The Pathway of Movement of the Phosphorus Cycle and Phosphorus that is Carried by Runoff into the Ocean

Pathway of Movement

• Phosphorus is typically found in the rocks in soil, and so the cycle can be said to begin with the erosion of rock.
• Water trickles down the rocks and dissolves the phosphorus, which runs into bodies of water.  There, the phosphorus combines with oxygen to create phosphates.
• The phosphates are then absorbed by plants along the water, which use them to synthesize organic molecules.  
• The phosphate is then concentrated in plant tissues.
• A consumer eats the phosphorus-containing plant.
• Once the consumer dies, its body returns the phosphates to the lake as it decomposes.  Plant waste does the same.
• Large amounts of phosphorus are then carried by rivers and streams as runoff into the ocean.
• It is then trapped in the ocean floor as marine sediment.
• Over time, geologic uplifting occurs, and the cycle restarts.

So...

• When water runs over phosphorus-containing rocks, the rocks usually erode, causing phosphate ions to slip into streams and then into oceans.  

• These phosphates can be trapped for millions of years in the ocean floor as sediment.