Li Fang, Lu Anxiang, Wang Jihua
Beijing Research Center for Agricultural Standards and Testing, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China.
Beijing Municipal Key Laboratory of Agriculture Environment Monitoring, Beijing 100097, China.
Int J Environ Res Public Health. 2017 Sep 30;14(10):1163. doi: 10.3390/ijerph14101163.
A modeling method based on discrete wavelet transform (DWT) was introduced to analyze the concentration of chromium, copper, zinc, arsenic and lead in soil with a portable X-ray fluorescence (XRF) spectrometer. A total of 111 soil samples were collected and observed. Denoising and baseline correction were performed on each spectrum before modeling. The optimum conditions for pre-processing were denoising with Coiflet 3 on the 3rd level and baseline correction with Coiflet 3 on the 9th level. Calibration curves were established for the five heavy metals (HMs). The detection limits were compared before and after the application of DWT, the qualitative detection limits and the quantitative detection limits were calculated to be three and ten times as high as the standard deviation with silicon dioxide (blank), respectively. The results showed that the detection limits of the instrument using DWT were lower, and that they were below national soil standards; the determination coefficients (R²) based on DWT-processed spectra were higher, and ranged from 0.990 to 0.996, indicating a high degree of linearity between the contents of the HMs in soil and the XRF spectral characteristic peak intensity with the instrument measurement.
介绍了一种基于离散小波变换（DWT）的建模方法，用于使用便携式X射线荧光（XRF）光谱仪分析土壤中铬、铜、锌、砷和铅的浓度。共采集并观察了111个土壤样品。在建模前对每个光谱进行去噪和基线校正。预处理的最佳条件是在第3级使用Coiflet 3进行去噪，在第9级使用Coiflet 3进行基线校正。建立了五种重金属（HMs）的校准曲线。比较了应用DWT前后的检测限，计算得出定性检测限和定量检测限分别是二氧化硅（空白）标准偏差的三倍和十倍。结果表明，使用DWT的仪器检测限较低，且低于国家土壤标准；基于DWT处理光谱的测定系数（R²）较高，范围为0.990至0.996，表明土壤中HMs含量与仪器测量的XRF光谱特征峰强度之间具有高度线性关系。
