Water, water everywhere. But how much of it is useful?
Earth is the water planet. From space, Earth is a blue ball, unlike any of the other planets in our solar system. Life, also unique to Earth of the planets in our solar system, depends on this water. While there's a lot of salt water, a surprisingly small amount of it is fresh water.
Distribution of Water
Earth’s oceans contain 97% of the planet’s water. That leaves just 3% as fresh water, water with low concentrations of salts ( Figure below ). Most fresh water is trapped as ice in the vast glaciers and ice sheets of Greenland and Antarctica.
How is the 3% of fresh water divided into different reservoirs? How much of that water is useful for living creatures? How much for people?
The distribution of Earth’s water.
A storage location for water such as an ocean, glacier, pond, or even the atmosphere is known as a reservoir . A water molecule may pass through a reservoir very quickly or may remain for much longer. The amount of time a molecule stays in a reservoir is known as its residence time .
- Of Earth's water, 97% is in the oceans.
- Of the remaining 3%, much is trapped in ice and glaciers.
- A substance is stored in a reservoir and the amount of time it stays in that reservoir is its residence time.
Use the resource below to answer the questions that follow.
- Where is the Fresh Water? at http://ga.water.usgs.gov/edu/earthwherewater.html
- How much of the Earth's water is ocean water?
- How much freshwater is in glaciers?
- How much freshwater is groundwater?
- How much freshwater is in surface water and how much surface water is in lakes?
- What is that tiny 3rd ball over Georgia?
- If Earth is the water planet, why is water sometimes a scarce resource?
- What are the reservoirs for water?
- In which reservoirs does water have the longest residence times? The shortest?