We have tried to understand the recent observations related to metallicity
in Ly alpha forest clouds in the framework of the two-component modal sugge
sted by Chiba & Nath. The model consists of mini-halos having circular velo
cities smaller than similar to 55 km s(-1) with no star formation and galac
tic halos with higher circular velocities less than or equal to 250 km s(-1
) having clouds, star formation, and consequent metal enrichment. The numbe
r of clouds in the galactic halos was determined from the observed redshift
distribution of Ly alpha lines. We find that even if the mini-halos were c
hemically enriched by an earlier generation of stars, to have [C/H] similar
or equal to -2.5, the number of C Iv lines with column density > 10(12) cm
(-2), contributed by the mini-halos at the redshift of 3, would be only abo
ut 10% of the total number of lines for a chemical enrichment rate of (1 z)(-3) in, th, galaxies. Not much information about the degree of enrichmen
t of the mini-halos can therefore be obtained from observations of C Iv lin
es with column density >10(12) cm(-2). The recently reported absence of hea
vy-element lines associated with most of the Ly alpha lines with H I column
density between 10(13.5) and 10(14) cm(-2) by Lu and coworkers, if correct
, gives an upper limit on [C/H] = -3.7 not only in the mini-halos, but also
in the outer parts of galactic halos. This is consistent with the results
of numerical simulations, according to which the chemical elements associat
ed with the Ly alpha clouds are formed in situ in clouds rather than in an
earlier generation of stars. However, the mean value of 7 x 10(-3) for the
column density ratio of C Iv and H I, determined by Cowie & Songaila for ow
-Ly alpha optical depths, implies an abundance of [C/H] = -2.5 in mini-halo
s as well as most of the region in galactic halos, presumably enriched by a
n earlier generation of stars. The redshift and column density distribution
of C Iv has been shown to be in reasonable agreement with the observations
.