Methane emission dynamics from an old Danish landfill

Temporal variability on landfill methane (CH₄) emissions from an old Danish landfill was investigated in this study. Two direct field quantification techniques, namely the dynamic tracer dispersion method (TDM) and the eddy covariance method (EC), were applied simultaneously in the period December 2019 to June 2020. Results showed a large temporal emission variation ranging from 0 to 100 kg∙h^-1 and 0 to 12 μmol∙m^-2∙s^-1, respectively. Rate of change in barometric pressure was found to have the strongest effect on the response of CH₄ emissions/fluxes and correlated inversely. Periods with decreasing barometric pressure showed elevated CH4 emissions/fluxes, while increasing barometric pressure suppressed the fugitive CH₄ emission almost to zero. Temperature had not significant effect, whereas wind speed presented a weak positive correlation with CH₄ emissions. CH₄ fluxes measured continuously using the EC method were strongly correlated with emissions from the periodic measurements using TDM, demonstrating similar emission dynamics.