Formation mechanisms and control factors of vesicular soil structure
Formation mechanisms and control factors of vesicular soil structure
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多孔土壤结构的形成机制及控制因素
DOI：
10.1016/j.catena.2012.06.011
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发表时间：
2012
期刊：
影响因子：
6.2
通讯作者：
A. Kleber
中科院分区：
文献类型：
--
作者：
M. Dietze;S. Bartel;M. Lindner;A. Kleber
多孔结构是干旱环境中土壤的一个普遍特征。通常与石头路面相关，它具有控制灰尘和水通量的主要功能，因此，对场地生态有重要影响。以往的泡状结构的形成和稳定性的模型是不一致的，主要集中在孤立的控制参数的调查。为了测试现有的模型，推断泡状结构形成的合理机制，并揭示控制环境和沉积学参数，我们提出了人工和天然囊泡的囊泡特性的定量数据。囊泡不是不稳定的，但它们的大小变化随时间呈非线性。它们的形成是由于表面的密封，通过水坑和湿润锋，它向下推进，从而提高沉积物基质内的气体压力。粘土移位或碳酸钙沉淀支持囊泡稳定。泡状结构在广泛的环境和沉积环境中形成：每个润湿循环至少6.3-15.7mm的水，0-70%的砂含量，0.8-5.6mS/cm的电导率和1-28%的碳酸钙含量。高含砂量有利于更大更圆的囊泡，而增加碳酸钙含量则有相反的效果。溶解离子的浓度对囊泡的形成影响不大。在人工覆盖下，石泡根本无法形成，而它们集中在石缘周围。在自然环境中，泡囊形成的主要限制因素是根系活性。表面覆盖的类型和密度决定了细物质进入泡状层聚集体的通量。小泡的形状可能与沙尘的入流强度有关。因此，视野与球形囊泡可能表明恒定的低粉尘流入植被不良的表面，因此，作为环境条件的代理。
Vesicular structure is a widespread feature of soils in arid environments. Typically associated with stone pavements, it has a major control function for dust and water fluxes and, hence, for site ecology. Previous models of vesicular structure formation and stability are inconsistent and mostly focused on the investigation of isolated control parameters. To test existing models, to infer plausible mechanisms of vesicular structure formation and to unveil controlling environmental and sedimentological parameters, we present quantitative data of vesicle properties of artificial and natural vesicles. Vesicles are not unstable but their changes in size are non-linear with time. They form due to surface sealing by puddling and by a wetting front, which advances downward, thereby elevating gas pressure within the sediment matrix. Translocation of clay or precipitation of calcium carbonate support vesicle stabilisation. Vesicular structure forms within a wide range of environmental and sedimentological settings: at least 6.3–15.7mm of water per wetting cycle, 0–70% sand content, 0.8–5.6mS/cm electric conductivity and 1–28% calcium carbonate content. High sand contents favour larger and rounder vesicles, whereas increasing calcium carbonate content has the opposite effect. The concentration of dissolved ions does not considerably influence vesicle formation. Under an artificial cover stone vesicles could not be created at all, whereas they were concentrated around stone margins. The main limiting factor for vesicle formation in natural environments is root activity. The type and density of surface cover determine fine material fluxes into the aggregates of vesicular horizons. The shape of vesicles may be related to dust influx intensity. Accordingly, horizons with spherical vesicles may indicate constant low dust influx on poorly vegetated surfaces and be, therefore, used as proxies of environmental conditions.