We present and compare conceptual and numerical modeling approaches for a quantitative interpretation of in-situ experiments that consisted in monitoring the temporal change of adsorbed-As concentration by incubating As-loaded goethite coated sand in the groundwater. We employed the diffuse double layer (DDL) and charge distribution multisite complexation (CD-MUSIC) models to simulate the measured As-sorbed concentration and to investigate the effects of multicomponent adsorption processes on As mobility.