ON THE ABUNDANCES OF DAMPED LY-ALPHA ABSORBERS

Recent determinations of chemical abundances in high redshift DLA syst ems suggest that the relative abundances of elements may be close to t he solar ones, although with absolute abundances more than two orders of magnitude lower than solar (Molaro et al. 1995). This result comes either from DLA absorbers with negligible dust contribution and neglig ible HII contamination, or from the [SII/ZnII] ratio, which is a relia ble diagnostic of the true abundance. In two systems nitrogen is detec ted at a particularly high level with [N/O]approximate to 0 (Molaro et al. 1995, Green et al. 1995). Here we present a first attempt to expl ain such unexpected abundance patterns in the framework of a chemical evolution model which incorporates differential galactic winds and a p rimary origin for nitrogen. Such model is the most successful in descr ibing the chemical abundances of dwarf irregular galaxies. Thus, the p resent interpretation seems to favour dwarf galaxies rather than spira l galaxies as the progenitors of at least some of the DLA systems.