多頻道PM10-PM2.5採樣器的研發

Abstract

國內學者常使用之懸浮微粒採樣器大部分僅能採集一個PM10濾紙樣本或PM2.5濾紙樣本，且其流量控制易受環境溫度及壓力的影響，容易造成採樣過程的誤差。本研究設計一台具有高效率、低成本及容易操作之新式多頻道懸浮微粒採樣器，能同時收集四個PM10濾紙以及四個PM2.5濾紙樣本，並搭配主動式流量控制系統，以便能得到正確的大氣微粒濃度。 本研究將於實驗室與現場進行採樣器的校正與性能測試，首先在實驗室進行採樣器頻道間的流量均勻度與濾紙均勻度測試、採樣器液體微粒收集效率的校正。經由PM10與 PM2.5採樣器對液體微粒的測試結果發現，50 %微粒收集效率之截取氣動直徑值分別為9.8 μm和2.5 μm；固體微粒的測試結果也發現，50 %微粒收集效率之截取氣動直徑值分別為10.2 μm和2.5 μm，且以直徑25mm和8 mm玻璃纖維濾紙分別塗敷0.234 ml和0.024 ml的Dow Corning 704 diffusion pump oil作為PM10及PM2.5衝擊器的衝擊板，可以有效的降低固體微粒彈跳問題，使得固體微粒和液體微粒的收集效率曲線相當一致。本研究之多頻道PM10-PM2.5採樣器與雙道採樣器(Dichotomous Sampler, SA 241, Thermo Andersen, Smyrna, GA, USA) 在低濃度與高濃度懸浮微粒現場濃度測試比對結果顯示，本多頻道PM10-PM2.5採樣器可以同時有效均勻的採集四片PM10與PM2.5樣本且採集到微粒濃度值與雙道採樣器之結果相當吻合，因此每片濾紙樣本皆可以真實有效呈現採樣地點的PM10與PM2.5濃度情況，有利於濾紙樣本進行後續的化學分析，且有效降低大氣採樣成本。

The most frequently used samplers can only collect one kind of PM10 or PM2.5 and sampling bias often occurs due to the uncertainty of flow rate changed with ambient air and temperature. This study aimed at designing and calibrating a novel PM10-PM2.5 sampler for collecting of four pieces of PM10 and PM2.5 simultaneously with active flow rate control system for atmospheric sampling. Laboratory calibration shows that the liquid particle cut-off diameter is 9.8 and 2.5 □m for PM10 and PM2.5 sampler, respectively. Solid particle bounce can be avoided by using 0.234 and 0.024ml Dow Corning 704 diffusion pump oil-immersed glass fiber filters for PM10 and PM2.5 impactor substrate, respectively, together with 10.2 and 2.5□m cut-off. The liquid particles collection efficiency curve is identical to that of solid particles. Field comparisons also show that multi-channel PM10-PM2.5 sampler was similar to Dichotomous Sampler in measuring of PM10 and PM2.5. Meanwhile, particles are all deposited uniformity on the four pieces of collecting filters for PM10 and PM2.5 sampler, respectively. It is expected that the multi-channel PM10-PM2.5 sampler was structured to obtain a complete material balance for sequential chemical analysis procedures in collecting of PM10 and PM2.5.