Chromium (Cr) pollution in soil can cause serious harm to both human health and the environment. Cr (Ⅵ) is of particular concern due to its strong carcinogenic, teratogenic, and mutagenic effects on humans. It can also lead to soil hardening and crop yield reduction. Recently, hyperspectral approaches have become a popular way of analyzing heavy metal pollution in soil, and are both convenientand cost-effective, compared with chemical analysis. However, the complex composition of soil makes it challenging to directly analyze the influence of heavy metals on soil spectra and achieve efficient and rapid identification of heavy metal contamination in soil. In this research, a simulation experiment was designed for soil Cr content. Threshold detection-Hilbert-Huang transform (TD-HHT) was implemented to remove the complex environmental noise of soil spectra, to extract the weak heavy metal information. The results showed that the TD-HHT amplitude fluctuates at different Cr concentrations, and heavy metal pollution can be directly detected from the amplitude curve at around 600 mg/kg. To verify this threshold value, the correlation between the soil optical constant and the soil heavy metal concentration was explored through the bidirectional reflectance distribution function, based on the threshold validation-Hapke (TV-Hapke) model. At around 600 mg/kg, Cr can be directly detected using the soil radiative transfer model, which can be utilized to rapidly detect soil heavy metal pollution.

中文翻译：

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基于高光谱遥感数据的土壤铬污染快速检测方法

土壤中的铬（Cr）污染会对人类健康和环境造成严重危害。 Cr(Ⅵ)因其对人类强烈的致癌、致畸和致突变作用而受到特别关注。它还会导致土壤板结和农作物减产。近年来，高光谱方法已成为分析土壤重金属污染的流行方法，与化学分析相比，既方便又经济。然而，土壤成分的复杂性使得直接分析重金属对土壤光谱的影响并实现土壤重金属污染的高效快速识别具有挑战性。本研究设计了土壤Cr含量模拟试验。采用阈值检测-希尔伯特-黄变换（TD-HHT）去除土壤光谱中复杂的环境噪声，提取微弱的重金属信息。结果表明，不同Cr浓度下TD-HHT振幅存在波动，在600 mg/kg左右时，可以从振幅曲线上直接检测出重金属污染。为了验证该阈值，基于阈值验证-Hapke（TV-Hapke）模型，通过双向反射率分布函数探索土壤光学常数与土壤重金属浓度之间的相关性。利用土壤辐射传输模型可以直接检测出600 mg/kg左右的Cr，可用于快速检测土壤重金属污染。