SULFATE SORPTION IN SOILS UNDER ACID DEPOSITION - COMPARISON OF 2 MODELING APPROACHES

Soil acidification under the impact of acid deposition Is often modele d by adsorption isotherms. The assumption of solubility equilibria for basic Al sulfates is an alternative modeling approach. Similarities a nd differences between both concepts are discussed. A simple solubilit y equilibrium model is defined and used to demonstrate that the second model can explain results that are well describef by typical adsorpti on isotherms. The same model can also explain a pH dependency of adsor ption isotherms that has been widely reported. In the application to a ssumed soil acidification scenarios, predictions Pre presented that co uld not be described by an adsorption isotherm approach.