  Constraining dust properties of planet-forming disks via high angular
resolution observations is fundamental to understanding how solids are trapped
in substructures and how dust growth may be favored or accelerated therein. We
use ALMA dust continuum observations of the Molecules with ALMA at
Planet-forming Scales (MAPS) disks and explore a large parameter space to
constrain the radial distribution of solid mass and maximum grain size in each
disk, including or excluding dust scattering. In the nonscattering model, the
dust surface density and maximum grain size profiles decrease from the inner
disks to the outer disks, with local maxima at the bright ring locations, as
expected from dust trapping models. The inferred maximum grain sizes from the
inner to outer disks decrease from ~1 cm to 1 mm. For IM Lup, HD 163296, and
MWC 480 in the scattering model, two solutions are compatible with their
observed inner disk emission: one solution corresponding to a maximum grain
size of a few millimeters (similar to the nonscattering model), and the other
corresponding to a few hundred micrometer sizes. Based on the estimated Toomre
parameter, only IM Lup -- which shows a prominent spiral morphology in
millimeter dust -- is found to be gravitationally unstable. The estimated
maximum Stokes number in all the disks lies between 0.01 and 0.3, and the
estimated turbulence parameters in the rings of AS 209 and HD 163296 are close
to the threshold where dust growth is limited by turbulent fragmentation. This
paper is part of the MAPS special issue of the Astrophysical Journal
Supplement.
