Gaseous diffusion through peat

Relative gas diffusivity (D/D₀) was measured in peat cores equilibrated to set moisture tensions between zero and - l0 kPa, using the radioactive gas ⁸⁵Kr. A relationship between relative diffusivity and the air filled porosity was obtained, which showed lower values of D/D₀ at air-filled porosities above about 0.13m³m⁻³, and higher values at porosities below about 0.10m³m⁻³ than some of those found in the literature for mineral soils. The likely effects of shrinkage behaviour on drying in the field, on the relationship between D/D₀ and air-filled porosity, are discussed.