Water From The Sea
Bit about the Ocean
You
look down at our planet from outer space, most of what you see is water; 71% of the planet's surface is covered by ocean and
it is because of this that the Earth is sometimes called "the water planet". Only about three-tenths of our globe is covered
with land.
The
ocean wraps the globe and is divided into four major regions: the Atlantic Ocean, the Pacific Ocean, the Indian Ocean and
the Arctic Ocean. Some scientists consider the waters around Antarctica to be a separate, fifth ocean as well. These oceans,
although distinct in some ways, are all interconnected; the same water is circulated throughout them all.
Seventy-one
percent of the Earth's surface is ocean.
If
all the continents were crammed into one corner of the Earth, the vast extent of the world ocean could easily be seen. In
reality, of course, the continents are not bunched together as shown in the figure to the right, but instead are spread out
over the entire Earth's surface. Most oceanographers, however, believe that a long time ago in the Earth's geologic history
all of the continents were once grouped closely together in much the same manner.
Turning Sea Water Into Drinking Water Hows' it Done
& At What Cost?
Desalination plants are widespread in places such as Tenerife
and Gran Canaria, where minimal rainfall means natural water resources are scarce.
Israel and Saudi Arabia already rely heavily on such plants
to supply their populations, while the American states of Florida and California have also ventured down this road.
Desalination is a relatively recent solution, coming of age in the Middle East in the 1980s and 1990s. Thames Water
plans to use a process known as "reverse osmosis" to draw salt from the brackish flow of the Thames estuary.
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HOW REVERSE OSMOSIS DESALINATION WORKS
1. Water flows in from the estuary or sea
2. Salt water contains sodium and chloride ions
3. Pressure is applied to force salt water through
membrane
4. Semi-permeable membrane with millions of microscopic
holes
5. Clean water fit for drinking
6. Saline concentrate flows out |
It works by pushing salty water through a series of ultra-fine
membranes which draw out the tiny sodium and chloride ions.
But it comes at a cost - financial and environmental. Water prices are expected to
rise towards the end of the decade, to reflect the growing demand.
