The Phosphorus Cycle

Characteristics of the Phosphorus Cycle

• Phosphorus is a sedimentary cycle, meaning it is found dissolved in water or held in soil and rock formations.
• The cycle never involves an atmospheric or gaseous phase.
• Phosphorus is a crucial nutrient found in most living things and especially in animal waste.

Sources and Liberation Processes

• Rock formations store significant amounts of phosphorus.
• Geological processes such as earthquakes, landslides, and erosion liberate phosphorus from these formations.
• Once liberated, phosphorus is dissolved by the water cycle and flushed into surrounding areas.

Biological Uptake and the Food Chain

• Plants uptake phosphorus very quickly from the environment to use for growth.
• The nutrient enters the food chain when consumers eat plants or when aquatic organisms uptake phosphorus from the water.
• Phosphorus causes plants to grow very rapidly and is a primary ingredient in many fertilizers.

Chemical Forms and Deposition

• Phosphorus often exists as a phosphate, such as a $PO_{4}$ molecule.
• It may also be found combined with ammonia as ammonium phosphate.
• The cycle is completed when phosphorus is deposited back into nature through animal waste, decomposition, or dissolution.
• Final deposition often occurs as sediments at the bottom of lakes.