Page 89 - Science Course 2 (Book 2)

Mo10-L2b: What is the Phosphorus Cycle?

Rocks in the geosphere include minerals that contain phosphates.

Phosphorus dissolved in liquid water does not evaporate into the atmosphere.

The cycling of phosphorus through the geosphere and the hydrosphere
occurs over long periods of time.

Phosphorus stored in organisms in the biosphere recycles more quickly.
Clearing the trees in rain forests disturbs the phosphorus cycle.

Runoff from farms, homes, and factories can contain phosphorus.
Algae consume the phosphorus, and the algae population increases.

Excess algae decompose and use up oxygen in the water.

Increased level of
Residential sewage nitrates and Chemical runoff
and industrial runoff phosphates in rivers from fertilizers
and ponds

result in thick scum Less light causes death
on water surface
of some
photosynthesis plants

Large amounts of
death of some algae
organic matter.

Death of f sh and other Aerobic decomposition
aquatic organisms (bacteria uses up
oxygen in water)

SUMMARY
What is the Phosphorus Cycle?

Rocks exposed at Earth’s surface release phosphates when they weather.

The phosphorus cycle moves phosphorus among three Earth systems.

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