Seasonal fluxes of phosphate across the sediment-water interface in Edku Lagoon, Egypt

>Edku Lagoon is a shallow, brackish, coastal wetland located in thenorth-western part of the Nile Delta. It suffers from a high level ofeutrophication, owing to the heavy load of nutrients, especially phosphorus.The purpose of this paper was to study the flux rates of organic and inorganicphosphorus across the sediment water interface in Edku Lagoon. Both theorganic and inorganic phosphorus of surface sediments, pore water and theirconcentrations in the water just above the sediments were used to calculatethe flux rates and to derive the geochemical models. These suggest that, atpresent, the flux of inorganic and organic phosphorus is from water tosediments via the sedimentation of inorganic particles and organic matter. Theresults show that phosphorus deposition to the sediments exceeds the rate ofinorganic phosphorus release from the sediments to the water column. In asteady state, the rates of organic phosphorus release more or less match therates of deposition. These reflect the imbalance (accumulation) of phosphorusin the geochemical cycle in the lagoon and its highly eutrophic status.Efforts to control the eutrophication of Edku Lagoon have focused on reducing thephosphorus input.