We study the dispersion relation of left-hand-polarized Alfv¿n waves in multicomponent plasmas. If initially the plasma components are not drifting relative to each other, the Alfv¿n waves propagate until they meet the gyrofrequency of the species with the largest Ml=ml/zlmp value (ml is the ion mass, zl is the degree of ionization, and mp is the proton mass). As a result of resonance absorption, these ions are heated and accelerated by quasi-linear resonant interaction. When these ions reach a given velocity, the dispersion relation of the Alfv¿n waves changes drastically. The Alfv¿n branch of the dispersion relations no longer goes to the gyrofrequency of the ion species with the largest Ml value, but it goes to the gyrofrequency of the species with the second largest Ml value. In this way, more and more channels open up. We apply these results to high-speed solar wind streams, and we argue that Alfv¿n waves generated in coronal holes or in nearby regions can heat and accelerate heavy ions. ¿ American Geophysical Union 1996