Concentration waves, the solutions of the Riemann problem, are calculated in the framework of multicomponent chromatography. Unlike ion exchange surfaces, oxides bind cations by predominantly chemical forces, except perhaps in pristine water (at low ionic strengths I less than or equal to 10(-4) mol/L and trace metal concentrations), where electrostatic constraints give adsorption the appearance of a metal-proton exchange process. In addition to the ionic strength threshold there is another threshold in concentration space, a line along which the metal ions cover half of the surface sites (equivalence line). On its low pH side analytical expressions for the waves in pristine water are good approximations for the I = 0.1 mol/L case, as constructed from eigenvectors and eigenvalues of the Jacobian of the multicomponent isotherms. At pH values above the equivalence threshold, competition for adsorption sites has a negligible effect on the waves in water at I = 0.1 mol/L.