FRESH WATER
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FRESH WATER
Water in its liquid state is the most abundantly found element in the biosphere and also the most important for life itself.
In its solid state, water floats, a characteristic that protects sea dwellers from the cold winter.
Water dissolves a great number of substances without reacting chemically with them.
It also has a high “latent heat” and several other, extremely important characteristics as far as living beings are concerned.
Roles played by the Seas in the biosphere.
Water consumption. Farming.
Water supply difficulties already exist on a world scale.
Fresh water resources are limited.
A world with a water shortage is an unstable world.
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1’ 52’’ INTRODUCTION
If we were asked what the most important substance for life is, we would answer it is water.
Life on Earth began in the seas, and all living beings need water to survive.
The liquid of life itself is a common and abundant element on Earth.
3’ 01’’ THE QUALITIES OF WATER
Water is a compound made up of two hydrogen and one oxygen atoms.
It is liquid at room temperature, when it should be a gas.
Ice, water’s solid state, floats upon liquid water.
In liquid water molecules stick to one another, thus considerably increasing its viscosity and surface tension.
The structure of liquid water is finely organised.
Water is a universal solvent.
Enormous heat exchanges take place in oceans.
Seas are the planet’s biggest C02 trappers.
1’ 33’’ FRESH WATER AND LIVING BEINGS
Life started in and still depends upon water.
Living-beings are mostly made of water.
No known form of life exists that can do without water.
The water we drink is referred to as “fresh” or “drinking water”, but, it also contains different salts and minerals dissolved in it.
3’ 58 FRESH WATER DISTRIBUTION
Water is one of the few substances which can be found in large quantities in nature in solid, liquid and gaseous states.
In its solid state, water is found as ice in glaciers and in the Poles.
As gas, it is found in water vapour forming clouds.
In its liquid state it is found in seas, oceans, lakes, rivers and underground streams.
Water on our Planet is in a continuous transformation process, known as the hydrologic cycle.
We think that fresh water is an inexhaustible natural resource, but it is not.
The Earth’s human population is increasing and also de consumption of fresh water per inhabitant.
3’ 25’’ RAIN WATER IS NO LONGER ENOUGH
Towns and villages were founded near rivers and lakes where there was abundant supply of water.
The urban expansion resulted in the best growing lands being asphalted over.
Rainwater is no longer enough. Water is being pumped up from the subsoil at alarming rates, more than nature can possibly replenish.
Lack of fresh water is the worst problem facing humanity in the whole of man’s relationship with Planet Earth.
Desalination represents our brightest hope for the future.
Should food production diminish due to the lack of water, it will be extremely hard to feed all the members of the human race in the XXI st century.
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