  Splitting of the strongest absorption lines with a lower-level excitation
potential $\chi<$1eV has been detected for the first time in the optical
spectra of the post-AGB star V354Lac obtained with a spectral resolution
R=60000 at the 6-m telescope BTA. Analysis of the kinematics shows that the
short-wavelength component of the split line originates in the star's thick
gas-dust envelope. Disregarding the splitting of strong lines when the chemical
composition is calculated leads to overestimated excess of s-process elements
(Ba, La, Ce, Nd) in the stellar atmosphere. The profiles of strong absorption
lines have been found to be variable. The available radial-velocity data
suggest the absence of any trend in the velocity field in the atmosphere and
circumstellar envelope of V354Lac over 15 years of its observations.
