Characteristics and mobility of heavy metals in an MSW landfill: implications in risk assessment and reclamation.

To assess the reclamation feasibility of a landfill, the characteristics, distribution, and mobility of heavy metals in the landfill were investigated. The refuse was characterized as containing high concentrations of heavy metals, a relatively high pH, and a high ratio of NH(4)-N to total nitrogen (TN). The results of heavy metal distribution showed that relatively high levels of heavy metals were accumulated in the landfill. Sequential extraction revealed that the relative amounts of heavy metals were different in the samples. Zn demonstrated the greatest mobility compared to other heavy metals, whereas Cd was well retained in the landfill. Leaching experiments indicated that the mobility of heavy metals in the landfill was generally low under normal neutral conditions. However, release of heavy metals can be increased greatly when medium conditions become more acidic and aerobic.