ABSTRACT
In the preceding parts of this book, many different basic concepts have been reviewed: in Part I, Chapters 3 through 5, important principles of surface chemistry have been addressed-the equilibrium adsorption behavior of ions to soil colloids (and to colloidal particles in general), the necessary electrostatic considerations for an interface between two charge-bearing phases, and the concomitant development of surface charges; in Part II, Chapters 8 through 10, the chemical structure and surface properties of the most important types of soil colloids have been discussed, where it can be seen that, despite the different types of surfaces and surface groups, there are two main modes of ionsurface interaction-electrostatic attraction/repulsion between a charged surface and ions of opposite/same charge leading to outer sphere complexes in the case of attraction, and specic interaction resulting in chemically bound inner sphere complexes. A general treatment of ion binding should in principle take into account all these elements. As a detailed microscopic knowledge of the surface of soil colloids is lacking (not to speak of the multicomponent aggregates found in the actual soils, to be considered in Chapter 14), phenomenological modeling is the usual way to reach the ability to make quantitative predictions, which are useful in many aspects of soil science, particularly in geochemistry (Mattigod and Zachara 1996; Zachara and Westall 1998; Koretsky 2000; Perdue 2001; Goldberg 2005; Senesi and Loffredo 2005; Van Riemsdijk et al. 2006).
