  We calculate nuclear enhanced power corrections to structure functions
measured in deeply inelastic lepton-nucleus scattering in Quantum
Chromodynamics (QCD). We find that the nuclear medium enhanced power
corrections at order of $O(\alpha_s/Q^2)$ enhance the longitudinal structure
function $F_L$, and suppress the transverse structure function $F_1$. We
demonstrate that strong nuclear effects in $\sigma_A/\sigma_D$ and $R_A/R_D$,
recently observed by HERMES Collaboration, can be explained in terms of the
nuclear enhanced power corrections.
