The last theme concerns heterogeneity and reactivity in natural environments.
At the pore scale, this particular point is addressed under the European Research Council (ERC) project ReactiveFronts. The aim of this project is to better understand reactive mixing interfaces such as contaminant plumes or contact areas between various bodies of water. The heterogeneity of environments creates hotspots for chemical and microbiological reactivity that the project aims to study through new 2D and 3D millifluidic imaging experiments, 3D modeling in which the interactions between run-off, mixing and biochemical reactions are introduced.
In particular, one of the new aspects concerns bio-microfluidics and the dynamics of biofilms in porous media subjected to run-off.
These issues of pore-scale chemical and biological reactivity are integrated at larger scales through modeling and new types of in situ measurements.
For example, a new theme around hydrology and microbial ecology is being developed as part of an ADEME project in collaboration with ECOBIO, to better understand the relationships between functionalities & microbial diversity and environmental heterogeneity. This project uses the environmental genomics platform to characterize microbial diversity and to use it as a tracer of subsurface water flows and connectivity.
The ANR’s Soilmicro3D project also addresses the problem of pesticide degradation in the soil coupled with substrate heterogeneity and microbial ecology. It couples X-ray tomographic imagery of the soil, experiments and 3D bio-physical modeling to better understand the fate of pesticides at the plot scale.
This change of scale is also theoretically approached under the ANR Young Researcher project headed by Tanguy Le Borgne.
At the watershed scale, the link between geomorphic structure, transfer heterogeneity, biochemical reactions and degradation of the elements is approached as part of ITN (Marie-Curie Initial Training Network) interfaces involving ECOBIO, AGROCAMPUS and Applied Maths.
Digital modeling plays a fundamental role in all of these approaches, and involves the development of specific numerical methods as part of the collaboration with INRIA and ITASCA.