Potentially Toxic Element Contamination in Soils Affected by the Antimony Mine Spill in Northwest China

Abstract

This study provides a comprehensive assessment of the potential ecological and health risks in the area of the antimony mine spill in Longnan, Northwest China, and identifies the sources of potentially toxic elements (PTEs) in the soil as a result of the spill. The geo-accumulation index and enrichment factor show that the study area is highly contaminated with arsenic (As), mercury (Hg) and antimony (Sb). The ecological risk index in the tailings spill area ranged from 320.43 to 5820.46 (mean: 1489.82), indicating a very-high potential ecological risk, with mean values of 104.86, 1118.87 and 248.84 for As, Hg and Sb, respectively. The multivariate statistical analysis suggested that Sb and Hg come from tailings leakage, while copper (Cu), nickel (Ni) and zinc (Zn) may be imported from natural sources, and As and lead (Pb) originate from agricultural activities. In addition As and Sb pose a high health risk. With the exception of the non-carcinogenic risk in adults, all other risks are significantly exceeded in other populations, with children being the highest-risk group. These findings provide important quantitative information for the assessment and management of PTE contamination in other tailings spill areas.

Keywords: antimony; mining spill; multivariate analysis; potentially toxic elements; risk assessment; soil pollution.

Figure 1

Map of the study area and sampling locations. The numbers on the figure indicate the point numbers of the sampling locations. There are 27 sampling points.

Figure 2

Spatial interpolation results of the content of heavily contaminated PTEs. The numbers next to the sampling locations indicate the numbers of the sampling points.

Figure 3

Ecological potential risk index of the various PTEs recorded in soils of the study area.

Figure 4

Three-dimensional principal component loading plot of the PCA results.

Figure 5

Dendrogram of HCA of the concentration of PTEs in the soil samples.

Figure 6

HI and CCR for the contamination of PTEs overall for adults, adolescents and children. The three reference lines in Figure 6 are, in order of meaning from bottom to top: the reference line for HI = 1, the reference line for CCR = 10⁻⁶ and the reference line for CCR = 10⁻⁴.

Figure 7

Non-carcinogenic and carcinogenic risks of different PTEs for three populations. The black reference line in Figure 7 is the reference line for HQ = 1 and the red reference line is the reference line for CCR = 10⁻⁴.