Methane oxidation in landfill cover soils, is a 10% default value reasonable?

Area of Science:

• Environmental Science
• Geochemistry
• Microbiology

Background:

• Methane is a potent greenhouse gas, and its oxidation in soils and landfill covers is a critical natural process.
• Understanding methane oxidation is vital for accurate climate modeling and landfill management.

Purpose of the Study:

• To synthesize and analyze existing data on methane oxidation fractions and rates in various soil types and landfill covers.
• To compare observed methane oxidation with the default 10% value often used in environmental assessments.

Main Methods:

• Literature review of 42 determinations of methane oxidation fraction and 30 determinations of methane oxidation rate.
• Inclusion of both laboratory column measurements and in situ field measurements.
• Analysis of data across different soil types, landfill covers, and geographic locations.

Main Results:

• The overall mean fraction of methane oxidized was 36% (±6%), with values ranging from 22% to 55% across different soil types.
• Mean methane oxidation rates varied from 3.7 to 6.4 mol m⁻² d⁻¹ (52-102 g m⁻² d⁻¹).
• Only four out of 42 studies reported methane oxidation fractions of 10% or less, suggesting typical values are higher.

Conclusions:

• Methane oxidation in soil and landfill covers is substantial, generally exceeding the default 10% assumption.
• Soil type significantly influences methane oxidation efficiency, with clayey soils showing different rates than sandy materials.
• Geographic location and annual cycles also play a role, though the overall mean fraction oxidized remained consistent across studies.