- 學位論文
河川揚塵特性及其再懸浮評估-以彰化縣境為例
Characteristics and Re-suspension Evaluation of River Fugitive Dust—A Field Study in Chunghua County
摘要
本研究主要以彰化縣境內，河川裸露地及河川沙洲區域因季風所引起河川揚塵之特性及其再懸浮進行調查。研究主要選擇濁水溪及烏溪兩條河流進行監測，時間從2011年6月29日至2012年6月28日止。季風發生期間，利用VEREWA-F701 PM10、VEREWA-F701 PM2.5持續監測河流沿岸的河川揚塵濃度。並利用氣象監測系統(Weather Link, Davis Vantage Pro)測定風速、方向、溫度和濕度。河川裸露地面積之估算則以衛星圖像，輔以電腦程式之影像像素估算進行。再懸浮研究部分則收集烏溪及濁水溪河川表面沙土，配合氣動粒徑分析儀(Aerodynamic Particle Sizer, APS)在風洞系統內進行揚塵再懸浮分析。 結果顯示，影響培英及潭墘監測站之PM濃度主要因素為降雨、風向及氣候因素，而採樣期間彰化縣境內並未發生河川揚塵事件。另由再懸浮模擬測試發現，烏溪沙土樣本含水率0 %、在風洞內風速14 m/s時，經過30秒吹拂，可將200公克表層沙土樣本再懸浮逸散達32.3 – 43.9 %之重量百分比，而含水率增為2.5 %時則為11.8 – 12.4 %。而在濁水溪含水率0 %時，則為43.2 – 51.8 %，但當含水率增為5 %時，其沙土樣本逸散則減為0 – 1.3 %。而沙土樣本在不同含水率及風速與沙土再懸浮之檢定結果顯示：含水率越低與揚塵再懸浮率越高，而風速越高與揚塵再懸浮率越高皆達統計顯著。而烏溪及濁水溪之沙土樣本在含水率0 %，風速14 m/s下之粒徑分佈峰值主要範圍為1.382 – 1.596 µm。
並列摘要
The major work of this study was to investigate the characteristics of fugitive dust along the riverside included the bare land, riverbed of rivers which was caused by monsoon in Chunghwa County, Taiwan. This study was conducted for one year which began in June 29th, 2011, until June 28th, 2012. Two rivers, Wu River and Chuoshui River, were recruited in the study. VEREWA-F701 PM10, PM2.5, Micro-Orifice Uniform Deposit Impactor, and TSI 8520 DustTrak Aerosol Monitor were used to sample the concentrations of fugitive dust along the riverside during the monsoon duration. The wind speed, direction, temperature and humidity were measured by Weather Link (Davis Vantage Pro) meteorological monitoring system. The total area of bare land of riverside was estimated each season by means of the image processing techniques of satellites images and photos taken in-site. The surface layer of river sand and soil were collected (Chuoshui River), re-suspended and tested under wind tunnel by using Aerodynamic Particle Sizer. The results of wind tunnel re-suspension indicated the higher wind speed could produce higher particle concentration, and smaller modal size of the size distribution. Moreover, when the water content of the river sand was below 2.5 %, the wind tended to re-suspend the river sand easily even in 1m/s of the wind speed under the wind tunnel. However, if the water content of the river sand was above 2.5 %, even in 14 m/s of the wind speed under the wind tunnel, few particles was re-suspended by wind blow. For instance, when the water content was in 0 % and wind speed in 14 m/s, the 30-second resuspension rate of 200-gram river sand was around 32.3 – 43.9 % in Wu River, but decreased to 11.8 – 12.4 %, when the water content increased to 2.5 %. On the other hand, when the water content was in 0 % and wind speed in 14 m/s, the 30-second resuspension rate of 200-gram river sand was around 43.2 – 51.8 % in Chuoshui River, but decreased to 0 – 1.3 %, when the water content increased to 5 %. Moreover, the statistical results also showed the agreement of the above association. In both rivers, the modal size range of river sand resuspension was around 1.382~1.596 µm under water content of 0 % and wind speed of 14 m/s.
參考文獻
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