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oai:figshare.com:article/34054557 2026-10-02T05:37:06Z category_34 portal_316 item_type_3 month_year_10_2026

Supplementary file 1_Methane consumption by a landfill cover soil under variable soil moisture and temperature conditions.docx Christina Lam (10199066) Mehdi Ramezanzadeh (25162614) Stephanie Slowinski (9609047) Olivia Penn (25162617) Laura A. Hug (7129301) Philippe Van Cappellen (7321892) Fereidoun Rezanezhad (4803657) Environmental Science CH4 emissions CH4 oxidation hot-spots landfill soils moisture temperature <p>Landfills are one of the largest anthropogenic sources of methane (CH₄), and hot-spots of CH₄ emissions in landfill cover soils can enrich microbes that oxidize CH₄ to carbon dioxide (CO₂). CH₄ oxidation rates are modulated by multiple variables including soil moisture and temperature, although the interactive effects of these factors on CH₄ oxidation rates have not been well-studied. Here, we conducted closed-headspace batch incubations with cover soil from a former landfill in Ontario, Canada to measure the variations in CH₄ consumption and CO₂ efflux rates associated with combined variations in soil moisture and temperature. Soil samples were incubated under a factorial design of 5 soil moisture contents (20%, 40%, 60%, 80%, and 100% water-filled pore space; %WFPS), and 4 temperatures (1, 15, 25, and 35 °C). At each temperature and moisture combination, CH₄ was spiked into the headspace through multiple consecutive injections, and headspace CH₄ and CO₂ concentrations were measured to calculate CH₄ consumption and CO₂ efflux rates. The maximum CH₄ consumption rate was observed at the moderate soil moisture and temperature conditions (330 ± 12.3 nmol h^-1 g DW^-1 at 60% WFPS and 25 °C), while the maximum CO₂ efflux rate was observed at the maximal WFPS and temperature conditions of the experiment (652 ± 85.0 nmol h^-1 g DW^-1 at 100% WFPS and 35 °C). A diffusion-reaction model was fit to the observed data to represent the effects of temperature and soil moisture on the CH₄ consumption and CO₂ efflux rates. The model predicted similar optimal conditions as those observed for both the CH₄ consumption and the CO₂ efflux rates. The modeling and experimental results show that the dominant controls on the optimal soil moisture for CH₄ consumption are the interactive effects of moisture limitation of microbial activity and of gas (CH₄ and oxygen) diffusion, whereas for the CO₂ effluxes, the dominant controls were the interactive effects of moisture limitation of gas (oxygen) diffusion and solute mobility. These results provide insight into how seasonal changes in soil moisture and temperature could impact CH₄ oxidation rates, and therefore also net CH₄ emissions, in landfill cover soils and other environments.</p> 2026-10-02T05:37:06Z Dataset Dataset 10.3389/fenvs.2026.1960703.s001 https://figshare.com/articles/dataset/Supplementary_file_1_Methane_consumption_by_a_landfill_cover_soil_under_variable_soil_moisture_and_temperature_conditions_docx/34054557 CC BY 4.0