Earth Science

Water on Earth

Water Distribution

Study Tip
Studying diagrams for this topic will help you visualize the relative amounts of water.

Distribution

  • Earth’s oceans contain 97% of the planet’s water.
  • That leaves just 3% as fresh water (water with low concentrations of salts).  
  • Most are trapped as ice in vast glaciers and ice sheets in Greenland.
Study Tip
Studying diagrams for this topic will help you visualize the relative amounts of water.

Reservoirs

  • A reservoir is a storage location for a substance (e.g. the atmosphere is a reservoir for carbon dioxide).
  • A water molecule may pass through a reservoir very quickly or may remain.  
  • The residence time is the amount of time a substance remains in a reservoir.
Reservoirs
Concept Check
  • Compare the amount of fresh water to the amount of salt water.
  • What is the relationship between reservoir and residence time?