Ecological Assessment, Spatial Analysis, and Potential Sources of Heavy Metals (HMs) in Soils with High Background Values in the Lead-Zinc Mine, Hezhang County, Southwestern China

Fugui Zhang,Ling He,Chengwen Wang,Xiaomeng Cheng,Honghong Ma

doi:10.3390/w14050783

Fugui Zhang, Ling He + Show 3 more

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https://doi.org/10.3390/w14050783

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Abstract

The heavy metals (HMs) usually have high natural background levels in lead-zinc mines. Strengthening the ecological risk assessment and accurate identification sources of HMs is an important component of land resource utilization and food security. A total of 795 soil samples (with a depth of 0~20 cm) were collected in Hezhang County, an area of typical high background levels of HMs with more than 18 large lead-zinc deposits. In this study, inductively coupled plasma emission spectrometry (ICP-OES), inductively coupled plasma mass spectrometry (ICP-MS), atomic fluorescence spectrometry (AFS), and the potentiometric method (POT) were used to test the total concentration of HMs and pH values. The geographic information system was used to model the concentration distribution of HMs, and the ecological risk was assessed according to the source analysis results. The results suggest that: (1) the mean concentration of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn were 24.55, 2.25, 176.4, 89.6, 0.19, 64.2, 102, and 257 mg·kg−1, respectively, which exceeded the average background value of soils in Guizhou Province by 1.23, 3.41, 1.84, 2.80, 1.73, 1.64, 2.90, and 2.58 times, respectively, and the average concentrations of Cd, Cr, Cu, Ni, Pb and Zn exceed the screening values specified in soil contamination risk in agricultural land; (2) the results of enrichment factor (EF) showed that 29.73% of Cd are moderately polluted, and other HMs were slightly polluted in a small area or near the baseline value (EF ≈ 1); and (3) PMF analysis showed that there are five main sources, pyrite, lead-zinc ore, basalt, carbonate rock, and agricultural production, with the risk contribution ratios of 5.25%, 27.37%, 28.94%, 17.91%, and 20.53%, respectively.

Highlights

Soil is the basis for agricultural production and human survival, and it is the guarantee for human food and the ecological environment [1]
The mean concentrations of heavy metals (HMs) in topsoil are higher than the average background value (ABV) of Guizhou
The average concentrations of Cd, Cr, Cu, Ni, Pb, and Zn exceed the screening values specified in the risk control standard for soil contamination of agricultural land (GB 15618–2018), indicating HMs accumulated in the topsoil

Summary

Introduction

Soil is the basis for agricultural production and human survival, and it is the guarantee for human food and the ecological environment [1]. With the development of industry and the continuous expansion of urbanization in recent years, the problem of soil pollution caused by heavy metals (HMs) has become a hot issue in modern society [2,3]. When HMs in the soil are transformed into ionic form and enter into the crops, they are introduced into the human body through the food chain, which may cause serious harmful impacts on human health [7–13]. Protection Agency (USEPA) and the Ministry of Ecology and Environment of China (MEE), have formulated the maximum allowable limits of HMs in agricultural soils to protect environmental quality and human health [14]. China’s economy has grown rapidly, with an increasingly prominent soil pollution problem.

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