2024-03-29T08:07:10Zhttps://eprints.lib.hokudai.ac.jp/dspace-oai/requestoai:eprints.lib.hokudai.ac.jp:2115/707252023-08-21T04:20:45Zhdl_2115_20046hdl_2115_138Saturated hydraulic conductivity of a volcanic ash soil affected by repulsive potential energy in a multivalent anionic system1000000294439Ishiguro, MunehideNakaishi, KatsuyaNakajima, Tomoopen accessCopyright © 2003 Elsevier B.V. All rights reserved.,© 2003. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 InternationalHydraulic conductivityVolcanic ash soilRepulsive potential energyDispersionFlocculation519Introduction:Acid rain has been a serious problem around the world. The adverse effects of acid rain on soils must be assessed. Because soils have pH-dependent charges, the solution pH affects saturated hydraulic conductivity (K) [1–7]. A volcanic ash soil whose predominant clay minerals are allophane and imogolite contains a substantial pH-dependent charge [8–10]. Its K decreases when a higher- or lower-pH solution percolates [3–6]. When dilute nitrate percolates in the soil, K decreases due to the swelling and dispersion of the soil. On the other hand, when dilute sulfate percolates, K does not decrease; under this condition, the soil neither disperses nor swells [6].Although K is supposed to decrease in response to an increase in electric repulsive force among soil particles, the relationship between K and repulsive potential energy has not been evaluated. The relationship between rheological properties and the potential energy of the interaction between sodium montmorillonite particles was discussed [11]. A numerical solution of the equation for swelling pressure in mixed systems with nonsymmetrical electrolytes was proposed [12]. However, research into repulsive potential energy in multivalent counterion systems has been rare.In this paper, repulsive potential energies for a volcanic ash soil (allophanic Andisol), which is characterized by a number of pH-dependent charges, were evaluated in an NO3–SO4 system at pH’s 3 and 4. In order to determine the mechanism of the change in K of the soil during dilute acid leaching, the relationship between K and the repulsive potential energies was evaluated. Because the acidity in rain is caused mainly by HNO3 and H2SO4, mixed dilute solutions of these acids were used in the experiment.Elsevier2003-12-10engjournal articleAMhttp://hdl.handle.net/2115/70725https://doi.org/10.1016/j.colsurfa.2003.09.0130927-7757Colloids and Surfaces A: Physicochemical and Engineering Aspects2301-38188https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/70725/3/Saturated%20hydraulic%20condutivity.pdfapplication/pdf295.42 KB2003-12-10