Field Methane Oxidation Efficiency at Municipal Solid Waste Landfills Located in the North of China

Municipal solid waste (MSW) landfills are one of main sources of anthropogenic methane emissions in China, and methane has been predicted to be the most significant greenhouse gas after 2030. In landfills, oxidation can take place naturally with methane migrating through the landfill cover. The value of fraction of methane oxidation recommended by the US EPA is 10%, which, however, is being challenged with more and more field measurement data from the Europe and the US. The characteristic of MSW in China is extremely different from that in the US, probably resulting in distinct differences in both methane generation and oxidation. The objective of this study was to determine the fraction of methane oxidized at MSW landfills in China and its spatial and temporal variations. Stable isotope technique was applied to determine the fraction of methane oxidized. The results showed that the fraction of methane oxidized where MSW was covered by soil ranged from 6.3% to 100% in Northeast China and 31% to 100% in North China. Methane oxidation could hardly occur in the operating surface. Besides, soil cover always had a high methane oxidation efficiency in summer. The fractional oxidation of methane in summer was more than 2 times than that in winter. All over the year, with the sampling depth decreasing, the fraction of methane oxidation of soil cover increased.