  We calculate heavy element enrichment in a Jupiter-mass protoplanet formed by
disk instability at various radial distances from the star, considering
different disk masses and surface density distributions. Although the available
mass for accretion increases with radial distance (a) for disk solid surface
density (sigma) functions sigma=sigma_0*a^(-alpha) with alpha < 2, the
accretion timescale is significantly longer at larger radial distances.
Efficient accretion is limited to the first ~ 1E5 years of planetary evolution,
when the planet is extended and before gap opening and type II migration take
place. The accreted mass is calculated for disk masses of 0.01, 0.05 and 0.1
M_sun with alpha = 1/2, 1, and 3/2. We show that a Jupiter-mass protoplanet can
accrete 1 to 110 M_earth of heavy elements, depending on the disk properties.
Our results explain the large variation in heavy element enrichment found in
extra-solar giant planets. Since higher disk surface density is found to lead
to larger heavy element enrichment, our model results are consistent with the
correlation between heavy element enrichment and stellar metallicity. Our
calculations also suggest that Jupiter could have formed at a larger radial
distance than its current location while still accreting the mass of heavy
elements predicted by interior models. We conclude that in the disk instability
model the final composition of a giant planet is strongly determined by its
formation environment. The heavy element abundance of a giant planet does not
discriminate between its origin by either disk instability or core accretion.
