Three-dimensional self-potential inversion for subsurface DNAPL contaminant detection at the Savannah River Site, South Carolina

摘要: [1] Self-potential (SP) data are collected over an area of approximately 250 m2 at the Department Energy Savannah River Site where there is known subsurface dense nonaqueous phase liquid (DNAPL) contamination. Nonpolarizing electrodes used to measure SP signal on a two-dimensional (2-D) surface grid with 2-m spacing in both horizontal directions, and four borehole arrays 3.7-m electrode 25.6-m total depth. The primary contaminants, tetrachloroethylene (PCE) trichloroethylene (TCE), undergo redox reactions environment. Variations conditions proposed as electrochemical source for signals measured this investigation. A 3-D self-potential inversion algorithm find electrical current model, taking into account resistivity structure derived from spectral induced polarization survey same field location. sources sinks can be related zones relative high or low potential therefore interpreted context contaminated areas. These results reasonably correlated DNAPL concentration obtained several ground-truth well measurements, indicating that indicator areas mechanisms active. In cases, however, contaminant concentrations not correlated, reflecting spatial variability biogeochemical parameters Earth control response addition concentration. More extensive geochemical information needed validate methodology develop it predictive tool sites.