\begin{table}%t8
%\centering
\par
\caption{\label{table8}Abundances, relative to solid H$_2$O and total~H, of the S-bearing species detected in the icy grain mantles.}
\small \begin{tabular}{l c c c c}
\hline\hline\noalign{\smallskip}
Source   & \multicolumn{4}{c} {Abundances}\\
& N(OCS)/N(H$_2$O)  &   N(SO$_2$)/N(H$_2$O)  &   N(OCS)/N(H)\tablefootmark{a}    &    N(SO$_2$)/N(H)\tablefootmark{a}\\
\hline\noalign{\smallskip}
Mon R2 IRS 2   & $5.5 \times 10^{-4}$\tablefootmark{b}  &    &  $3.2 \times 10^{-8}$\tablefootmark{b}      \\
AFGL 989 & $1.0 \times 10^{-3}$\tablefootmark{b}& &   $2.3 \times 10^{-8}$\tablefootmark{b}\\
W33A           & $4.0 \times 10^{-4}$\tablefootmark{b}  & ($3.1 \pm 1.6)\times 10^{-3}$\tablefootmark{c}  & $7.0 \times 10^{-8}$\tablefootmark{b}   &  ($6.2 \pm 3.2) \times 10^{-7}$\tablefootmark{c}\\
NGC~7538 IRS 1 & $<$$5.0 \times 10^{-4}$\tablefootmark{d}     & ($8.0 \pm 2.0) \times 10^{-3}$\tablefootmark{c}   & $<$$7.6 \times 10^{-9}$\tablefootmark{d}  &   ($1.2 \pm 0.3) \times 10^{-7}$\tablefootmark{c}  \\
NGC 7538 IRS 9 & $5.0 \times 10^{-4}$\tablefootmark{e}    & $<$$5.0 \times 10^{-3}$\tablefootmark{c}  &  $3.4 \times 10^{-8}$\tablefootmark{e}  & $<$$3.4 \times 10^{-7}$\tablefootmark{c} \\
\hline
\end{tabular}
\tablefoot{\tablefoottext{a}{N(H) column densities are taken from Tielens et~al. (\cite{tielens91}) and Boogert et~al. (\cite{boogert97});} \tablefoottext{b}{Palumbo et~al. (\cite{palumbo97});} 
\tablefoottext{c}{Boogert et~al. (\cite{boogert97});} \tablefoottext{d}{Gibb et~al. (\cite{gibb04});} \tablefoottext{e}{Charnley et~al. (\cite{charnley01}).}}
\end{table}