Why are the Earth's oceans and seas full of sodium chloride?

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In summary, the sodium and chlorine in seawater are due to their behavior in the differentiation of the igneous melts, presumably all the way back to the initial formation of the earth. The abundance of sodium and chlorine in the present biosphere is ultimately due to their behavior in the differentiation of the igneous melts, presumably all the way back to the initial formation of the earth.
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rootone
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Why are the Earth's oceans and seas full of sodium chloride?
I know there are other salts and compound dissolved in it, but comparatively small amounts.
Where did all the Sodium and Chlorine originate from?, these are not rare on Earth, but other elements like aluminum are magnesium are in greater abundance and easily make water soluble compounds.
 
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Read Ch. 6, Mason, Principles of Geochemistry, and come back with something more specific than a "why is there air question."
 
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Bystander said:
Read Ch. 6, Mason, Principles of Geochemistry,

can find it online without having to pay for it ... if the OP doesn't come back
I would be interested in you copying and pasting the relevant section
 
  • #4
davenn said:
can find it online without having to pay for it ...
"Can," or "can not?"
 
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Bystander said:
"Can," or "can not?"
oops .. typo too early in morning

cannot
 
  • #6
rootone said:
Why are the Earth's oceans and seas full of sodium chloride?
I know there are other salts and compound dissolved in it, but comparatively small amounts.
Where did all the Sodium and Chlorine originate from?, these are not rare on Earth, but other elements like aluminum are magnesium are in greater abundance and easily make water soluble compounds.
http://water.usgs.gov/edu/whyoceansalty.html

Note we find salt deposits inland. Look at locations of salt mines. Also, note the Great Salt Lake in Utah.

Look at the abundance of sodium and chlorine with respect to the other elements, and also the solubility of NaCl compared to the salts.

Also - http://oceanservice.noaa.gov/facts/whysalty.html

https://en.wikipedia.org/wiki/Seawater
 
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Ah thanks, I think got it.
Other elements in sea water tend to be get more involved in reactions that cause them to drop out as sediment, or get used up by life and other things.
Sodium and Chlorine don't have many sinks once they are there in sea water, so it builds up
 
  • #8
rootone said:
Sodium and Chlorine don't have many sinks once they are there in sea water, so it builds up
For your next effort/project explain the relatively short "residence time" of NaCl in seawater, ~70 Ma.
 
  • #9
The abundance of sodium and chlorine in the present biosphere is ultimately due to their behavior in the differentiation of the igneous melts, presumably all the way back to the initial formation of the earth. In basaltic magmas, both elements end up as residual ions in late stage minerals, or more importantly, in residual brines or brine inclusions. Presumably, the brines would have been spewed out of early volcanic eruptions, undersea initially. As a crust developed, brines would have accumulated on land. There they eventually formed salt flats and other deposits, eventually mixing with sediments filling in low elevations. I recall reading that the brines found in inclusions are several times more concentrated than sea water. I'd have to look up some of the theories that try to explain the fate of sodium and chlorine later in sedimentary rocks and the salinity of the oceans. At any rate, the availability of sodium and chlorine seems to have been fixed by their place in igneous differentiation.

Actually, the first brines might wells have spewed on hardened lava flows before the hydrosphere even developed, making the first oceans somewhat saline.
 
  • #10
It's all about residence time. River water is not dilute sea water. It's a lot richer in calcium and sulfate than sea water. When water reaches the sea, biological and chemical processes remove certain elements. Calcium and silicon are taken out to build shells for organisms. The residence time of calcium, average time a calcium atom stays in sea water, is tens of thousands of years. Aluminum goes into sea floor minerals and has a residence time of only a few hundred years. But very few processes take sodium and chlorine out of sea water, so they tend to accumulate. Both elements have residence times of tens or hundreds of millions of years. So they've accumulated in the sea over geologic time.
 
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  • #11
Bystander said:
For your next effort/project explain the relatively short "residence time" of NaCl in seawater, ~70 Ma.
Although there are comparatively few processes that remove Na and Cl from sea water, there are some processes. Marine salt deposits do end up on dry land and some even gets recycled by wind, since sea spray furnishes salt crystals as nuclei for raindrops. A good deal of sea water soaks into the rocks of the sea floor and some re-emerges at hot sea-floor springs. Other water ends up in magma at subduction zones. And if you're hinting at some creationist style complaint that dating methods are inconsistent, bear in mind the residence time is a minimum age for the oceans (pretty much all geologic ages are minimum ages), and is about 10,000 times too long for the creationist time scale.
 
  • #12
http://www.gly.uga.edu/railsback/3030/3030Tres.pdf
Bruce Railsback is one of my favorite geologists and very highly regarded for his insights and syntheses. In the above link, he calculates the residence time of Na at 72 million years and that of Cl as 130 million years. I am a bit uneasy about these types of calculations and try to avoid problems that require that sort of info. At the same time, Railsback has a fine website on geochemistry:
Some Fundamentals of Mineralogy and Geochemistry
http://www.gly.uga.edu/railsback/FundamentalsIndex.html
 
  • #13
CapnGranite said:
I am a bit uneasy about these types of calculations and try to avoid problems that require that sort of info.
Geochemical "cycles"/stations of the cross --- as long as it's understood there is more than enough room to over-interpret ...
 

Related to Why are the Earth's oceans and seas full of sodium chloride?

1. What is sodium chloride and why is it found in the Earth's oceans and seas?

Sodium chloride, also known as table salt, is a compound made up of sodium and chlorine atoms. It is found in the Earth's oceans and seas because it is the result of millions of years of weathering and erosion of rocks that contain sodium and chlorine minerals.

2. How much sodium chloride is in the Earth's oceans and seas?

The concentration of sodium chloride in the Earth's oceans and seas is approximately 3.5%, meaning that for every liter of water, there is 35 grams of salt. This concentration has remained relatively constant for millions of years.

3. Why is sodium chloride important for marine life?

Sodium chloride is important for marine life because it helps regulate the osmotic balance of their cells. This means that it helps maintain the proper balance of water and salts inside their bodies, which is crucial for their survival.

4. How does sodium chloride affect the salinity of the Earth's oceans and seas?

Sodium chloride is the main contributor to the salinity of the Earth's oceans and seas. Salinity refers to the amount of dissolved salt in water, and sodium chloride makes up the majority of this salt. Changes in the amount of sodium chloride can affect the salinity of the oceans and seas, which can have impacts on marine life and ocean currents.

5. Are there other sources of sodium chloride in the Earth's oceans and seas?

While the majority of sodium chloride in the Earth's oceans and seas comes from weathering and erosion of rocks, there are other sources as well. These include volcanic activity, hydrothermal vents, and human activities such as mining and industrial processes. However, these sources contribute a relatively small amount compared to natural weathering and erosion.

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