HDXRF法农田土壤镉测定结果准确度评价与精准校正模型构建

Accuracy Evaluation and Precision Correction Model Construction of Cadmium Determination in Farmland Soil by HDXRF Method

以甘肃白银某污灌区重金属污染农田土壤为研究对象,对影响高精度便携式X荧光光谱(HDXRF)法总镉(CdT)测定精度的主要因素进行了筛选,分别研究了土壤水分、有机质类型与含量、土壤类型对HDXRF法CdT测定的影响,并采用相对误差(RE)、相对标准偏差(RSD)和决定系数(R^(2))对测定结果的准确度和精密度进行了评价。结果表明:HDXRF法CdT测定的RE≤10%、RSD≤10%、R^(2)>0.99,符合农田土壤环境质量监测技术规范和美国环境保护署标准的准确度和精密度规定。HDXRF法CdT测定结果随着土壤水分含量的增加呈指数衰减趋势,衰减方程为y=0.803e^(–1.3284x),衰减系数(μω)为–1.3284,R^(2)为0.9845。HDXRF法CdT测定结果与有机质含量呈显著的负相关关系(r=–0.955),且腐殖酸(HA)比泥炭(Peat)对测定结果的影响更大,HA与测定结果的校正方程为y=–1.555x+0.780,R^(2)为0.9344。土壤类型对HDXRF法CdT测定结果存在一定的影响,相对于红壤和水稻土,灰钙土的测定结果与传统实验室分析方法测定结果更接近。总之,虽然HDXRF法CdT测定结果受多种因素影响,但通过校正模型校正,其校正结果的可靠性能够满足Cd污染农田土壤精准调查需求。

The main factors affecting the accuracy of high-precision portable X-ray fluorescence spectrometry(HDXRF)for the determination of total cadmium concentration(CdT)in soil were screened with the heavy metal contaminated farmland soil in a sewage irrigation area of Baiyin City,Gansu Province as the object of the research.The influences of moisture,organic matter type and content,and soil type on the determination results of CdT by HDXRF were studied,respectively.The relative error(RE),relative standard deviation(RSD)and determination coefficient(R^(2))were used to evaluate the accuracy and precision of HDXRF method.The results showed that the RE and RSD of HDXRF were≤10%,R^(2)>0.99,which met the accuracy and precision requirements of farmland soil environmental quality monitoring technical specifications and US Environmental Protection Agency standards.The determination results of CdT by HDXRF method was exponentially decayed with the increase of moisture,and the attenuation equation was y=0.803e–1.3284x with an attenuation coefficient(μω)of–1.3284 and a coefficient of determination(R^(2))of 0.9845.There was a significant negative correlation between CdT by HDXRF method and organic matter content(r=–0.955),and humic acid(HA)had a much stronger influence on determination results by HDXRF method than that of peat(Peat).The correction equation of HA was y=–1.555x+0.780 with a R^(2)of 0.9344.The influence of soil type on the determination results of CdT by HDXRF method was limited,and the determination results of CdT in sierozem by HDXRF method were closer to the determination results by traditional laboratory analysis method than that of red soil and paddy soil.In conclusion,although the determination results of HDXRF are affected by many factors,the reliability of the correction results can meet the needs of accurate investigation of cadmium contaminated farmland soils through model correction.