EPA-104-1602-02-08

104

2,642 千元

2015/03/19

2015/12/31

蔡春進

環檢所

李世偉

國立交通大學(環境工程研究所)

大氣空氣、環境監測及檢測

氣膠化學成分分析儀、奈米微粒數目及粒徑分佈量測、奈米PM2.5空氣動力鏡

aerosol chemical speciation monitor, number concentration and size distribution of nanoparticles, PM2.5 aerodynamic lens

林思帆

03-5712121#55511

sihfanlin@gmail.com

本計畫使用氣膠化學成分分析儀(Aerosol chemical speciation monitor, ACSM)量測台灣北部都會區(竹東及新莊測站與交大校園)細懸浮微粒的化學組成，並使用SMPS同步監測微粒數目濃度，利用測得之數據推估微粒有效密度。在ACSM監測大氣微粒化學組成的部分，CMB法分析竹東測站、新莊測站及交大校園有機氣膠組成得知竹東測站與交大校園受光化反應影響，有機氣膠主要為二次有機氣膠(SOA)，在竹東測站及交大校園SOA在總有機氣膠中的比例為62.2 ± 16.3 及65 ± 19.3%; 新莊測站受交通排放影響較明顯，一次有機氣膠(POA)為總有機氣膠的主要成分，比例高達61 ± 2.54%。以CMB法與PPPMF法分析竹東測站、新莊測站及交通大學之有機物組成可發現，PPPMF法獲得之總有機物質量濃度較實際測得之有機物低，三個測點分別低估了19%、14%及13%，而CMB法分析獲得之結果與實測值幾乎相同，顯示CMB法優於PPPMF法。在總有機氣膠與有機碳的轉換係數部分，竹東測站、新莊測站及交大校園的OM/OC係數分別為1.63 ± 0.76、1.93 ± 1.84及1.61 ± 0.79。在奈米微粒數目濃度量測的部分，竹東測站奈米微粒數目濃度平均值為(1.0 ± 0.6)×104 #/cm3，微粒數目濃度與O3具相關性(R2 = 0.71)；新莊測站平均為(1.1 ± 0.6) ×104 #/cm3，微粒數目濃度與NOx及CO相關，R2值均在0.78以上；交大校園平均為(1.09 ± 0.59) ×104 #/cm3，微粒數目濃度與NOx及CO具高相關性，R2值均大於0.84。竹東測站大氣奈米微粒主要由光化反應所貢獻，新莊測站及交大校園大氣奈米微粒以交通排放為主要貢獻來源。SMPS與NanoScan SMPS的比對結果顯示，對粒徑(dm)小於400 nm的微粒，NanoScan SMPS與SMPS具良好的相關性(R2 = 0.99)。微粒有效密度推估的部分，竹東測站、新莊測站及交大校園的微粒有效密度分別為2.45、1.49及2.17 g/cm3。 因為本計畫初期PM2.5空氣動力鏡尚未製作完成，在竹東測站只能使用裝有PM1空氣動力鏡的ACSM，以ACSM的PM1微粒各化學成分與PILS所量測之PM2.5水溶性無機離子(NH4+、Cl-、NO3-及SO42-)進行比對，評估ACSM量測微粒化學成分的正確性。結果顯示兩種儀器的相關性不理想，可能是因為: 1. 竹東測站使用的PM1空氣動力鏡只適用於1 μm以下，若是因長程傳輸使二次無機氣膠長得較大而使得有一部份質量濃度分佈在1 μm以上時，ACSM將會低估濃度。2. 竹東地區的日平均NO3-濃度低於1μg m-3，比一般的文獻值低。為了改進ACSM與PILS比對結果，本研究後期於新莊測站及交大校園將ACSM內部PM1空氣動力鏡更換成PM2.5空氣動力鏡，ACSM測值與PILS所量測之PM2.5水溶性無機離子(NH4+、Cl-、NO3-及SO42-)比對結果顯示兩種儀器的相關性明顯提高，其中NH4+及SO42-濃度較高，誤差較小，R2大約介在0.78-0.81間，但Cl-濃度較低，儀器跳動性較大，兩者儀器間相關性較差。 竹東測站3-6月份PM2.5濃度為16.08 ± 12.09 μg m-3，水溶性無機鹽所占PM2.5比例約為55.95 ± 16.39%；新莊測站8-9月份常受到颱風影響，且採樣時期為夏季天氣型態，夏季多有午後雷陣雨，且因對流旺盛，微粒容易擴散，故PM2.5濃度較低，PM2.5濃度在該時期為13.05 ± 10.51 μg m-3，SIA所占PM2.5比例約為45.36 ± 29.74%，SOA所占PM2.5比例約為16.79 ± 13.48%，POA所占PM2.5比例約為27.26 ± 38.79%；交大校園採樣期間為10-11月份，主要吹東北風，天氣為偏涼型態，其餘時間溫度較為溫暖。由於天氣型態漸漸轉為秋季，大氣擴散較差，且在採樣期間台灣西部及沿海地區受到霾污染，因此空氣品質較差，PM2.5濃度在該時期為29.04±17.72 μg m-3，SIA所占PM2.5比例約為51.80 ± 27.66%，SOA所占PM2.5比例約為10.62 ± 4.36%，POA所占PM2.5比例約為6.26 ± 5.28%。

氣膠化學成分分析儀、奈米微粒數目及粒徑分佈量測、奈米PM2.5空氣動力鏡

EPA10416020208.pdf

21MB

2016/2/1 上午 12:00:00

In this project, chemical components and number concentration of PM2.5 were measured by Aerosol Chemical Speciation Monitor (ACSM) and SMPS in Northern Taiwan (Judong, Sinjhung and NCTU campus). The CMB results showed that SOA was the main component of organic aerosols in Judong and NCTU campus due to photochemical reaction, which accounted for 62.2 ± 16.3 and 65 ± 19.3% of total organic aerosols, respectively. In contrast, POA was the main component of organic aerosols in Sinjhung due to traffic emission, which accounted for 61 ± 2.54% of total organic aerosols. The PPPMF results underestimated the total organic aerosols at the three sites mentioned above by 19%, 14% and 13%, while the results analyzed by CMB showed almost no difference between measured values, suggesting that CMB is more accurate comparing to PPPMF. The conversion factors of OC to OM in Judong、Sinjhung and NCTU campus were 1.63 ± 0.76, 1.93 ± 1.84 and 1.61 ± 0.79, respectively. The average number concentration measured were (1.0 ± 0.6)×104 #/cm3 in Judong, having high correlation with O3 (R2 = 0.71), (1.1 ± 0.6) ×104 #/cm3 in Sinjhung, having high correlation with NOx and CO (both R2 = 0.78), and (1.09 ± 0.59) ×104 #/cm3 in NCTU campus , having high correlation with NOx and CO (both R2 = 0.84). The results measured by NanoScan SMPS matched well with those measured by SMPS for particle diameter (dm) smaller than 400nm with R2 of 0.99. Base on the number concentrations and chemical components measured above, the effective density in Judong、Sinjhung and NCTU campus sites were 2.45, 1.49 and 2.17 g/cm3, respectively. In this study, the applicability of the ACSM for the real time atmospheric chemical composition measurement was investigated. In the beginning at Judong air monitoring station, agreement between soluble inorganic ions of aerosol chemical speciation monitor (ACSM), which used PM1 aerodynamic lens, and Particle into Liquid Sampler (PILS) was poor. There are two possible reasons. One reason is that only PM1 aerodynamic lens was available at Judong station which only detected particles less than 1 μm resulting in understimation of PM2.5 mass concentrations. The other reason is due to very low nitrate concentration, which was typically less than 1 μg m-3 at Judong station, while monodipsere nitrate particles of 300 nm was used to calibrate the ACSM. To overcome these shortcomings, a new PM2.5 lens was acquired to replace the PM2.5 lens of the ACSM at both Sinjhung station and National Chiao Tung University (NCTU) campus for conducting the comparsion test. Results showed that coefficients of determination (R2) were much better and that the NH4+and SO42- in PM2.5 measured by the ACSM were in good agreement with those measured by the PILS with R2 > 0.78. In Sinjhung station, the study period was in summer. PM2.5 average concentration was 13.05±10.51 μg m-3, secondary inorganic aerosol (SIA) accounted for 45.36± 29.74%, secondary organic aerosol (SOA) accounted for 16.79± 13.48%, while primary organic aerosol (POA) accounted for 27.26 ± 38.79% in Sinjhung station. At NCTU campus, study period was in fall. PM2.5 average concentration was 29.04±17.72 μg m-3, SIA accounted for 51.80±27.66%, SOA accounted for 10.62±4.36%, while POA accounted for 6.26±5.28% at NCTU campus.

aerosol chemical speciation monitor, number concentration and size distribution of nanoparticles, PM2.5 aerodynamic lens