Risk Assessment and Source Identification of Toxic Metals in the Agricultural Soil around a Pb/Zn Mining and Smelting Area in Southwest China

Abstract

Mining and smelting activities are the primary sources of toxic metal pollution in China. The purpose of this study was to investigate the pollution risk and identify sources of metals in the arable soil of a Zn/Pb mining and smelting district located in Huize, in Southwest China. Topsoil (346) and profile (three) samples were collected and analyzed to determine the total concentrations of eight toxic elements (Cd, Hg, As, Pb, Cr, Cu, Zn and Ni). The results showed that the mean Cd, Hg, As, Pb, Cr, Cu, Zn and Ni concentrations were 9.07, 0.37, 25.0, 512, 88.7, 239, 1761 and 90.3 mg/kg, respectively, all of which exceeded both the Huize and Yunnan soil background levels. Overall the topsoil was quite acidic, with a mean pH of 5.51. The mean geoaccumulation index (Igeo) revealed that the pollution level was in the order of Pb > Zn > Cd > Hg > As > Ni > Cu > Cr. The ecological risk index (Ei) indicated that there were serious contamination risks for Cd and Hg, high risk for Pb, moderate risk for As, and Cd and Hg were the dominant contributors to the high combined ecological risk index (Er) with a mean parameter of 699 meaning a serious ecological risk. The Nemerow pollution index (Pn) showed that 99.1% of soil samples were highly polluted or worse. Horizontally, high concentrations of Cd, Hg, As, Pb and Zn appeared in the north and middle of the study area, while Cr, Cu and Ni showed an opposite trend. Vertically, as the depth increased, Cd, Hg, As, Pb and Zn contents declined, but Cr, Cu and Ni exhibited an increasing trend. The mobilities of the metals were in the order of Zn > Cd > Hg > As > Pb. Horizontal and vertical distribution, coupled with correlation analysis, PCA and CA suggested that Cd, Hg, As, Pb and Zn mainly came from the anthropogenic sources, whereas Cr and Ni had a lithogenic origin. The source of Cu was a combination of the presence of parent materials as well as human activities. This study provides a base for the local government to control the toxic metal pollution and restore the soil environment system and an effective method to identify the sources of the studied pollutants.

Evaluating Metal(loid)s Contamination in Soil of a Typical In-Dustry Smelting Site in South Central China: Levels, Possible Sources and Human Health Risk Analysis

“…Correlation analysis (CA) and PCA can reflect the correlation among metal(loid)s levels to some extent and distinguish the different groups of metal(loid)s [44], which was used to reveal the association of the source of metal(loid)s in the study area. A strong correlation can reveal the close relationship between elements, indicating that these elements may have common sources and similar migration pathways [35,49], which can provide a reference for the traceability of metal(loid)s. The relationships among Cr, Mn, Zn, Pb, Cd, As, and pH were examined by Pearson's correlation analysis, as shown in Table 2. The correlations among Pb, Zn and Cd were highly significant at the p < 0.01 level (r > 0.77).…”

“…Moreover, exploring the pollution sources and spatial distribution of metal(loid)s has provided an important reference for identifying the pollution degree and formulating pollution prevention strategies [8]. Currently, kriging interpolation combined with correlation analysis, principal component analysis (PCA), and positive matrix factorization model (PMF), have been considered as highly effective methods used to determine the possible sources of pollutants [34][35][36], and allocate natural or anthropic contribution [8,35]. Furthermore, the influence of metal(loid)s on human health can be examined by determining whether the carcinogenic risk and hazard quotient of elements exceed the risk acceptance threshold.…”

Environmental Impact of Lefa Gold Mining on Its Local Population, Republic of Guinea

“…Traditional wells recharge from surface water and precipitation, mining by its nature consumes can seriously affect water resources [39] which can be a danger for the surrounding population, which can occur by chemical contamination and pollution, and erosion and sedimentation. Indeed, the diffusion of the contamination in the air, water and towards the biosphere, and the chain may subject people to exposure to metals that may pose a health risk if toxicity thresholds determined by international health surveillance institutions (US EPA, OM) are exceeded [40]. In Table 6 The result of the extraction of the ore and the process used to get the gold…”

Source and Health Risk Assessment of Heavy Metals in Non-Certified Organic Rice Farming at Nakhon Nayok Province, Thailand

“…Relationship analysis was undertaken to assess the relationship between Pb, Cu, Ni, Mn, Zn content and the area's physical properties, BAF or heavy metal content in soils and rice grain at P=0.05 or P=0.01 level according to statistical software. As the preferred tool for identifying pollution sources, principal component analysis (PCA) was applied to the data from this study [16][17] analysis.…”