Water-soil interaction and solute transport at a crude-oil spill site

摘要

We are investigating solute transport at the Bemidji, Minnesota crude-oil spill site. We measured time of travel using breakthrough curves for rhodamine WT and bromide tracers moving from the soil surface through oil-contaminated and oil-free unsaturated zones to the water table. Results indicated that the rate of solute transport Was greater in the oily zone compared to the oil-free area. Apparently, some change in "water-soil" interaction in the oil-contaminated zone has occurred that modified the solute transport characteristics. One explanation of this result is that because of soil hydrophobicity, water flows in "preferential" channels in the oily zone, bypassing most of the pore space, which results in reduced interaction with the soil, adsorption, and dispersion. Results may have important implications for modeling the fate and transport of dissolved contaminants at hydrocarbon spill sites.