Vegetation plays an important role in CH4 transport and oxidation in landfill cover soil. This study investigated CH4 emission fluxes in two landfills with different surface coverage conditions and it found that the CH4 emission fluxes presented spatial and temporal disparities. A significant discrepancy in CH4 emission flux between day and night in areas covered with Kochia sieversiana indicated that enhanced diffusion induced by rising temperature was the main mechanism for CH4 transport during daytime. A significant increase of CH4 emission flux after the K. sieversiana and Suaeda glauca plants were cut indicated that these plants provide greater contributions to CH4 oxidation than to CH4 transport. Diel CH4 emission flux was found closely correlated with the climatic conditions. Diffusion was determined as the main mechanism for CH4 transport at daytime in bare area, mediated by solar radiation and air temperature. Diffusion and plant-mediated transport by convection was established as the main transport mechanism in areas covered with K. sieversiana. Our results further the understanding of both the CH4 emission mechanism and the impact of vegetation on CH4 oxidation, transport, and emission, which will benefit the development of a reliable model for landfill CH4 emissions.
Keywords: CH emission; diffusion; landfill; meteorological parameters; vegetation.