Potentially toxic elements in tailing-contaminated soils of Tongling, China: Pollution status, health risks and environmental capacity.

Comprehensive and accurate assessment regarding pollution status, health risks, and environmental capacity of potentially toxic elements (PTEs) in mine tailings is crucial for environmental management. This study develops a novel integrated framework that combines site-specific pollution assessment, probabilistic health-risk analysis, and dynamic environmental-capacity prediction. Application of framework to representative polymetallic tailing site revealed that As and Cu were primary pollutants in tailing-impacted soils of Tongling. Extreme anthropogenic enrichment of these elements and high ecological risk of Cd caused severe environmental degradation. Cumulative exposure to eight PTEs, primarily through oral ingestion, raised critical human health concerns, although individual elements presented low risks. Notably, scenario-based evaluation of Cr species provided precise risk boundaries and prevented severe toxicity overestimation. Compared to adults, vulnerable children experienced severe non-carcinogenic and carcinogenic risks, with exceedance probabilities ranges of 64.23-91.86% and 53.88-68.04%, respectively. Intense anthropogenic inputs completely exhausted static environmental capacities, causing severe deficits reaching -772.60 kg/hm2 for As and -692.31 kg/hm2 for Cu. Dynamic capacity simulations predicted continuous decline of residual capacity, while long-term conservation gradually restored environmental capacity in overloaded areas. The proposed integrated model provides standardized, globally applicable tool to quantify ecological red lines and guide remediation.