Reactive “organic” phosphorus revisited

While soluble reactive P is often equated with free ortho-phosphate ion, the standard molybdenum-blue method used to determine srP can potentially hydrolyse “organic” P compounds or displace P from colloids (Levine and Schindler, 1980). A number of synthetic and natural P species were shown to be susceptible to analysis-induced hydrolysis/displacement. Most notably, weak-anion exchange chromatography was used to show that free ortho-phosphate represented only a small fraction of the soluble reactive P found in water samples from an eutrophic wetland.