Phosphorus, redox, iron

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Phosphorus, redox, iron

• 23 Feb 2007
• AWER 4500

http//www.fiu.edu/trexlerj/periphyton2.JPG
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(No Transcript)
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Nutrient Cycling in Streams
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Algal P Uptake

• Phytoplankton periphyton
• have several adaptations
• to low-P conditions
• Alkaline phosphatase
• Luxury uptake

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Epilimnetic Phosphate Cycling
P Cycling in the Water Column
Cycle times particulate? PO4
Minutes to hours !
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Phosphorus and lake sediments

• Forms
• Particulate Organic P
• (phytoplankton, bacteria detritus)
• Particulate Inorganic P
• (clays adsorbed to P, Iron Bound P)
• Dissolved P in interstitial water

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REDOX

• Reduction-oxidation In these reactions, there is
  a net gain or loss of electrons.

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Sequence of microbially-mediated redox processes
(W. Stumm and JJ Morgan 1981)
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REDOX

• Reduction-oxidation In these reactions, there is
  a net gain or loss of electrons.
• Redox potential relative availability of
  electrons for chemical reactions.
• Redox conditions will determine if certain
  chemical reactions take place.
• REDOX state controlled by presence or absence of
  oxygen.

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Redox
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The Ferrous Wheel Oxygen recycling between
strata or sediment-water interface