Ecological risk assessment of toxic metal pollution in the industrial zone on the northern slope of the East Tianshan Mountains in Xinjiang, NW China

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.