[1] Interfacial areas between an immiscible organic liquid (NAPL), and water were measured for two natural porous media using two methods, aqueous-phase interfacial partitioning tracer tests and synchrotron X-ray microtomography. The interfacial areas measured with the tracer tests were similar to previously reported values obtained with the method. The values were, however, significantly larger than those obtained from microtomography. Analysis of microtomography data collected before and after introduction of the interfacial tracer solution indicated that the surfactant tracer had minimal impact on fluid-phase configuration and interfacial areas under conditions associated with typical laboratory application. The disparity between the tracer test and microtomography values is attributed primarily to the inability of the microtomography method to resolve interfacial area associated with microscopic surface heterogeneity. This hypothesis is consistent with results recently reported for a comparison of microtomographic analysis and interfacial tracer tests conducted for an air-water system. The tracer test method provides a measure of effective, total (capillary and film) interfacial area, whereas microtomography can be used to determine separately both capillary-associated and film-associated interfacial areas. Both methods appear to provide useful information for given applications. A key to their effective use is recognizing the specific nature of the information provided by each, as well as associated limitations.

Interfacial areas between an organic immiscible liquid and water were measured for two natural soils using the aqueous-phase interfacial partitioning tracer test method. The measured values were compared to measured values for silica sands compiled from the literature. The data were compared using the maximum specific interfacial area as a system index, which is useful for cases wherein fluid saturations differ. The maximum specific interfacial areas measured for the soils were significantly larger than the values obtained for the sands. The disparity between the values was attributed to the impact of surface roughness on solid surface area and hence film-associated interfacial area. A good correlation was observed between maximum specific interfacial area and specific solid surface area measured with the N2/BET method. The correlation may serve as a means by which to estimate maximum specific organic-liquid/water interfacial areas. Interfacial areas measured with the interfacial partitioning tracer method were compared to interfacial areas measured with high-resolution microtomography. Values measured with the former method were consistently larger than those measured with the latter, consistent with the general inability of the microtomography method to characterize roughness-associated surface area.

The effectiveness of permanganate for in situ chemical oxidation of organic liquid (trichloroethene) trapped in lower-permeability (K) zones located within a higher-permeability matrix was examined in a series of flow-cell experiments. The permanganate solution was applied in both continuous and pulsed-injection modes. Manganese-oxide precipitation, as confirmed by use of SEM-EDS, occurred within, adjacent to, and downgradient of the lower-K zones, reflective of trichloroethene oxidation. During flow interruptions, precipitate formed within the surrounding higher-permeability matrix, indicating diffusive flux of aqueous-phase trichloroethene from the lower-K zones. The impact of permanganate treatment on mass flux behavior was examined by conducting water floods after permanganate injection. The results were compared to those of water-flood control experiments. The amount of water flushing required for complete contaminant mass removal was reduced for all permanganate treatments for which complete removal was characterized. However, the nature of the mass-flux-reduction/mass-removal relationship observed during water flooding varied as a function of the specific permanganate treatment.