Influence of salinity on the concentration and rate of interchange of dissolved phosphate between water and sediment in Fuente Piedra lagoon (S. Spain)

Short (60 minutes) and long term (3 hours) experiments were performed to measure the final equilibrium phosphate concentration in water and the net fluxes of phosphate interchange between water and sediment at different salinities. The rate of phosphate release from the sediment increases with the salinity increment, as well as the final equilibrium phosphate concentration. In both short and long term experiments, the net rate of dissolved phosphate removal follows a saturation kinetics except for long term experiments at 70 g l^–1 salinity. In this case, the relationship between net removal and dissolved phosphate concentration is linear. The experiments show that salinity stimulates phosphate release from sediment.