1. Phosphorus Cycle Name:______________________
Date:_______________________
Period:_______

2. The Phosphorus Cycle: Why is Phosphorus important?
Does not cycle through the atmosphere
In all living organisms: DNA, energy storage
In plants: root development, stem strength and seed production
In animals: works with calcium to strengthen bones, in shells

3. How is Phosphorus Stored?
Trapped in rocks and sediments of ocean floors in various forms of phosphates:
(PO43-, HPO42- and H2PO4-)

4. How is Phosphorus Cycled Through Ecosystems Naturally?
Weathering = break down of rock into small fragments, which then releases phosphates into the soil
2 types of weathering: Chemical & Physical
Chemical Weathering
Chemical reactions release P from rocks into soil
Can be caused by acid rain or chemicals released by lichens
Physical weathering
Wind, rain and freezing release particles of rocks and P into the soil

5. How is Phosphorus Cycled through ecosystems naturally?
Plants take up phosphate from soil through roots
Animals obtain phosphorus by eating plants
Decomposers breakdown solid waste and dead organisms to return phosphorus to soil for plants again

6. How is Phosphorus Cycled Through Ecosystems Naturally?
Erosion, leeching and run-off moves phosphorus to aquatic ecosystems
Water plants take up phosphorus and pass it along food chains
Run off carrying the phosphorus into lakes and ocean bottoms to form sediments.
Over time, phosphorus is incorporated into sedimentary rock (this takes millions of years)
Geological uplift = mountain building where Earth’s crust folds and exposes deep rock layers may make phosphorus available again from sedimentary rock.

9. Human Activity and the Phosphorous Cycle
Humans add excess phosphorus to the environment through mining for fertilizer components.
Extra phosphorus, often along with potassium, then enters the ecosystems faster than methods can replenish the natural stores.
Humans can also reduce phosphorus supplies.
Slash-and-burning of forests removes phosphorus from trees, and it then is deposited as ash in waterways.