DISPLACEMENT OF SOIL PORE-WATER BY TRICHLOROETHYLENE

Dense nonaqueous phase liquids (DNAPLS) are important pollutants becau se of their widespread use as chemical and industrial solvents. An exa mple of the pollution caused by the discharge of DNAPLs is found at th e Picatinny Arsenal, New Jersey, where trichloroethylene (TCE) has bee n discharged directly into the unsaturated zone. This discharge has re sulted in the formation of a plume of TCE-contaminated water in the aq uifer downgradient of the discharge. A zone of dark-colored groundwate r containing a high dissolved organic C content has been found near th e point of discharge of the TCE. The colored-water plume extends from the point of discharge at least 30 m (100 feet) downgradient. Fulvic a cids isolated from the colored-waters plume, from water from a backgro und well that has not been affected by the discharge of chlorinated so lvents, and from soil pore water collected in a lysimeter installed at an uncontaminated site upgradient of the study area have been compare d. Nuclear magnetic resonance spectra of the fulvic acids from the col ored waters and from the lysimeter are very similar, but are markedly- different from the nuclear magnetic resonance spectrum of the fulvic a cid from the background well. The three-dimensional fluorescence spect rum and the DOC fractionation profile of the colored groundwater and t he soil pore water are very similar to each other, but quite different from those of the background water. It is proposed from these observa tions that this colored water is soil pore water that has been displac ed by a separate DNAPL liquid phase downward to the saturated zone.