基于高光谱的北京铁矿区土壤重金属镍元素含量反演研究

An Inversion of Soil Nickel Contents with Hyperspectral in Iron Mine Area of Beijing

  • 摘要: 运用高光谱数据对北京典型铁矿区土壤重金属镍含量进行建模反演,探索高光谱遥感技术在土壤重金属污染快速监测上应用的可行性。使用便携式地物光谱仪采集研究区土壤样本光谱反射率数据,光谱反射率数据经多种数学变换后,经逐步回归方法筛选最佳特征波段,利用多元线性回归(SLR)和偏最小二乘回归(PLSR)方法建立模型以光谱反射数据对土壤重金属镍元素含量进行反演。基于光谱二阶微分的多元线性回归模型(SD-MLR)的稳定性和精度最高(R2 = 0.842,RMSE = 4.474),能够良好地预测研究区土壤镍元素含量。光谱数据数学变换能够有效提高其与土壤镍元素含量间的相关性。不同的光谱变换形式建立模型的预测能力和精度有如下关系,光谱二阶微分 > 光谱倒数对数一阶微分 > 光谱一阶微分 > 光谱倒数对数 > 光谱连续统去除 > 原始光谱。采用光谱二阶微分建立多元线性回归模型为研究区土壤镍元素含量反演的最佳模型,可为土壤重金属污染快速监测提供技术参考。

     

    Abstract: Inversion modeling of heavy metal nickel in soils of typical iron mine area in Beijing was carried out with hyperspectral data, in order to explore the feasibility of hyperspectral remote sensing technology in rapid monitoring of soil heavy metal pollution. The spectral reflectance data of soil samples in the study area were obtained by portable spectrometer, and the original spectral data were mathematically transformed. Optimum feature bands were extracted with Stepwise regression method. The inversion model of soil nickel content was established with Multiple Linear Regression (SLR) and Partial Least Squares Regression (PLSR). The multiple linear regression model based on spectral second derivative (SD-MLR) had the highest stability and accuracy (R2 = 0.842, RMSE = 4.474), which was the best inverse of the nickel content in the soil of the study area. Spectral mathematical transformation can effectively improve the correlation between spectral data and element content. The following relationship exists in the modeling predictive power and accuracy of spectrum reflectance under different transformations: second derivative > absorbance transformation first derivative > first derivative > absorbance transformation > continuum removed > original spectra.The SD-MLR model could well predict the nickel content in the area and provide a technical reference for rapid monitoring of soil heavy metal pollution.

     

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