Integrated assessment of environmental risk in AMD-affected mine waste: mineralogical and geochemical perspectives

Abstract The long-term environmental legacy of mining in sulfide-rich regions remains a critical concern due to the persistent generation of acid mine drainage (AMD) and the mobilization of potentially toxic elements (PTEs). This study presents a comprehensive, site-specific assessment of mine waste from two contrasting geochemical zones, Nuestra Señora del Carmen (NSC) and Volta Falsa (VF), within the historically under-characterized Trimpancho Mining Complex, located in the Iberian Pyrite Belt (IPB). A multidisciplinary approach combining mineralogical characterization, physicochemical and geochemical analyses, multivariate statistics, and contamination indices, provided insights into the behavior, mobility, and ecological risk of key PTEs such as Cu, As, and Zn. The NSC zone is dominated by pyrite and secondary sulfates, promoting acidic conditions (pH values ranging from 2.42 to 3.60) and high Cu mobility, whereas VF waste materials show a more heterogeneous mineralogy, higher pH (ranging from 2.77 to 5.05), and broader PTE enrichment. Principal Component Analysis revealed distinct geochemical regimes shaped by the presence of sulfides or silicates. Contamination indices underscored significant ecological risk in both zones, but with distinct pollution signatures. This integrated framework supports site-specific environmental risk management and remediation strategies and applies to other AMD-impacted volcanogenic massive sulfide (VMS) mining environments facing renewed exploration pressures.