农田土壤有效态镉的分析方法筛选与优化

Selection and Optimization of Methods for Analyzing Available Cadmium in Farmland Soils

【目的】准确测定污染农田土壤中镉(cadmium,Cd)的有效态含量,并高效预测农作物可食部分的Cd含量。【方法】基于原始碳酸氢铵—二乙三胺五乙酸(ammonium bicarbonate-diethylenetriamine pentaacetic acid,AB-DTPA)浸提法,运用正交试验法对浸提剂pH、加入量及浸提时间3种提取条件进行正交组合,筛选最优条件,确定优化方法。采用野外采样和室内盆栽2种方式,对土壤—作物系统中Cd的迁移效应进行拟合验证。【结果】优化AB-DTPA法提取土壤有效态Cd的最佳条件为:提取剂加入量50 mL,pH 7.0,振荡时间60 min。优化AB-DTPA法提取的土壤有效态Cd含量对作物可食部分Cd吸收量的预测效果最佳。优化AB-DTPA法提取Cd元素测定结果的相对标准偏差均小于20%,加标回收率为100.00%~115.00%。【结论】优化后的AB-DTPA法适用于分析污染农田土壤中Cd的有效态含量,并预测农作物可食部分吸收的Cd含量,具有可行性、广泛适用性和准确性,能满足有效态Cd的批量分析要求。

[Purpose]To accurately measure the available cadmium(Cd)content in contaminated farmland soils and efficiently predict the Cd content in the edible parts of crops.[Methods]Based on the original ammonium bicarbonate-diethylenetriamine pentaacetic acid(AB-DTPA)extraction method,an orthogonal experimental design was used to optimize three extraction conditions:pH of the extractant,volume added,and extraction time.The optimal conditions were determined,and the optimized method was validated by fitting the migration effects of Cd in the soil-crop system through field sampling and indoor pot experiments.[Results]The optimal conditions for extracting available Cd using the optimized AB-DTPA method were:extractant volume of 50 mL,pH 7.0,and oscillation time of 60 minutes.The optimized AB-DTPA method provided the best prediction of Cd uptake in the edible parts of crops.The relative standard deviation of the Cd extraction results was less than 20%,with a spiked recovery rate ranging from 100.00%to 115.00%.[Conclusion]The optimized AB-DTPA method is suitable for analyzing available Cd in contaminated farmland soils and predicting Cd uptake in the edible parts of crops.It is feasible,widely applicable,and accurate,meeting the requirements for batch analysis of available Cd.