  Ablation of interplanetary dust supplies oxygen to the upper atmospheres of
Jupiter, Saturn, Uranus, and Neptune. Using recent dynamical model predictions
for the dust influx rates to the giant planets (Poppe, A.R.~et al.~[2016],
Icarus 264, 369), we calculate the ablation profiles and investigate the
subsequent coupled oxygen-hydrocarbon neutral photochemistry in the
stratospheres of these planets. We find that dust grains from the
Edgeworth-Kuiper Belt, Jupiter-family comets, and Oort-cloud comets supply an
effective oxygen influx rate of 1.0$^{+2.2}_{-0.7} \, \times \, 10^7$ O atoms
cm$^{-2}$ s$^{-1}$ to Jupiter, 7.4$^{+16}_{-5.1} \, \times 10^4$ cm$^{-2}$
s$^{-1}$ to Saturn, 8.9$^{+19}_{-6.1} \, \times \, 10^4$ cm$^{-2}$ s$^{-1}$ to
Uranus, and 7.5$^{+16}_{-5.1} \, \times \, 10^5$ cm$^{-2}$ s$^{-1}$ to Neptune.
The fate of the ablated oxygen depends in part on the molecular/atomic form of
the initially delivered products, and on the altitude at which it was
deposited. The dominant stratospheric products are CO, H$_2$O, and CO$_2$,
which are relatively stable photochemically. Model-data comparisons suggest
that interplanetary dust grains deliver an important component of the external
oxygen to Jupiter and Uranus but fall far short of the amount needed to explain
the CO abundance currently seen in the middle stratospheres of Saturn and
Neptune. Our results are consistent with the theory that all of the giant
planets have experienced large cometary impacts within the last few hundred
years. Our results also suggest that the low background H$_2$O abundance in
Jupiter's stratosphere is indicative of effective conversion of meteoric oxygen
to CO during or immediately after the ablation process -- photochemistry alone
cannot efficiently convert the H$_2$O into CO on the giant planets.
