  The Sun is believed to have been the recipient of a substantial amount of
metal-rich material over the course of its evolution, particularly in the early
stages of the Solar System. With a long diffusion timescale, the majority of
this accreted matter should still exist in the solar convection zone, enhancing
its observed surface abundance, and implying a lower-abundance core. While
helioseismology rules out solar models with near-zero metallicity cores, some
solar models with enhanced metallicity in the convection zone might be viable,
as small perturbations to the standard model. Because of the reduced interior
opacity and core temperature, the neutrino flux predicted for such models is
lower than that predicted by the standard solar model. This paper examines how
compatible inhomogeneous solar models of this kind are with the observed low
and intermediate degree p-mode oscillation data, and with the solar neutrino
data from the SNO Collaboration. We set an upper limit on how much metal-rich
accretion took place during the early evolution of the Sun at about 2 Earth
masses of iron (or about 40 Earth masses of meteoric material).
