Dipolar arrays of interfacial water molecules are thought to be the main contributors to this potential. Multipolar contributions may also be important. Our own work with the Miller group and the preceding study by Chen and Singer 75 also show surface potentials due to water polarization at negatively charged oxide:electrolyte interfaces estimated from molecular dynamics simulations are negative and in the range of multiple tens of mV, decreasing in magnitude with ionic strength. Those outcomes are consistent with earlier MD reports on structured water at charged aqueous:insulator interfaces, by, for instance, Borguet and Klein and co-workers. New mean-field models beyond the standard model have been introduced that account for non-ideal behavior (short-range ion correlations, surface site availability, etc.) of aqueous electrolytes and ionic liquids. A related issue is the spatial variation of the (field-dependent) relative permittivity, er, which the standard model neglects, i.e. the solvent is modeled as a uniform continuum, despite large differences in reported er. The experimentally determined F(0)tot estimates obtained here include all the contributions to the potential and should thus be an Ma and Geiger 16 appropriate experimental benchmark to which theory must conform. It will also be informative to determine how ion-specific effects manifests themselves on other oxides, such as hematite, which is an area we are actively pursuing.