Localization of soil organic matter in soil aggregates using synchrotron-based X-ray microtomography
2014
Peth, Stephan | Chenu, Claire | Leblond, Nelly | Mordhorst, Anneka | Garnier, Patricia | Nunan, Naoise | Pot-Genty, Valerie | Ogurreck, Malte | Beckmann, Felix | University of Kassel | Biogéochimie et écologie des milieux continentaux (Bioemco) ; École normale supérieure - Paris (ENS-PSL) ; Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-AgroParisTech-Centre National de la Recherche Scientifique (CNRS) | Centre National de la Recherche Scientifique (CNRS) | Christian-Albrechts-Universität zu Kiel = Christian-Albrechts University of Kiel = Université Christian-Albrechts de Kiel (CAU) | Environnement et Grandes Cultures (EGC) ; Institut National de la Recherche Agronomique (INRA)-AgroParisTech | Helmholtz-Zentrum Geesthacht (GKSS)
Modelling carbon mineralisation in natural soils is a major topic in soil and climate research. Current models need to be improved to include soil structure as an influencing factor to better predict C fluxes between pedosphere and atmosphere and to estimate carbon sequestration potentials. Geometry-based mechanistic modelling approaches have recently been developed to systematically study the effect of soil structure on carbon decomposition. Such models require spatially explicit input parameters describing the architecture of the pore space and the heterogeneous distribution of microbes and organic matter as decomposable substrate. The latter is very difficult to determine in situ, resulting in increased uncertainty in the models. To obtain more realistic input data, we have developed a novel approach to locate soil organic matter (SOM) in undisturbed aggregates of soil using a combination of synchrotron-based X-ray microtomography and osmium as a staining agent for SOM. Here, we present the first results using 5 mm sized soil aggregate samples with contrasting C-contents in which we obtained maps of organic matter distributions in relation to the pore networks at the aggregate scale.
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