基于小波变换的便携式X射线荧光光谱仪检测模型的建立与改进

发布时间：2018-03-02 15:46

本文选题：X射线荧光光谱仪　切入点：重金属　出处：《光谱学与光谱分析》2015年04期 　论文类型：期刊论文

【摘要】：应用便携式X射线荧光光谱仪对土壤中Cr,Cu,Zn,As,Pb等重金属含量进行检测,每个样品扫描检测3次,利用小波阈值滤噪的方法对所测谱线进行光滑去噪处理后,根据土壤重金属的标准值和相应的计数率(取三次处理后检测谱线的平均值)建立各重金属的标准曲线。运用小波阈值滤噪方法时,为确定最佳的小波基和小波分解层数,以信噪比(SNR),均方根误差(MSE)和信息熵(H)作为评估指标评价降噪效果。为验证仪器的稳定性,根据土壤样品中重金属浓度的不同挑选部分样品并同时选用H3BO3(空白对照)进行重测。结果表明:运用小波变换方法时,选取coif3小波基对谱线进行三层分解,取得了最佳的去噪效果;建立好模型后,仪器的决定系数R2范围是0.990~0.996,表明在0~1 500mg·kg-1范围内,土壤样品中各重金属元素含量与X射线荧光光谱特征峰强度之间的线性关系良好;经过重复检测和计算得知仪器的检出限均低于国家一级土壤标准。将小波变换的方法实际运用到X射线荧光光谱仪检测模型的建立与改进中,有效的提高了模型的准确性,同时经验证,仪器具有良好的精密度,可运用于实际土壤重金属污染的现场快速筛查。
[Abstract]:A portable X-ray fluorescence spectrometer was used to detect the contents of heavy metals such as Cr-CuCuZZZZZn-As-Pb in soil. Each sample was scanned for 3 times. The wavelet threshold method was used to filter the noise of the measured spectral lines, and the measured lines were treated with smooth de-noising. According to the standard value of soil heavy metals and the corresponding counting rate (taking the average value of the detection spectral line after three times treatment), the standard curve of each heavy metal is established. In order to determine the best wavelet basis and wavelet decomposition layer number, the wavelet threshold noise filtering method is used to determine the optimal number of wavelet basis and wavelet decomposition layer. SNR (SNR), MSE (root mean square error (MSE)) and information entropy (HH) are used as evaluation indexes to evaluate the effect of noise reduction, and to verify the stability of the instrument, According to the different concentrations of heavy metals in soil samples, some samples were selected and the H _ 3BO _ 3 (blank control) was selected for re-test. The results show that when wavelet transform is used, the coif3 wavelet basis is selected to decompose the spectral lines in three layers. After the model was established, the coefficient of determination (R2) of the instrument was 0.990 ~ 0.996, which indicated that the linear relationship between the content of heavy metals in soil samples and the intensity of the characteristic peak of X-ray fluorescence spectra was good in the range of 0 ~ 1 500 mg 路kg-1. After repeated detection and calculation, the detection limit of the instrument is lower than the national first grade soil standard. The wavelet transform method is applied to the establishment and improvement of the detection model of X-ray fluorescence spectrometer, which effectively improves the accuracy of the model. At the same time, it is proved that the instrument has good precision and can be used in the field rapid screening of soil heavy metal contamination.
【作者单位】：吉林大学生物与农业工程学院;北京农业质量标准与检测技术研究中心;
【基金】：北京市科技计划项目(Z121100001612002)资助
【分类号】：TH744.1

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