Residence Time of Dissolved Phosphate in Natural Waters

Residence time varies from approximately 0.05 to 200 hours. Short residence times are indictative of depleted phosphate, active metabolic activity, or both. The turnover rate of phosphate is between 0.1 and 1.0 mg of phosphorus per cubic meter, per hour, regardless of phosphate concentration, except in biologically active systems where it is 1.0 to 20. The turnover rate of phosphate may be more important than the phosphate concentration in maintaining highly productive systems.