ORALS

Redox reactions are fundamental to life and local heterogeneities in the critical zone create gradients in pH, redox and chemical concentrations that support chemical reactions. Among the chemical reactions that act on the transformation of soils, oxidation-reduction reactions have a special place because by acting on the environment, they allow living organisms to recover the energy necessary for their metabolism. Layered Double Hydroxide compounds form a large group of minerals, also including green rusts, the natural form of which is fougerite. They can drive self-organizing reactions, including redox reactions, usable for storage and replication of chemical information. LDHs, by their 2D structure, are able to support auto-organization of reactions facilitating chemical reactions, including redox reactions and are good mineral candidates for the storage and replication of information over long-range order both in the plane (a, b) and along the c-axis, perpendicular to the sheets.These will be illustrated by some results obtained both: (i) by in situ monitoring of water and mineral transformations in soils from the Fougère’s forest (Brittany, France) and from Camargue’s rice fields (South region, France) [1], (ii) in situ sampling of fluids in alkaline hydrothermal vents from Lost City (medio Atlantic ridge) [2] and (iii) experimental data from laboratory and modelling [3].

References:
[1] [1] F. Trolard and G. Bourrié, Encyclopedia of Soils in the Environment, Second Edition, 2023, doi: 10.1016/B978-0-12-8229743.00194-4 [2] F. Trolard, S. Duval, W. Nitschke, B. Ménez, C. Pisapia, J. Ben Nacib, M. Andréani, G. Bourrié, 2022, Earth science Reviews, 225, 103910 [3] F. Trolard and G. Bourrié, “ Reactions, redox potential and kinetics”, Encyclopedia of Soils in the Environment, Second Edition, 2023 (in press)