保定市三县交接处土壤铅锌元素高光谱反演研究

    Hyperspectral inversion of lead and zinc elements in soil at the junction of three counties in Baoding City

    • 摘要: 保定市清苑县、安新县和高阳县三县交汇处曾是钢铁冶炼加工区,由于多年的粗放式冶炼,导致该区存在一定的土壤重金属污染。首先,以三县交接处为研究区,通过土壤样品采集、土壤光谱测量与实验室铅元素、锌元素含量测定,获得研究区的基础数据;其次,对基础数据进行相关性分析、统计分析和模型建模反演;最后,利用偏最小二乘法和反向传播神经网络法两种建模方法建立铅元素、锌元素含量的定量估算模型。研究结果表明:通过Pearson相关分析得出六种光谱变换有利于高光谱波段与铅元素、锌元素含量建立相关关系的特征波段;综合六种光谱变换、偏最小二乘法和反向传播神经网络法,反向传播神经网络法能够提高土壤中铅含量、锌含量的预测精度;铅元素应用反向传播神经网络法基于连续统去除建立的估算模型为最佳估算模型,其中,建模精度R2为0.949,验证精度R2为0.980;锌元素应用反向传播神经网络法基于标准正态变换建立的估算模型为最佳估算模型,其中,建模精度R2为0.874,验证精度R2为0.957。经过研究,通过反向传播神经网络法建立的估算模型可为该地区开展土壤重金属铅元素、锌元素污染调查提供研究基础。

       

      Abstract: The intersection of Qingyuan County, Anxin County and Gaoyang County in Baoding City used to be an iron and steel smelting and processing area. Due to years of extensive smelting, there is a certain amount of soil heavy metal pollution in this area. Firstly, takes the junction of three counties as the study area, obtains the basic data of the study area through soil sample collection, soil spectral measurement and laboratory content determination of lead and zinc elements. Then, carries out correlation analysis, statistical analysis and model modeling inversion on the basic data. Finally, two modeling methods, partial least squares and back propagation neural network are used to establish the quantitative estimation model of content of lead and zinc elements. The results show that six mathematical transformations are beneficial to establish the characteristic bands of correlation between hyperspectral bands and content of lead and zinc elements by Pearson correlation analysis; based on the analysis of six spectral transformations, partial least squares and back propagation neural network, the back propagation neural network can improve the prediction accuracy of content of lead and zinc elements in soil; the estimation model of lead element based on continuum removal established by back propagation neural network is the best estimation model, in which the modeling accuracy R2 is 0.949 and the verification accuracy R2 is 0.980; the estimation model of zinc element based on standard transformation established by back propagation neural network is the best estimation model, in which the modeling accuracy R2 is 0.874 and the verification accuracy R2 is 0.957. Through the study, the estimation model established by the back propagation neural network can provide a research basis for the investigation of soil heavy metal lead and zinc pollution in this area.

       

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