Initial behaviour of the characteristics in the propagation of isotopic disequilibrium by diffusion

We study the initial behaviour of the characteristics of an hyperbolic system of first order equations, which models the diffusion of n species of stable isotopes of the same element in a medium. The model is based on the assumption that, since the isotopes are chemically indistinguishable, the flux of each isotope depends on the gradient of the total concentration of the element weighted by the relative percentage of the isotope. We consider here the influence of initial irregularities of the total concentration on the characteristics.