类标准化土壤样品Cd含量高光谱定量反演

Quantitative Estimation of Cd Concentrations of Type Standard Soil Samples Using Hyperspectral Data

针对土壤Cd高光谱遥感反演精度低、特征波段难以有效识别的问题,以湖南省某典型重金属污染矿区为例,开展类标准化Cd污染土壤样品和自然污染土壤样品Cd含量高光谱定量反演对比研究。创新之处主要在于以相对清洁的背景土壤作为内控样本,通过实验室定量添加Cd标准溶液制备符合自然污染规律的类标准化Cd污染土壤样品方案的提出与对比实验的开展,研究实验过程还包括自然污染土壤样品野外采集,类标准化样品与自然样品土壤重金属、有机质含量及350~2 500nm光谱反射率等的测定,光谱全要素主成分逐步回归土壤Cd含量反演建模。研究发现,类标准化土壤样品Cd含量高光谱反演模型精度(adj R2=0.87)明显高于野外自然污染土壤样品Cd含量高光谱反演建模结果(adj R2=0.39)。土壤Cd含量与土壤光谱反射率间确实存在一定的响应关系,但各光谱波段对土壤Cd含量及其变化产生响应的程度存在差异,其中1 000,2 000以及2 300nm波段光谱响应信号较强。该研究创新引入的类标准化Cd污染土壤样品制备方法有助于深入探索重金属Cd污染土壤光谱特征响应规律并发现重金属Cd含量及其变化的真正指示性特征波段,可为多要素混淆污染模式下模拟反演土壤重金属含量提供先验知识。

Due to the low accuracy of soil Cd concentrations estimation and the great difficulty of characteristic spectral wavelength identification using hyperspectraldata,a comparative study on quantitative estimation of soil Cd concentrations was carried out in this paper by using the type standard soil samples and naturally contaminated soil samples from one mine in Hunan province,China.The main innovation includes the schemeproposition of type standard soil samples production and the development of comparative experiments.This study produced the type standard soil samples by adding quantitative standard solution of Cd into relatively clean background soil.The experimental process also includes the field collection of naturally contaminated soil samples,the determination of soil composition,such asheavy metals,organic matter,the measurement of 350~2 500 nm soil spectral reflectance,and the total factor principal component stepwise regression modeling of soil Cd concentrations using spectral reflectance.The results showed that accuracy of the model based on type standard soil samples was higher(adj R2=0.87)than traditional modeling results based on naturally contaminated soil samples(adj R 2=0.39).In addition,this study defined the existence of the spectral response between soil Cd concentrations and spectral reflectance.However,the effect of Cd concentrations on the soil spectral reflectance acted on all thewavelengths in various degrees among which,the spectral response signals in the wavelength of 1 000,2 000 and 2 300 nm were relatively stronger.In this study,the innovatory scheme of type standard soil samples production is helpful todeeply explore spectral response characteristics of soil Cd and find out the real indicative characteristic bands of soil heavy metal concentrations.Furthermore,it will provide priori knowledge for quantitative estimation of soil heavymetal concentrations in the mode of multi-factor confounding pollution.