| Summary: | 碩士 === 國立嘉義大學 === 史地學系研究所 === 98 === ABSTRACT
This study is aimed to investigate the weekend effect, defined as the difference in concentrations of air pollutants between weekends and weekdays, in the Taipei, Taichung and Kaohsiung metropolitan areas. Surface measurements from twenty-seven stations of the Environmental Protection Administration (EPA) from 1994 to 2008 are used to analyze air pollutants including NOX, CO, NMHC, O3, SO2, PM10, NO2, NO, NO2+O3, and solar radiations of UV-A and UV-B. The daily mean concentrations of nine air pollutants are all found with weekend effect in the three metropolitan areas. Except O3, the other eight air pollutants are lower on weekends than on weekdays. For the four seasons, the nine air pollutant concentrations in the three metropolitan areas are found with weekend effect except O3 in summer in the Taichung metropolitan area, CO and NO2+O3 in summer and O3 in spring, autumn, and winter in the Kaohsiung metropolitan area. For the natural seasons, the nine air pollutant concentrations in the three metropolitan areas are found with weekend effect except NO2+O3 in autumn and PM10 in winter in the Taipei metropolitan area, PM10 in winter in the Taichung metropolitan area, O3 in the spring rainfall and winter seasons, NO2+O3 in the plum rain and typhoon seasons, and CO and PM10 in the typhoon season in the Kaohsiung metropolitan area. The daily mean radiations of UV-A and UV-B are observed no weekend effect in the three metropolitan areas.
For the diurnal cycle, a common traffic-related double-peak variation is observed in the concentrations of NOX, CO, NMHC, NO2, NO, SO2 and PM10 in the three metropolitan areas on weekdays while the double-peak pattern is not significant on weekends. Except O3, the hourly concentrations of other eight air pollutants are mostly lower on weekends than weekdays for each hour. The ozone weekend effect might be due to the NO titration effect since the ozone precursors are lower during weekends than weekdays, however, the solar radiations are not significant different between the two periods.
Except O3, the interannual variations of other eight air pollutants are lower on weekends than weekdays for each year. The concentrations of most air pollutants have decreasing trends not only on weekends but also on weekdays. There is a weakening weekend effect of SO2 in the Taipei and Taichung metropolitan areas due to the larger decreasing trend on weekdays than weekends. The weekend effect on NOX, CO, NO2 and NO2+O3 in the Kaohsiung metropolitan area is increasing due to the smaller decreasing trend on weekdays than weekends.
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