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A new in situ method to determine 2 D patterns of soil gas diffusivity and methane oxidation in a soil profile

Martin Maier1, Helmer Schack-Kirchner1, Friederieke Lang1
1 Chair of Soil Ecology, University of Freiburg

P 3.11 in Fluxes between the atmosphere and ecosystems

Poster Session 2 on Tuesday, 16:30-18:00

The apparent gas diffusion coefficient in soil (DS) is an important parameter describing soil aeration, which makes it a key parameter for root growth and gas production and consumption. Horizontal homogeneity in soil profiles is assumed in most studies for soil properties - including DS. This assumption, however, is not valid, even in apparently homogenous soils, as we know from studies using destructive sampling methods. Using destructive methods may allow catching a glimpse, but a large uncertainty remains, since locations between the sampling positions cannot be analyzed, and measurements cannot be repeated.

We develop a new method to determine in situ the apparent soil gas diffusion coefficient in order to examine 2 D pattern of DS and methane oxidation in a soil profile. Different tracer gases (SF6, CF4, C2H6) are injected continuously into the subsoil. The resulting concentrations of tracer gases are measured at several locations in the soil profile. These data allow for modelling inversely the 2 D patterns of DS between the sampling locations using Finite Element Modeling. The 2D-DS patterns are  then used together with (naturally occurring) CH4 and CO2 concentrations sampled at the same locations to derive the 2D pattern of soil respiration and methane oxidation in the soil profile.

Letzte Änderung 19.06.2014