\begin{table}%t2
  \caption {\label{metal}Abundance estimates from photoionization modeling for the intervening (upper part) and associated systems (lower part), respectively.
  }
    $$
  \begin{array}{l c c l c c c c c c c }
    \hline\hline
    \noalign{\smallskip}
{\rm QSO} & z_{{\rm abs}} & \alpha & {\rm Ratio} & {\rm [C/H]} & {\rm [N/H]} & {\rm [O/H]} & {\rm [Si/H]} & {\rm [N/C]} & [\element{N}/\alpha ] & [\alpha/\element{C}]\\         \noalign{\smallskip}
    \hline
    \noalign{\smallskip}
\textrm{PKS~1448-232} & ~1.5855~ & \dots & \mbox{\ion{Si}{iii}/\ion{Si}{iv}} &-0.82 &\phantom{<}-1.33 &\dots &+0.41&\phantom{<}-0.51&\phantom{<}-1.74&+1.23\\
\textrm{PKS~0237-23 } & 1.5966 & \dots & \mbox{\ion{Si}{iii}/\ion{Si}{iv}} &-0.93 &\phantom{<}-1.33 &\dots &+0.48&\phantom{<}-0.40&\phantom{<}-1.81&+1.41\\
\textrm{PKS~1448-232} & 1.7236 & \dots & \mbox{\ion{Si}{iii}/\ion{Si}{iv}} &-0.85 &\phantom{<}-0.97 &\dots &-0.31&\phantom{<}-0.12&\phantom{<}-0.66&+0.54\\
\textrm{HE~2217-2818} & 1.9656 & \dots & \mbox{\ion{C}{iv}/\ion{O}{vi}}    &-0.63 &\phantom{<}-1.09 & - &+0.05&\phantom{<}-0.45&\phantom{<}-1.13&+0.68\\
\textrm{Q~0122-380  } & 1.9744 & \dots & \mbox{\ion{Si}{iii}/\ion{Si}{iv}} &+0.17 &\phantom{<}+0.22 &\dots &-0.29&\phantom{<}+0.05&\phantom{<}+0.51&-0.46\\
\textrm{PKS~0237-23 } & 2.0422 & \dots & \mbox{\ion{C}{iv}/\ion{O}{vi}}    &+0.23 &\phantom{<}-0.08 & - &\dots&\phantom{<}-0.30&\phantom{<}\dots&\dots\\
\textrm{Q~0122-380  } & 2.0626 & \dots & \mbox{\ion{C}{iv}/\ion{O}{vi} }   &+0.16 &\phantom{<}+0.17 & - &\dots&\phantom{<+}0.00&\phantom{<}\dots&\dots\\
\textrm{Q~0329-385  } & 2.0764 & \dots & \mbox{\ion{C}{iv}/\ion{O}{vi}}    &-0.59 &\phantom{<}-0.37 & - &-0.37&\phantom{<}+0.22&\phantom{<-}0.00&+0.22\\
\textrm{PKS~1448-232} & 2.1098 & \dots & \mbox{\ion{C}{iv}/\ion{O}{vi}}    &-0.38 &\phantom{<}-0.59 & - &\dots&\phantom{<}-0.21&\phantom{<}\dots&\dots\\
\textrm{HE~1347-2457} & 2.1162 & \dots & \mbox{\ion{C}{iv}/\ion{O}{vi}}    &-0.87 &\phantom{<}-0.96 & - &\dots&\phantom{<}-0.54&\phantom{<}\dots&\dots\\
\textrm{HE~1347-2457} & 2.1162 & \dots & \mbox{\ion{C}{iv}/\ion{O}{vi}}    &-0.65 &\phantom{<}-1.19 & - &\dots&\phantom{<}-0.09&\phantom{<}\dots&\dots\\
\textrm{HE~0940-1050} & 2.2212 & \dots & \mbox{\ion{Si}{iii}/\ion{Si}{iv}} &-0.84 &\phantom{<}-0.75& \dots & -0.71&\phantom{<}+0.10&\phantom{<}-0.04&+0.14\\
\textrm{HE~1158-1843} & 2.2354 & \dots & \mbox{\ion{C}{iii}/\ion{C}{iv}}   &-1.74 &{<}\!-0.82 &-1.36 &\dots&{<}\!+0.92&{<}\!+0.54&+0.38\\
\textrm{Q~0420-388  } & 2.2464 & \dots & \mbox{\ion{Si}{iii}/\ion{Si}{iv}} &-2.27 &\phantom{<}-2.07 &\dots &-1.06&\phantom{<}+0.20&\phantom{<}-1.01&+1.21\\
\textrm{Q~0329-385  } & 2.2510 & \dots & \mbox{\ion{C}{iii}/\ion{C}{iv}}   &-1.19 &\phantom{<}-1.84 &-1.33 &-0.72&\phantom{<}-0.65&\phantom{<}-1.11&+0.46\\
\textrm{HE~2347-4342} & 2.2753 & \dots & \mbox{\ion{C}{iv}/\ion{O}{vi}}    &-0.19 &\phantom{<}-0.15 & - &\dots&\phantom{<}-0.04&\phantom{<}\dots&\dots\\
\textrm{HE~0151-4326} & 2.4686 & \dots & \mbox{\ion{C}{iii}/\ion{C}{iv}}   &-0.08 &\phantom{<}+0.15 &+0.28 &\dots&\phantom{<}+0.22&\phantom{<}-0.13&+0.35\\
\textrm{HE~0151-4326} & 2.4686 & \dots & \mbox{\ion{C}{iii}/\ion{C}{iv}}   &+0.08 &\phantom{<}+0.31 &+0.43 &\dots&\phantom{<}+0.22&\phantom{<}-0.13&+0.35\\
    \hline
    \noalign{\smallskip}
\textrm{HE~1341-1020} & 2.1462 &-1.0\phantom{0} &\mbox{\ion{C}{iii}/\ion{C}{iv}} &+0.82\pm^{0.14}_{0.36}&+0.66\pm^{0.23}_{0.39}&+0.62\pm^{0.25}_{0.39}&\dots&-0.21\pm^{0.03}_{0.08}&+0.01\pm^{0.20}_{0.15}&-0.22\pm^{0.07}_{0.17}\\
\textrm{HE~1341-1020} & 2.1462 &-1.0\phantom{0} &\mbox{\ion{C}{iii}/\ion{C}{iv}} &+0.73\pm^{0.17}_{0.35}&+0.52\pm^{0.20}_{0.43}&+0.51\pm^{0.24}_{0.52}&\dots&-0.16\pm^{0.09}_{0.03}&+0.05\pm^{0.12}_{0.14}&-0.21\pm^{0.11}_{0.03}\\
\textrm{HE~1341-1020} & 2.1475 &-1.0\phantom{0} &\mbox{\ion{C}{ii}/\ion{C}{ii}}^\ast &-0.44\pm^{0.86}_{0.29}&-0.83\pm^{1.11}_{0.47}& -0.72\pm^{1.15}_{0.53} &-0.73\pm^{1.47}_{0.53}&-0.40\pm^{0.25}_{0.18}&-0.11\pm^{0.49}_{0.79}&-0.29\pm^{0.61}_{0.24}\\
\textrm{Q~0329-385  } & 2.3520 &-0.37^{{a}} &\mbox{\ion{C}{iii}/\ion{C}{iv}} &+1.82\pm^{0.14}_{0.44}&+2.04\pm^{0.20}_{0.45}&+1.26\pm^{0.24}_{0.46}&\dots&+0.22\pm^{0.06}_{0.02}&+0.78\pm^{0.09}_{0.11}&-0.56\pm^{0.10}_{0.03}\\
\textrm{HE~1158-1843} & 2.4278 &-1.0\phantom{0} &\mbox{\ion{C}{iv}/\ion{O}{vi}}  &+0.08\pm^{0.21}_{0.46}&+0.63\pm^{0.22}_{0.47}& \phantom{+}-\phantom{\pm^{0.00}_{0.00}} &\dots&+0.55\pm^{0.01}_{0.01}&\dots&\dots\\
\textrm{HE~1158-1843} & 2.4427 &-1.0\phantom{0} &\mbox{\ion{C}{iii}/\ion{C}{iv}} &+1.18\pm^{0.20}_{0.44}&+1.54\pm^{0.21}_{0.48}& +1.18\phantom{\pm^{0.00}_{0.00}} &\dots&+0.36\pm^{0.01}_{0.04}&+0.36\pm^{0.01}_{0.04}&\phantom{-}0.00\phantom{\pm^{0.00}_{0.00}}\\
\textrm{Q~0453-423  } & 2.6362 &-0.89^{{a}} &\mbox{\ion{C}{iii}/\ion{C}{iv}} &-0.12\pm^{0.25}_{0.61}&-0.61\pm^{0.29}_{0.69}&+0.12\pm^{0.35}_{0.83}&-0.24\pm^{0.49}_{0.68}&-0.49\pm^{0.03}_{0.08}&-0.37\pm^{0.11}_{0.32}&-0.12\pm^{0.23}_{0.07}\\
\textrm{PKS~0329-255} & 2.7091 &-1.0\phantom{0} &\mbox{\ion{C}{iii}/\ion{C}{iv}} &+0.69\pm^{0.21}_{0.48}&+0.10\pm^{0.25}_{0.49}&+0.28\pm^{0.24}_{0.49}&\dots&-0.58\pm^{0.04}_{0.01}&-0.18\pm^{0.05}_{0.05}&-0.40\pm^{0.04}_{0.01}\\
\textrm{HE~2347-4342} & 2.8916 & \dots^{{b}} &\mbox{\ion{C}{iii}/\ion{C}{iv}} &+0.99\phantom{\pm^{0.10}_{0.33}}&+0.84\phantom{\pm^{0.11}_{0.33}}&+0.27\phantom{\pm^{0.11}_{0.33}}&\dots&-0.15\phantom{\pm^{0.00}_{0.00}}&+0.58\phantom{\pm^{0.00}_{0.00}}&-0.72\phantom{\pm^{0.00}_{0.00}}\\
\textrm{HE~2347-4342} & 2.8972 & \dots^{{b}} &\mbox{\ion{C}{iii}/\ion{C}{iv}} &+1.37\phantom{\pm^{0.12}_{0.38}}&+0.57\phantom{\pm^{0.13}_{0.39}}&\phantom{+}0.00\phantom{\pm^{0.13}_{0.39}}&\dots&-0.80\phantom{\pm^{0.00}_{0.00}}&+0.57\phantom{\pm^{0.00}_{0.00}}&-1.37 \phantom{\pm^{0.00}_{0.00}}\\
\textrm{HE~2347-4342} & 2.9027 & +0.56^{{c}} &\mbox{\ion{C}{iii}/\ion{C}{iv}} &+0.98\pm^{0.06}_{0.20}&+0.61\pm^{0.06}_{0.20}& \phantom{+}\dots\phantom{\pm^{0.00}_{0.00}} &\dots&-0.37\pm^{0.01}_{0.01}&\dots&\dots\\
    \noalign{\smallskip}
    \hline
  \end{array}
  $$
\par
  \smallskip
  \mbox{ $^{{a}}$  \citet{chengetal1991};
   $^{{b}}$  no additional power law spectrum adopted (see discussion in 
  Sect.~\ref{res_asso});
   $^{{c}}$  \citet{telferetal2002}.}
\end{table}