Program > Browse abstracts by speaker > Sarr Mohamadou

Most of the drinking water resources is hosted in the critical zone, i.e the near-surface environment from the canopy to the unaltered rocks. Understanding the water-rock interactions in the critical zone is of great importance for environmental engineering applications, including pollutant transport and groundwater resources. Calcite is one of the most abundant minerals in the critical zone. Its study matters for various applications, from risk management to groundwater remediation. Additionally, the characterization of such hydrogeochemical couplings at different scales is relevant because microscopic mechanisms impact large-scale behaviors. Therefore, studying the critical zone requires an interdisciplinary and multi-scale approach.

To investigate water-rock interactions, we have developed an experimental approach that combines microfluidics and Raman spectroscopy. Thanks to transparent micromodels, microfluidic devices allow direct visualization of flows and reactions at the pore-scale. Raman spectroscopy is a non-invasive and non-destructive technique used for in situ monitoring of structural and chemical changes [1]. The present study focuses on the detection of species during mineral dissolution to enhance our prediction capacity of physicochemical processes in the critical zone. Raman is already used for studying mineralogical evolution, but a few study for detecting species in solutions. First, our methodology has been applied to study the calcite dissolution in real time under static or dynamic conditions. Analysis of Raman spectra allowed identifying the chemical species involved in a dissolution process. Thus, it provides new insights into the hydrogeochemical couplings involved in geological environments. Second, more complex flow-through reactive micromodels will be considered to localize concentration gradients generated by dissolution and precipitation. These new experimental results will extend the numerical models developed for the simulation of the calcite dissolution at the pore scale [2].

References

[1] J. Poonoosamy et al. Lab on Chip, 20(14):2562, 2020.

[2] C. Soulaine et al. J. Fluid Mechanics, 827:457, 2017