Methane Fluxes from a Swedish Landfill Determined by Geostatistical Treatment of Static Chamber Measurements

Methane emissions from a Swedish landfill were measured with a static chamber technique on three occasions during 1997. Methane flux rates ranged from −15.2 × 10 - 3 to 40 g of CH 4 m - 2 h - 1, and the spatial variability was high (CV = 343−386%). The spatial distribution of the emissions was estimated with the help of ordinary kriging, which is a spatial interpolation method. Three different approaches to estimate the total amounts were used: kriging on logarithm-transformed data, kriging with extremes excluded, and linear interpolation of measurements. These were compared between themselves and with the flux rates measured with a tracer gas technique. While the latter gave an estimate of 41 kg of CH 4 h - 1 from the landfill (with small variations), the highest possible estimate obtained with static chambers and geostatistical methods was 9.7 kg of CH 4 h - 1 . The conclusion is that static chambers can hardly be trusted for making more than small-scale estimates of landfill gas emissions.