Redox couples in wetlands

A number of redox couples simultaneously function in wetlands, making it difficult to quantitatively use thermodynamic equilibrium relationships in predicting the activities of a redox pair (Rowell, 1981). However, if any of the redox pair is sufficiently high in concentration, it is possible to predict the behavior of that redox couple (assuming that the effect of other redox couples is minimal). The Eh values are good indicators of redox couples with reversible reactions at the electrode surface. Eor example. Eh may be useful in determining the concentrations of a redox system dominated by Ee(OH)3/Ee and MnOj/Mn. But electrodes poorly respond to O2/H2O, NO3/N2, SO4 /H2S, and CO2/CH4 redox couples. Thus, caution should be exercised while interpreting the Eh values. 

Although several redox couples function in wetland soils, the reactions shown in Table 4.5 are the most common reduction reactions involving a specific redox couple. A discussion on each of these redox couples is presented in respective chapters. 

The reduction of inorganic redox systems in wetland soils can be described by intensity and capacity. 

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