Soil is a heterogeneous system consisting of minerals and organic material. They are intimately associated, thereby creating a hierarchically ordered structure of aggregates. With the NanoSIMS, we study both primary particles and soil aggregates. After the establishment of appropriate sample preparation techniques, we primarily focus on the elucidation of the elemental/isotopic composition and the three-dimensional structural association of organic and mineral soil components at submicron resolution. This provides a new approach to investigate especially the complex structure of organo-mineral associations and aggregates.
One focus of research is the simultaneous analysis of the characteristic elements in organo-mineral associations like C, N, Si, Al and Fe. A second objective is the analysis of various stable isotopes, in particular of C and N, which provides in combination with labelling studies, one of the most promising approaches for the quantitative evaluation of the C and N cycle of soils at a resolution that was not possible before. Moreover, labelled substances can also be used as tracers to probe different specific surface sites.
Research topics to be addressed with the NanoSIMS 50 L are:
- Properties, composition and heterogeneity of organic and mineral surfaces in soil,
- Association of organic and mineral components,
- Location, composition and properties of organic residues in soils,
- Fate and location of C and N,
- Properties of soil hot spots (e.g. rhizosphere, preferential flow paths, aggregate surface, microbial microhabitats) versus bulk soil.