  We provide a discussion of the bulk viscosity of two-flavor quark plasma,
described by the Nambu--Jona-Lasinio model, within the framework of
Kubo-Zubarev formalism. This discussion, which is complementary to our earlier
study, contains a new, detailed derivation of the bulk viscosity in the case of
multiple conserved charges. We also provide some numerical details of the
computation of the bulk viscosity close to the Mott transition line, where the
dissipation is dominated by decays of mesons into quarks and their inverse
processes. We close with a summary of our current understanding of this
quantity, which stresses the importance of loop resummation for obtaining the
qualitatively correct result near the Mott line.
