| 摘要: | 氣膠本身化學特性會直接影響微粒的散光係數，因此本研究為了了解不同類型都會區大氣PM2.5細氣膠微粒的化學特性對散光係數造成的影響，並追溯氣膠的污染來源類型，本研究於1999年12月20日至2000年1月28日間，以及2000年3月20日至2000年5月18日間，分別在高雄市小港區港興活動中心及臺北市交通部中央氣象局使用Honeycomb denuder及cyclone進行氣膠採樣，探討大氣氣膠的化學特性。本研究分析了PM2.5氣膠的水溶性離子、總碳量、金屬成份及氣膠含水量，並使用過去建立的迴歸模式推估氣膠的理論含水量(Lee and Hsu , 1998)。 小港地區在採樣期間平均質量濃度為93.0μg/m3，標準偏差為29.1μg/m3，平均質量散光效率為2.37m2/g。細粒徑氣膠主要成份為水溶性離子，其所佔的總質量濃度百分比為33.5%，碳含量佔27.6%、金屬元素佔18%、含水量佔4.6%，未解析佔16.3%。 化學物種中硫酸鹽、硝酸鹽與綠光散光係數間有高相關性，以此組合利用多元線性複迴歸模式推估的氣膠散光係數與量測值間有中高度的線性關係。以加強因子法分析得知PM2.5細粒徑氣膠中的SO42-及K+大都來自非海鹽氣膠；Cl-、Mg2+、Ca2+主要是來自海水飛沫。由氯離子損失法所推估的結果指出，高雄水溶性離子的污染源中，海水飛沫的貢獻量不大，以二次硝酸鹽與二次硫酸鹽為主要污染源。以主成分推估結果顯示高雄地區以-二次光化反應污染、海水飛沫來源、農廢燃燒為主要的污染來源。 台北地區在採樣期間平均質量濃度為50μg/m3，標準偏差為22.3μg/m3，平均質量散光效率為3.1m2/g。細粒徑氣膠來源為水溶性離子，其所佔的總質量濃度百分比為35%，碳含量佔31%、金屬元素佔12%、含水量佔2%，未解析佔20%。 多元線性複迴歸模式推估氣膠散光係數的主要參數為硫酸鹽和硝酸鹽。以加強因子法分析得知PM2.5細粒徑氣膠中的SO42-、K+及Ca2+大都來自非海鹽氣膠；Cl-及Mg2+主要是來自海水飛沫。由氯離子損失法所推估的結果指出，台北水溶性離子的污染源中，以二次硫酸鹽為主要污染源。以主成分推估結果顯示台北地區以-二次光化反應污染、農廢燃燒為主要的污染來源。 Aerosol chemical properties are important in source apportionment, health effect, and radiative forcing. The goal of this study is to compare aerosol characteristics in terms of chemical properties on light-scattering coefficient and apportionment of source contributions from two different types of city in Taiwan. Atmospheric aerosols were collected using Honeycomb denuder and cyclone in Kao-hsiung City from December 20, 1999 to January 28, 2000 and in Taipei City from March 20 to May 18, 2000. Water-soluble ions, carbonaceous contents, metal elements, and water mass of aerosols are analyzed. A regression model for theoretical aerosol water mass is adopted for comparisons with the measurements (Lee and Hsu , 1998). The daytime average of PM2.5 in Kao-hsiung City is 93.0μg/m3 with a standard deviation of 29.1μg/m3. Meanwhile, the average of aerosol mass scattering efficiency during this time period is at 2.37m2/g. Chemical analysis shows the mass fraction of water-soluble ions, carbonaceous contents, metal elements, water content, and unknown is 33.5%, 27.6%, 18%, 4.6%, and 16.3%, respectively. Among the analyzed species, sulfate and nitrate ions are correlated well with aerosol light-scattering coefficient. The analysis of enhancement factor reveals sulfate and potassium ions are mostly originated from non-sea-salt aerosol, while chloride, magnesium, and calcium ions are mainly from sea-salt. As pointed out by chlorine loss algorithm, the water-soluble ions in Kao-hsiung city is mostly from the secondary photochemical reaction. The APCA analysis shows Kao-hsiung aerosols are contributed from the secondary reaction, sea-salt, and agricultural burning. In contrast, the daytime average of PM2.5 in Taipei City is relatively lower at 50μg/m3 with a standard deviation of 22.3μg/m3. During this period, the average of aerosol mass scattering efficiency is higher at 3.1m2/g. Water-soluble ion is still the prominent species, the mass fraction of water-soluble ions, carbonaceous contents, metal elements, water content, and unknown is 35%, 31%, 12%, 2%, and 20%, respectively. The regression analysis shows sulfate and nitrate ions are the two parameters adopted in the model to account for the variations of aerosol light-scattering coefficient. Similarly, the analysis of enhancement factor reveals sulfate, calcium and potassium ions are mostly originated from non-sea-salt aerosol, while chloride and magnesium ions are mainly from sea-salt. The chlorine loss algorithm infers the water-soluble ions in PM2.5 from Taipei City are mostly from the secondary photochemical reaction. The APCA analysis confirms Taipei City aerosols are contributed from the secondary reaction and agricultural burning. |
