摘要
Abstract
Exchangeable calcium(Ca)and magnesium(Mg)in the soil can reflect its ability to supply these essential nutrients to crops.Therefore,determining the content of exchangeable Ca and Mg in the soil is of great significance for promoting crop growth and guiding agricultural development.During the process of extracting exchangeable Ca and Mg in calcareous soils using ethanol-ammonium chloride and determining them by atomic absorption spectrophotometry,issues such as low extraction efficiency and poor data stability often arise.In this study,two standard reference materials for soil available components,ASA-9a-CZ and ASA-2b-CZ,were selected to conduct comparative experiments under three conditions:sample pretreatment methods,laboratory environmental temperature,and the matrix of the analyzed solution.Based on the experimental data,the most suitable conditions were determined:using oscillation and centrifugation for sample pretreatment,maintaining the laboratory and extraction solution temperature at 25±5 ℃,and diluting the solution with secondary deionized water before analysis.Subsequently,the improved method was validated experimentally.The standard curves for exchangeable Ca and Mg showed excellent linearity with correlation coefficients(R2)of 0.999 7 and 0.999 5,respectively.The detection limits for exchangeable Ca and Mg were 0.20 cmol·kg-1 and 0.03 cmol·kg-1,respectively,indicating low detection limits.The precision of the method was tested using two soil samples from Pinggu District,Beijing,and the relative standard deviation(RSD%)of seven replicate measurements for exchangeable Ca and Mg was less than 5%,demonstrating good precision.The accuracy of the method was verified using the standard reference materials ASA-9a-CZ and ASA-2b-CZ,and the measured values and their averages for exchangeable Ca and Mg fell within the recommended uncertainty range.Overall,this method is suitable for determining exchangeable Ca and Mg in calcareous soils and provides a reference for ecological geochemical evaluation.关键词
石灰性土壤/交换性钙/交换性镁/原子吸收光谱(AAS)Key words
calcareous soil/exchangeable calcium/exchangeable magnesium/atomic absorption spectrum分类
化学化工
