  Perturbative and non-perturbative terms of the cross sections of
ultraperipheral production of lepton pairs in ion collisions are taken into
account. It is shown that production of low-mass $e^+e^-$ pairs is strongly
enhanced (compared to perturbative estimates) due to the non-perturbative
Sommerfeld-Gamow-Sakharov (SGS) factor. Coulomb attraction of the
non-relativistic components of those pairs leads to the finite value of their
mass distribution at lowest masses. Their annihilation can result in the
increased intensity of 511 keV photons. It can be recorded at the NICA collider
and is especially crucial in astrophysical implications regarding the 511 keV
line emitted from the Galactic center. The analogous effect can be observed in
lepton pairs production at LHC. Energy spectra of lepton pairs created in
ultraperipheral nuclear collisions and their transverse momenta are calculated.
