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| Titel |
Production and transport of gases in the soil: from 1-D soil gas profiles towards 2- and 3-D representations of soil gas processes |
| VerfasserIn |
Martin Maier, Friederike Lang, Helmer Schack-Kirchner |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250149545
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| Publikation (Nr.) |
 EGU/EGU2017-13903.pdf |
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| Zusammenfassung |
| Most studies implicitly use a 1 dimensional simplification of soil processes with a dominating
vertical profile, e.g in soil physical and chemical properties. In many cases, this is a useful
and sufficient representation of the realty which helps to answer research questions in an
efficient way. Yet, in some cases, a 2 D or 3 D analysis of the processes is necessary to avoid
misinterpretation of experimental results, e.g. modeling the impact of chamber deployment
time during the measurement of gas fluxes (von Fischer et al. 2009) or trenching experiments
(Jassal et al. 2006).
We developed a new method to determine the 2 D patterns of the soil gas diffusion coefficient
DS/D0 in situ, using simultaneously several inert tracer gases. Soil gas transport was
modelled inversely using the Finite Element Modeling program COMSOL. In combination
with measurements of target gases such as CO2, CH4 and N2O, this allowed us for modelling
the 2-D patterns of transport and production of CO2, CH4 and N2O in the soil. We observed
how methane oxidation and soil respiration zones shifted within the soil profile while the gas
fluxes at the surface remain rather stable during a 3 week campaign. The soil was a net sink
for N2O, yet, in the subsoil local (weak) source of N2O lead to horizontal fluxes of
N2O.
We are testing the 3 D approach in the lab on defined substrates and objects to quantify the
spatial resolution and reliability of the method. In a next step, we want to test the
method in the field and study the ventilation and soil gas fluxes of an ant nest in
3D.
References:
von Fischer, J. C., G. Butters, P. C. Duchateau, R. J. Thelwell, and R. Siller (2009), In situ
measures of methanotroph activity in upland soils: A reaction-diffusion model and field
observation of water stress, J. Geophys. Res., 114, G01015,
Jassal RS, Black TA (2006) Estimating heterotrophic and autotrophic soil respiration
using small-area trenched plot technique: theory and practice. Agric. For. Meteorol.
140:193–202 |
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