Phosphorus%20Cycling%20-Limnology,%20Wetzel,%20RG

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Phosphorus Cycling -Limnology, Wetzel, RG

• Chuck Hansen 3.7.13

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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

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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

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Origins and Basic cycle
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(No Transcript)
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Aquatic Sytem and Spiraling
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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

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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.

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Sediment to Water Exchange
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Iron Trapping

• Iron trap for P
•   - In oxygenated waters, iron is present as Fe3
  (ferric)
• pH lt 7 Fe3 PO43- FePO4 (Vivianite)
• pH gt 7 Fe3 PO43- OH- Fe2, OH, PO4

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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