-range transport of Asian dust and manmade pollutants from China on Taiwan. In the autumn, the lowest BC mass and particle number concentrations were mostly likely owing to meteorological conditions that favored dispersion of local air pollutants. Additionally, the highest particle number concentration could be observed in the summer due to that the activities of the chemical nucleation and gas-to-particle reactions in the summer were more intense than those in other seasons. Furthermore, PM2.5, black carbon and particle number levels peaked during the morning (7:00–9:00) and evening (18:00-20:00) rush hours. During these two periods, higher concentrations could be elevated due to heavy traffic with an increasing pollutant emission. The 24-hour variations of particle number concentrations in summer differed from those in other seasons. Particle number concentration had a significant peak at noon (12:00) time. Particles with an increasing number may result from new generations of airborne particulates through photochemical reactions by existed tracer gases at a high temperature condition.
According to this study, measurement results pointed out that the variations in concentrations between black carbon mass and particulate number were similar, indicating the airborne black carbon and particulate may came from the same source. Additionally, the N/BC in summer was higher than those in other seasons, especially during the noon time (11:00-13:00). In this period, N/BC had a significant peak, especially in the range of 56-100 nm, suggesting the mainly size of secondary particles existed in airborne could be in the range of 56-100 nm, followed by 32-56 nm and 100-180 nm.
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