title: Modeling the effects of vegetation on methane oxidation and emissions through soil landfill final covers across different climates.
abstract: Plant roots are reported to enhance the aeration of soil by creating secondary macropores which improve the diffusion of oxygen into soil as well as the supply of methane to bacteria. Therefore, methane oxidation can be improved considerably by the soil structuring processes of vegetation, along with the increase of organic biomass in the soil associated with plant roots. This study consisted of using a numerical model that combines flow of water and heat with gas transport and oxidation in soils, to simulate methane emission and oxidation through simulated vegetated and non-vegetated landfill covers under different climatic conditions. Different simulations were performed using different methane loading flux (5-200 g m(-2) d(-1)) as the bottom boundary. The lowest modeled surface emissions were always obtained with vegetated soil covers for all simulated climates. The largest differences in simulated surface emissions between the vegetated and non-vegetated scenarios occur during the growing season. Higher average yearly percent oxidation was obtained in simulations with vegetated soil covers as compared to non-vegetated scenario. The modeled effects of vegetation on methane surface emissions and percent oxidation were attributed to two separate mechanisms: (1) increase in methane oxidation associated with the change of the physical properties of the upper vegetative layer and (2) increase in organic matter associated with vegetated soil layers. Finally, correlations between percent oxidation and methane loading into simulated vegetated and non-vegetated covers were proposed to allow decision makers to compare vegetated versus non-vegetated soil landfill covers. These results were obtained using a modeling study with several simplifying assumptions that do not capture the complexities of vegetated soils under field conditions.
authors.affiliation: Dept of Civil and Environmental Engineering, Florida State University, 2525 Pottsdamer Street, Tallahassee, FL 32311, USA. Electronic address: abichou@eng.fsu.edu.
authors.forename: Tarek
authors.initials: T
authors.lastname: Abichou
authors.affiliation: Ecole Nationale d'Ingénieurs de Gabès, University of Gabès, Rue Omar Ibn-Elkhattab 6029, Gabès, Tunisia; LASMAP, Ecole Polytechnique de Tunisie, University of Carthage, B.P. 743, La Marsa 2078, Tunisia.
authors.forename: Tarek
authors.initials: T
authors.lastname: Kormi
authors.affiliation: Geosyntec Consultants, Columbia, MD 21046, USA.
authors.forename: Lei
authors.initials: L
authors.lastname: Yuan
authors.affiliation: Waste Management, Inc., Minneapolis, MN 55337, USA.
authors.forename: Terry
authors.initials: T
authors.lastname: Johnson
authors.affiliation: Dept of Civil and Environmental Engineering, Florida State University, 2525 Pottsdamer Street, Tallahassee, FL 32311, USA.
authors.forename: Escobar
authors.initials: E
authors.lastname: Francisco
mesh_terms: D000393:Air Pollutants / Q000378:metabolism*; D002980:Climate; D004784:Environmental Monitoring; D008697:Methane / Q000378:metabolism*; D008962:Models, Theoretical; D009930:Organic Chemicals / Q000378:metabolism*; D010084:Oxidation-Reduction; D010944:Plants / Q000378:metabolism*; D012987:Soil / Q000737:chemistry*; D014481:United States; D064091:Waste Disposal Facilities; D018505:Waste Management / Q000379:methods*
chemical_list: D000393:Air Pollutants; D009930:Organic Chemicals; D012987:Soil; D008697:Methane
keywords: Final covers; Greenhouse gas emissions; Landfill emissions; Methane oxidation; Percent oxidation; Vegetation