What metal stable isotopes tell us about the role of erosion, water, and plants in setting the geochemistry of the critical zone

Séminaire de Julien Bouchez (Institut de Physique du Globe de Paris)

Julien Bouchez montrera notamment comment les isotopes stables de différents éléments (Li, Si, Sr, Ba) peuvent être utilisés pour quantifier les processus opérant dans la zone critique.

Résumé: The critical zone hosts a variety of intricate processes that are recorded by the composition of its compartments such as soils, plants, or rivers. The stable isotope signatures of non-volatile elements hosts a wealth of information on the relative rates of major critical zone processes such as mineral dissolution, soil formation, or nutrient uptake. I will show examples of how lithium, silicon, strontium, or baryum stable isotopes can be used to identify and quantify such processes from the scale of a soil plot to that of a large river catchment, using both mass balance arguments and reactive transport modeling, and applied to data emerging from various instrumented sites (critical zone observatories) around the world.