Remote Laser-Induced Fluorescence Monitoring of Groundwater Contaminants: Prototype Field Instrument

Direct, in situ monitoring of many groundwater contaminants is possible using the Remote Laser-Induced Fluorescence (RLIF) technique. We have designed, laboratory-tested, and field-tested a prototype mobile instrument capable of performing such monitoring. It consists of a portable, computer-controlled fluorimeter with a frequency-quadrupled Nd:YAG laser as a UV excitation source, detachable fiber optic sensor, and a detection module employing two photomultiplier tubes and a dual-channel boxcar averager for signal recovery. In this report, we give a complete description of the hardware and software utilized in the instrument, along with a summary of our field testing procedures and experiences, and an assessment of the technique's current and potential capabilities.