Abstract
From field observations in a stratified reservoir with an anaerobic hypolimnion, thin turbid layer was found between the oxidative and reductive layers. This phenomenon is considered to result from an oxidation-reduction reaction of iron and phosphorus in the hypolimnion. Thus, to investigate the behavior of iron and phosphorus and the adsorption of phosphorus to iron under such conditions, laboratory experiments were carried out. Ferrous iron released from anaerobic sediments is oxidized, forms iron hydroxide, and adsorbs phosphate. Therefore, as a certain quantity of phosphate released from anaerobic sediments is adsorbed by iron, phosphates are not completely utilized by phytoplankton in the surface euphotic layer.
