Effect of water entrapment by a hydrogel on the microstructural stability of artificial soils with various clay content
Effect of water entrapment by a hydrogel on the microstructural stability of artificial soils with various clay content
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DOI：
10.1007/s11104-016-3110-z
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发表时间：
2017-05
期刊：
影响因子：
4.9
通讯作者：
C. Buchmann;G. Schaumann
中科院分区：
文献类型：
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作者：
C. Buchmann;G. Schaumann
背景和目的土壤成分之间的相互作用决定了土壤微观结构的稳定性，并由可膨胀的有机物质(水凝胶)增强，如胞外聚合物(EPS)、根部粘液或合成聚合物。这项研究的目的是确定水凝胶诱导土壤微结构稳定性背后的大部分仍不清楚的机制。我们假设土壤的微观结构稳定性随着土壤颗粒间水凝胶膨胀极限的增加而增加。方法对未处理和聚丙烯酸(PAA)处理的人工土壤在不同粘粒含量和PAA浓度下进行一维和二维1H-核磁共振弛豫(1H-核磁共振弛豫法)测量。结果PAA处理可显著提高土壤微结构稳定性，提高土壤微结构稳定性达5倍以上，尤其是在高粘粒含量时。在PAA处理的人工土壤中，土壤的微结构稳定性随着水的旋转迁移率的降低而增加。在PAA浓度最高的两种浓度下，微结构的稳定性最高，但水分子的迁移率没有受到进一步的限制。结论在人工土壤中，矿物颗粒之间的水凝胶结构的粘度以及聚合物-粘土相互作用形成的额外的外部网络，如多价阳离子桥联，似乎促进了微结构的稳定性。
Background and aimsInteractions between soil constituents define soil microstructural stability and are enhanced by swellable organic substances (hydrogels) such as extracellular polymeric substances (EPS), root mucilage or synthetic polymers. This study aims to identify the still largely unknown mechanisms behind hydrogel-induced soil microstructural stability. We hypothesized that soil microstructural stability increased with increasing limitation of hydrogel swelling between soil particles.MethodsOne- and two-dimensional1H proton nuclear magnetic resonance relaxometry (1H–NMR relaxometry) measurements were performed with untreated and polyacrylic-acid (PAA) treated artificial soils at various clay content and PAA concentrations. The results on the water distribution and water mobility in the artificial soils were related to their microstructural stability as measured by rheology.ResultsPAA treatment significantly increased soil microstructural stability up to five times, especially at high clay content. Soil microstructural stability increased with decreasing rotational mobility of water in the PAA-treated artificial. At the two highest PAA concentrations, the microstructural stability was the highest, although the mobility of water molecules was not further restricted.ConclusionIn artificial soils, the viscosity of hydrogel structures between mineral particles and the additional formation of an external network by polymer-clay interactions such as polyvalent cation bridging seem to promote microstructural stability.