  Elemental and isotopic abundances are the fossils of galactic archaeology.
The observed [X/Fe]-[Fe/H] relations in the Galactic bulge and disk and the
mass-metallicity relation of galaxies are roughly reproduced with
chemodynamical simulations of galaxies under the standard \Lambda-CDM picture
and standard stellar physics. The isotopic ratios such as ^{17,18}O and
^{25,26}Mg may require a refinement of modelling of supernova and asymptotic
giant branch stars. The recent observation of the Carbon-rich damped Lyman
\alpha system can be reproduced only with faint core-collapse supernovae. This
suggests that chemical enrichment by the first stars in the first galaxies is
driven not by pair-instability supernovae but by core-collapse supernovae (\sim
20-50M_\odot). The observed F abundances can be reproduced with the neutrino
processes of core-collapse supernovae. As in F, the observations of elemental
abundances in small systems may requires further complications of chemical
enrichment. In globular clusters the relative contribution from low-mass
supernovae is likely to be smaller than in the field, while the contribution
from massive supernovae seems smaller in dwarf spheroidal galaxies than in the
solar neighbourhood.
