Long-term dynamics of leachate production, leakage from hazardous waste landfill sites and the impact on groundwater quality and human health.

The long-term dynamics of leachate leakage from hazardous waste landfills (HWLs) and its influence on the surrounding groundwater and human health urgently requires decision-making processes for long-term HWL management and risk control. This study, based on the DMFU model, which is described in the literature as simulating the performance degradation of a landfill's main functional units, constructs a comprehensive model by coupling the HELP, EPACMTP, and Dose-Effect modules to investigate the long-term emissions of leachate from HWLs and their potential influence on groundwater quality and human health. Our results showed that the leakage rate over a long time period (50-1000 years) is 10 times higher than that of either a short (0-10 years) or medium (10-50 years) period. Due to the substantial increase in leakage rate, the negative influence on regional groundwater quality and human health changes from "insignificant" in the short term to "slight but acceptable" in the medium term, and finally to "substantial and unacceptable" in the long term. Studies also reveal that the uncertainty of risk increases over time. The information gained from this research provides useful insights into the long-term dynamics of leachate leakage, its risk consequences, and associated uncertainty, which can help landfill owners or risk managers make better decisions regarding the after-closure management of landfills.