Abstract—

The mineralogical composition of nano-clays (NCs), and their potential implications in soil bulk properties of Indian Vertisols are unexplored. In this study, we have isolated NCs (<100 nm) from Deccan basalt (DB) alluvium derived Vertisols (Typic Haplusterts) of central India and characterized them for their mineralogy and crystalline behavior. The soils are clayey (>60%) in texture, rich in smectite mineral (60–80% in <2 μm fraction), alkaline (pH 7.8–8.5), calcareous, and contain <1.0% organic carbon. The clay fraction (<2 μm) is dominated by smectitic NC (40–60%) followed by hydroxy-interlayered vermiculite (HIV), pedogenic chlorite (PCh), kaolinite, and mica. The smectite is little hydroxy-interlayered (HIS), and hydroxy-interlayering is less pronounced in NC smectites than in the coarser clay smectites. The NC smectites are of smaller crystallite size (3.5–5.5 nm) and higher in crystal strain (15–22%) than coarser size clays because of its low lattice charge. The abundance of smectitic NCs considerably reduces the saturated hydraulic conductivity (<1 cm hr^–1) of the soils due to high dispersion and swelling (COLE ≥ 0.20) of smectite clays even at the low level of exchangeable sodium percentage (ESP ≤ 5) and a moderate amount of exchangeable magnesium. The report on nano clays (<0.1 μm) highlights the unique role of nano smectites in some selected soil properties, as well as in the origin of SAT Vertisols of the Indian subcontinent.

中文翻译：

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纳米印度印第安溶胶的起源，矿物学及其对某些土壤性质的影响

摘要-

纳米粘土（NCs）的矿物学组成及其对印度Vertisols土体性质的潜在影响尚待探索。在这项研究中，我们从印度中部的Deccan玄武岩（DB）冲积粉衍生的Vertisols（Typical Haplusterts）中分离了NCs（<100 nm），并对其矿物学和结晶行为进行了表征。土壤质地为粘土质（> 60％），富含蒙脱石矿物（<2μm比例为60-80％），碱性（pH 7.8-8.5），钙质且有机碳含量<1.0％。粘土级分（<2μm）主要由近晶型NC（40-60％），其次是羟基夹层ver石（HIV），成绿绿泥石（PCh），高岭石和云母。蒙脱石几乎没有羟基夹层（HIS），并且与较粗糙的粘土蒙脱石相比，NC蒙脱石中的羟基夹层不那么明显。NC蒙脱石具有较小的晶格电荷，因此其晶粒尺寸较小（3.5–5.5 nm），而晶体应变较高（15–22％），其比粗尺寸粘土高。大量近晶NC大大降低了饱和水力传导率（<1 cm hr^–1）由于蒙脱石粘土的高分散和溶胀（COLE≥0.20）而导致的土壤，即使在低水平的可交换钠含量（ESP≤5）和适度的镁交换量下也是如此。关于纳米粘土（<0.1μm）的报告强调了纳米蒙脱石在某些选定的土壤特性以及印度次大陆的SAT垂直溶胶的起源中的独特作用。