Heavy metal contamination, source apportionment and health risk in soil-crop systems of high-geochemical-background Pb-Zn mining area

Abstract

Summary Mining and smelting, combined with high-geochemical-backgrounds, cause heavy metal accumulation in soil-crop systems, endangering food-chain health. Topsoil (0–20 cm) and three local crops were sampled from Yunnan’s Huize lead-zinc mining area. Pb, Zn, Cu, Cd contamination, spatial patterns, source contributions and risks were assessed via ArcGIS interpolation, PN, RI, APCS-MLR, PMF, and USEPA health risk models. All soils exceeded Yunnan background values (100% exceedance), presenting extreme ecological risks mainly driven by Cd (92.94%). Cd has the highest bioavailability, while Pb existed mostly potentially bioavailable. Leafy crops show 100% over-standard rates for Pb and Cd, maize exceeds Pb limits. Four pollution sources were identified. Ingestion was the primary exposure pathway. Children suffered prominent non-carcinogenic Pb risks, while all populations encountered unacceptable Cd carcinogenic risks. Mismatches between soil metal contents and crop safety reveals uniform soil-standard limitations, offering references for pollution control, crop-layout optimization and differentiated risk management in analogous mining areas.