Dust surface density as a function of the grain size for different turbulence parameters. All discs feature a water abundance of 50%, a dust-to-gas ratio of 1%, and a dust fragmentation velocity of 1 m s⁻¹. The dust surface density profiles are taken at a temperature of ~180 K. The minimum grain size is 0.025 μm; the maximum grain size is computed using Eq. (5). The total dust surface density at each orbital distance is determined by the local gas surface density and the dust-to-gas ratio.