Highly-resolved imaging in soils: dynamics of interfaces induced by oxygen, pH and water content

Principle investigator: Prof. Dr. S.E. Oswald

Co-worker: N. Rudolph

In soils and sediments there is a strong coupling between local biogeochemical processes and the distribution of water, electron acceptors, acids, nutrients and pollutants. Both sides are closely related and affect each other from small scale to larger scale. Soil structures such as aggregates, roots, layers, macropores and wettability differences occurring in natural soils enhance the patchiness of these distributions. At the same time the spatial distribution and temporal dynamics of these important parameters is difficult to access. By applying non-destructive measurements it is possible to overcome these limitations. Our non-invasive fluorescence imaging technique can directly quantity distribution and changes of oxygen and pH. Similarly, the water content distribution can be visualized in situ also by optical imaging, but more precisely by neutron radiography. By applying a combined approach we will clarify the formation and architecture of interfaces induced by oxygen consumption, pH changes and water distribution. We will map and model the effects of microbial and plant root respiration for restricted oxygen supply due to locally high water saturation, in natural as well as artificial soils. Further aspects will be biologically induced pH changes, influence on fate of chemicals, and oxygen delivery from trapped gas phase.

Cooperation within the SPP:
PD Dr. S. Kolb (University Bayreuth), PD Dr. T. Baumann (TU Munich), Prof. Dr. J. Bachmann (University Hannover) and inside Thematic Group 4

Methods used in the project:
- Fluorescence foil imaging
- Fluorescence dissolved dye imaging
- Neutron radiography