[Kinetics of interaction of H+ with constant and variable charge soils]

The kinetics of interaction of H+ ions with constant and variable charge soils were studied, among which changes of H+ concentration, positive surface charge and soluble Al with time and their influencing factors were investigated in detail. The results showed that the consumption processes of H+ ions in both constant and variable charge soils could be divided into fast and slow processes, but the manifestations and influencing factors were different for the two types of soils. The variations in positive surface charges for variable and constant charge soils, due to the difference in the contents of free Fe-oxides, are remarkably different and thus can not be modeled mathematically in the same manner for the two types of soils. The variations in soluble Al for both variable and constant charge soils were controlled by the components, solubility and solution kinetics of dominant clay minerals in soils, and could be described by both modified Elovich and two-constant rate equations mathematically.