2 hypoxia n nutrient loading
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Transcript of 2 hypoxia n nutrient loading
2. Hypoxia & Nutrient Loading
Nutrients are usually limited
• This limits the amount of plant growth• In oceans, the limiting nutrient is usually
Nitrogen (N)
• Where does N come from?• Is it limiting in estuaries? Why?
Eutrophication
• Too much of a good thing!• Over fertilized plants (mostly plankton) in water
cause an increase “aging” of the estuary• How?• Excess Nutrients=Increased phytoplankton growthdeathsinkdecomposition
Problem
• During decomposition, dissolved Oxygen is used up during the death that comes after eutrophication, there’s way too much O2 leaving the system-what happens when oxygen is lacking?
Result
• Extremely low O2 dissolved in the water.
• What is this known as. . . . ?
HYPOXIA!!!!
When is hypoxia a problem?
• March & August. . . Why?• During these months, more than usual, the
thermocline prevents mixing of warm, less dense surface water with cooler, denser bottom water
• The result. . . . Not enough O2
Solutions to Hypoxia• Improve STP’s (each one treats > 40 million gallons/day!)
Treatments: 1º – filtering & settling to remove solids2º – biologically remove organic nutrients,
required by law, grow bacteria to help decompose organics3º - advanced; chemically removes inorganic
nutrients, very costly
Solutions to Hypoxia cont.2) Reduce runoff
To reduce chemicals getting into wetlands or out to estuaries, some companies put down
-Sheets/tarps-Haybales-Terracing
Solutions to Hypoxia cont.
3) Reduce fertilizers on lawns/crops– Think about what times of
year fertilizers are usually applied!
Solutions to Hypoxia cont.4) Reduce phosphates & other
nutrients in products we use (i.e. soaps, which we did)
Mmmm. . .
so fun to swim in this!