  We aim to determine the constraints that observed chemical abundances put on
the potential role of mass loss in metal poor dwarfs. Self-consistent stellar
evolutionary models that include all the effects of atomic diffusion and
radiative accelerations for 28 chemical species were computed for stellar
masses between 0.6 and 0.8 Msun. Models with an initial metallicity of
Z_0=0.00017 and mass loss rates from 10e-15 Msun to 10e-12 Msun were
calculated. They were then compared to previous models with mass loss, as well
as to models with turbulent mixing. For models with an initial metallicity of
Fe/H=-2.31, mass loss rates of about 10e-12 Msun lead to surface abundance
profiles that are very similar to those obtained in models with turbulence.
Both models have about the same level of agreement with observations of
galactic-halo lithium abundances, as well as lithium and other elemental
abundances from metal poor globular clusters such as NGC 6397. In this cluster,
models with mass loss agree slightly better with subgiant observations of Li
abundance than those with turbulence. Lower red giant branch stars instead
favor the models with turbulence. Larger differences between models with mass
loss and those with turbulence appear in the interior concentrations of metals.
The relatively high mass loss rates required to reproduce plateau-like lithium
abundances appear unlikely when compared to the solar mass-loss rate. However
the presence of a chromosphere on these stars justifies further investigation
of the mass-loss rates.
