2 hypoxia n nutrient loading
DESCRIPTION
Long Island Sound-hypoxia and nutrient loading class notesTRANSCRIPT
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 Hypoxia1) Improve STP’s (each one treats > 40 million gallons/day!)
Treatments:
1º – filtering & settling to remove solids
2º – biologically remove organic nutrients,
required by law, grow bacteria to help decompose organics
3º - 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!