This paper is the result of geological survey engineering.

Objective A total of 775 soil samples were collected in Longshan County to analyze the content characteristics of heavy metals in soil, including As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn, and to evaluate the health risks associated with these contaminants.

Methods The geo−accumulation index was applied to assess soil heavy metal pollution levels. Correlation analysis and principal component analysis were used to identify the sources of soil heavy metals. A health risk model was employed to evaluate the potential risks posed by these metals to human health.

Results The analysis revealed that the average Cd concentration in Longshan County soils significantly exceeds the background value for Hunan Province, indicating a certain degree of Cd enrichment. The variation coefficients for As and Cd exceeded 0.5, while Hg's coefficient surpassed 1, suggesting a potential influence from human activities. Various degrees of contamination by As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn were identified, with widespread Cd pollution and severe Hg contamination in certain areas. The sources of these heavy metals were categorized into three groups: (1) Cr, Cu, and Ni primarily originate from soil parent materials; (2) As, Cd, Pb, and Zn are largely linked to lead−zinc mining and smelting, with Cd also showing some association with geological background; (3) Hg primarily stems from fossil fuel combustion. The health risk assessment indicated that children face higher risks from soil heavy metals compared to adults. Attention should be focused on the health risks in Liye Town, Miaoertan Town, and Luota Town. As and Cr were identified as the primary contributors to non−carcinogenic risks, while Cr and Ni were the main contributors to carcinogenic risks. Oral ingestion was found to be the dominant exposure pathway for health risks.

Conclusions Heavy metal pollution in Longshan County soils exists at varying levels. As, Cd, and Ni are the primary contributors to health risks.