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Chuck Hansen 3.7.13. Phosphorus Cycling -Limnology, Wetzel, RG. Phosphorus Info. Dissolved Inorganic Phosphorus (DIP) aka Soluble Reactive Phosphorus (SRP) Disolved Organic Phosphorus (DOP) Particulate Phosphorus (PP) Total P = DIP + DOP + PP Found in the form of Phosphates (PO 4 -3 )
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Chuck Hansen 3.7.13 Phosphorus Cycling-Limnology, Wetzel, RG
Phosphorus Info • Dissolved Inorganic Phosphorus (DIP) aka Soluble Reactive Phosphorus (SRP) • Disolved Organic Phosphorus (DOP) • Particulate Phosphorus (PP) • Total P = DIP + DOP + PP • Found in the form of Phosphates (PO4-3) • Important to plants, animals, and microbiota • Growth – Limiting Nutrient
Sources of Phosphorus • Weathering of Apatite • Point Sources • Sewage, Urban Runoff • Nonpoint Sources • Agriculture, Animal Waste, Fertilizers • Modes of Entry to Aquatic Systems • Precipitation (dust in air), Groundwater Adsorption, Surface Runoff
Uptake & Adsorption • Decreases Downstream • Can occur faster than needed for growth • Rate of uptake dependant upon how much organic matter there is to take it in, and the metabolism of those constituents
Questions/Discussion • How does the solubility of Fe influence the phosphorus redox reactions? As a result, explain how sulfur and iron trapping influences the concentration of phosphorus in the hypolimnion at overturn in a lake. • Others….
Iron Trapping • Iron trap for P • - In oxygenated waters, iron is present as Fe3+ (ferric) • pH < 7 : Fe3+ + PO43- : FePO4 (Vivianite) • pH > 7 : Fe3+ + PO43- + OH- : Fe2, OH, PO4
Redox Reactions • Fe3+ conversion to Fe2+ releases PO43- • Sulfur trap may lower iron concentrations enough to allow some phosphate to remain at overturn • All these reactions mediated by bacteria