  We study the disk-halo interaction, in the context of orbits and Giant
Molecular loops (GMLs) in the Galactic center (GC) region. We present a large
scale survey in the central kpc in SiO(J=2-1), HCO$^+$(J=1-0) and
H$^{13}$CO$^+$ (J=1-0), observations in 3mm lines toward a region in two clumps
M+5.3-0.3 and M-3.8+0.9 placed in the foot point of two molecular loops, and
observations toward selected positions, to trace accretion of the gas from the
halo
