\begin{table}%t3
%%\centering

\par
\caption{\label{table3}Fractional abundances for hydrogen species in surface and mantle phases.} 
\begin{tabular}{cccc}
\hline\hline
Species&Surface&Mantle&Mantle-to-surface\\
\hline
${\rm H_{2}}$&1.17E-05&2.34E-07&2.00E-02\\
H&1.25E-18&2.17E-20&1.73E-02\\
H (chemically bound)&6.84E-05&1.12E-03&1.64E+01\\
\hline
\end{tabular}
\end{table}