Abstract
Abstract The ecological risks of six toxic metals (Zn, Cu, Cr, Pb, Hg, and As) in the industrial zone on the northern slope of the East Tianshan Mountains in Xinjiang, northwest (NW) China, were assessed. The results showed that the soil toxic metal contents of Zn, Pb, Hg, and As exceeded the regional background values, and concentrations of Zn, Cu, Pb, and As exceeded the national soil environmental quality standards of China (GB15618-1995). The Cu and Cr contamination levels were lower than the limits of both soil standards and mainly originated from the parent material, Pb mainly originated from agricultural activity and traffic emissions, and Hg mainly originated from the coal burning and chemical industries. As contamination originated from automobile exhaust emissions, and Zn contamination was influenced by a combination of natural factors and human activities. The mean geo-accumulation index (I geo) values of As, Hg, and Pb ranged from unpolluted to moderately polluted. There was an area not polluted by Zn, Cu, and Cr. The pollution index (PI) value of the six heavy metals showed that the mean PI values of Zn, Cr, and Cu showed no pollution, As and Pb presented medium pollution, and Hg presented heavy pollution. The results of the potential ecological risk analysis in this region showed that Zn, Cu, Cr, and Pb in all sample sites presented a low risk, while Hg presented a high ecological risk. Therefore, it is necessary to prevent further Hg contamination in this region.
Highlights
Toxic metals are one of the major pollutants that cause potential hazards in the soil system
The potential ecological risk index (PRI) was proposed by the Swedish scientist Hakanson in 1980 to assess the ecological risk of soil toxic metals [39]
Where PRI is the sum of the potential ecological risk index of the toxic metals in the soil, ecological risk coefficients (Eri) is the potential ecological risk coefficient of a certain toxic metal, Tni is the toxicity coefficient, Cri is the pollution factor of the toxic metal, Ci is the measured value of the toxic metals in the soil, and Cni is the background value of the toxic metals
Summary
Toxic metals are one of the major pollutants that cause potential hazards in the soil system. A high concentration of soil toxic metals can cause significant degeneration of an ecosystem’s structure and function [7,8,9,10,11]; it has become a topic of great concern [12,13,14,15,16]. Both human activities and natural processes lead to heavy metal contamination in soils [3], human activities are typically the main contributor [17,18]. Effective monitoring and the management of toxic metal pollution in soils caused by coal mining are important areas of study
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