\begin{table}%t4
\caption{\label{comp_cremonese}Comparison of the production rate $S_{i}$ of released
elements caused by micrometeoritic impacts.}
%\centerline
{\small
\begin{tabular}{cc|cc|cc}
\hline
\hline
 & \multicolumn{1}{c}{Cintala} & \multicolumn{2}{c}{Dermott et~al.}  & \multicolumn{2}{c}{Wiegert et~al.} \\ 
 &   & BM-LB & BM-G &  BM-LB & BM-G  \\
 \hline\noalign{\smallskip}
 Na &$9.1000\times 10^{5}$ & $3.9417\times 10^{8}$ & $2.2008\times 10^{8}$ & $2.3889\times 10^{7}$ & $1.338\times 10^{7}$\\
K &$1.8305\times 10^{4}$ & $7.9291\times 10^{6}$ & $4.4271\times 10^{6}$ & $4.8055\times 10^{5}$ & $2.6831\times 10^{5}$\\
Mg &$2.7861\times 10^{5}$ & $1.2068\times 10^{8}$ & $6.7381\times 10^{7}$ & $7.3141\times 10^{6}$ & $4.0837\times 10^{6}$\\
Ca &$1.0948\times 10^{6}$ & $4.7423\times 10^{8}$ & $2.6478\times 10^{8}$ & $2.8741\times 10^{7}$ & $1.6047\times 10^{7}$\\
\hline
\end{tabular}}
\tablefoot{Here we consider the estimate of the flux given by \citet{cintala} tuned by the fraction
of dust of asteroidal origin given by \citet{derm3} and \citet{wie},
respectively. The assumed mineralogical surface composition follows from \citet{cremonese}. $S_{i}$ is given in $N$~cm$^{-2}$~s$^{-1}$.}
\tablebib{(1) \citet{cintala}; (2) \citet{derm3}; (3) \citet{cremonese}; (4) \citet{wie}.}
\end{table}