EPA-91-U1L1-02-107

091

1,430 千元

2002/03/01

2002/12/31

李崇德

監資處

國立中央大學環境工程研究所

環境資訊系統

大陸沙塵暴、背景氣膠、氣膠質量濃度、氣膠成分、空氣品質管理

Asia dust storm, background aerosol, aerosol mass concentration, aerosol chemical compositions, air quality management

柳中明

大陸沙塵暴近年來發生頻率及強度均有增加的趨勢，在氣象條件適當時，大陸沙塵往往會影響台灣地區的空氣品質。本計畫在陽明山進行PM10及PM2.5的質量濃度採樣及成份分析，在花蓮進行TSP和PM10質量濃度採樣及分析，總計在沙塵期間分別完成41、69與32個TSP、PM10與PM2.5有效樣本，在非沙塵期間分別完成14、25與12個TSP、PM10與PM2.5有效樣本，共計完成193個有效樣本。 陽明山平日PM10質量濃度在10μg/m3左右，沙塵期間最高可達到119μg/m3﹔平日PM2.5質量濃度常在個位數，沙塵期間最高可達到51μg/m3。花蓮平日TSP質量濃度在100μg/m3以下，沙塵期間最高可達到204μg/m3﹔PM10質量濃度平日在80μg/m3以下，沙塵期間最高可達到139μg/m3，可見大陸沙塵帶來甚多懸浮微粒。 在氣膠成分方面，陽明山在非沙塵期間PM10及PM2.5主要元素是S及K，在沙塵期間則可偵測到大量的Si、Ca、Al等塵土元素。水溶性離子不管在沙塵或非沙塵期間及PM10或PM2.5主要的離子為硫酸根離子、硝酸根離子、銨根離子，但在沙塵期間鈣離子濃度特別顯著。氣膠碳成分無論是PM10或PM2.5均以有機碳的含量較多，但在沙塵期間，PM10較 PM2.5元素碳顯著為高。 針對花蓮採樣的氣膠配合HYSPLIT氣流逆軌跡線 (Draxler, 1999)分析，顯示沙塵暴對於花蓮地區空氣品質的影響最為劇烈，其次為大氣擴散不良的天氣型態（如海陸風、高壓迴流、山脈背風面的弱風區等）也會導致微粒質量濃度的增高。 科學管理組評估在2002年1~5月間，按中尺度數值模擬應有11個大陸沙塵影響台灣空氣品質的案例，但只有2個案例為大陸沙塵影響顯著者，而出現PSI大於100的日期僅在：2月9日與11日。至於在沙塵侵台預報方面，2002年實驗期間共發出八次警報，其中出現一次漏報(4月9~11日)與一次誤報(4月12日~13日) ，成果屬良好，未來會改進到更好。

大陸沙塵暴、背景氣膠、氣膠質量濃度、氣膠成分、空氣品質管理

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[期末報告]公開完整版

2014/10/31 下午 02:07:46

The occurrence frequency and strength of Asian dust storm has been increased in recent years. Under the appropriate meteorological conditions, Asian dust storm could affect Ta iwan’s air quality significantly. This work collected PM10 and PM2.5 at Youngmin mountain for the analyses of mass and chemical compositions. In addition, TSP and PM10 were also collected at Hauwlain site for mass weighing. During the Asian dust (AD) perio ds, the TSP, PM10, and PM2.5 were acquired 41, 69, and 32 effective samples, respectively. In contrast, during non- Asian- dust (NAD) periods, the effective samples of TSP, PM10, and PM2.5 were 14, 25, and 12, respectively. In total, this work collected 193 effective aerosol samples. At Youngming mountain, the PM10 was normally at around 10μg/m3 during NAD periods; however, the PM10 reached as high as 119μg/m3 during AD periods. For PM2.5, the level was at single- digit number for NAD periods, and it could jump up high at 51μg/m3 for AD periods. The TSP was normally below 100μg/m3 at Hauwlian site, while a maximum value of 204μg/m3 was observed during AD periods. Similarly, the PM10 was normally below 80μg/m3 at Hauwlian site, it went up high at 139μg/m3 dur ing AD periods. Evidently, the AD brought a great amount of dusts to Taiwan. For aerosol chemical compositions, the major elements in PM10 and PM2.5 at Youngmin mountain were S and K during NAD periods. During AD periods, the Si, Ca, and Al were cont rasted to be significant. For water- soluble ions, the major ions were sulfate ion, nitrate ion, and ammonium ion both in PM10 and PM2.5 as well as in AD and NAD periods. However, calcium ion was significantly higher during AD periods. The organic carbon was in greater amount than elemental carbon both in PM10 and PM2.5. It was observed that the elemental carbon in PM10 was significantly higher than that in PM2.5 during AD periods. By using HYSPLIT backward air trajectory model (Draxler, 1999), we analyzed aerosol variations collected at Hauwlian site. The results showed that AD influenced the air quality of Hauwlian most significantly. It was followed by poor dispersion of air such as land- sea breeze, re-circulated high- pressure system, and the depression at the lee side of a mountain. The assessment from Science Team indicated that 11 AD events influenced Taiwan’s air quality judged from mesoscale numerical simulation from January to May in 2002. Among them, only two AD events affected Taiwan signific antly and the dates when PSI significantly greater than 100 were only on 9 February and 11 February 2002. For the assessment of AD forecast, a miss on 9 April and an error on 12 April for eight warnings issued in 2002. The results are reasonably good, and the aspect for future forecast is expected to be better.

Asia dust storm, background aerosol, aerosol mass concentration, aerosol chemical compositions, air quality management