分光光度法测定土壤阳离子交换量的探讨与改进

Discussion and Improvement of Determination of Soil Cation Exchange Capacity(CEC)by Spectrophotometry

土壤阳离子交换量(Cation exchange capacity,以下简称CEC),指的是土壤胶体能吸附各种阳离子的总量,在农业生产上应用广泛。传统测试方法测试繁琐、重现性差、资源浪费较为严重。本实验在六氨合氯化钴交换-分光光度法的使用基础上,研究一种稳定且普遍适用的方法。通过实验测试表明,影响测试结果准确性的因素主要为土壤的酸碱性、土壤的黏度等以及CEC含量的高低等。通过对不同酸碱性、不同质地以及不同CEC含量的土壤进行反复多次测试,并且用有证标准物质进行验证,最终得到合理的pH值调节范围以及不同CEC含量对应不同的固液比。

The cation exchange capacity(CEC)of soil,refers to the total amount of various cations that can be absorbed by soil colloids,and is widely used in agricultural production.However,traditional testing methods are cumbersome to test,have poor reproducibility and waste more resources.This experiment is based on the use of Hexaamminecobalt(III)chloride exchange-spectrophotometry to study a stable and universally applicable method.Experimental tests show that the main factors affecting the accuracy of the test results are the acidity and alkalinity of the soil,the viscosity of the soil and the level of CEC content.Through repeated tests on soils with different acidity and alkalinity,different textures and different CEC contents and verified with certified reference materials,a reasonable pH adjustment range and different solid and liquid ratio corresponding to different CEC contents are finally obtained.