Pollution Characteristics and Risk Assessment of Heavy Metals in Soil of Alisma orientale in Sichuan
Heavy metal contamination in soil severely compromises the quality and safety of Alisma orientale medicinal materials, and consumption of contaminated herbal preparations poses health risks. To characterize contamination and risks in Sichuan's genuine producing areas, 159 paired soil and plant samples were collected. Concentrations of Cu, Zn, Pb, Cd, and Ni were determined via ICP-OES. Soil pollution was assessed using the Single Pollution Index (Pi), Nemerow Comprehensive Index (Pn), and Potential Ecological Risk Index (RI). Human health risks from heavy metals in Alisma were evaluated via Target Hazard Quotient (THQ) and Hazard Index (HI). Mean soil concentrations were Cu 29.57, Zn 61.86, Pb 29.51, Cd 1.77, and Ni 28.08 mg·kg−1. Except for Cd, all elements were below agricultural soil screening values. Pi and Pn confirmed Cd contamination, with Cd posing slight to strong potential ecological risks. Cu, Cd, Pb, and Ni showed highly significant positive correlations, indicating common origins. Heavy metal concentrations in Alisma did not exceed pharmacopeial limits. The plant exhibited strong Zn enrichment but weak accumulation of Cu, Cd, and Pb, and negligible Ni enrichment. THQ and HI values indicated no potential health risks under current exposure. Quantitative assessment is critical for soil pollution control, safe cultivation, and medication safety.