The Naked Scientists

The Naked Scientists Forum

Author Topic: Why is the Dead Sea so salty?  (Read 8756 times)

Offline chris

  • Neilep Level Member
  • ******
  • Posts: 5336
  • Thanked: 65 times
  • The Naked Scientist
    • View Profile
    • The Naked Scientists
Why is the Dead Sea so salty?
« on: 12/03/2010 08:37:37 »
Oceans are salty because water evaporated from the sea-surface rains down over land, dissolving minerals and washing them into the ocean along rivers. This leads to the accumulation of salts in the water. But the oceans are not becoming increasingly salty. So some sort of chemical equilibrium is occurring whereby any added salt burden is being being removed in insoluble forms, keeping the overall saltiness the same.

But what about the Dead Sea? Why is that so salty compared with other seas and bodies of water?

Chris


 

Offline neilep

  • Withdrawnmist
  • Naked Science Forum GOD!
  • *******
  • Posts: 20602
  • Thanked: 8 times
    • View Profile
Why is the Dead Sea so salty?
« Reply #1 on: 12/03/2010 14:09:18 »
I swum in it....as you can imagine...one becomes ever so buoyant !
 

Offline Geezer

  • Neilep Level Member
  • ******
  • Posts: 8328
  • "Vive la résistance!"
    • View Profile
Why is the Dead Sea so salty?
« Reply #2 on: 12/03/2010 21:40:01 »
I swum in it....as you can imagine...one becomes ever so buoyant !

Is it a bit pongy? The lake in Utah is.
 

Offline neilep

  • Withdrawnmist
  • Naked Science Forum GOD!
  • *******
  • Posts: 20602
  • Thanked: 8 times
    • View Profile
Why is the Dead Sea so salty?
« Reply #3 on: 13/03/2010 00:13:59 »
I swum in it....as you can imagine...one becomes ever so buoyant !

Is it a bit pongy? The lake in Utah is.


Gosh !...it was erhmmm...27 years ago !...I think I do remember an odour but not a pongy pong !!....actually (hang on a minute !)

A few minutes later !!




VOILA !!





As ewe can see...we are all very buoyant !!..and we are treading water here !!

 

Offline FuzzyUK

  • Sr. Member
  • ****
  • Posts: 206
    • View Profile
    • http://www.fusniak.co.uk
Why is the Dead Sea so salty?
« Reply #4 on: 22/04/2010 19:32:24 »
Oceans are salty because water evaporated from the sea-surface rains down over land, dissolving minerals and washing them into the ocean along rivers. This leads to the accumulation of salts in the water. But the oceans are not becoming increasingly salty. So some sort of chemical equilibrium is occurring whereby any added salt burden is being being removed in insoluble forms, keeping the overall saltiness the same.

This doesn't explain why there is so much sodium chloride in seas over riding all sorts of other salts, Chris.
 

Offline frethack

  • Sr. Member
  • ****
  • Posts: 394
    • View Profile
Why is the Dead Sea so salty?
« Reply #5 on: 22/04/2010 23:18:25 »
Ill take a stab at this one.  I think that the likely cause is the abundance of plagioclase...there is a calcic end member and a sodium end member with a solid solution in between.  A very good portion of the earths crust is plagioclase feldspar (not sure on the exact percentage off hand...Bass or JimBob would probably know).  The aluminum weathers to clay, and the cations (sodium) are taken up into salts in the oceans.
 

Offline Geezer

  • Neilep Level Member
  • ******
  • Posts: 8328
  • "Vive la résistance!"
    • View Profile
Why is the Dead Sea so salty?
« Reply #6 on: 23/04/2010 20:20:38 »
Oceans are salty because water evaporated from the sea-surface rains down over land, dissolving minerals and washing them into the ocean along rivers. This leads to the accumulation of salts in the water. But the oceans are not becoming increasingly salty. So some sort of chemical equilibrium is occurring whereby any added salt burden is being being removed in insoluble forms, keeping the overall saltiness the same.

This doesn't explain why there is so much sodium chloride in seas over riding all sorts of other salts, Chris.

The rivers dump a lot of other salts into the oceans and comparatively small amounts of sodium. Most of these salts are taken out of solution by marine life. For example, corals remove calcium. However, there are no known biological processes that remove sodium from seawater.

There are chemical processes that precipitate sodium and it is believed that, currently, the chemical precipitation rate for sodium is approximately equal to the intake rate from the rivers. However, when the Earth was much younger, the salt intake would have been much greater while there was continuous rainfall and temperatures were much higher.

The first seas would have been loaded with lots of different salts until marine life removed most of them and left the sodium behind.
 

Offline JimBob

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 6564
  • Thanked: 7 times
  • Moderator
    • View Profile
Why is the Dead Sea so salty?
« Reply #7 on: 24/04/2010 04:19:33 »
Oceans are salty because water evaporated from the sea-surface rains down over land, dissolving minerals and washing them into the ocean along rivers. This leads to the accumulation of salts in the water. But the oceans are not becoming increasingly salty. So some sort of chemical equilibrium is occurring whereby any added salt burden is being being removed in insoluble forms, keeping the overall saltiness the same.

This doesn't explain why there is so much sodium chloride in seas over riding all sorts of other salts, Chris.

The rivers dump a lot of other salts into the oceans and comparatively small amounts of sodium. Most of these salts are taken out of solution by marine life. For example, corals remove calcium. However, there are no known biological processes that remove sodium from seawater.

There are chemical processes that precipitate sodium and it is believed that, currently, the chemical precipitation rate for sodium is approximately equal to the intake rate from the rivers. However, when the Earth was much younger, the salt intake would have been much greater while there was continuous rainfall and temperatures were much higher.

The first seas would have been loaded with lots of different salts until marine life removed most of them and left the sodium behind.

See there frethac? That is what is called "reasoning" and "thinking"!

Or is that "Googleing" http://www.palomar.edu/oceanography/salty_ocean.htm " ... here are no known biological processes that remove sodium from seawater." is directly from this page.
 

Offline Geezer

  • Neilep Level Member
  • ******
  • Posts: 8328
  • "Vive la résistance!"
    • View Profile
Why is the Dead Sea so salty?
« Reply #8 on: 24/04/2010 07:50:58 »
Oceans are salty because water evaporated from the sea-surface rains down over land, dissolving minerals and washing them into the ocean along rivers. This leads to the accumulation of salts in the water. But the oceans are not becoming increasingly salty. So some sort of chemical equilibrium is occurring whereby any added salt burden is being being removed in insoluble forms, keeping the overall saltiness the same.

This doesn't explain why there is so much sodium chloride in seas over riding all sorts of other salts, Chris.

The rivers dump a lot of other salts into the oceans and comparatively small amounts of sodium. Most of these salts are taken out of solution by marine life. For example, corals remove calcium. However, there are no known biological processes that remove sodium from seawater.

There are chemical processes that precipitate sodium and it is believed that, currently, the chemical precipitation rate for sodium is approximately equal to the intake rate from the rivers. However, when the Earth was much younger, the salt intake would have been much greater while there was continuous rainfall and temperatures were much higher.

The first seas would have been loaded with lots of different salts until marine life removed most of them and left the sodium behind.

See there frethac? That is what is called "reasoning" and "thinking"!

Or is that "Googleing" http://www.palomar.edu/oceanography/salty_ocean.htm " ... here are no known biological processes that remove sodium from seawater." is directly from this page.

It's a fair cop gov'ner.  ;D

Actually, I worked out the last bit by myself. I don't think they said that anywhere.
 

Offline JimBob

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 6564
  • Thanked: 7 times
  • Moderator
    • View Profile
Why is the Dead Sea so salty?
« Reply #9 on: 24/04/2010 17:48:31 »
It is OK old man. We know how it gets there in the nursing home trying to stay away from the  oversexed  old women. I, too, would retire to my chambers and engage in a bit of plagiarism.

(In fact, I did it in college before the PC - just fortan punch cards and a tray that always spilled or was rendered useless by the rain on the way to submit the program to the Computer Center.)


 

Offline Geezer

  • Neilep Level Member
  • ******
  • Posts: 8328
  • "Vive la résistance!"
    • View Profile
Why is the Dead Sea so salty?
« Reply #10 on: 24/04/2010 18:01:02 »
So I guess you were Googling to try to find the answer too  :D
 

Offline JimBob

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 6564
  • Thanked: 7 times
  • Moderator
    • View Profile
Why is the Dead Sea so salty?
« Reply #11 on: 25/04/2010 05:26:54 »
ah, er.. NO!!! I knew you didn't have that set of knowledge. You would blow mo out of the water with your expertise in physics, especially electrical and mechanical theory, which is you profession.

I can spot the writing done by someone in my profession very easily and know that you don't have a professional level of knowledge in my field.

The rest was easy (He said, smugly)

I was a very good and correct answer, though.
 

Offline Bored chemist

  • Neilep Level Member
  • ******
  • Posts: 8659
  • Thanked: 42 times
    • View Profile
Why is the Dead Sea so salty?
« Reply #12 on: 25/04/2010 15:25:23 »
Since practically all sodium salts are soluble I'd like to hear more about this idea "There are chemical processes that precipitate sodium and it is believed that, currently, the chemical precipitation rate for sodium is approximately equal to the intake rate from the rivers. "
 

Offline Geezer

  • Neilep Level Member
  • ******
  • Posts: 8328
  • "Vive la résistance!"
    • View Profile
Why is the Dead Sea so salty?
« Reply #13 on: 25/04/2010 15:32:15 »
Here's where I pinched er, borrowed it.

http://www.palomar.edu/oceanography/salty_ocean.htm

Are you thinking there would be little to no precipitation?

BTW - assuming all this is correct, if, by some strange event the salt was removed from the oceans, they might remain "fresh" indefinitely.
 

Offline RD

  • Neilep Level Member
  • ******
  • Posts: 8126
  • Thanked: 53 times
    • View Profile
Why is the Dead Sea so salty?
« Reply #14 on: 25/04/2010 19:49:46 »
The water in the Dead Sea (or should that be "Dead hypersaline lake") can only leave by evaporation ...

Quote
... in an endorheic basin, rain (or other precipitation) that falls within it does not flow out but may only leave the drainage system by evaporation and seepage. The bottom of such a basin is typically occupied by a salt lake or salt pan.
http://en.wikipedia.org/wiki/Endorheic_basin
« Last Edit: 25/04/2010 19:53:20 by RD »
 

Offline SeanB

  • Neilep Level Member
  • ******
  • Posts: 1118
  • Thanked: 3 times
    • View Profile
Why is the Dead Sea so salty?
« Reply #15 on: 25/04/2010 20:01:02 »
There are planty of salt pans here, mostly in the Karoo. They are generally dry until rain falls and makes a temporary saline mud lake, which rapidly disappears.
 

Offline Geezer

  • Neilep Level Member
  • ******
  • Posts: 8328
  • "Vive la résistance!"
    • View Profile
Why is the Dead Sea so salty?
« Reply #16 on: 25/04/2010 20:17:36 »
The water in the Dead Sea (or should that be "Dead hypersaline lake") can only leave by evaporation ...


Er, would that not also be true for all the oceans?

I don't think there's a plug hole anywhere.
 

Offline JimBob

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 6564
  • Thanked: 7 times
  • Moderator
    • View Profile
Why is the Dead Sea so salty?
« Reply #17 on: 25/04/2010 20:35:51 »
Sodium removal from the oceans take place in three main ways. These is direct precipitation due to evaporation, which at present is occurring in restricted marine environments, such as the saline lagoons behind coastal barrier islands and waters with restricted circulation (Netherlands, Atlantic and Gulf Coasts of the US and Mexico, Gulf of California, western Mexico, salt marshes in all tropical zones of the world, etc.) This is how the fossil deposits of salt that is what is on everyone's dinner table are formed. (A very small percentage is produced by evaporation in man-made coastal salt pans. (Southern France, Italy, etc.))  

Although this is probably a minor method of sequestration, NaCl reacts with basalt minerals from volcanic eruptions into sea water.

The most important - and least understood method - well, I am not that smart. It takes a strange type of person to be a specialist in marine clay mineralogy. Heck, ANY type of clay mineralogy for that matter! This is, however, the predominant method of sodium sequestration in the oceans. Occurring moistly in the deeper parts of the ocean, NaCl reacts with the clay minerals of the Phyllosilicate Group of minerals, removing the sodium ion and releasing the chlorine.

If there is one of those strange creatures - marine clay mineralogist - that can be captured and who wishes to cooperate by posting a READABLE AND UNDERSTANDABLE synopsis of how the process works I would be very glad to hear from them.

I doubt there are more than 1000 people in the world that completely understand the processes by which this occurs, although geologist are taught that this process exists.

See Geeze? - there is more than one way to turn a crank shaft (leaves to go grocery shopping so he doesn't get hit with a bomb)

« Last Edit: 26/04/2010 01:29:34 by JimBob »
 

The Naked Scientists Forum

Why is the Dead Sea so salty?
« Reply #17 on: 25/04/2010 20:35:51 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums