A New Plant Indicator (Artemisia lavandulaefolia DC.) of Mercury in Soil Developed by Fourier-Transform Near-Infrared Spectroscopy Coupled with Least Squares Support Vector Machine.

Lu Xu,Qiong Shi,Bang-Cheng Tang,Shunping Xie

doi:10.1155/2019/3240126

Abstract

A rapid indicator of mercury in soil using a plant (Artemisia lavandulaefolia DC., ALDC) commonly distributed in mercury mining area was established by fusion of Fourier-transform near-infrared (FT-NIR) spectroscopy coupled with least squares support vector machine (LS-SVM). The representative samples of ALDC (stem and leaf) were gathered from the surrounding and distant areas of the mercury mines. As a reference method, the total mercury contents in soil and ALDC samples were determined by a direct mercury analyzer incorporating high-temperature decomposition, catalytic adsorption for impurity removal, amalgamation capture, and atomic absorption spectrometry (AAS). Based on the FT-NIR data of ALDC samples, LS-SVM models were established to distinguish mercury-contaminated and ordinary soil. The results of reference analysis showed that the mercury level of the areas surrounding mercury mines (0–3 kilometers, 7.52–88.59 mg/kg) was significantly higher than that of the areas distant from mercury mines (>5 kilometers, 0–0.75 mg/kg). The LS-SVM classification model of ALDC samples was established based on the original spectra, smoothed spectra, second-derivative (D2) spectra, and standard normal transformation (SNV) spectra, respectively. The prediction accuracy of D2-LS-SVM was the highest (0.950). FT-NIR combined with LS-SVM modeling can quickly and accurately identify the contaminated ALDC. Compared with traditional methods which rely on naked eye observation of plants, this method is objective and more sensitive and applicable.

Highlights

Excessive mercury is one of the major heavy metal pollutants in the environment, which can cause great toxicity to human body [1,2,3]
Mercury exists in soils in different forms, such as Hg0, Hg22+, Hg2+, and organic mercury. ere is a complex interaction between different forms of mercury under specific environmental conditions; for example, mercury can be converted into highly toxic methylmercury in the soil [6]
According to previous research experience, there is little difference in mercury content between plants near the same sampling location, and considering that the rapid spectral identification method is qualitative, the mercury content of batches of samples near mercury mines and batches of samples far away from mercury mines was determined in this paper as a reference for the

Summary

Introduction

Excessive mercury is one of the major heavy metal pollutants in the environment, which can cause great toxicity to human body [1,2,3]. A series of environmental pollution incidents have aroused great attention to mercury pollution in the world [4]. The study of mercury pollution in soil has become one of the hotspots of environmental protection [5]. Ere is a complex interaction between different forms of mercury under specific environmental conditions; for example, mercury can be converted into highly toxic methylmercury in the soil [6]. Erefore, in recent years, the development of trace mercury extraction, enrichment, and detection methods [7] has become one of the hot research fields of analytical chemistry. Easy migration, and high toxicity of mercury pollution in soil, the analysis and detection technology of mercury in soil is of great significance to soil monitoring and the effective control of mercury pollution.

Methods

Results

Conclusion