摘要
土壤品质直接影响着农作物的生长,其中交换性钙镁的含量可以反映土壤对农作物钙镁的供应能力,因此测定土壤中交换性钙镁的含量对于促进作物生长,指导农业发展具有重要意义。对于乙醇-氯化铵提取、原子吸收分光光谱测定石灰性土壤中交换性钙镁的过程中,常遇到的提取率低、数据稳定性差等问题,选取土壤有效态成分标准物质ASA-9a-CZ、ASA-2b-CZ,对样品前处理方法、实验室环境温度和被测溶液基体三个条件进行对比试验。根据数据结果选出最适合的实验条件:选择震荡离心法进行样品前处理,保持实验室及交换液温度在25±5℃,上机测试前溶液用二次去离子水稀释后定容。后对改进过的新方法进行实验验证:交换性钙标准曲线相关系数R~2=0.9997,交换性镁标准曲线相关系数R~2=0.9995,均线性良好;交换性钙检出限为0.20 cmol·kg^(-1),交换性镁检出限为0.03 cmol·kg^(-1),该方法检出限较低;选取两个来自北京平谷的土壤样品对方法进行精密度验证,交换性钙镁7次平行测定结果的相对标准偏差(RSD%)均<5%,方法精密度良好;选取土壤有效态成分标准物质ASA-9a-CZ、ASA-2b-CZ进行方法准确度验证,其交换性钙镁的测定值及其平均值均在推荐值不确定度范围内,方法准确度高。因此,本方法可用于石灰性土壤中交换性钙镁的测定,为生态地球化学的评估工作提供参考。
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(R^(²))of 0.9997 and 0.9995,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.
作者
王娅楠
曾远
崔建勇
李黎
孙进
WANG Yanan;ZENG Yuan;CUI Jianyong;LI Li;SUN Jin(Beijing Research Institute of Uranium Geology,Beijing 100029,China;Hubei Three Gorges Laboratory,Yichang 443007,China)
出处
《世界核地质科学》
2025年第5期1065-1073,共9页
World Nuclear Geoscience
