\begin{table}%T4
\par
\caption{\label{tab:abs}Chemical abundances. [X/H] is defined as $\log ($X/H$) - \log$~(X/H)$_\odot$, where $\log$~(X/H)$_\odot$ is the solar abundance. Solar abundances are from Asplund et~al.\ (\cite{Asplund2005}).}
\small%\centerline
{
         \begin{tabular}{p{0.3\linewidth}lll}
\hline\hline
            \noalign{\smallskip}
Element (tracer) & $\log$ (X/H) & [X/H]$_{\rm n}$ & [X/H]$_i$$^b$   \\
            \noalign{\smallskip}
\hline  
            \noalign{\smallskip}
N (N{~\sc i}) &  $-6.10\pm0.42$ & $-1.88\pm0.42$ & $-1.31\pm0.06$ \\
O  (O{~\sc i}) &  $-4.72\pm0.41$ & $-1.38\pm0.41$ & $-0.61\pm0.05$ \\
Si (Si{~\sc ii}) & $-5.24\pm0.47$  & $-0.75\pm0.47$ &  \\
P (P{~\sc ii}) &$ -7.52\pm0.47$ &  $-0.88\pm0.47$ &   \\
Ar (Ar{~\sc i}) & $-7.12\pm0.47$ & $-1.30\pm0.47$ & $-0.42\pm0.06$ \\
Fe (Fe{~\sc ii}) & $-6.32\pm0.42$ & $-1.77\pm0.42$ & $-1.62\pm0.11$ \\
\hline
\end{tabular}}
\smallskip
$^a$  Abundance in the neutral gas (this study). \\
$^b$   Abundance in the ionized gas (Izotov \& Thuan \cite{Izotov2004}). 
\end{table}