  High-resolution spectra of lambda Bootis stars reveal the presence of
circumstellar gas for example in the Ca K line.
  The example of the normal A star beta Pictoris shows, that the narrow stable
absorption component in Ca K can be reproduced using appropriate disk models
and a calcium underabundance in the circumstellar gas of a factor of ~30.
  Similar models are suggested for the group of metal-deficient lambda Bootis
stars, but the observational material is still very poor.
