Relationship between dielectric permittivity and water content for vadose zone materials of volcanic origin
Relationship between dielectric permittivity and water content for vadose zone materials of volcanic origin
复制标题
火山源包气带材料的介电常数与含水量之间的关系
作者：
R. Stenger;T. Wöhling;G. Barkle;A. Wall
在实验室研究中研究了七种材料，包括年轻的火山土壤、其母质、两种较古老的埋藏土壤（古土壤）以及下面的较古老的火山存款，以确定介电常数（ε c）和含水量（θ）之间的关系。经验三阶多项式模型一般拟合数据优于半物理三相混合模型和归一化转换函数。基于它们不同的介电响应，这可能主要是由于它们不同的体积密度（从而孔隙度），材料可以分为凝灰岩材料和古土壤材料。古土壤相对于古寒武纪凝灰岩，表现出一个特别柔和的响应在低端的介电常数测量，这可能是由于一个特别高的量的结合水在这些富含脲基烷的材料和/或更大的微观结构和相位配置的影响。应用Topp方程导致两组的含水量大大低估。以前在新西兰桑迪火山土壤上建立的关系与我们的灰凝灰岩材料非常吻合，但仍然大大低估了古土壤的含水量。标准化转换函数对两种材料分组的描述相当好，表明堆密度差异可以解释不同材料之间的α c-θ关系变化的很大一部分。
Seven materials, encompassing a young volcanic soil, its parent material, two older buried soils (Palaeosols), and an underlying older volcanic deposit were investigated in a laboratory study to determine the relationship between dielectric permittivity (ϵc) and water content (θ). Empirical 3rd-order polynomial models generally fitted the data better than semi-physical 3-phase mixing models and normalised conversion functions. Based on their different dielectric response, which presumably is mainly due to their different bulk density (and thus porosity), the materials could be grouped into Ignimbrite materials and Palaeosol materials. Relative to the Ignimbrites, Palaeosols showed a particularly muted response at the low end of dielectric permittivity measurements, which could be due to a particularly high amount of bound water in these allophane-rich materials and/or to greater microstructural and phase configuration effects. Applying the Topp equation resulted in substantial underestimations of the water contents of both groups. A relationship previously developed on New Zealand sandy volcanic soils fitted our Ignimbrite materials well, but still underestimated the water contents of the Palaeosols substantially. Normalised conversion functions described both material groupings reasonably well, demonstrating that bulk density differences can explain a substantial part of the variation of ϵc–θ relationships between different materials.
影响因子：
2.9
作者：
T. Miyamoto;T. Annaka;J. Chikushi
通讯作者：
T. Miyamoto;T. Annaka;J. Chikushi