  Using the NMC and E665 nuclear structure function ratios $F_2^A/F_2^D$ and
$F_2^A/F_2^{C}$ from deep inelastic lepton-nucleus collisions, and the E772
Drell--Yan dilepton cross sections from proton-nucleus collisions, and
incorporating baryon number and momentum sum rules, we determine nuclear parton
distributions at an initial scale $Q_0^2$. With these distributions, we study
QCD scale evolution of nuclear parton densities. The emphasis is on small
values of $x$, especially on scale dependence of nuclear shadowing. As the main
result, we show that a consistent picture can be obtained within the leading
twist DGLAP evolution, and in particular, that the calculated $Q^2$ dependence
of $F_2^{Sn}/F_2^{C}$ agrees very well with the recent NMC data.
