Groundwater in many US historical legacy sites is contaminated with dense non-aqueous phase liquids (DNAPLs), most of which are chlorinated hydrocarbons, such as trichloroethylene (TCE). Due to migration in the subsurface over time, it is practically impossible to completely remove these contaminants. In order to assess the status of the pollutants and to address public concern, technologies for long-term monitoring groundwater contaminants are needed. Current monitoring methods usually involve complex procedures such as installation of groundwater wells, sampling and shipping of the groundwater with efforts to protect sample integrity, and laboratory analysis using gas chromatography-mass spectrometry (EPA Method 8260). These methods are labor-intensive, thus expensive, and slow. Besides, because these procedures are delayed and performed at different locations, contaminants can escape, giving misleading site characterization. Therefore, it is desirable to have technologies that combine sampling and detection of the contaminants with high reliability and sensitivity.
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