The objective of this thesis is to estimate the ability of boron and its isotopes to evaluate mineral weathering budgets and mechanisms in soils. In this goal, 3 different approaches were conducted:1) an experimental approach during which a test-mineral (biotite) undergoes the action of different weathering agents, representative of those found in soils.2) an in-situ approach in an acid soil profile led on different minerals (biotite, muscovite, K-feldspar and albite) handpicked at various depths and weathering state (Breuil-Chenue forest experimental site, France).The objective of this study is to determine the sensitivity of boron to soil formation processes.3) an second in-situ approach conducted on the same study site but this time on sub-surface horizons (horizon A and Al-oxi-hydroxides accumulation horizon), which aim is to evaluate the sensitivity of boron and its isotopes to mechanisms in close vicinity to vegetation (seasonal variations, vicinity of the roots). B and its isotopes able, thanks to its high reactivity during weathering mechanisms in comparison to major elements that constitute the crystallographic network (observed in experimental as well as in in-situ approaches), to trace with a great sensitivity primary minerals dissolution or transformation mechanisms, and opens new insights for the comprehension of soils.
Boron isotopes as a proxy of weathering mechanisms and balance in soil minerals