國內土壤及地下水的污染問題相當嚴重而且普遍。污染地下水的有機物，又稱NAPL（Non Aqueous Phase Liquid，非水相液體），為土壤及地下水污染主要來源之一。土壤及地下水有機化合物污染監測不易，採樣時需設置監測井採集地下水樣，過程耗力、費時且成本高。所以國外已發展可即時(real-time)、現地(in-situ)的新興監測技術，但國外儀器昂貴、維修不易且不適合台灣水文地質狀況。因此需要發展適合台灣水文地質狀況的即時、現地的調查監測技術，稱為薄膜擴散採樣器(Membrane Diffusion Sampling，MDS)。MDS主要分為採樣模組與分析模組兩大部分，採樣模組利用高分子薄膜當作透氣不透水的門戶，收集NAPL蒸氣相後由攜帶氣體帶到地表給分析模組，分析模組可得到水中污染物的種類與濃度。本研究著重於採樣模組的部分，目的為製造採樣模組雛型機並由砂箱實驗與數學模式建立採樣室中NAPL蒸氣相濃度與砂箱內水溶液濃度間的轉換關係。實驗結果證明採樣模組確實可在砂箱內採集NAPL蒸氣相；發展的數學理論能與實驗數據匹配良好，並瞭解苯、甲苯、乙苯與二甲苯的蒸氣相濃度與其水溶液濃度間的關係。 The contamination problem in Taiwan’s soil and groundwater is very serious and prevalent. The organic compound of pollution groundwater is called NPAL (Non Aqueous Phase Liquid) and it is the main source in soil and groundwater contamination problem. The organic compound in soil and groundwater is hard to monitor and sampler needs to setup up monitoring equipment well. The whole process is complex, time-consuming and costly. Actually, the new monitoring technique which can receive real-time and in-situ is developed in the foreign countries. But the instrument is expensive, hard to repair and does not fit the hydrogeology in Taiwan. So we need to develop the monitoring technique which is suitable for Taiwan’s hydrogeology and can receive real-time and in-situ. The technique is called Membrane Diffusion Sampler, MDS. The MDS is based on two parts, sampling system and analytic system. Sampling system uses the membrane to be a window—preventing liquid from passing through while allowing vapors to diffuse through. When the sampling system collects the NAPL vapors, the carry gas will transfer it to the surface analytic system. The analytic system will analyze the concentration and the type of organic compound in water. The research focuses on making sampling system. The purpose of this study is to make experiment and develop mathematical model to find the relationship between NAPL vapor phase concentration and liquid phase concentration. The experiment results confirm that sampling system can sample NAPL vapor phase and the mathematical model fits well with the laboratory data. So we realize the benzene, toluene, ethybenzene, and xylene’s relationship in NAPL vapor phase concentration and liquid phase concentration, and we get these organic compounds’ diffusion coefficient in membrane.
