The role of fulvic acids in phosphorus sorption and release from mineral particles

The competitive sorption of phosphates and marine fulvic acids on mineral particles (sand, calcite, bentonite and hematite) has been studied under simulated estuarine conditions. Afterwards, the release and desorption of bound phosphates by solutions containing dissolved fulvic acids was determined. It was found out that due to the favorable sorption of fulvic acids onto minerals studied binding of phosphate was significantly decreased. Desorption experiments showed that fulvic acids, present at high concentration level, similar to that in interstitial water of an oxygenated sediment, increase phosphate desorption by 10-20%.