Pathways of Mercury Emissions to Atmosphere from Closed Municipal Landfills
封闭式城市生活垃圾填埋场向大气释放汞的途径

Using the automated mercury vapor analyzer and dynamic flux chamber (DFC) method, the pathways of mercury emissions to atmosphere were measured at a closed landfill in Wuhan, China. The results show that the mainly pathway is by the surface cover, and emissions from vent pipes is negligible. Average Hg fluxes during the observation period was (192.5 +/- 245.3) ng x (m2 x h)(-1), which was 1 - 2 orders of magnitude greater than that from background zone. Hg flux exhibited a clearly diurnal pattern, reaching the maximum near midday and the lowest during night. Solar radiation was the environmental factor that has highest relationship with Hg flux, with coefficient of 0.77, this indicated that photo-reduction of Hg(II) being a prominent process in the production of volatile elemental mercury (Hg(0)). Mercury concentrations in landfill gas (LFG) at different vent pipes averaged from 7.0 - 68.9 ng x m(-3), which was much lower than that of operational landfills, and the flow rate of landfill gas was very slow.