From Active Use to Abandoned Risk: Evaluating Heavy Metal Persistence and Soil Ecotoxicity in Eastern Free State Landfills, South Africa

Open dumps and poorly managed landfill sites pose significant environmental, health, and ecological risks. This study investigated the extent of heavy metal contamination in soils collected from two municipal landfill sites in the eastern Free State, South Africa, over the period 2022–2024. One of these sites remains operational, while the other has been abandoned. Soil samples were collected at 20‐cm depth and analyzed for physicochemical properties, heavy metal concentrations, and ecotoxicological effects on earthworms ( Eisenia fetida ) and collembolans ( Folsomia candida ). Elevated concentrations of heavy metals exceeding South African allowable limits were detected at both sites. At the abandoned landfill, chromium (65.8 ppb) and manganese (4920 ppb) concentrations exceeded permissible levels, while at the active landfill, copper (176 ppb) and manganese (4740 ppb) surpassed threshold values. Ecotoxicological assays revealed that approximately 65% of earthworms avoided soils from the active landfill, suggesting higher contamination and biological stress, whereas only 20% avoided soils from the abandoned landfill, indicating reduced but persistent contamination. Notably, manganese and copper concentrations, which were previously undetectable in 2022 at the abandoned site, reappeared and increased in 2024, suggesting remobilization of residue contaminants. These findings highlight the enduring environmental risks associated with abandoned landfills and underscore the importance of effective remediation strategies and robust waste management practices to reduce long‐term ecological impacts.