Fig. 7. P_i adsorption on goethite with 0.01 M NaClO₄ background electrolyte. P_i,T = 40 µM. Goethite concentration 0.5 g L^-1, specific surface area 66.5 m² g^-1. Open symbols represent experimentally determined P_i adsorption. Filled symbols with dotted lines represent adsorbed P_i species based on optimized CD-MUSIC fit to experimental data. Solid line represents cumulative total of adsorbed P_i species predicted by CD-MUSIC model.