Investigation of methane fluxes from temporary cover of Xi’an Jiangcungou landfill, China

Abstract

Methane emissions from the Jiangcungou municipal solid waste landfill in China were examined using a static chamber. The monitoring results were compared firstly with those obtained from the California Landfill Methane Inventory Model (Calmim). The monitoring results show that average methane emission flux from the temporary cover is one to two orders of magnitude greater than those from the final cover and the working face. This is because the methane generation rate reaches its maximum at less than 1 year after the wastes were landfilled. The observed methane fluxes are comparable with those obtained by Calmim. The observed results are lower than those predicted by Calmim, which were 74.98 and 98.64 (g/m2)/day, respectively. The difference is reasonable because the results obtained by field monitoring are transient, while those simulated by Calmim are the average daily flux. Moreover, Calmim considers only one-dimensional gas transport through the cover and neglects lateral gas migration. The model results indicate that there is a strong seasonal variability due to the variation in rainfall amount in different months. The methane emission amount was greatly reduced with the increase in vegetation coverage due to the increase in the volumetric water content of the soil induced by the water retention capability of vegetation.