Soil Heavy Metal Pollution and Health Risk Assessment Based on Monte Carlo Simulation: Case Study of Xicheng Lead-Zinc Mining Area
Lixia Wang, Qiang Liu, Ronglong Bai
Abstract
To investigate the status of heavy metal pollution and the associated ecological and health risks in farmland surrounding the Xicheng lead and zinc mining area, we collected soil samples (0–20 cm) and measured the level of As, Ni, Cu, Zn, Cd, Pb, Hg, and Cr. The characteristics of soil heavy metals, pollution levels, and ecological, and health risks were quantitatively assessed using Monte Carlo simulation in conjunction with the geo-accumulation index (Igeo), pollution index (Pi), ecological risk index (Er), and human health risk assessment model. The results indicated that the average concentrations of As, Ni, Cu, Zn, Cd, Pb, Hg, and Cr in the soil of the study area were 26.92, 39.46, 31.18, 340.23, 1.13, 184.61, 0.34, and 71.15 mg·kg−1, respectively. These values were significantly higher than the soil background levels reported for Gansu Province. The average Igeo for Hg was 3.27, and the average Er was 679.13, indicating that Hg had the highest accumulation and posed the greatest ecological risk in the study area. The average single-factor pollution index for Cd was 2.52, marking it as the heavy metal with the highest pollution level. The cumulative probability of health risk derived from Monte Carlo simulation indicates that the non-carcinogenic hazard indices for adults and children were 2.79 × 10−1 and 1.67, respectively, with 94.82% of children exceeding the non-carcinogenic risk threshold. The carcinogenic risk indices (TCR) for adults and children were 8.09 × 10−5 and 4.60 × 10−4, respectively, and 100% of the samples exceeded the TCR standard for children. As and Cd were identified as the primary contributors to both carcinogenic and non-carcinogenic risks. The findings enhance our understanding of heavy metal contamination in farmland soils and establish an empirical framework for developing targeted remediation approaches and sustainable land management practices.