Trace metal pollution and ecological effects on five crops around a typical manganese mining area in Chongqing, China

Manganese mining and smelting release trace metals into surrounding agricultural systems, posing potential ecological and human health risks through crop contamination. We assessed the accumulation, tissue distribution, and risks of nine trace metals (Mn, Cd, Cu, Zn, Ni, Pb, As, Cr, and Sb) in five staple crops (rice, maize, peanut, soybean, and sweet potato) from a manganese mining area in Chongqing, China, using bioconcentration factors, pollution indices, and USEPA-based health risk models. Mn was the most abundant metal in all crops, with rice showing higher accumulation than other species (2.27–3.37-fold, p < 0.05). Rice also exhibited the highest Cr and As concentrations, while Cd and Zn were preferentially enriched in peanuts and soybeans (BCF > 1). Most metals were retained in roots and leaves, with limited accumulation in edible parts (BCF: 0.01–0.05). Pollution assessment identified rice as the most contaminated crop, with Cr and As in rice exceeding food safety thresholds (PN > 25). Health risk assessments indicated that rice consumption poses a potential risk of chronic arsenic exposure in adults and exhibits chronic toxic effects in children, whereas all other crops remained below the risk level (THQ < 1) for both adults and children. Rice is the dominant exposure pathway for trace metal health risks in mining-affected regions, whereas sweet potato, peanut, soybean, and maize are comparatively safer. These findings support crop substitution strategies and targeted soil remediation to enhance food safety in mining-impacted agricultural systems.