A technique to measure biological methane oxidation in landfill cover soils that is gaining increased interest is the measurement of stable isotope fractionation in the methane. Usually to quantify methane oxidation, only fractionation by oxidation is taken into account. Recently it was shown that neglecting the isotope fractionation by diffusion results in underestimation of the methane oxidation. In this study a simulation model was developed that describes gas transport and methane oxidation in landfill cover soils. The model distinguishes between 12CH4, 13CH4, and 12CH3D explicitly, and includes isotope fractionation by diffusion and oxidation. To evaluate the model, the simulations were compared with column experiments from previous studies. The predicted concentration profiles and isotopic profiles match the measured ones very well, with a root mean square deviation (RMSD) of 1.7 vol% in the concentration and a RMSD of 0.8? in the ä13C value, with ä13C the relative 13C abundance as compared to an international standard. Overall, the comparison shows that a model-based isotope approach for the determination of methane oxidation efficiencies is feasible and superior to existing isotope methods.

Keywords: methane oxidation, landfill cover soils, stable isotope fractionation, methane, methane oxidation

Auteur: Koenraad Mahieu, Alex De Visscher, Peter A. Vanrolleghem, Oswald Van Cleemput
Herkomst: Waste Management, Volume 28, Issue 9, 2008, Pages 1535-1542
Referentie: Referentie