Vinsamlegast notið þetta auðkenni þegar þið vitnið til verksins eða tengið í það: http://hdl.handle.net/1946/18690
Landfilling of biodegradable organic waste results in the generation of methane, along with other gases. If the gas is not collected through a recovery system, it will migrate through pores in the landfill cover and be released into the atmosphere, where it contributes to the global greenhouse gas budget. This study presents the first direct measurements of CH4 emissions from Icelandic landfill surface-covers. The main objective was to obtain evidence on the occurrence and scale of CH4 emissions at two Icelandic landfills, as well as the spatial variability of CH4 emissions over their surfaces. Gas flux measurements were conducted with a portable static chamber at two landfills, Kirkjuferjuhjáleiga and Fíflholt, in fall and winter 2012-2013. Data was statistically analyzed and showed that average CH4 emissions from the surveyed areas were 68 g m-2 day-1 from 65 measurements at Kirkjuferjuhjáleiga and 3 g m-2 day-1 from 54 measurements at Fíflholt. The results confirmed that CH4 emissions were not uniformly distributed, but rather heterogenous over the surveyed surfaces. Spatial variability was however more distinct at Kirkjuferjuhjáleiga than at Fíflholt, especially on a small-scale grid with 1.5-2 m between measurement points. Higher CO2:CH4 ratios in landfill gas emissions than the CO2:CH4 ratio in landfill gas from monitoring-wells, confirmed that oxidation was taking place in the cover at both landfill sites. Analysis of the landfill cover soils suggests that the cover at Fíflholt is more adequate for CH4 oxidation than the cover at Kirkjuferjuhjáleiga, mainly due to coarser soil texture, allowing for greater oxygen flow from the atmosphere into the soil. Conditions for CH4 oxidation were therefore assumed to be better at Fíflholt. Meteorological data showed that the intensity of average annual precipitation at Kirkjuferjuhjáleiga was almost double the intensity at Fíflholt in the previous years. It is suggested that greater precipitation at Kirkjuferjuhjáleiga may have enhancing effect on CH4 generation inside the landfill and inhibiting effect on oxidation in the cover soil. Finally, it was concluded that the portable static chamber used in the study is well suitable for methane measurements on confined areas rather than the whole-cell surface due to its small footprint and furthermore, only on smooth surfaces because of air-tightness limitations.