Nature of the clay-cation bond affects soil structure as verified by X-ray computed tomography
Article
Article Title | Nature of the clay-cation bond affects soil structure as verified by X-ray computed tomography |
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ERA Journal ID | 5248 |
Article Category | Article |
Authors | Marchuk, Alla (Author), Rengasamy, Pichu (Author), McNeill, Ann (Author) and Kumar, Anupama (Author) |
Journal Title | Soil Research |
Journal Citation | 50 (8), pp. 638-644 |
Number of Pages | 7 |
Year | 2012 |
Publisher | CSIRO Publishing |
Place of Publication | Melbourne, Australia |
ISSN | 0004-9573 |
1446-568X | |
1838-675X | |
1838-6768 | |
Digital Object Identifier (DOI) | https://doi.org/10.1071/SR12276 |
Abstract | Non-destructive X-ray computed tomography (μCT) scanning was used to characterise changes in pore architecture as influenced by the proportion of cations (Na, K, Mg, or Ca) bonded to soil particles. These observed changes were correlated with measured saturated hydraulic conductivity, clay dispersion, and zeta potential, as well as cation ratio of structural stability (CROSS) and exchangeable cation ratio. Pore architectural parameters such as total porosity, closed porosity, and pore connectivity, as characterised from μCT scans, were influenced by the valence of the cation and the extent it dominated in the soil. Soils with a dominance of Ca or Mg exhibited a well-developed pore structure and pore interconnectedness, whereas in soil dominated by Na or K there were a large number of isolated pore clusters surrounded by solid matrix where the pores were filled with dispersed clay particles. Saturated hydraulic conductivities of cationic soils dominated by a single cation were dependent on the observed pore structural parameters, and were significantly correlated with active porosity (R2≤0.76) and pore connectivity (R2≤0.97). Hydraulic conductivity of cation-treated soils decreased in the order Ca>Mg>K>Na, while clay dispersion, as measured by turbidity and the negative charge of the dispersed clays from these soils, measured as zeta potential, decreased in the order Na>K>Mg>Ca. The results of the study confirm that structural changes during soil-water interaction depend on the ionicity of clay-cation bonding. All of the structural parameters studied were highly correlated with the ionicity indices of dominant cations. The degree of ionicity of an individual cation also explains the different effects caused by cations within a monovalent or divalent category. While sodium adsorption ratio as a measure of soil structural stability is only applicable to sodium-dominant soils, CROSS derived from the ionicity of clay-cation bonds is better suited to soils containing multiple cations in various proportions. |
Keywords | architectural parameters; cation ratio; clay dispersion; clay particles; exchangeable cation; ionicities; isolated pores; multiple cations; negative charge; non destructive; pore architecture; pore connectivity; pore structural parameters; saturated hydraulic conductivity; sodium adsorption ratio; soil particles; soil structural stability; soil-water interaction; solid matrixes; structural change; structural parameter; structural stabilities; total porosity; x-ray computed tomography |
ANZSRC Field of Research 2020 | 410604. Soil chemistry and soil carbon sequestration (excl. carbon sequestration science) |
410605. Soil physics | |
460306. Image processing | |
Public Notes | Files associated with this item cannot be displayed due to copyright restrictions. |
Byline Affiliations | University of Adelaide |
Commonwealth Scientific and Industrial Research Organisation (CSIRO), Australia | |
Institution of Origin | University of Southern Queensland |
https://research.usq.edu.au/item/q2968/nature-of-the-clay-cation-bond-affects-soil-structure-as-verified-by-x-ray-computed-tomography
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