A geochemical baseline-source analysis-multidimensional risk assessment-management response framework for lead-zinc...

Soil trace metal(loid) background values (BVs) are important in risk assessment, but regional BVs are difficult to obtain. Here, BVs in the Daqiao river basin were established using a cumulative frequency distribution approach with deep (> 100 cm) soil samples. A multidimensional risk assessment method evaluated the metal(loid) pollution and risks across three irrigated areas (first, FI; second, SI; and third, TI) and one unirrigated control area (UI). In addition, correlation analysis and positive matrix factorization were used to identify and quantify the pollution sources. The average BVs of chromium (Cr), nickel (Ni), copper (Cu), arsenic (As), cadmium (Cd), lead (Pb), and zinc (Zn) were 81.3, 41.4, 41.4, 16.6, 0.34, 43.7, and 118.0 mg kg^-1, respectively. In FI, SI, and TI, soils were highly contaminated with Cd, Pb, Zn, and As, derived primarily from wastewater irrigation, occupying 58-73%; and Cr, Ni, and Cu mainly from natural sources, occupying 62-89%. UI was slightly contaminated with Cu, Cd, and Pb, derived mainly from atmospheric deposition (38-52%) and natural sources (34-44%). Cadmium posed high potential ecological risks in FI (93%) and SI (96%), and Cd and As represented a health risk to children in irrigated regions. Soil remediation should be prioritized in FI, then in SI and TI; Cd should be targeted first, followed by Pb, As, Cu and Zn. This systems approach offers scalable solutions for global mining landscapes threatened by legacy pollution and evolving irrigation practices.