USE OF LASER INDUCED FLUORESCENCE TO DETECT DNAPL AND FLUOROPHORE MIXTURES IN-SITU

摘要

We present results from laboratory investigations on the fluorescence of Dense Non-rnAqueous Phase Liquids (DNAPL) and fluorophore mixtures, characterized using arnLuminescence Spectrometer. Fluorophores such as aromatic compounds (e.g.rnbenzene, toluene, ethylbenzene and xylenes, as well as other constituents ofrnpetroleum fuels, oils, lubricants and greases) are present as co-contaminants inrnmany DNAPL spills. Concentration as low as 5% of fluorophore in the DNAPL solventrnare easily detectable. Using the difference in characteristic fluorescence wavelengthsrnfor the various fluorophores, we are able to distinguish between naturally occurringrnfluorophores in the DNAPL solvent and introduced fluorophores. Field investigationsrnusing a Laser Induced Fluorescence (LIF) probe at several sites corroborate ourrnlaboratory results. Results to date indicate that the LIF probe will be applicable onlyrnfor a qualitative assessment of DNAPL saturation, but may be useful in combinationrnwith other probes in the cone penetrometer for DNAPL source delineation.