We present a study of inhomogeneous big bang nucleosynthesis with emphasis on transport phenomena .
We combine a hydrodynamic treatment to a nuclear reaction network and compute the light element abundances for a range of inhomogeneity parameters .
We find that shortly after annihilation of electron-positron pairs , Thomson scattering on background photons prevents the diffusion of the remaining electrons .
Protons and multiply charged ions then tend to diffuse into opposite directions so that no net charge is carried .
Ions with Z > 1 get enriched in the overdense regions , while protons diffuse out into regions of lower density .
This leads to a second burst of nucleosynthesis in the overdense regions at T < 20 keV , leading to enhanched destruction of deuterium and lithium .
We find a region in the parameter space at 2.1 \times 10 ^ { -10 } < \eta < 5.2 \times 10 ^ { -10 } where constraints ^ { 7 } { Li } / { H } < 10 ^ { -9.7 } and { D } / { H } < 10 ^ { -4.4 } are satisfied simultaneously .