Assessment of the Effects of Heavy Metals in Soils after Removal by Nanoscale Zero-Valent Iron with Three Methods

Tianen Zhang,Bing Xia,Shu Jin,Hongfeng Chen,Rongrong Ying,Yuanyuan Lu,Xiaoyu Zhang

doi:10.3390/su14042273

Tianen Zhang, Bing Xia + Show 5 more

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https://doi.org/10.3390/su14042273

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Abstract

Nanoscale zero-valent iron (nZVI) has been broadly applied in the remediation of heavy metals pollution. In this research, the toxicity characteristic leaching procedure (TCLP), the in vitro gastrointestinal (IVG) method, and the diffusive gradients in thin-films (DGT) technique were used to evaluate the effects of heavy metals in soil with remediation by nZVI. The results indicate that, compared with the dose of 0.5 g·L−1, the nZVI in the dose of 1.0 g·L−1 can remove the heavy metals in the soil. The leaching toxicities of the heavy metals (Cr, Cu, Zn, Pb) showed apparent decreases after the remediation by nZVI. In the gastric phase, the highest bioaccessibility values of the Cr, Cu, Zn, Pb were decreased by 27.2, 31.7, 11.7, and 20.1%, respectively. Moreover, in the gastric phase, the highest bioaccessibility values of the Cr, Cu, Zn, Pb were decreased by 5.5, 1.29, 8.0, and 7.3%, respectively. The availabilities of the heavy metals were also reduced. The above results show that the nZVI effectively reduced the heavy metal pollution in the soil.

Highlights

Soil is the material basis for human survival
Whether the pollution is in industrial and mining wastelands, or in contaminated agricultural soil in relatively small amounts, it is often manifested as the compound pollution of multiple heavy metals [7]
Heavy metals often enter the environment in the form of inorganic and organic mixtures, and they contain a variety of metals, which jointly produce a certain synergistic, or antagonistic, effect, and which have an impact on organisms and ecosystems

Summary

Introduction

Soil is the material basis for human survival. With the development of industry and agriculture, and the application of the three main types of industrial wastes (municipal solid waste, and agricultural fertilizers and pesticides), large amounts of heavy metals are discharged into the environment [1]. Of the pollutants produced in the world every year are discharged into the soil, and that the pollution of heavy metals in the soil is becoming more and more serious [2,3,4]. The pollution of heavy metals in soil is diverse. When heavy metals exist in the soil for a long time, they reduce the soil quality of the surrounding area [5]. If heavy metals invade the surface and enter the water area, they affect the global water environment, cause a serious waste of ecological resources, and destroy the balance of the natural ecosystem [6]. Whether the pollution is in industrial and mining wastelands, or in contaminated agricultural soil in relatively small amounts, it is often manifested as the compound pollution of multiple heavy metals [7]. Heavy metals cannot be degraded by microorganisms; they can only undergo morphological transformation [8]

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