  We study the motion of small inertial particles in stratified turbulence. We
derive a simplified model, valid within the Boussinesq approximation, for the
dynamics of small particles in presence of a mean linear density profile. By
means of extensive direct numerical simulations, we investigate the statistical
distribution of particles as a function of the two dimensionless parameters of
the problem. We find that vertical confinement of particles is mainly ruled by
the degree of stratification, with a weak dependency on the particle
properties. Conversely, small scale fractal clustering, typical of inertial
particles in turbulence, depends on the particle relaxation time and is almost
independent on the flow stratification. The implications of our findings for
the formation of thin phytoplankton layers are discussed.
