Left: distribution of the with dust-corrected [Zn/H]_TOT (the intrinsic metallicity), for the GRB-DLAs (black) in our sample and the UVES QSO-DLAs (gray) sample of Noterdaeme et al. (2008). The MW, SMC (three lines of sight) and LMC values are displayed for comparison, where the latter two are two representative values derived from the observed [Zn/Fe] along two lines of sight (see text for details). Filled symbols highlight the measurements drawn from high-resolution spectroscopy. The thick green arrow shows the literature value (derived from the M_dust/M_H measured by Herrera-Camus et al. 2012) for the nearby blue compact dwarf galaxy I Zw 18. Right: the distribution of the with the total column density of Zn ii, corrected for dust depletion.