Microstructural development in volcanic ash soils from South Chile
Microstructural development in volcanic ash soils from South Chile
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智利南部火山灰土壤的微观结构发育
DOI：
10.1016/j.still.2013.01.007
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发表时间：
2013
影响因子：
6.5
通讯作者：
Dörner
中科院分区：
文献类型：
--
作者：
Baumgarten;Dörner
在智利南部的一系列安多索上进行了流电位测量和振幅扫描测试，以了解其聚集强度和机制，以及触变性和微观结构稳定性。考虑并比较了土壤发育的不同阶段和土地利用类型（牧场与天然林）。较年轻的，alu- Andosols和Al-腐殖质复合物含有较高水平的火山玻璃，这表明它们的pH值较低（[公式：见文本]），焦磷酸钠可提取的Al （Alp）与酸草酸铵可提取的Al （Alo）的比例较高（Alp/Alo>0.5）。除了通常高含量的无定形铁（水合铁）外，还发现alu - Andosols具有（超）疏水性。相反，在发育良好的硅质安土中（Alp/Alo<0.5）， allophane含量增加，pH值也随之升高（[公式：见文]和<7）。根据流变学数据，较好地定义了硅溶胶中的凝胶-溶胶-凝胶转化（触变性）。积分z是一个代表准弹性的无量纲流变参数，用于量化刚度退化，并识别allophanic Andosols的单阶段触变性。扫描电镜结果显示，较年轻的酸性岩溶岩的矿物成分主要为火山玻璃（如水疱状）和无定形氧化铁以及真菌菌丝，而在发育较好的岩溶岩中则没有这些特征。这里还发现了黑云母、高岭土、（原）铁长石和allophanes等风化矿物，表明脱硅和从铝-硅-硅安多索岩向硅-硅安多索岩转变。传导粒子电荷密度（PCD）测量得到的Zeta电位支持以下假设：(i) al -腐殖质复合物促进了部分超疏水的alu- Andosols表层土壤的聚集，特别是在未放牧的地点（或放牧1年）；（ii）触变行为与allophanic， silan - Andosols有关，并且在放牧50年的地点更为明显。
Streaming potential measurements and amplitude sweep tests were performed on a range of Andosols from South Chile to find out about aggregation strength and mechanisms, as well as thixotropy and microstructural stability. Different stages in soil development and types of land use (pasture vs. natural forest) were considered and compared. Younger, alu-andic Andosols along with Al-humus-complexes contained higher levels of volcanic glass, indicated by their low pH values ( [Formula: see text] ), and high ratios of sodium pyrophosphate extractable Al (Alp) to acid ammonium oxalate extractable Al (Alo) (Alp/Alo>0.5). Alu-andic Andosols were also found to have (super)hydrophobicity in addition to typically high contents of amorphous iron (ferrihydrite). On the contrary, in well-developed, sil-andic Andosols (Alp/Alo<0.5), allophane contents increased, accompanied by higher pH values ( [Formula: see text] and <7). Based on rheological data, the gel–sol–gel transformation (thixotropy) was better defined in sil-andic Andosols. Integral z, a dimensionless rheological parameter that represents quasi-elasticity was used to quantify stiffness degradation, and to identify single stages of thixotropy in allophanic Andosols. Scanning electron micrographs revealed that mineralogical components were predominated by volcanic glass (e.g. vesicular) and amorphous iron oxides in addition to fungal hyphae in younger acidic Andosols, while these characteristics were absent in well-developed Andosols. Here weathered minerals e.g. biotite, as well as halloysite, (proto)imogolite and allophanes were identified, indicating desilication and a shift from alu-andic to sil-andic Andosols. Zeta potentials derived from conducted particle charge density (PCD) measurements supported the assumptions that (i) Al-humus-complexes promoted aggregation in partially superhydrophobic topsoils of alu-andic Andosols, especially at ungrazed sites (or 1 year under pasture), and that (ii) thixotropic behaviour is related to allophanic, sil-andic Andosols, and better pronounced at sites which had been under pasture for 50 years.
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影响因子：
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作者：
M. Escudey;G. Galindo
通讯作者：
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影响因子：
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D. Sparks
DOI：
--
发表时间：
1993
期刊：
影响因子：
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作者：
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通讯作者：
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影响因子：
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作者：
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