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有机组分的土水分配系数(Kd)是描述有机组分在地下系统中吸附特征的重要参数。同时,它也是物质运移模拟和环境评价中的主要参数之一。影响Kd的因素可概括为三个方面:土壤性质、有机组分本身特征及水相的物理化学性质。一般而言,对于非极性和弱极性有机组分,土壤中的有机质含量(foc )是影响Kd的最主要因素。但是,对于极性有机组分(POCs), 特别是在土壤有机质含量较低的情况下,土壤中矿物的种类和含量、水化学组分特征(pH、离子力等)经常在吸附过程中起重要作用。实验室内测定Kd的方法包括批实验和柱实验方法。批实验法适用于研究Kd较高情况下的吸附。在Kd较低的情况下,如低有机质土壤对极性有机污染物的吸附,土柱色谱法(SCC)是更适宜的选择。另外,可用土柱色谱法快速了解各种因素对吸附过程的影响,并获取详细的吸附和解吸信息。应用土柱色谱法时应当注意非平衡吸附和可能的柱堵塞问题。很多文献中提到结合柱实验和已有的吸附数据来预测土壤有机碳标准化的分配系数Koc(=Kd/foc)。但是,如果没有考虑吸附中特定的作用过程(如矿物吸附),对极性有机组分Koc的预测将会产生很大的误差。在环境评价中,将从一种土壤测定的Koc 应用到不同性质的土壤中,可能会导致错误的认识。在进行室内实验时,应把标准土(如Eurosoi
The soil-water partition coefficient (Kd) of organic components is an important parameter describing the adsorption characteristics of organic components in the subsurface system. At the same time, it is also one of the main parameters in material migration simulation and environmental assessment. Factors affecting Kd can be summarized in three aspects: the nature of the soil, the nature of the organic components and the physico-chemical properties of the water phase. In general, soil organic matter (foc) is the most important factor affecting Kd for both nonpolar and weakly polar organic components. However, for polar organic components (POCs), especially in the case of low soil organic matter content, the type and content of minerals in the soil, the characteristics of the water chemistry components (pH, ionic forces, etc.) often play a role in the adsorption process Important role. Methods of Kd determination in the laboratory include batch experiments and column experiments. Batch experimental method is suitable for the study of Kd adsorption under higher conditions. Soil column chromatography (SCC) is the more suitable choice for low Kd adsorption, such as low organic matter adsorption on polar organic contaminants. In addition, soil column chromatography can be used to quickly understand the impact of various factors on the adsorption process and to obtain detailed adsorption and desorption information. When applying column chromatography, attention should be paid to unbalanced adsorption and possible column plugging problems. Many references have been made to predict the normalized partition coefficient of soil organic carbon, Koc (= Kd / foc), using binding column experiments and available adsorption data. However, the prediction of Koc, a polar organic component, will produce significant errors without considering specific processes of adsorption (such as mineral adsorption). In environmental assessment, the application of KOC, measured from one soil, to soils of different nature may lead to erroneous perceptions. In laboratory experiments, the standard soil (such as Eurosoi