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首页> 外文期刊>Soil Science Society of America Journal >Properties of Water-Dispersible Colloids from Macropore Deposits and Bulk Horizons of an Agrudalf
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Properties of Water-Dispersible Colloids from Macropore Deposits and Bulk Horizons of an Agrudalf

机译：Agrudalf的大孔沉积物和大视野中水分散性胶体的性质

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摘要

Mobility of colloids depends in part on the release from aggregates and the stability in suspension. This study determined the soil dispersibility of the different horizons in a Typic Agrudalf. Water-dispersible colloids (WDC) from bulk horizons and macropore deposits were characterized for mineralogy and physical chemical properties. The effect of solution pH and ionic strength on -potential and flocculation behavior was evaluated using dynamic light scattering, and the role of colloid associated organic C (OC) and sesquioxides were elucidated. The soil dispersibility did not reflect the contrasting physicochemical conditions, but was directly correlated with total clay content. Generally, WDC were enriched in OC and sesquioxides. Water-dispersible colloids from the Ap-horizon and from macropore deposits differed markedly from the remaining WDC-fractions due to a significantly higher content of OC (14–35 g kg–1), AlCBD (9.3–10.6 g kg–1) and a much smaller N2–adsorption surface area (14–25 m2 g–1). Treatment with Na2S2O8 for removal of OC increased the surface area by 171–225%, indicating surface coatings of OC. The contribution of OC to the colloidal stability was inferred from: (i) a more negative -potential and larger suspension stability of WDC with larger content of OC, and (ii) reduced negative -potential as well as suspension stability after OC removal. Large variations were observed in the flocculation behavior for WDC with rather similar mineralogical composition. A two-fold increase of the initial particle diameter occurred at an electric conductivity of 91 µS cm–1 for the least stable colloids and at 1023 µS cm–1 for the most stable and OC-rich colloids. The effect of solution pH on flocculation was significant only at pH below 4.5.
机译：胶体的流动性部分取决于聚集体 的释放和悬浮液的稳定性。本研究确定了典型Agrudalf中不同层位的土壤 分散性。 散层位和大孔 沉积物中的水分散性胶体（WDC）为具有矿物学和物理化学 特性的特征。使用动态 光散射评估溶液pH和离子强度对 电势和絮凝行为的影响，以及胶体相关有机 C的作用（OC）和倍半氧化物被阐明。土壤的分散性 没有反映相反的理化条件， 却与总粘土含量直接相关。通常， WDC富含OC和倍半氧化物。 Ap地平线和大孔沉积物中的水分散性 胶体与其余的WDC馏分显着不同 ，这是由于OC含量明显 （14–35 g kg –1 ），Al CBD （9.3–10.6 g kg -1 ）和N 2 -吸附表面 区域要小得多（14–25 m 2 g -1 ）。 Na 2 S 2 O 8 处理可去除OC的 ，表面积增加了171–225％， 表示OC的表面涂层。 OC对 胶体稳定性的贡献可从以下方面推断：（i）具有更大 含量的WDC的负负 电位和较大的悬浮稳定性。 OC的去除；以及（ii）去除OC后悬浮液的负电位也降低了 。 矿物质成分相当相似的WDC的絮凝行为观察到很大的变化。对于最不稳定的胶体，电导率为91 µS cm –1 时，初始 粒径增加了两倍 µS cm –1 用于最稳定和富含OC的胶体。 溶液pH值对絮凝的影响仅是显着的 在pH值低于4.5时。

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