Extension of the Practical Salinity Scale to Estimate Major Ion Concentrations: Application to the San Francisco Estuary

Abstract This paper presents a novel approach to estimate major ion concentrations in estuaries from known specific conductance. Assuming two-source conservative mixing at steady state, we propose an extension of the Practical Salinity Scale 1978 ions and total dissolved solids as functions conductivity ratio, which is ratio sample seawater conductivity. We employ extensive salinity data set that includes measurements conductance demonstrate its validity limitations for San Francisco estuary. show proposed be valid waters influenced by intrusion values greater than or equal 0.25 mS/cm adjusted model constants account ionic composition under less saline conditions. observed evidence seasonal bias residuals hypothesize this related simplified assumption fixed upstream end member concentrations. finding suggests are more reflective high alkalinity freshwater contributions December through June, compared other months.