1. Hydrosphere p

2. Hydrosphere Formed by all bodies of water on the Earth’s surface
Includes oceans, rivers, streams, lakes and other waterways

3. Hydrosphere Covers 75% of Earth’s surface
Without water there would be no life
Water can either be fresh or salty

4. Why are the seas and Oceans salty?
Seas and Oceans are salty because there are a great quantity of mineral salts dissolved in it
Mineral salts come from rocks
When it rains, some minerals (which form the rocks) dissolve
Minerals run into the ocean where they accumulate

5. Are some Seas saltier than others?
The amount of salt in seas vary depending on the region in the world
The Dead Sea – Saltwater Lake in the Middle East with salinity of 27%

6. Which type of water can humans drink?
Humans can only drink fresh water because they can’t absorb the large quantity of mineral salts contained in salt water
When water is safe
to drink it is called potable.
Potable water = drinkable water

7. Potable Water
To be potable water it must have the following characteristics:
Perfectly transparent
No suspended particles
No unpleasant odour
Contains little dissolved minerals
Contains dissolved oxygen
No micro-organisms that cause disease

8. Potable Water 7 billion people in the world (March 2012)
780 million people in the world without access to adequate water and sanitation
3.5 million people die each year from water, sanitation, and hygiene-related causes.
The rate of child deaths is equivalent to a jumbo jet crashing every four hours.
Water is whose responsibility?

9. But how much water is available for humans to drink?
Works out to be about 0.02% available fresh water

10. The Water Cycle
Where this is the way earth cleans its water – but there is a limit

11. The Water Cycle
a) Evaporation - water from lakes, rivers and oceans changes to water vapour by the action of the sun.
b) Transpiration - water vapour is released from plants by the action of the sun.
c) Condensation - water vapour changes to droplets of liquid as it cools, leading to the formation of clouds.

12. d) Precipitation - water from clouds is released back into lakes, rivers and oceans, as rain, snow or hail, or onto land where it seeps through the soil and travels as ground water back to the ocean.
e) Melting - ice and snow change to liquid water by the addition of heat, and flow into lakes, rivers and oceans.

13. People upset the natural water cycle
That is because we:
Create pollution
Remove the natural vegetation such as plants and trees
Pave over the natural environment and build houses etc.
Put in irrigation systems, build dams, change natural drainage systems, build wells