Remote detection of groundwater contaminants using far-ultraviolet laser-induced fluorescence

Abstract

Results are reported for a successful test of remote fluorescence analysis of groundwater contaminants by using UV lasers and fiber optics. Several priority pollutants (phenol, o-cresol, toluene, o-chlorophenol, p-nitrophenol, 2,4-dinitrophenol, and xylenes) as well as naturally occurring humic acid, at environmentally significant concentrations, were readily detected by using the technique. At an instrument/analyte distance of 25 m, which equals or exceeds the depth of many aquifers used as drinking-water supplies, individual compounds had detection limits at or below the parts per billion level. Phenolic and humic acid contaminants in actual landfill and barkpile leachates were easily detected at 25 m after 10,000-fold dilution. Practical problems in implementing a UV-laser-based system, such as efficient coupling, fiber damage threshold, scattered light, shape of response curve, etc., have been examined and simple solutions demonstrated. 16 references, 6 figures, 2 tables.