Soil permeability as affected by repulsive potential energy

摘要

The repulsive potential of soil affects its pore structure and consequently water permeability. This is evident in Allophanic Andisols, which have a significant pH-dependent charge. Therefore, at low and high pH, soil dispersion and swelling occur easily due to electric repulsive force. The permeability of the soil then decreases because of structural changes that occur when dilute monovalent acid or alkaline solution is percolated in the soil. However, soil permeabihty does not decrease, rather increases, when dilute H_2SO_4 is percolated in the soil. This is because SO_4~(2-) strongly adsorbs on the soil surface at low pH and the soil remains flocculated. The difference of permeability is explained by the calculated repulsive potential energy based on zeta potential. Permeability of a high humic soil with only negative charge decreases when an anionic surfactant solution is percolated. The surfactant is adsorbed in the soil by hydrophobic interaction. The repulsive potential energy increases andthe permeability decreases due to the increase of negative charge.