Observational data on the early galactic abundances of the light elements
lithium, beryllium and boron are combined with data related to the reionization
of the intergalactic medium (IGM) in a search of processes happening in the
early universe. Early massive metal-free stars (Pop III), largely held
responsible for the reionization of the IGM, are proposed to have been also at
the origin of the lithium-6 plateau, through their winds. In this sense the
evolution of the Li-6/Be-9 ratio appears to be a key parameter for the history
of nucleosynthesis, as a monitor of the early formation of metals and their
subsequent injection in high energy particles.Comment: 5 pages, no figures, to appear in "Element Stratification in Stars,
40 years of Atomic Diffusion", Eds. G, Alecian, O. Richard and S. Vauclai
