Why is the sea salty?Why is the sea salty?

By Ginny (P7)

SALTY SEAS & OCEANSSALTY SEAS & OCEANS

How did it get there?

Nobody really knows. It’s a mystery!

We DO knowWe DO know……..

that salts dissolve in water = WATERSOLUBLE.

BUT

there is an enormous amount of salt in the waters of the seas and oceans of the

world.

Image by:

Lets look at the WATER CYCLELets look at the WATER CYCLE

WATER CYCLEWATER CYCLE

•A cycle is a continuous pattern of life. The water cycle is the simplest natural cycle on Earth.

•The water cycle occurs when the sun evaporates water from ocean,lakes and rivers.

•Millions of litres of water rise into the atmosphere as an invisible gas = WATER VAPOUR.. This process is called evaporation.. ••As the water vapour is pushed over the land by winds and rises over mountains, the water vapour cools and turns back into tiny waterdroplets, forming clouds.

•The droplets joining together is termed condensation. These droplets fall to earth as rain (precipitation).••The rain runs into streams and rivers, which eventually flow into lakes or the sea and the cycle begins all over again.

SOURCE: http://www.sawater.com.au/NR/rdonlyres/657AC917-D6E3-4E55-AAD1-38119A0ACBB4/0/diag_water_cycle.gif

INTERESTING FACTINTERESTING FACT

No new water is being made and water can’t escape from the Earth.

The water we use is recycled over and over again.

There will never be any more freshwater on Earth than there is now…

There are various theoriesThere are various theories……

Lets look at them Different answer sources

anSWERanSWER source 1source 1Why Is The Sea Salty, But Not Rivers And Lakes?Why Is The Sea Salty, But Not Rivers And Lakes?Why Is The Sea Salty, But Not Rivers And Lakes?Why Is The Sea Salty, But Not Rivers And Lakes?

It all comes down to a thing called the water cycle.

Rain, which is fresh water, falls from clouds onto the land and finds its way into lakes and rivers, and also through the ground, back to the sea, picking up salts and minerals as it goes.

Once it reaches the sea, the water can be evaporated again to form new clouds containing fresh water, and the salt is left behind, so over millions of years the oceans have slowly been accumulating salt washed off the land by fresh water. So is the sea becoming more salty ?

Probably not because if the level of salt rises any further the extra is removed by various processes, including chemical reactions, so the sea is now about as salty as it is going to get.

That’s not to say you can’t get saltier seas – like the Dead Sea – these are just bodies of water cut off from the main ocean and in which more water is evaporating than being returned by rivers, so the water becomes more concentrated.

26th Oct 2003SOURCE: http://www.thenakedscientists.com/HTML/content/news/news/582/

answer source 2answer source 2

The salt in our oceans is the result of millions of years of minerals leaching and dissolving from the solid earth. The major portion comes from rivers, while a good quantity of the salts are dissolved from rocks and sediments below the ocean floor, through volcanic vents.

The weather is also responsible, to a lesser degree, as the rain deposits mineral particles into the oceans.

The sun's heat distills or vaporizes almost pure water from the surface of the sea, leaving the salts and minerals behind.

The water returns to the ocean, via rivers or precipitation, to wash down more salt, which becomes ever more concentrated.

This process is part of the continual exchange of water between the Earth and the atmosphere that is called the hydrological or water cycle.

anSWERanSWER source 2 source 2 (CONTINUED)(CONTINUED)Answer IIAnswer IIAnswer IIAnswer IIRain water, or precipitation, is slightly acidic due to dissolved compounds.

When this acidic water beats down on the land and rocks, they end up dissolving the minerals in the rocks and return them to the water.

The minerals are salt compounds-- not just sodium chloride. A salt is any ionic compound (metal and a non-metal), such as calcium chloride or magnesium chloride.

The salt(s) then flow down rivers and streams to their final destination in the oceans, where they remain.

Over the course of millions of years, this salt has accumulated to be a substantial component of the oceans.

SOURCE: http://wiki.answers.com/Q/Why_are_the_oceans_salty

anSWERanSWER source 3source 3WEATHERING and erosion of the minerals of the earth's surface release many ions to be washed into the seas.

The main ones are iron, magnesium, potassium, calcium carbonate, sulphate, chlorine and sodium. All except the last two are readily involved in organic and chemical reactions, yielding new sedimentary rocks.

Sodium and chlorine therefore have built up as a residue throughout geological time, and indeed the salinity of the sea has been used as a basis of measuring the age of the ocean.

E J Marsden (retired teacher of geology), Stockport.

SOURCE: http://www.guardian.co.uk/notesandqueries/query/0,5753,-1532,00.html

anSWERanSWER source 3 source 3 CONTINUEdCONTINUEdTHE REAL puzzle about the sea is why it is not more salty.

It is a relatively simple matter to measure the rate at which sodium chloride is carried to the sea by rivers and then calculate how quickly the concentration of salts builds up.

These estimates indicate that it would take only a few hundred million years for the sea to become a completely saturated sodium chloride solution - yet the sea at present is well below saturation point.

Furthermore, palaeontological evidence seems to show that the concentration of the sea stays relatively constant.

Where has all the excess sodium chloride been going over four billion years of earth history?

How is it returned to the land, or lost into the earth's crust? Human and biological activity has negligible effect.

Some salt is removed at ocean ridge hot springs, and this process accounts for the balance in concentration of salts of other elements (iron, magnesium, etc) but does not remove nearly enough sodium chloride to explain why the sea is not saturated.

Is anyone able to throw any more light on this problem?

Thomas Chapman, King's College, Cambridge.SOURCE: http://www.guardian.co.uk/notesandqueries/query/0,5753,-1532,00.html

anSWERanSWER source 3 source 3 CONTINUEDCONTINUED

Why the sea isn't more salty is because of tectonic plate movement.

The concentrations of salts are indeed recycled back into the earth as a plate subducts under another.

Peter Roberts, Oxford, England

SOURCE: http://www.guardian.co.uk/notesandqueries/query/0,5753,-1532,00.html

anSWERanSWER source 4source 4ClanadClanadClanadClanad(16:03 on Sat 28/Oct/06)

Until about twenty years ago, theory suggested that, over millions of years, dissolved mineral that flowed into the oceans from rivers and streams, was responsible for the saltiness.

Then, according to The University of Texas Department of Geology "... About twenty years ago, features on the crest of oceanic ridges were discovered that modified our view on how the sea became salty.

These features, known as hydrothermal vents, represent places on the ocean floor where sea water that has seeped into the rocks of the oceanic crust, has become hotter, and has dissolved some of the minerals from the crust, now flows back into the ocean.

With the hot water comes a large complement of dissolved minerals.

Estimates of the amount of hydrothermal fluids now flowing from these vents indicate that the entire volume of the oceans could seep through the oceanic crust in about 10 million years.

Thus, this process has a very important effect on salinity.

The reactions between seawater and oceanic basalt, the rock of ocean crust, are not one-way, however; some of the dissolved salts react with the rock and are removed from the water...

" It's also believed that under sea volcanos contribute significantly to the saline content...

SOURCE: http://www.theanswerbank.co.uk/Animals-and-Nature/Environment/Question313260.html

anSWERanSWER source 4 source 4 CONTINUEDCONTINUED

KingarooKingarooKingarooKingaroo(19:08 on Wed 01/Nov/06)

Did you want a simpler answer?

Salt naturally occurs in soil and rocks, on land and under the sea.

It washes into the ocean in rivers and comes up in vents from below the ocean bottom.

When water evaporates from the ocean, it leaves behind all the minerals it was carrying, and they accumulate in the ocean.

SOURCE: http://www.theanswerbank.co.uk/Animals-and-Nature/Environment/Question313260.html

What DO YOU THINK?What DO YOU THINK?

Why don’t you have a think about it

and read up a bit more on it

and let me know your ideas ?

ReferencesReferences

• BOOK: Tell me Why by Hamlyn • http://mendocoastcurrent.files.wordpress.com/2009/05/wave-ocean-blue-

sea-water-white-foam-photo.jpg• http://media-cdn.tripadvisor.com/media/photo-s/01/31/17/7b/lovely-clear-

sea-water.jpg• http://earspecialist.eu/Image/savasodas/tengerviz.jpg• http://www.thoughtsanddeeds.com/wp-

content/uploads/2009/05/waves.jpg• http://blogs.kqed.org/climatewatch/files/2008/11/wave.jpg• http://www.femtalks.com/wp-content/uploads/2008/11/poseidon-fiji-

05.jpg• http://www.51yala.com/UPLOAD/NewsIMG/20075311154290.jpg• http://www.stlwater.com/images/waterdrip.jpg• http://www.kaheel7.com/userimages/Sea_.jpg• http://users.resist.ca/~kirstena/photoventurasunset1.jpg• http://stahlworks.com/piclib/1280x1024/sls0066_sunlight_reflections_in_se

a_water.jpg• http://aquafornia.com/wordpress/wp-content/uploads/2008/11/salton-

sea-5-02-2008.jpg• http://www.7lul.com/blog/wp-content/uploads/sea-water-isthmus.gif• http://cccncsnl.files.wordpress.com/2007/11/sea-the-light.jpg