摘要：Mercury (Hg) released from landfill Hg waste poses serious health and environmental risks. The Minamata Convention on Mercury (2017) emphasizes preventative management: landfills are to be stabilized and Hg waste controlled. When developing stabilization/solidification technologies to ensure the safety of landfilled Hg waste, leaching and headspace tests are currently used to assess dissolution and diffusion. However, it remains unclear whether Hg wastes remain stable in real landfill environments because there are few findings from long-term landfill experiments on Hg wastes. We used lysimeters and followed previous long-term semi-aerobic/anaerobic simulated-landfill experiments on dry-cell batteries to investigate Hg dissolution and diffusion of sulfurized/solidified Hg wastes in simulated landfill environments. Total Hg (THg) release from the lysimeters, containing sulfurized/solidified Hg waste, to the atmosphere was extremely small. Examination of Hg behavior in different landfill types, however, found semi-aerobic types to be associated with lower Hg dissolution and diffusion risks than anaerobic types. Regarding Hg behavior of sulfurized/solidified Hg wastes, Hg sulfide (HgS) waste solidified by cement was found to be more stable than non-solidified HgS waste and dry-cell batteries. Methyl Hg (M-Hg) monitoring in leachates found M-Hg concentration in leachates to fall below 0.5 µg/L under almost all landfilling conditions, with time change trends moving in tandem with changes in leachate T-Hg. Volatilization and leaching tests involving sulfurized/ solidified Hg wastes were performed while simulating landfill changes to judge important factors in landfilling conditions regarding Hg dissolution and diffusion through comparison with lysimeter experiment results. Laboratory tests showed temperature and pH (alkaline) to affect the stability of sulfurized/solidified Hg wastes and elucidated effects assumed to enhance Hg dissolution and diffusion in the lysimeter experiments.
