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Fig. 3. Nuclear magnetic resonance T2 time distributions can be used to distinguish DNAPL and water in subsurface soils. The figure shows four soil (sand) configurations with water and a dense nonaqueous phase liquid, trichloroethylene (TCE). In the case with water-wet sand pores filled with TCE (blue curve), one can see that the water component of the T2 distribution lies below 50 ms, whereas the TCE component lies above 50 ms. For comparison, measurements of the TCE-wet saturated sand (magenta) and the water-wet sand unsaturated (green) are shown. The peaks seen above 500 ms are due to components from bulk water and TCE fluids in voids in the soil packs.
