  We study how helicity affects the spectrum of a passive scalar in rotating
turbulent flows, using numerical simulations of turbulent flows with or without
rotation, and with or without injection of helicity. Scaling laws for energy
and passive scalar spectra in the direction perpendicular to the rotation axis
differ in rotating helical flows from the ones found in the non-helical case,
with the spectrum of passive scalar variance in the former case being shallower
than in the latter. A simple phenomenological model that links the effects of
helicity on the energy spectrum with the passive scalar spectrum is presented.
