大氣濕度及異常生成物對微粒手動採樣器準確度的影響

Abstract

我國環保署最近通過了 PM2.5 空氣品質標準的修正草案，以確保國民健康。環保署 的空品測站使用貝他計或錐狀元件振盪天秤測量PM2.5 小時濃度值，然而本研究團隊在 測站的比對結果發現，因大氣濕度及微粒負荷於PM2.5 進口的衝擊板上造成了自動監測 的濃度值比手動採樣的值高估許多，其中手動採樣的問題也包括進口分徑器造成的質量 濃度誤差，以及大氣濕度、濾紙壓損及濾紙調理過程造成的質量濃度誤差，及無機盬類 及有機碳(OC)/元素碳(EC)異常生成物。為了充份了解並解決手動採樣誤差的問題，本計 畫擬利用三年的時間，將一個本研究團隊自行開發的多濾紙PM10-PM2.5 採樣器加以改裝 並加上進口的濕度調節，以連接不同的檢測儀器，針對細微粒或奈米微粒的質量、無機 盬類及OC/EC 同時進行手動採樣和即時監測，以探討上述的問題。手動分析項目包括 濾紙秤重、水溶性離子的IC 化學分析及OC/EC 的TOR 分析，質量濃度的即時監測使 用FDMS 氣膠質量濃度連續分析儀，無機氣體及氣膠的監測使用本研究團隊自行研發的 平行平板溼式固氣分離器或溼式靜電集塵器和IC 的串聯系統，OC/EC 的監測則使用氣 膠碳成分連續監測儀。預期本計畫完成之後可釐清手動採樣器的質量及成份的誤差，並 提升細微粒及奈米微粒檢測結果的正確性。

To better protection of public health, recently the Taiwan Environmental Protection Agency (EPA) promulgated the revised PM2.5 air quality draft standard. The beta gauge or taper element oscillating mass monitors are used in the EPA's air monitoring stations for measuring hourly PM2.5 concentrations. However, the recent comparison study at the air monitoring stations conducted by our research team found that the PM2.5 concentration of the real-time monitors exceeded those of manual samplers by a large extent due to the influence of the ambient relative humidity and the particle loading of the sampling inlets. In addition, the manual sampling problems include the errors of mass concentrations due to the sampling inlets, the effects of the ambient relative humidity, the pressure drop across the filter and filter conditioning procedure on the mass concentration errors and the artifact formation of inorganic soluble ions and organic carbon (OC)/elemental carbon (EC). This 3-year project is proposed to understand and resolve these sampling errors by using a multi-filter PM10-PM2.5 sampler designed by our research team, which will be modified for connecting to different detection instruments to enable the simultaneous manual sampling and real-time monitoring of fine and ultrafine particles. The analysis after manual sampling includes gravimetric analysis, IC analysis of water-soluble ions and Thermo-Optical Reflection (TOR) analysis of OC/EC. For real-time monitoring, a filter dynamic measurement system (FDMS) will be used to monitor the mass concentration, a parallel plate wet denuder (PPWD) or a wet electrostatic precipitator (WetESP) connected with an IC (PPWD or WetESP+IC) designed by our research team will be used to monitor the inorganic gases or aerosols, respectively, and the SunSet Laboratory OCEC Analyzer will be used to monitor the OC/EC. It is expected that the errors of mass and chemical species will be clarified after the completion of this project and the sampling and monitoring accuracy of fine and nanoparticles will be much better improved.