| 摘要: | 氣膠對太陽輻射同時具有散射或吸收的能力，因而造成有效日照時數的縮短，對於農作物生長、視程的衰竭以及人們生活作息造成極重大的威脅，因此，對全球氣候變遷有重大的影響。本研究於民國88年12月至89年1月在高雄及89年春季3月到5月於台北進行氣膠採樣，量測氣膠散光係數、氣膠粒徑分布、粒徑小於2.5?m的氣膠質量濃度及細粒徑氣膠物種組成。在台北採樣時並以MOUDI採集分階粒徑氣膠，以供進一步分析氣膠的化學組成。同時，更測定採樣地點的風向、風速、相對溼度等氣象資料，期能有助解釋環境對氣膠散光係數和化學成份的影響。 研究結果顯示高雄地區氣膠的綠光散光係數日平均值範圍介於0.122~0.564km-1之間，平均值為0.321km-1，氣膠散光係數主要來自於北方的污染源。在兩小時採樣區間下，細粒徑氣膠質量濃度範圍介於160.8~25.4?g/m3，對照環保署小港測站PM10數值後，得到PM2.5/PM10的平均值為0.62，所量測的氣膠質量濃度與散光係數有良好的相關性(r=0.78)。 相對地，台北都會區綠光散光係數日平均值範圍介於0.032~0.484km-1之間，平均值為0.181 km-1。在沙塵暴期間，超微米氣膠對散光係數的貢獻量由平時的26%提升為47%，其含塵氣膠尖峰粒徑為2?m。由MOUDI分粒徑化學採樣分析的結果，顯示台北地區細粒氣膠組成以SO42-、TC和 NH4+為主，粗粒徑氣膠主要成份則為NO3-、Si及海鹽離子。 Atmospheric aerosols reduce effective sunlight received by the Earth through scattering and absorbing solar radiation. This results in a threat to agricultural growth, visibility degradation, and human activity; which exerts a dramatic effect on global climate change. This study measures PM2.5, light-scattering coefficient (?sp), size spectra, and chemical compositions of atmospheric aerosols in Kaohsiung and Taipei areas from December in 1999 to January in 2000 and from March to May in 2000, respectively. In addition, size-resolved aerosols are collected using MOUDI samplers and analyzed for their chemical contents in Taipei study. Meanwhile, wind direction, wind speed, and relative humidity are collected simultaneously for analyzing the effects of environment on aerosol optical property and chemical compositions. The results show daily averages of the smallest 5-min ?sp from green wavelength in Kaohsiung ranging from 0.122 to 0.564km-1, with an average of 0.321km-1. The 2-hr intervals of PM2.5 collected in this study are in the range from 160.8 to 25.4?g/m3. By taking PM10 values from a nearby EPA air quality monitoring station, a ratio of PM2.5/PM10 at 0.62 is obtained. The measured ?sp is correlated well (r=0.78) with the collected aerosol mass. In contrast, the daily averages of the 5-min ?sp in Taipei range from 0.032 to 0.484km-1 with the average at 0.181 km-1. During the landing of yellow storm, the contribution from supermicron aerosols to ?sp increases from 26% to 47%. The modal diameter of the supermicron particles is at 2?m. The size-fractionated chemical contents from MOUDI reveals SO42-, NH4+, and TC are dominant in the fine mode, while NO3-, Si, and sea-salts are major compositions in the coarse mode. |
