  We have implemented a chemical evolution model on the parallel AP3M+SPH DEVA
code which we use to perform high resolution simulations of spiral galaxy
formation. It includes feedback by SNII and SNIa using the Qij matrix
formalism. We also include a diffusion mechanism that spreads newly introduced
metals. The gas cooling rate depends on its specific composition. We study the
stellar populations of the resulting bulges finding a potential scenario where
they seem to be composed of two populations: an old, metal poor,
$\alpha$-enriched population, formed in a multiclump scenario at the beginning
of the simulation and a younger one, formed by slow accretion of satellites or
gas, possibly from the disk due to instabilities.
