Soil Science Society of America Journal
Li, SongLi, HangXu, Chen-YangHuang, Xue-RuXie, De-TiNi, Jiu-Pai
Soil particle transport causes serious environmental problems, and particle interaction forces will be the controlling force for soil transport during rainfall. However, few reports can be found in literature concerning the quantitative evaluation of particle interaction forces on soil particle transport. In this study, purple soil was adopted to study soil particle transport under different force strength conditions of particle interaction during rainfall simulation with precipitation intensity of 150 mm h(-1) for 110 min. We first analyzed soil particle interaction forces quantitatively under different KNO3 and Ca(NO3) (2) concentrations (0.0001, 0.001, 0.005, 0.01, 0.05, 0.1, and 1 mol L-1) which adjusted surface potential of soil particle from -323 to -50 mV. The results indicated that the net Derjaguin-Landau-Verwey-Overbeek (DLVO) force could not solely cause soil particle transport during rainfall. The hydration repulsive force, which was much stronger than the DLVO force, played a crucial role in soil particle transport. During rainfall, soil particle in aggregate was separated to a distance of 1.5 to 2 nm by the strong hydration repulsive force (swelling process). Then aggregate was thoroughly broken by the electrostatic repulsive force. The hydration repulsive force dominated aggregate swelling, and the electrostatic force determined the transport intensity. We found that, at surface potentials lower than -100 mV, soil transport did not occur even precipitation intensity reaching 150 mm h-1; and -200 mV of surface potential was the critical potential for soil particle transport. We conclude that the surface hydration force and electrostatic repulsive force were the controlling force for soil particle transport during rainfall.
