| Summary: | 碩士 === 國立屏東科技大學 === 環境工程與科學系 === 94 === This research mainly focuses on the components and properties of particulate matters (PM2.5/PM10) collected at a sandstone extracting zone. We sampled particulate matters at an exclusive sandstone extracting zone (Longhsiang Park) and the Likang Township Office using MOUDI, Dichot, and PS-1 samplers on Apr 11th and Oct 18th, 2005. The sampling at Longhsiang Park was performed in six hour-periods: 8-10, 10-12, 12-14, 14-16, 16-18, and 18-8 whereas the three sampling hour-periods at the Likang Township Office (background value) were 8-12, 12-18, and 18-8. The first sampling at the sandstone extracting zone, on Apr 11th, 2005, the highest and lowest TSP concentrations (547 and 237 g/m3, respectively) occurred during the periods of 2-4 pm, and the 18 pm-8 am, respectively. The average concentration of coarse particulate matters (particle size ranging 10-100 m) was 217 g/m3. The TSP/PM10 values were between 1.7 and 7.0, and the average was 2.9. This result shows that regular sand/gravel extraction was conducted on the riverbed of Ailiao River and at the nearby processing sites before the first sampling at Likang exclusive sandstone extracting zone. Thus, the collected particles were mainly coarse grains with sizes larger than 10 m. For the first sampling, the average PM10 concentration at Longhsiang Park river banks (116 g/m3) was significantly higher (about 2 times) than the value observed at Likang Township Office; moreover, the average PM2.5 concentration (93.3 g/m3) was 2.8 times of the value measured at the Likang Township Office. The average concentrations of PM2.5-10 at the two sites were similar. In the second sampling, the average PM10 and PM2.5 concentrations (111 and 76.7 g/m3, respectively) at the Longhsiang Park river bank site were about 1.32 and 1.65 times higher than the values measured at Likang Township Office, respectively. The values were similar to those obatined in the first sampling. The average concentrations of PM2.5-10 at the two sites were also similar. At the Likang sand/gravel extraction site, the size distribution of particulate matters ranged between 3.2-5.6 m when the sand/gravel extraction was normally operated. At the first sampling at Likang exclusive sandstone extracting zone, due to the contribution from ongoing operations of sandstone extraction on the riverbed of Ailiao River, the cumulative percentage of PM2.5-10 was 36.2%, significantly higher than the value (25.3%) measured in the second sampling when the sandstone extraction ceased. This finding indicates that coarse particulate matters accounted for a higher proportion than the fine particles during sand/gravel extraction. For the water soluable ions in both PM2.5 and PM2.5-10 sampled at the two sites, the concentrations of secondary aerosol (NO3-、SO42- and NH4+) were higher than the others, probably due to the frequent access of gravel trucks to the extraction site and operations of fixed/mobile machines. The exhausted NOx and SO2 from the trucks were converted into nitrates and sulphates after their release into the atmosphere while ammonium salts were mainly generated from argricultural activities and the burning of argricultural waste. At the Likang exclusive sandstone extracting zone, the contents of Ca2+ and Mg2+ in PM2.5-10 were 2.9 and 8.6 times of the background values measured at Likang Township Office, respectively. However, this phenomenon was not observed for PM2.5, probably due to the frequent in/out access of gravel trucks during the sampling periods. Dust windblown by frequently accessing gravel trucks or gravel processing operations may cause the emission of coarse particulate matters that contain Ca2+ and Mg2+. Therefore, the contents of Ca2+ and Mg2+ in coarse particulate matters were higher than the values measured at the Likang Township Office. No matter at the Longhsiang Park river banks or Likang Township Office, the main metal contents in PM2.5 and PM2.5-10 were Na, Si, S, K, Ca, and Fe.
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