Why do we have salt water?

[michel123456]

So you are saying there is no plate tectonics? Can you back that up with anything other than your Opinion?

 

No, I didn't say that. I said plate tectonics has no relation with salty rivers...

[zapatos]

(emphasis mine)

 

In order to reach an equilibrium, those 2 processes must be linked together by some sort of mechanism. Like water evapourating from the oceans is in equilibrium with the water raining from the clouds. What is that mysterious mechanism that connects salt coming from rivers with salt going away by plate tectonics? IMO there is no such mechanism: the explanation is incorrect.

I placed a cup in my sink below the faucet and turned the water on. For a while the volume of water contained in the cup rose, but then at some point the amount of water in the cup stopped increasing. Even though I kept adding water to the cup, the amount of water in the cup was stable. Must the process of adding water be linked by some mechanism to the process of water moving out of the cup to keep it in equilibrium?

 

 

"Many salt components are absorbed into the bodies of living organisms. For instance, coral polyps, mollusks, and crustaceans harvest calcium, a salt component, for their shells and skeletons. Microscopic algas called diatoms extract silica. Bacteria and other organisms consume dissolved organic matter. When these organisms die or are eaten, the salts and minerals in their bodies eventually settle to the seafloor as dead matter or feces.

Many salts not removed by biochemical processes are disposed of in other ways. For example, clay and other terrestrial materials that find their way into the oceans by means of rivers, land runoff, and volcanic fallout may bind certain salts and carry them down to the seafloor. Some salts also bind to rock. Thus, through a number of processes, much of the salt ends up being added to the seafloor.

Many researchers believe that geophysical processes complete the cycle, albeit over aeons of time. The earth’s crust is made up of gigantic plates. Some of these meet at subduction zones, where one plate plunges beneath its neighbor and sinks into the hot mantle. Usually, the denser oceanic plate sinks beneath its lighter continental neighbor, at the same time carrying its cargo of salty sediments with it like a great conveyor belt. In this way much of the earth’s crust slowly gets recycled. Earthquakes, volcanoes, and rift zones are three manifestations of this process."

 

http://scienceray.com/earth-sciences/why-is-the-sea-salty/

 

Doesn't seem all that mysterious to me.

[michel123456]

You told the story of rivers salt getting into ocean's floor and Earth's crust. You have to continue the story and raise the salt back to the rivers floor, otherwise there is no cycle, and thus no recycling.

Edited October 6, 2010 by michel123456

[Moontanman]

You told the story of rivers salt getting into ocean's floor and Earth's crust. You have to continue the story and raise the salt back to the rivers floor, otherwise there is no cycle, and thus no recycling.

 

 

Plate tectonics completes the circle, the sea floor is raised into mountains, volcanoes erupt melted sea floor that is sub-ducted... Why is this a problem?

[D H]

In order to reach an equilibrium, those 2 processes must be linked together by some sort of mechanism.

A simple model: The amount of salt added by rivers is roughly constant; while erosion depletes the surface soil and rock of salt it also exposes new soil and rock to erosion. Vulcanism, uplift, earthquakes, etc. will also expose new soil and rock to rain and draining water. The amount of water removed from the oceans (and eventually recycled as new land) by plate tectonics is also roughly constant. This means the amount of salt removed from the oceans by plate tectonics is roughly proportional to the salinity of the ocean water. In math, [math]\frac{ds}{dt} = r - p[/math]. Here s is the salt content of the oceans, r is the rate at which rivers bring new salts into the oceans, and p is the rate at which plate tectonics removes salts from the oceans. That the tectonic removal rate is proportional to salinity suggest replacing p with ks, where k is the constant of proportionality for this removal process. Setting the rate to zero yields the equilibrium salt quantity, [math]s=r/k[/math].

Edited October 6, 2010 by D H

[michel123456]

A simple model: The amount of salt added by rivers is roughly constant; while erosion depletes the surface soil and rock of salt it also exposes new soil and rock to erosion. Vulcanism, uplift, earthquakes, etc. will also expose new soil and rock to rain and draining water. The amount of water removed from the oceans (and eventually recycled as new land) by plate tectonics is also roughly constant. This means the amount of salt removed from the oceans by plate tectonics is roughly proportional to the salinity of the ocean water. In math, [math]\frac{ds}{dt} = r - p[/math]. Here s is the salt content of the oceans, r is the rate at which rivers bring new salts into the oceans, and p is the rate at which plate tectonics removes salts from the oceans. That the tectonic removal rate is proportional to salinity suggest replacing p with ks, where k is the constant of proportionality for this removal process. Setting the rate to zero yields the equilibrium salt quantity, [math]s=r/k[/math].

 

So you are suggesting that plate tectonics has an influence on the salinity of the rivers, if I understand well.

 

Plate tectonics completes the circle, the sea floor is raised into mountains, volcanoes erupt melted sea floor that is sub-ducted... Why is this a problem?

 

And you too.

[Moontanman]

So you are suggesting that plate tectonics has an influence on the salinity of the rivers, if I understand well.

 

 

 

And you too.

 

 

Yes it does, uplift exposes new material that was once at the bottom of the sea, this sediment turned to rock has a load of salt that used to be in the ocean. As uplifted material is eroded away the salt is taken away as well as it is exposed.

 

Volcanoes around zones of subduction release magma that is essentially melted sedimentary rocks that were at one time at the bottom of the ocean as well.

[zapatos]

Yes it does, uplift exposes new material that was once at the bottom of the sea, this sediment turned to rock has a load of salt that used to be in the ocean. As uplifted material is eroded away the salt is taken away as well as it is exposed.

 

Volcanoes around zones of subduction release magma that is essentially melted sedimentary rocks that were at one time at the bottom of the ocean as well.

I'm not sure that is quite accurate, at least in the short term (geologically speaking). Plate tectonics is in part responsible for salt being removed from the ocean, and is responsible for recycling material back to the surface so that the cycle can continue. But if no ocean floor made its way to the surface, I would expect that the level of salt in rivers would remain roughly constant as long as there is rock to erode.

 

So, I'd say plate tectonics has an influence on the salinity of the ocean, but it only influences the salinity in rivers in the sense that it keeps the process going.

[pioneer]

Water at very high temperatures and pressures or supercritical water can dissolve stable minerals with small cations like Na+ increasing this effect.

 

Picture the infant earth, with its surface composed of molten minerals. On top of this, we have a very dense atmosphere composed of all the ocean water, plus other gases. This will create hydrothermal conditions at the surface, that will allow water to dissolve all types of minerals. Supercritical water is neither a liquid or gas. It occupies the volume of a liquid, while not being a liquid. But it is not exactly a gas either, but a dense fluid that can eat almost any mineral to various degrees, with small cations making the water even more aggressive. As things cool and the critical state of water is lost, many minerals begin to precipitate out of the sub-critical water, with the stuff that remains in solution, becoming the base minerals for the oceans.

Edited October 8, 2010 by pioneer

[random]

well my question was answered the reason we have salt water to begin with is a direct result of an abundance of sodium and chlorine in the universe. I could ask what the speculation is as to why this was formed to begin with but...........that's just opening another can of worms for the great debaters of this forum. ah heck with it I'm asking?

[Moontanman]

well my question was answered the reason we have salt water to begin with is a direct result of an abundance of sodium and chlorine in the universe. I could ask what the speculation is as to why this was formed to begin with but...........that's just opening another can of worms for the great debaters of this forum. ah heck with it I'm asking?

 

 

So you want to know why there is so much sodium and chlorine in the universe?

[insane_alien]

http://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth%27s_crust <sodium and chlorine are fairly high up the list for the earths crust.

[random]

So you want to know why there is so much sodium and chlorine in the universe?

 

 

yes please. What is the theory behind why the big bang explosion created sodium and chlorine anyway? I do not much care for speculative science where we really do not know just make best guess but I would like to hear the explanation for this one.

[insane_alien]

The big bang didn't generate very much sodium and chlorine.

 

sodium and chlorine were primarily formed by the nuclear fusion process in stars. it called nucleosynthesis.

 

the stars that produced these then exploded and sprayed these new elements all over the universe.

[dragonstar57]

rivers could never be salty because the rivers have such a large "outflow" into the sea.

the salt would go out as fast as it went in

[IronParrot]

Ammm...basically because it's made out of salt , but the answer is that I really don't know the answer.

Edited January 13, 2011 by IronParrot