Fig. 1. Fit of the constant capacitance model to As(V) adsorption on Southwestern soils: (a) Altamont soil; (b) Arlington soil; (c) Pachappa soil; and (d) Ramona soil. Experimental data are represented by circles for the surface 0 to 25 cm and by squares for the subsurface 25 to 51 cm. Model fits are represented by solid lines for the surface and dashed lines for the subsurface.