Methane emission dynamics from a Danish landfill: The effect of changes in barometric pressure.

K Kissas,C Scheutz,A Ibrom,P Kjeldsen

doi:10.1016/j.wasman.2021.11.043

K Kissas, C Scheutz + Show 2 more

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https://doi.org/10.1016/j.wasman.2021.11.043

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Abstract

This study investigates temporal variability on landfill methane (CH4) emissions from an old abandoned Danish landfill, caused by the rate of changes in barometric pressure. Two different emission quantification techniques, namely the dynamic tracer dispersion method (TDM) and the eddy covariance method (EC), were applied simultaneously and their results compared. The results showed a large spatial and temporal CH4 emission variation ranging from 0 to 100kgh-1 and 0 to 12μmol m-2 s-1, respectively. Landfill CH4 emissions dynamics were influenced by two environmental factors: the rate of change in barometric pressure (a strong negative correlation) and wind speed (a weak positive correlation). The relationship between CH4 emissions and the rate of change in barometric pressure was more complicated than a linear one, thereby making it difficult to estimate accurately annual CH4 emissions from a landfill based on discrete measurements. Furthermore, the results did not show any clear relationship between CH4 emissions and ambient temperature. Large seasonal variations were identified by the two methods, whereas no diurnal variability was observed throughout the investigated period. CH4 fluxes measured with the EC method were strongly correlated with emissions from the TDM method, even though no direct relationship could be established, due to the different sampling ranges of the two methods and the spatial heterogeneity of CH4 emissions.

Highlights

Atmospheric methane (CH4) concentration has steadily increased from 1650 ppbv to 1850 ppbv over the last 40 years, following the application of systematic measurements (IPCC, 2019a)
Landfill CH4 emissions dynamics were influenced by two environmental factors: the rate of change in barometric pressure and wind speed
The highest CH4 fluxes were detected in the western sector of the eddy covariance method (EC) mast, where a hotspot is located inside the footprint area of the measuring station (Fig. 1)

Summary

Introduction

Atmospheric methane (CH4) concentration has steadily increased from 1650 ppbv to 1850 ppbv over the last 40 years, following the application of systematic measurements (IPCC, 2019a) This increase can be attributed – with a very high level of confidence – to anthropogenic activities such as agriculture and waste management, which contribute more than 50% of worldwide anthropogenic CH4 emissions (Ciais et al, 2013). According to the most recent Denmark’s National Inventory Report (Nielsen et al, 2020), Danish waste disposal facilities represent the second largest anthropogenic CH4 source, ac counting for around 7.5% in 2018 These results are based on modelled estimates using input parameters such as disposed waste amounts and compositions (IPCC, 2019b, 2006). Various measurement techniques have been used to quantify CH4 emissions from landfills, for example surface flux chambers, tracer gas dispersion, mass balance and eddy covariance (Mønster et al, 2019)

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