碳酸钙对黄土纳米颗粒凝聚的影响机制

Soil nanoparticles are the most active components in soils. The ion-particle and particle-particle interactions determine the coagulation and dispersion processes of nanoparticle suspension. Calcium carbonate is the main cementing material for loess soils and the surface charges of calcium carbonate may strongly affect the surface properties and coagulation kinetics of loess nanoparticles. However, the interactions between the calcium carbonate and loess nanoparticles have not been thoroughly understood. The project plans to symmetrically characterize the properties of typical natural nanoparticles from loess soils on the Loess Plateau through modern analysis techniques. Furthermore, the dynamic light scattering technique will be adopted to investigate the homoaggregation processes of loess nanoparticles under various environmentally-related conditions and the heteroaggregation processes of calcium carbonates and loess nanoparticles, during which the key parameters influencing the aggregation kinetics would be quantitatively compared and analyzed. The aim of the present project is to reveal the influence of calcium carbonates on the aggregation kinetics of loess nanoparticles. The results could provide theoretical references for further explaining the role of calcium carbonate in promoting the formation and stability of soil aggregates.

土壤纳米颗粒是土壤中最具活性的组分。纳米颗粒与离子以及纳米颗粒间的相互作用决定了体系的凝聚与分散过程。碳酸钙是黄土的主要胶结物质，其表面电荷可能会对黄土纳米颗粒的表面性质和凝聚过程产生重要影响，然而碳酸钙与黄土纳米颗粒之间的相互作用尚不清楚。本项目拟通过现代分析技术对黄土高原地区典型黄土纳米颗粒的性质进行系统表征；利用动态光散射技术研究不同环境化学条件下黄土纳米颗粒的同质凝聚过程以及碳酸钙和黄土纳米颗粒的异质凝聚过程，进而定量分析黄土纳米颗粒凝聚动力学过程中的关键参数，揭示碳酸钙对黄土纳米颗粒凝聚的影响机制。研究结果可为进一步深入揭示碳酸钙对黄土团聚体形成与稳定的促进作用提供理论依据。

本项目以黄土高原黄土母质发育形成的五种土壤中所含黄土纳米颗粒以及碳酸钙纳米颗粒为研究对象，采用元素分析仪、X射线衍射仪、红外光谱仪、电位分析仪和动态光散射仪等对胶体物质的元素组成、矿物组成、表面官能团类型、表面电位和临界聚沉浓度进行了分析，以此对典型黄土发育土壤中有机质和碳酸钙对黄土纳米颗粒凝聚的影响进行了定量描述，阐明了碳酸钙的胶体特征，揭示了胶结物质增强团聚体稳定性的微观机制。研究结果对于评估组成成分复杂的天然纳米颗粒的反应活性和迁移特性提供了基础数据，为深入解析团聚体的形成机制提供了理论依据。