title: Implementation of sulfate adsorption in the SAFE model.
abstract: An SO4(2-) adsorption submodel has been implemented in the dynamic soil chemistry model SAFE. The submodel calculates pH-dependent SO4(2-) and H+ adsorption to the soil, as well as the net surface charge development due to uneven adsorption of SO4(2-) and H+, using the empirical equations derived from an electrostatic model (Extended Constant Capacitance Model, ECCM) of SO4(2-) adsorption. The resulting new SAFE model was applied on a roof experiment plot in the Norway spruce [Picea abies (L.) H. Karst.] stand at Solling, Germany, where atmospheric S and N deposition was artificially reduced by the roof construction. The model performance was compared with the previous versions that used a pH-independent Freudlich model of SO4(2-) adsorption or assumed no SO4(2-) adsorption. With the ECCM-based SO4(2-) adsorption submodel, SAFE simulated soil solution SO4(2-) concentration and base saturation better, in comparison with measured data, than with the previous SO4(2-) adsorption formulations. Through the model application, also, need of additional improvement was suggested, such as calibration of mass transfer coefficients.
authors.affiliation: Department of Chemical Engineering II, Lund University, Sweden. tamon@niaes.affrc.go.jp
authors.forename: T
authors.initials: T
authors.lastname: Fumoto
authors.forename: H
authors.initials: H
authors.lastname: Sverdrup
mesh_terms: D000327:Adsorption; D002138:Calibration; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008962:Models, Theoretical; D012989:Soil Pollutants / Q000493:pharmacokinetics*; D013431:Sulfates / Q000493:pharmacokinetics*
chemical_list: D012989:Soil Pollutants; D013431:Sulfates