  Numerical simulations predict that a large number of baryons reside in
intergalactic space at temperatures between 10^5-10^7 K. Highly-ionized metals,
such as O VII and O VIII, are good tracers of this ``warm-hot intergalactic
medium'', or WHIM. For collisionally-ionized gas, the ionization fraction of
each ion peaks at some particular temperature (``peak temperatures''), so
different ions can therefore trace the IGM at different temperatures. We
performed a hydrodynamic simulation to study the metal distributions in the
IGM. By studying the distribution functions of H- and He-like O, Si and Fe in a
collisionally-ionized IGM and comparing with semi-analytic results based on the
Press-Schechter formalism, we find: (1) ions with higher peak temperatures (for
instance, Fe XXVI) tend to concentrate around virialized halos, which can be
well described by the Press-Schechter distribution, ions with lower peak
temperatures are found both in small halos (such as groups of galaxies) and in
filaments; (2) lower peak temperature ions are more abundant and should be
easily observed; (3) peculiar velocities contribute a significant part to the
broadening of the resonant absorption lines.
