Nonwetting soils

These characteristics of nonwetting soils are intimately related to the formation of soil organic matter (SOM) coatings, where they have been... 

Figure 2 AFM in tapping mode using siiicon tips showing the topography of (A) palmitic acid (0.22pg/cm2), (B) stigmasteroi (0.35 pg/cm ), and (C) equimolar mixture of palmitic acid and stigmasteroi mixture (0.11 pg PA+ 0.18pgST/cm ). Line analyses indicated the dimensions of the nanostructurai features formed on the respective surfaces. SOM concentration used is equivalent to the quantities assayed in the natural nonwetting soils.

The capillary imbibition behavior of packed bed columns with a range of model hydrophobic soil types prepared by using two routes to hydrophobicity is shown (1) trimethylchlorosilane and (2) model hydrophobic SOM consisting of either individual or equimolar mixture of palmitic acid (PA) and stigmasterol (ST) at quantities equivalent to that in natural nonwetting soils.With increasing proportion of hydrophobic particulate content in the packed bed column, the... 

The pore spaces in earthen materials may be occupied by gases, liquids, or both. For example, with respect to the liquid phase in a soil, a diy soil results when the pores are completely occupied by a gas, typically air (Fig. la), whereas a saturated soil results when the pores are completely filled with a liquid, typically water (Fig. lb). An unsaturated soil results when the pores comprise both a gas and a liquid (Fig. Ic). In the case of unsaturated soils containing both water and air (Fig. Ic), the water is the wetting fluid because the water is preferentially absorbed (i.e., relative to the air, the nonwetting fluid) to... 

The difficulty of quantifying the pore space geometry has been a principal obstacle in obtaining quantitative predictions of interfacial area. This paper presents a way to overcome this obstacle by means of a geometrically determinate porous medium that is physically representative of simple soils and sandstones. We demonstrate the approach for drainage, the displacement of a wetting fluid by a nonwetting fluid under the control of capillary forces. 

FIGURE 8.9 Hydraulic gradient necessary to initiate blob mobilization at for nonwetting NAPLs with various interfacial tensions, (gr cm/s ), in different soil types. (From Wilson, J. L. and S. H. Conrad. 1984. In Proceedings of the Nationcd Water Well Association Conference on Petroleum Hydrocarbons and Organic Chemicals in Groundwater, Houston, TX, Nov. 5-7, 1984, pp. 274—298. With permission.)... 

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