Ecological and health risk assessment of heavy metals in soils and their distribution in dominant plants in the Xikuangshan mining area

In order to understand the characteristics of heavy metals in the soil around the Xikuangshan mining area(XKS) and their distribution in dominant plants, field investigations were conducted to analyze the quantities, sources, ecological and health risks, enrichment coefficients, and transfer factors of heavy metals in the dominant plants at 16 sampling points in the XKS. The results showed that the average concentrations of Sb, Cd, and Hg exceeded the corresponding background values of Hunan by 100%. The source analysis suggested that Sb, Hg, Zn, Cd, Pb, and As were mainly contributed by human activities. However, the sources of heavy metal pollution were not completely consistent, and there was combined pollution. The potential ecological hazard factor analysis showed that Sb, Cd, and Hg were the main single ecological hazard factors, and 62.50% of the samples possessed a very high comprehensive ecological risk index. The heavy metal health risk assessment results showed that the main pathway of human exposure was oral ingestion, and children were more susceptible to heavy metal pollution. Sb and As were the major non-carcinogenic and carcinogenic contributors, respectively. The enrichment coefficients and transfer coefficients of As and Sb in Boehmeria nivea were greater than 1, and their retention rates in heavily polluted areas were lower than those in the other six dominant plant species. Generally, there were severe ecological risks and health risks in the XKS. Boehmeria nivea has a strong potential for remediation of heavy metals and can be used as a remediation plant for heavy metal pollution in the XKS