Abstract
A model of the mechanism of phosphate release from lake sediments was proposed and its validity was examined experimentally.
The complex process of phosphate release from sediments was assumed to be composed of three elementary processes : oxygenation of Fe(II) to Fe(III), formation of ferric hydroxides and adsorption of phosphate to ferric hydroxides. The model was examined experimentally by studying the transient behaviors of ferrous iron, ferric iron and phosphate concentrations and that of redox potential. The experimental results agreed with the calculated results assuming the oxygenation kinetics of Fe(II), the solubility product of ferric hydroxides and the adsorption ratio of phosphate to ferric hydroxides.
It suggests that the mechanism of phosphate release from sediments can be quantitatively described by our model. The difference of phosphate release rate under aerobic and anaerobic conditions can be also explained by our model considering the dependence of oxygenation rate of Fe(II) on DO.
