Landfill description and gas samplingField studies were conducted at a typical flat sanitary landfill innorthern China with a designed filling capacity of 1.19 107 m3.The landfill mainly deals with MSW that originate from several districtsof Beijing. The compacted waste is covered with an HDPEmembrane, except for the working face (i.e., the open cell), whichoften causes serious odor pollution to surrounding communities.Sampling campaigns were conducted at the working face of thelandfill on selected days in different seasons from 2012 to 2014(Table 2). Air samples at a height of 1.5 m above the surface (i.e.,breathing zone) of the working face were withdrew to 8 Lbio-oriented polyester odor free bags (Environmental Science andTechnology Development Co., Ltd., China) through a speciallydesigned sampler. Detailed sampling method was described bythe authors elsewhere (Duan et al., 2014). Meteorological dataincluding temperature, wind speed, and humidity were also recorded during sampling. All the samples were taken to the laboratoryand analyzed within 24