1.1 本试验方法描述了测量细粒无机土壤的可溶阳离子和结合阳离子以及阳离子交换容量（CEC）的程序。细粒土壤中的粘土矿物携带负表面电荷，由矿物表面附近的结合阳离子平衡。这些结合阳离子可以被孔隙水中的其他阳离子交换，这些阳离子被称为可溶阳离子。阳离子交换容量是矿物表面负表面电荷的度量。CEC通常由钙（Ca）、钠（Na）、镁（Mg）和钾（K）满足，尽管根据土壤存在的环境可能存在其他阳离子。该测试方法是根据Lavkulich（1981）中之前描述的概念开发的( 1. ) 2. 和Rhoades（1982）( 2. ). 在含有大量石膏或方解石的土壤中，这些矿物的溶解将释放出溶液中的钙，这可能会影响测量。 1.2 在本试验方法中，用去离子水洗去矿物表面的可溶性盐，然后测量提取物中可溶性盐的浓度。使用含有指数离子的溶液测量粘土的结合阳离子，该离子迫使结合层中的现有阳离子溶解。测量该溶液中结合阳离子和可溶性阳离子的总浓度。通过用另一种盐溶液置换指数离子并测量置换指数离子的量来测量CEC。 1.3 本标准并非旨在解决与其使用相关的所有安全问题（如有）。 本标准的用户有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.4 所有观察值和计算值应符合实践中制定的有效数字和舍入指南 D6026 . 实践中的程序 D6026 用于指定如何收集、记录和计算数据的标准被视为行业标准。此外，它们代表了通常应保留的有效数字。这些程序不考虑材料变化、获取数据的目的、特殊目的研究或用户目标的任何考虑因素。增加或减少报告数据的有效位数以符合这些考虑是常见做法。 工程设计分析方法中使用的有效数字超出了本标准的范围。 1.5 单位- 以国际单位制表示的数值应视为标准值。本标准不包括其他计量单位。以国际单位制以外的单位报告试验结果不应视为不符合本试验方法。 1.6 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 4.1 细粒土用于废物控制系统中，作为流动和污染物运输的屏障。 这些障碍物所含的液体可能含有离子，这些离子可能与细粒土壤中的矿物表面相互作用。 4.2 通过细粒土孔隙的液体可以与矿物表面相互作用，并影响土壤的物理和化学特性。该方法可作为评估这些相互作用的一部分。 注1: 本标准产生的结果的质量取决于执行测试的人员的能力以及所用设备和设施的适用性。符合实践标准的机构 D3740 通常认为能够胜任和客观的测试、抽样、检查等。本标准的用户应注意遵守惯例 D3740 本身不能确保可靠的结果。 可靠的结果取决于许多因素。实践 D3740 提供了一种评估其中一些因素的方法。

1.1 This test method describes the procedures for measuring the soluble and bound cations as well as the cation exchange capacity (CEC) of fine-grained inorganic soils. Clay minerals in fine-grained soils carry a negative surface charge that is balanced by bound cations near the mineral surface. These bound cations can be exchanged by other cations in the pore water, which are referred to as soluble cations. The cation exchange capacity is a measure of the negative surface charge on the mineral surface. The CEC generally is satisfied by calcium (Ca), sodium (Na), magnesium (Mg), and potassium (K), although other cations may be present depending on the environment in which the soil exists. This test method was developed from concepts described previously in Lavkulich (1981) ( 1 ) 2 and Rhoades (1982) ( 2 ). In soils with appreciable gypsum or calcite, dissolution of these minerals will release Ca in solution that may affect the measurement. 1.2 In this test method, the soluble salts from the mineral surface are washed off with de-ionized water and then the concentration of soluble salts within the extract is measured. The bound cations of the clay are measured by using a solution containing an index ion that forces the existing cations in the bound layer into solution. The total concentrations of bound and soluble cations in this solution are measured. The CEC is measured by displacing the index ion with another salt solution and measuring the amount of the displaced index ion. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.4 All observed and calculated values shall conform to the guide for significant digits and rounding established in Practice D6026 . The procedures in Practice D6026 that are used to specify how data are collected, recorded, and calculated are regarded as the industry standard. In addition, they are representative of the significant digits that should generally be retained. The procedures do not consider material variation, purpose for obtaining the data, special purpose studies, or any considerations for the objectives of the user. Increasing or reducing the significant digits of reported data to be commensurate with these considerations is common practice. Consideration of the significant digits to be used in analysis methods for engineering design is beyond the scope of this standard. 1.5 Units— The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. Reporting of test results in units other than SI shall not be regarded as nonconformance with this test method. 1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 4.1 Fine-grained soils are used in waste containment systems as barriers to flow and contaminant transport. Liquids contained by these barriers can contain ions that may interact with the mineral surfaces in fine-grained soils. 4.2 The liquid passing through the pores of fine-grained soil can interact with the mineral surface, and affect the physical and chemical characteristics of the soil. This method can be used as part of an evaluation of these interactions. Note 1: The quality of the result produced by this standard depends on the competence of the personnel performing the test and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective testing, sampling, inspection, etc. Users of this standard are cautioned that compliance with Practice D3740 does not in itself ensure reliable results. Reliable results depend on many factors. Practice D3740 provides a means of evaluating some of these factors.