| Summary: | 碩士 === 逢甲大學 === 環境工程與科學學系 === 103 === The transmission and distribution of air pollutants was discussed using the data of the air quality monitoring stations (Feng-Yuan, Shalu, Xitun, Chung-Ming and Dali) in Taichung Basin. The wind roses and concentrations variations of air pollutant were addressed, from which the transmission and distribution of pollutants in ozone even days were investigated. The air pollutants blow into Taichung Basin form Changhua and Hsinchu areas during the southwest and northeast monsoon periods, respectively. Because of the surface concentrations of air pollutants decrease with increasing mixing high and wind speed. In the basin, therefore, the concentration of air pollutants during the southwest monsoon period was higher than during the northeast monsoon season obviously.
The concentrations of air pollutants decrease with increasing wind speed and atmospherical temperature. Because of the wind speed and temperature in the basin are higher and lower in coastal due to the basin effect, so the monthly average concentration at Shalu station (in the coastal area) was often lower than at Dali and Chung-Ming stations (in the basin area). The urban heat island effect occurs at Dali, moreover, so the pollutant concentration at Dali station was higher than other stations generally.
Two high concentration periods of nitrogen oxide (ozone precursor) occur at 6:00-9:00 and 18:00-20:00 due to morning and evening traffic peaks. The monitoring results of carbon monoxide and particulate matter were same as nitrogen oxide. It means that the main source emission of nitrogen oxide was vehicles exhaust. Conversely, the period of high concentration of ozone occurred at 11:00-15:00. The variation of the concentration of sulfur dioxide was irregular, which may depend of wind direction and other weather parameters. The density of particulate matter higher than gas pollutants lead to it accumulate at locality easily. Therefore, the concentration occurred at after 18:00.
According to the monitoring results, it can summarize as following: (1) wind speed and temperature are two major weather factors for air quality, (2) main emission source is vehicle exhaust, especially at morning and evening traffic peak periods, and (3) high concentration periods of ozone precursor occur at 6:00-9:00 and 18:00-20:00, but high concentration occurs at 11:00-15:00 in the both basin and coastal areas. Therefore, in order to effectively reduce the carbonyls in ambient air, pollution from vehicle exhaust and hi-tech industry must be managed and controlled.
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