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Modelling of stable isotope fractionation by methane oxidation and diffusion in landfill cover soils

Journal Article · · Waste Management
 [1];  [2];  [3];  [1]
  1. Laboratory of Applied Physical Chemistry (ISOFYS), Ghent University, Coupure links 653, B-9000 Ghent (Belgium)
  2. Department of Chemical and Petroleum Engineering, Schulich School of Engineering, University of Calgary, 2500 University Drive N.W., Calgary, Alberta, T2N 1N4 (Canada)
  3. Department of Applied Mathematics, Biometrics and Process Control (BIOMATH), Ghent University, Coupure links 653, B-9000 Ghent (Belgium)
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 {sup 12}CH{sub 4}, {sup 13}CH{sub 4}, and {sup 12}CH{sub 3}D 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 per mille in the {delta}{sup 13}C value, with {delta}{sup 13}C the relative {sup 13}C 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.
OSTI ID:
21153983
Journal Information:
Waste Management, Journal Name: Waste Management Journal Issue: 9 Vol. 28; ISSN WAMAE2; ISSN 0956-053X
Country of Publication:
United States
Language:
English