Landfill methane emissions measured by enclosure and atmospheric tracer methods

Abstract

Methane (CH 4 ) emissions were measured from the Nashua, New Hampshire municipal landfill using static enclosure and atmospheric tracer methods. The spatial variability of emissions was also examined using geostatistical methods. One hundred and thirty nine enclosure measurements were performed on a regular grid pattern over the emitting surface of the landfill resulting in an estimate of whole landfill emissions of 15,800 L CH 4 min −1 . Omnidirectional variograms displayed spatial correlation among CH 4 fluxes below a separation distance of 7 m. Eleven tracer tests, using sulfur hexafluoride (SF 6 ) as a tracer gas, resulted in a mean emissions estimate of 17,750 L CH 4 min −1 . The favorable agreement between the emission estimates was further refined using the observed relationship between atmospheric pressure and CH 4 flux. This resulted in a pressure‐corrected tracer flux estimate of whole landfill emissions of 16,740 L CH 4 min −1 .