\begin{table} %t9 
\caption{\label{tab_rat}Column density ratios.}
\small%\centering
\par
\begin{tabular}{lllllllllll}
\hline \hline \noalign{\smallskip}
 Column & & This & work & & & \tablefootmark{1} & \tablefootmark{1} &
 \tablefootmark{2} & Dark clouds & Hot core\\
 density ratio & ER & CR & P & HC & Total & A & B &  &
 (TMC1) & \object{G327.3-0.6}\\
\hline
OCS/CS & 3 & 2 & 5 & 2 & 3 & 5 & 13 & 6(HC) & 0.5 & $<$4\\
CS/HCS$^+$ & 7700 & 100 & 50 & 420 & 180 & 1000 &
270 & ... & 10 & ...\\
CS/H$_2$CS & 14 & 50 & 2 & 12 & 7 & 25 & 8 & 4(CR) & 6 & $>$$5$\\
CS/CCS & 4000 & 1100 & 1200 & 420 & 530 & ... & ... & ... & 0.5 & 325\\ 
CS/C$_3$S & ... & ... & ... & 1050 & 1050 & ... & ... & ... & 4 & ...\\
CCS/C$_3$S & ... & ... & ... & 2.5 & 2.5 & ... & ... & ... & 8 & ...\\
CO/CS & 5000 & 500 & 10~000 &
2500 & 2800 & 66~700 & 133~300 & 2400(P) & 20~000 & 26~200\tablefootmark{3}\\
HCO$^+$/HCS$^+$ & 270 & 4 & 9 & 27 & 13 & 12 & 10 & ... & 20 & ...\\
H$_2$CO/H$_2$CS & 12 & 8 & 18 & 11 & 12 & 6250 &
1250 & 15(CR) & 71 & $>$$3$\\
\hline 
\end{tabular} 
\tablefoot{Derived column density ratios and comparison with other works
and sources. Column 1 gives the considered ratio, Cols. from 2 to 6
show the results obtained in this work in the different spectral cloud
components of Orion and the total value, Cols. 7 and 8 
ratios obtained by \citet{nom04} in their models of hot
cores (in model B trapping of mantle molecules in water ice is assumed), 
Col.~9 gives values in Orion by
\citet{per07}, Col.~10 in dark clouds (TMC-1) (\citealt{wal09} and
references within), and Col.~11 provides these ratios for the molecular
hot core G327.3-0.6, \citet{gib00}. \tablefoottext{1}{\citet{nom04};} 
\tablefoottext{2}{\citet{per07};} \tablefoottext{3}{Assuming $^{16}$O/$^{17}$O = 2625.}}
\end{table}