  In this work we have used 3D hydrodynamical (CO5BOLD) and 1D hydrostatic
(LHD) stellar atmosphere models to study the importance of convection and
horizontal temperature inhomogeneities in stellar abundance work related to
late-type giants. We have found that for a number of key elements, such as Na,
Mg, Si, Ca, Ti, Fe, Ni, Zn, Ba, Eu, differences in abundances predicted by 3D
and 1D models are typically minor (< 0.1 dex) at solar metallicity. However, at
[M/H] = -3 they become larger and reach to -0.5...-0.8 dex. In case of neutral
atoms and fixed metallicity, the largest abundance differences were obtained
for the spectral lines with lowest excitation potential, while for ionized
species the largest 3D-1D abundance differences were found for lines of highest
excitation potential. The large abundance differences at low metallicity are
caused by large horizontal temperature fluctuations and lower mean temperature
in the outer layers of the 3D hydrodynamical model compared with its 1D
counterpart.
