New chemical sensing technologies are critically important for addressing many of EM's priority needs as discussed. Many technology needs were addressed by this research. For example, improved detection strategies are needed for non-aqueous phase liquids (NAPL's), such as PCE (Cl2C=CCl2) and TCE (HClC=CCl2), which persist in the environment due their highly stable structures. By developing a miniature, ultra-sensitive, selective, and field-deployable detector for NAPL's, the approximate source location could be determined with minimal investigative expense. Contaminant plumes could also be characterized in detail. The miniature spectrometer developed under Project No. 60231 could also permit accurate rate measurements in less time, either in the field or the laboratory, which are critically important in the development, testing, and ultimate utilization of models for describing contaminant transport.