DIRECT-PUSH, FLUORESCENCE-BASED SENSOR SYSTEMS FOR IN-SITU MEASUREMENT OF PETROLEUM-HYDROCARBONS IN SOILS

By coupling fluorescence-based spectroscopic methods with a probe that can be pushed into the ground to depths of 50 m, it is now possible t o make realtime, in situ measurements of chemical contaminants in subs urface environments. Because this optical technique makes use of a las er, or other light source, to induce an optical response in the target analyte, analysis times are extremely fast, usually on the order of s econds. With this technology it is possible to make measurements nearl y continuously as the probe is pushed into the ground. The capability for real-time, high-spatial-resolution chemical measurement in the sub surface represents a significant improvement over traditional methods that have been used to delineate subsurface contamination. In this art icle the status of direct-push, fluorescence-based sensor systems that have been developed for the detection of petroleum hydrocarbon contam ination in soils is reviewed. An overview of the common elements of th e sensing scheme is provided. Important differences in the configurati on of various systems developed to date are summarized. Finally, the e ffect of key variables on overall system capability is discussed and t he status of the acceptance of this technology by the regulatory commu nity is addressed. (C) 1998 John Wiley & Sons, Inc.