Dense non-aqueous phase liquid contaminant detection using optimized fluorescence methods

Contamination from the use of chlorinated solvent dense non-aqueous phase liquid (DNAPL) contaminants continues to be one of the most pressing environmental problems. Many of these compounds are toxic, volatile, mutagenic, teratogenic, fat soluble, and relatively soluble in water. Remediation of sites contaminated by DNAPLs is an environmental challenge with global implications. This project is directed towards detecting DNAPL contaminants in ground water using an innovative fluorescence-based approach.; The new fluorescence detection approach incorporates spectral observations related to optimal detection parameters for commingled fluorophores (petroleum-derived and naturally occurring polyaromatic compounds) in order to locate DNAPL source areas with the greatest achievable sensitivity. Ultimately, these optimization results can be incorporated into a continuous profiling in-situ cone penetrometer sensor deployment platform, thereby allowing for data coupling to important hydrogeological parameters that control contaminant transport (e.g., soil type, direction and gradient of ground water flow, etc.). The coupled data can be transferred to multiphase flow models to generate probable realizations of contaminant distribution and potential migration pathways. These realizations can be used to design treatment systems that focus remediation efforts directly on the specific locations deemed to be appropriate for ultimate aquifer and soil restoration.; The primary objective is to evaluate the theory that DNAPL source zones can be identified and mapped using fluorescence techniques. A second objective is to develop fluorescence excitation/emission matrices (EEMs) for a wide range of organic pollutants, including chlorinated DNAPL solvents mixed with fuels, oils, lubricants, naturally occurring organic materials, and several soil types. Optimal sensor parameter settings for achieving the greatest detection capabilities will be identified using details observed in the EEMs. This information will be used to establish design criteria for new DNAPL site characterization cone penetrometer probe systems. Successful implementation will lead to improved detection capabilities and remediation cost reduction through generation of highly resolved conceptual models of contaminant and soil type distribution. Results indicate that DNAPL can be located using fluorescence methods, these approaches can be optimized by using the appropriate excitation source wavelength, and that a multi-wavelength fluorescence probe will be as a significant enhancement to the current commercially available systems.