Astronauts who have been lucky enough to observe our planet from space come back fascinated by itsincredible beauty and its amazing blue colour. This colour, which has earned Earth its nickname of the

“blue planet”, is partly linked to the vast expanses of water that cover it.

Condensation

Atmosphere0,001 %

On average a molecule of water remains in the atmosphere for 8 daysbefore falling back to the ground.Precipitation

Storage in depressions

(lakes, ponds, etc.)

Lakes0,01 %

Large and small rivers 0,0001 %

Plants and animals 0,0001 %

In soils0,005 %

Run-off

Infiltration

Subterranean watersources 0,6 %

Oceans 97,2 %

Glaciers and polar ice caps2,2 %

On average a drop ofwater remains in ariver for 2 weeksand in a lake for 17years.

A molecule of water remains for a fewhours only in the cell of a plant or ani-mal.

On average a drop of water remainsin the seas and oceans for 2,500years.

In the glaciers and polar ice caps, water is sometimes stored for up to 10,000 years.

Underground discharge

Evaporation

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The volume of water on Earth amounts to 1.385 billion km3. If it were to be spread out evenly over the surface of the globe, it would form a layer 2.7 km thick.

The oceans cover 71% of the Earth’s surface. It’s the blue planet.

Salt water accounts for 97.2% of water on Earth, with fresh water only accounting for 2.8%

The water available to mankind on Earth repre-sents less than 1% of the total volume.

Water is an asset that is poorly shared out on Earth. 40% of the world’s population lack water.

One kilogram of sea water contains on average 34.4 g of salt.

65% of an adult human’s body is made up of water.

billion

KeyBacteriological pollution

Hydrocarbon pollution Physical-chemical pollution

Waste pollution

Nitrate and phosphate pollution

ONE PLANET …

… AND MANYTYPES OFPOLLUTION!

Water is the preferred vehicle for all types ofpollution. Watercourses, rivers, then streams

sweep the poison along for miles before pouringit out into the ocean.

Water is present everywhere on earth and is indispensable for life.The quantity of water has remained unchanged for 4.4 billion years, and is distributed between four major sources :

oceans, coastal waters, the atmosphere and biosphere.

ONE WATER CYCLE …