  Aims: We wish to investigate what the effect of dust sedimentation is on the
observed 10 mum feature of protoplanetary disks and how this may affect the
interpretation of the observations.
  Methods: Using a combination of modeling tools, we simulated the
sedimentation of a dust grain size distribution in an axisymmetric 2-D model of
a turbulent protoplanetary disk, and we used a radiative transfer program to
compute the resulting spectra.
  Results: We find that the sedimentation can turn a flat feature into a pointy
one, but only to a limited degree and for a very limited set of particle size
distributions. Only if we have a bimodal size distribution, i.e. a very small
grain population and a bigger grain population, do we find that the
transformation from a flat to a pointy feature upon dust sedimentation is
strong. However, our model shows that, if sedimentation is the sole reason for
the variety of silicate feature strengths observed in protoplanetary disks,
then we would expect to find a correlation such that disks with weak mid- to
far-infrared excess have a stronger 10 mum silicate feature than disks with a
strong mid- to far-infrared excess. If this is contrary to what is observed,
then this would indicate that sedimentation cannot be the main reason for the
variety of 10 mum silicate features observed in protoplanetary disks.
