Micrometeorological Measurements of Methane and Carbon Dioxide Fluxes at a Municipal Landfill

摘要

Continuous and area-integrating monitoring of methane (CH_4) and carbon dioxide (CO_2) emissions was performed for 6 and 9 months, respectively, at a municipal landfill in Finland with the micrometeorological eddy covariance (EC) method. The mean CH_4 emission from June to December was 0.53 mg m~(-2) s~(-1), while the CO_2 emission between February and December averaged 1.78 mg m~(-2) s~(-1). The CH_4 emissions from the summit area of the landfill, where active waste deposition was going on, were 1.7 times as high as from the slope area with a better surface cover. The variation in emissions over the source area of the measurement was high. Significant seasonal variation, linked to air and soil temperature, was only seen in the CO_2 release rates. Results obtained with the EC method were comparable to those measured with closed static chambers. According to the EC measurements, the gas recovery system decreased CH_4 fluxes by 69-79%. The ratio of the measured CH_4 and CO_2 emissions roughly indicated the route of the landfill gas emission, resembling the ratio of the gases measured in the gas wells (1.24) when the emission originated from the area with no oxidizing cover layer and being smaller when CH_4 oxidation had taken place.