Why is the ocean salty? (2022)(usgs.gov)
usgs.gov
Why is the ocean salty? (2022)
https://www.usgs.gov/faqs/why-ocean-salty
187 comments
> we need a store of calcium to mediate blood pH
Blood pH is regulated mainly by dissolved carbon dioxide and bicarbonate [1]. There's an order of magnitude less calcium in the blood, usually in the form of calcium phosphate, than either of those, and the amount is extremely tightly regulated within a very narrow concentration range -- far too narrow to have a notable effect on pH.
[1]: https://www.ncbi.nlm.nih.gov/books/NBK482291
Blood pH is regulated mainly by dissolved carbon dioxide and bicarbonate [1]. There's an order of magnitude less calcium in the blood, usually in the form of calcium phosphate, than either of those, and the amount is extremely tightly regulated within a very narrow concentration range -- far too narrow to have a notable effect on pH.
[1]: https://www.ncbi.nlm.nih.gov/books/NBK482291
The majority of calcium ions within the cell are bound to intracellular proteins, leaving a minority freely dissociated. When calcium is added to or removed from the cytoplasm by transport across the cell membrane or sarcoplasmic reticulum, calcium buffers minimise the effect on changes in cytoplasmic free calcium concentration by binding calcium to or releasing calcium from intracellular proteins. As a result, 99% of the calcium added to the cytosol of a cardiomyocyte during each cardiac cycle becomes bound to calcium buffers, creating a relatively small change in free calcium.
https://en.m.wikipedia.org/wiki/Calcium_buffering
I raised and homeschooled two kids and watched a lot of when dinosaurs ruled the earth type stuff. That's my source for the idea that a store of calcium was critical for allowing life to leave the ocean and I've tried repeatedly to search for additional info on this and can never find it.
I have no problem imagining that calcium is essential for buffering pH in land mammals and that free calcium ions simultaneously are tightly regulated and not directly used to move that number for the blood in short time frames. That actually fits perfectly well with my mental models that cellular acidosis is a more fundamental problem that fuels acidosis of bodily fluids.
If anyone has any good sources that might clarify this relationship for me, that would be cool.
https://en.m.wikipedia.org/wiki/Calcium_buffering
I raised and homeschooled two kids and watched a lot of when dinosaurs ruled the earth type stuff. That's my source for the idea that a store of calcium was critical for allowing life to leave the ocean and I've tried repeatedly to search for additional info on this and can never find it.
I have no problem imagining that calcium is essential for buffering pH in land mammals and that free calcium ions simultaneously are tightly regulated and not directly used to move that number for the blood in short time frames. That actually fits perfectly well with my mental models that cellular acidosis is a more fundamental problem that fuels acidosis of bodily fluids.
If anyone has any good sources that might clarify this relationship for me, that would be cool.
> calcium is essential for buffering pH
Except that’s not what’s going on.
The Wikipedia article lays it out. The amount of hydrogen ions someplace is what PH means, so controlling PH is controlling the number of hydrogen ions.
The same thing happens with calcium, but rather than doing the buffering it’s the number of calcium ions being controlled. Calcium buffering is controlling the number of calcium ions.
> Calcium buffering describes the processes which help stabilise the concentration of free calcium ions within cells, in a similar manner to how pH buffers maintain a stable concentration of hydrogen ions.[1] The majority of calcium ions within the cell are bound to intracellular proteins, leaving a minority freely dissociated.[2] When calcium is added to or removed from the cytoplasm by transport across the cell membrane or sarcoplasmic reticulum, calcium buffers minimise the effect on changes in cytoplasmic free calcium concentration by binding calcium to or releasing calcium from intracellular proteins. As a result, 99% of the calcium added to the cytosol of a cardiomyocyte during each cardiac cycle becomes bound to calcium buffers, creating a relatively small change in free calcium.[2]
Except that’s not what’s going on.
The Wikipedia article lays it out. The amount of hydrogen ions someplace is what PH means, so controlling PH is controlling the number of hydrogen ions.
The same thing happens with calcium, but rather than doing the buffering it’s the number of calcium ions being controlled. Calcium buffering is controlling the number of calcium ions.
> Calcium buffering describes the processes which help stabilise the concentration of free calcium ions within cells, in a similar manner to how pH buffers maintain a stable concentration of hydrogen ions.[1] The majority of calcium ions within the cell are bound to intracellular proteins, leaving a minority freely dissociated.[2] When calcium is added to or removed from the cytoplasm by transport across the cell membrane or sarcoplasmic reticulum, calcium buffers minimise the effect on changes in cytoplasmic free calcium concentration by binding calcium to or releasing calcium from intracellular proteins. As a result, 99% of the calcium added to the cytosol of a cardiomyocyte during each cardiac cycle becomes bound to calcium buffers, creating a relatively small change in free calcium.[2]
Thank you.
In layman's terms, pH is a scale for measuring alkalinity vs acidity. Calcium is supposedly alkaline and high levels of intracellular calcium is associated with cell death (apoptosis).
So, for example, some people with CF avoid calcium because they think excess calcium causes cell death. But I think most likely excess calcium -- along with high levels of intracellular glutathione -- are a desperate attempt to buffer against something, including but not limited to excess acid.
So that's really what I'm interested in understanding. And also would love to see confirmation that calcium stores helped life leave the ocean and that wasn't something stupid and stated in error.
Though people with CF also likely misprocess sodium bicarbonate, in addition to being prone to very early onset osteoporosis (as early as their teens).
In layman's terms, pH is a scale for measuring alkalinity vs acidity. Calcium is supposedly alkaline and high levels of intracellular calcium is associated with cell death (apoptosis).
So, for example, some people with CF avoid calcium because they think excess calcium causes cell death. But I think most likely excess calcium -- along with high levels of intracellular glutathione -- are a desperate attempt to buffer against something, including but not limited to excess acid.
So that's really what I'm interested in understanding. And also would love to see confirmation that calcium stores helped life leave the ocean and that wasn't something stupid and stated in error.
Though people with CF also likely misprocess sodium bicarbonate, in addition to being prone to very early onset osteoporosis (as early as their teens).
> Calcium is supposedly alkaline
Most reliable sources of information describing calcium as alkaline stem from PRAL (potential renal acid load) and other kidney literature. Combined with the right chemicals (as you find in the kidneys), calcium does reduce acidity (contrasted with a buffering agent, the formulae are more linear, and a linear amount of other shit requires a linear amount of calcium or other alkalizing compounds to compensate) in the kidneys.
As something of a fun aside, most "alkaline diets" recommend a diet of weakly to strongly acidic foods which have an alkalizing effect on the kidneys and nearly no pH impact anywhere else in the body.
No comment on the rest. I just want to reiterate that acid/alkaline in one context (most commonly a description of the hydrogen concentration or other related ions) absolutely does not translate without extra effort and math and chemistry to other contexts (like anything describing calcium as alkaline). When those two ideas are mixed in presentation, a correct interpretation absolutely requires you to understand the details of what/where/why an author means when they refer to pH as something other than hydrogen/hydroxide concentration.
Most reliable sources of information describing calcium as alkaline stem from PRAL (potential renal acid load) and other kidney literature. Combined with the right chemicals (as you find in the kidneys), calcium does reduce acidity (contrasted with a buffering agent, the formulae are more linear, and a linear amount of other shit requires a linear amount of calcium or other alkalizing compounds to compensate) in the kidneys.
As something of a fun aside, most "alkaline diets" recommend a diet of weakly to strongly acidic foods which have an alkalizing effect on the kidneys and nearly no pH impact anywhere else in the body.
No comment on the rest. I just want to reiterate that acid/alkaline in one context (most commonly a description of the hydrogen concentration or other related ions) absolutely does not translate without extra effort and math and chemistry to other contexts (like anything describing calcium as alkaline). When those two ideas are mixed in presentation, a correct interpretation absolutely requires you to understand the details of what/where/why an author means when they refer to pH as something other than hydrogen/hydroxide concentration.
> Calcium is supposedly alkaline
More precisely, calcium is an alkali earth metal (second column from the left in the periodic table), and those metals are so named because the compounds in which they were first discovered were alkalis. But that does not mean all calcium compounds are alkalis. For example, calcium citrate, which is a common way to convey calcium in supplements, can be weakly acidic in water solution (because of the citrate ion).
More precisely, calcium is an alkali earth metal (second column from the left in the periodic table), and those metals are so named because the compounds in which they were first discovered were alkalis. But that does not mean all calcium compounds are alkalis. For example, calcium citrate, which is a common way to convey calcium in supplements, can be weakly acidic in water solution (because of the citrate ion).
It looks like there is a theory that dermal bone in early tetrapods was used this way, but it's still fairly speculative. https://www.nbcnews.com/id/wbna47176272
Thank you:
Breathing air came with challenges, though. A major one was getting rid of the air's carbon dioxide, which, when it builds up, reacts with water in the body and forms an acid.
Breathing air came with challenges, though. A major one was getting rid of the air's carbon dioxide, which, when it builds up, reacts with water in the body and forms an acid.
> I raised and homeschooled two kids and watched a lot of when dinosaurs ruled the earth type stuff. That's my source for the idea that a store of calcium was critical for allowing life to leave the ocean and I've tried repeatedly to search for additional info on this and can never find it.
Insects and friends manage to live on land just fine without any calcium bones.
Insects and friends manage to live on land just fine without any calcium bones.
Dragonflies used to get to a two-foot wingspan. They don't anymore. The atmosphere was thicker and contained more oxygen.
What works once life is established on land can be different from what it took to transition to land and that's what I'm asking about.
What works once life is established on land can be different from what it took to transition to land and that's what I'm asking about.
There was more oxygen in the air when the dinosaurs roamed, but not when insects (and other critters) first came on land.
https://forces.si.edu/atmosphere/02_02_06.html says
> As plants became firmly established on land, life once again had a major effect on Earth’s atmosphere during the Carboniferous Period. Oxygen made up 20 percent of the atmosphere—about today’s level—around 350 million years ago, and it rose to as much as 35 percent over the next 50 million years.
https://forces.si.edu/atmosphere/02_02_06.html says
> As plants became firmly established on land, life once again had a major effect on Earth’s atmosphere during the Carboniferous Period. Oxygen made up 20 percent of the atmosphere—about today’s level—around 350 million years ago, and it rose to as much as 35 percent over the next 50 million years.
Irrelevant.
Huh?
The high oxygen levels you mentioned occurred long after life had successfully made its way on land.
The high oxygen levels you mentioned occurred long after life had successfully made its way on land.
[deleted]
How refreshing. A non defensive critically thoughtful reply to feedback during a public discourse
It used to be somewhat common on HN. Then it got bigger and covid introduced the entire internet to Eternal September on steroids.
Even early Reddit used to be like this. Back when HN wasn't even opened yet.
YC was founded in March 2005 and Reddit in June 2005. Reddit is a YC company.
I know. And HN is younger than Reddit.
HN != YC.
HN != YC.
Paul Graham substantially shaped both cultures from what I gather. So hardly shocking if something once common here was also common there.
It's possible, but I suspect demographics are more likely to be the main reason here. 'Eternal September on steroids' as you say.
The Wikipedia article you linked as a reference makes no mention about bones, but it does mention intracellular proteins as the location of where the majority of calcium ions are found.
I'll take wikipedia as a reference (with reservations), but children's television shows?
I'll take wikipedia as a reference (with reservations), but children's television shows?
> Most land animals have a skeleton not just to provide physical scaffolding to hang tissue on but because we need a store of calcium to mediate blood pH, something sea life doesn't require thanks to those minerals in the water. That's why you can have sharks which are mostly supported by cartilage
Well, the other reason sea life doesn't require rigid bones is that water provides a lot more buoyancy than air. Jellyfish work fine in the water; on land they're immobile puddles of glop.
Well, the other reason sea life doesn't require rigid bones is that water provides a lot more buoyancy than air. Jellyfish work fine in the water; on land they're immobile puddles of glop.
I have long known sharks have cartilaginous skeletons but only just wondered whether that means shark bodies are squishy like human ears? Like if you hugged a shark would it deform?
I don't know but I wouldn't recommend trying it, at least not without wearing chain mail. Their skin is abrasive if you hug them and call them George and rub their skin backwards.
While you can’t hug them, see if your nearest aquarium has a touch tank experience. Usually they do those with rays/skates but you can also find them with Nurse sharks. Either way, you’ll literally get a feel for their composition.
From memory it’s more like the stiff parts of your nose running near/along the bone and unlike your ears in any way.
From memory it’s more like the stiff parts of your nose running near/along the bone and unlike your ears in any way.
No. The human nose is mostly cartilage and it's hard.
The lower half of the nose is cartilage and is pretty soft. The upper half of the nose hard and is bone.
This is probably a stupid question, but if the upper half of the nose is bone, why does a human skull seem to always have a hole where the nose is?
Anatomically correct skulls have an hole where the bottom of your nose is and the eyes are both smaller and higher up than you probably think.
https://en.wikipedia.org/wiki/Orbit_(anatomy)#/media/File:Ey...
Looking at yourself in a mirror, if you hold your finger over the top of your nose your eyes will see under your finger. Move your finger just low enough so you’re seeing over it and you should be touching the bottom of your nasal bone. At that point your nose should be more than a finger width froward from the bottom of your orbital socket which is where the hole in skulls starts in those skulls.
https://en.wikipedia.org/wiki/Orbit_(anatomy)#/media/File:Ey...
#/media/File:Eye_orbit_anatomy_anterior2.jpg){kind=link}
Looking at yourself in a mirror, if you hold your finger over the top of your nose your eyes will see under your finger. Move your finger just low enough so you’re seeing over it and you should be touching the bottom of your nasal bone. At that point your nose should be more than a finger width froward from the bottom of your orbital socket which is where the hole in skulls starts in those skulls.
That's where the cartilage was. You can find that hole in your own skull easily enough. There should be a small bump midway up your nasal ridge. That point is called the rhinion. Everything above it is laying on your skull. The parts of the nose below it cover your nasal cavity.
Look at a picture of a skull in profile. You'll see that there is half a nose, not no nose. That half of the nose that you can see is the bony part. The missing half is the cartilaginous part.
Why is there a hole? Because your nasal canal extends inside your skull to connect with the back of your throat. I guess I don't fully understand the question there.
Why is there a hole? Because your nasal canal extends inside your skull to connect with the back of your throat. I guess I don't fully understand the question there.
Because the bottom half isn't bone and the whole thing is hollow.
Yeah you (well, I) can feel a distinct line between the bone and cartilage.
My guess is that, yeah, if you empty them of water
Thanks, that is fascinating. The amount of gold/silver is too. Even just the amount of salt. Measure in parts per 1000! I like having a wow moment about something we take for granted.
> Most land animals have a skeleton [...]
Most land animals don't have a skeleton. Most land animals are insects and similar critters.
Most land animals don't have a skeleton. Most land animals are insects and similar critters.
The answer that springs to mind from general knowledge is that rainwater picks up minerals in solution on the way to the sea, where it gets concentrated by evaporation.
The real question is why the sea isn't saltier. Why is the Dead Sea so salty? (Because the Dead Sea is enclosed and in a hot location, so evaporation happens faster.) Why aren't the oceans as salty as the Dead Sea? What is cause of equilibrium? The article briefly mentions (a) "organisms" using the salts, and (b) concentrations continuing to rise (!). So is the ocean on its way to being as dead as the Dead Sea, just really slowly, or what?
The real question is why the sea isn't saltier. Why is the Dead Sea so salty? (Because the Dead Sea is enclosed and in a hot location, so evaporation happens faster.) Why aren't the oceans as salty as the Dead Sea? What is cause of equilibrium? The article briefly mentions (a) "organisms" using the salts, and (b) concentrations continuing to rise (!). So is the ocean on its way to being as dead as the Dead Sea, just really slowly, or what?
It was less salty in the past, so I always assumed it will get saltier and saltier.
Edit: Our blood has the same salt concentration the ocean had when our ancestors formed or split off or something. Someone with actual knowledge will surely come along and enlighten us with a comment.
Edit: Our blood has the same salt concentration the ocean had when our ancestors formed or split off or something. Someone with actual knowledge will surely come along and enlighten us with a comment.
> For instance, drilling in the Gulf of Mexico in 1967 revealed a vast layer of salt from the Jurassic beneath the oceanic sediments. The total global amount of halite (salt deposits) discovered was astonishing: the minimum estimate is 19.6 quintillion kilograms (19.6 × 1018 kg), or more than half of the total salt in the oceans today — the maximum estimate is that an unbelievable 95% of the present total is trapped in halite deposits. If all of this had been dissolved at one time, the salinity of seawater would have been much higher: 57‰ to 73‰ instead of today’s 34‰ to 35‰. This extreme scenario is unlikely, but one thing is clear: the salinity of the oceans has varied significantly over geologic time. The problem is how to quantify this change.
Exactly. It's been around for billion(s?) of years having rain water dissolve land and run into it. Shouldn't it be as salty as it can be?
Perhaps it's deep sea flour shenanigans keeping it at some stable level.
Perhaps it's deep sea flour shenanigans keeping it at some stable level.
These gluten-free artisinal flours are getting out of hand.
Well, there are also salt mines where we get the salt for eating and putting on the road from. They are dried up sea bed.
So whatever process produces the mineable deposits will necessarily remove salt from the wider oceans.
https://en.wikipedia.org/wiki/Salt_mining
So whatever process produces the mineable deposits will necessarily remove salt from the wider oceans.
https://en.wikipedia.org/wiki/Salt_mining
Does ocean salt deposit anywhere? There's huge underground stores of salt that we use for food and the roads and stuff, that's huge quantites of salt that are (no longer) in the oceans. I believe those deposits were formed by processes similar to the dead sea - evaporation, deposits, concentrations, etc until eventually the sea / lake dried out and other land formed on top over thousands of years.
There are some minerals that crystalize out of solution. Those are the nodules that the Glomar Explorer said publicly that they were going to scrape off the bottom of the ocean. The Glomar Explorer was really built (by Howard Hughes, on behalf of the CIA) to pick up a sunken Soviet submarine.
> Many of the dissolved ions are used by organisms in the ocean and are removed from the water. Others are not used up and are left for long periods of time where their concentrations increase over time.
> The two ions that are present most often in seawater are chloride and sodium.
This makes it sound like sodium and chloride are the most common ions because they're not used by the organisms in the ocean, unlike all the other dissolved ions. But that's not correct, is it? The ocean is salty because we don't need salt? But we do.
So why is there so much salt in the ocean? Do sodium and chloride simply happen to be the most common elements on Earth that are able to dissolve in water?
> The two ions that are present most often in seawater are chloride and sodium.
This makes it sound like sodium and chloride are the most common ions because they're not used by the organisms in the ocean, unlike all the other dissolved ions. But that's not correct, is it? The ocean is salty because we don't need salt? But we do.
So why is there so much salt in the ocean? Do sodium and chloride simply happen to be the most common elements on Earth that are able to dissolve in water?
They are used by organisms but they are not removed from circulation. Other ions, calcium etc. are used and incorporated into insoluble minerals.
Thanks. That sounds like the real explanation.
Although this graph of the abundance of elements[0] puts sodium with the rock-forming elements (and chloride just inside, but on the edge). So doesn't that mean they should also form insoluble minerals?
[0] https://en.wikipedia.org/wiki/File:Elemental_abundances.svg
Although this graph of the abundance of elements[0] puts sodium with the rock-forming elements (and chloride just inside, but on the edge). So doesn't that mean they should also form insoluble minerals?
[0] https://en.wikipedia.org/wiki/File:Elemental_abundances.svg
Chemistry stackexchange says yes, they do: https://chemistry.stackexchange.com/questions/82328/are-ther...
(wow, there are a lot of different minerals https://www.mindat.org/element/Sodium .. ah, 50% of the earth's rocks are feldspars which contain some sodium. https://www.imerys.com/minerals/feldspar )
(wow, there are a lot of different minerals https://www.mindat.org/element/Sodium .. ah, 50% of the earth's rocks are feldspars which contain some sodium. https://www.imerys.com/minerals/feldspar )
But if sodium does form insoluble rocks, why is there so much of it still in the oceans? And what about chloride?
> But if sodium does form insoluble rocks, why is there so much of it still in the oceans?
There's more than enough to go round?
(Feldspars in particular need aluminum, so once that's all bound up you aren't going to get more feldspar even if there is surplus sodium. Think of the sea as the leftovers in a non-stochiometric reaction.)
There's more than enough to go round?
(Feldspars in particular need aluminum, so once that's all bound up you aren't going to get more feldspar even if there is surplus sodium. Think of the sea as the leftovers in a non-stochiometric reaction.)
Makes sense, but still, according to https://en.wikipedia.org/wiki/File:Elemental_abundances.svg there's even more aluminum than sodium on earth.
Because the insoluble rocks are igneous, not biologically created. No mollusk has a feldspar shell or something.
This is a great perspective check.
Water is truly a near-infinite resource. If we can master desalination then humanity is in a great spot in regards to fresh water.
It also frames the challenge well. Desalinating a cubic mile gives you 120 million tons of leftovers. Another extremely difficult challenge.
Water is truly a near-infinite resource. If we can master desalination then humanity is in a great spot in regards to fresh water.
It also frames the challenge well. Desalinating a cubic mile gives you 120 million tons of leftovers. Another extremely difficult challenge.
The volume of the Pacific Ocean is 1.583x10^8 cubic miles. (https://www.wolframalpha.com/input?i=volume+of+pacific+ocean...)
The world's freshwater need is about 950 cubic miles a year. (https://www.wolframalpha.com/input?i=worldwide+water+use+in+...)
You can just put the leftovers back without worrying much about it.
The world's freshwater need is about 950 cubic miles a year. (https://www.wolframalpha.com/input?i=worldwide+water+use+in+...)
You can just put the leftovers back without worrying much about it.
For some reason this topic of desalinization waste keeps coming up on hacker news! The dilution principle here is correct but it’s not as easy as you think to dispose of the waste in the ocean, because if you just pipe it out to sea you’ll create a nasty big marine dead zone around the outlet of your pipe.
> You can just put the leftovers back without worrying much about it.
Yes, just not all in one place/time. Separating seawater into pure water in one place and pure brine in another, you don’t want to let that brine out all at once in one spot, it’ll kill a lot of ocean life. Most desal plants that are attempting to do this right, will pump the brine into pipes that diffuse it over a wide area to avoid oversalinating. And it still kills a lot of ocean life.
Yes, just not all in one place/time. Separating seawater into pure water in one place and pure brine in another, you don’t want to let that brine out all at once in one spot, it’ll kill a lot of ocean life. Most desal plants that are attempting to do this right, will pump the brine into pipes that diffuse it over a wide area to avoid oversalinating. And it still kills a lot of ocean life.
It might be better just to sacrifice specific spots rather than to try to spread it evenly.
Or another solution would be just to take a hit on efficiency and not produce highly concentrated brine as a water product. If instead we extract just a bit of fresh water out and return saltwater with slightly elevated salt concentration then it wouldn’t be so lethal to marine life.
Or we could have a premix station where we pump in sea water and mix it with brine at a certain ratio and then return that to the sea.
Or we could have a premix station where we pump in sea water and mix it with brine at a certain ratio and then return that to the sea.
Well yeah but the net result is just less fresh water; it's a fairly predictable process like that.
And with your second process, you still end up with a higher concentration of salt / brine around where it's returned to the sea, still killing animals.
I'm thinking of pumping the brine onto large evaporation lakes and harvest the salt or whatever - which also already happens to produce sea salt.
And if there's too much salt for the market, just stockpile it. Like underground salt mines.
And with your second process, you still end up with a higher concentration of salt / brine around where it's returned to the sea, still killing animals.
I'm thinking of pumping the brine onto large evaporation lakes and harvest the salt or whatever - which also already happens to produce sea salt.
And if there's too much salt for the market, just stockpile it. Like underground salt mines.
It will still need to spread from that spot.
Yeah, but depending on the details and design of the sacrificed area, it might be less environmental impact overall.
Why not sell the leftover salt?
The brine isn't that salty, it is twice as salty as sea water. The Dead Sea is 10x saltier than seawater. They make Dead Sea salt, but the concentration is only slight advantage.
The big problem with making salt from sea water is evaporating the water. It either takes a lot of energy, or a lot of time and area.
The big problem with making salt from sea water is evaporating the water. It either takes a lot of energy, or a lot of time and area.
On ocean scale, the waste won't do anything horrible.
But on local scales, near the waste dump location, the waste will damage local ecosystems and water quality.
It takes a lot of time for the salt to just diffuse out over the ocean.
It takes a lot of time for the salt to just diffuse out over the ocean.
Like others have said, there will always be a cost X to desalinate water.
I think the best way to pay for X, is to use energy from an external source. External from the Earth. I'm obviously talking about the Sun.
We could use the removed material as a general filler. I'm sure we can get creative about it. I think the problem is lack of incentives and misalignment of goals amongst people.
I truly think if we can figure out how to how to use the most out of the Sun's rays - i.e. as most directly as possible - we will solve all our needs. The energy is truly free to the Earth.
I think the best way to pay for X, is to use energy from an external source. External from the Earth. I'm obviously talking about the Sun.
We could use the removed material as a general filler. I'm sure we can get creative about it. I think the problem is lack of incentives and misalignment of goals amongst people.
I truly think if we can figure out how to how to use the most out of the Sun's rays - i.e. as most directly as possible - we will solve all our needs. The energy is truly free to the Earth.
You can also work on making that 'X' as small as possible.
There's a thermodynamic fundamental lower limit on the amount of energy needed to desalinate water, but it's absurdly small. Much smaller than the amount of energy we use in practice with current technologies.
(Just like there's a thermodynamic lower limit on how much energy a computer needs. But it's also extremely low. See https://en.wikipedia.org/wiki/Landauer%27s_principle )
There's a thermodynamic fundamental lower limit on the amount of energy needed to desalinate water, but it's absurdly small. Much smaller than the amount of energy we use in practice with current technologies.
(Just like there's a thermodynamic lower limit on how much energy a computer needs. But it's also extremely low. See https://en.wikipedia.org/wiki/Landauer%27s_principle )
Are you sure the thermodynamic limit on water desalination is extremely small ? I was under the impression that the salt bonds dissolved by water are quite strong and thus require a non-negligible amount of energy to reverse (for instance, if you go about it by evaporating the water, it is very much several thousands of order of magnitude above landauer levels).
Edit, found in another comment : For example, desalinating seawater with a typical seawater salt concentration of 35 g L–1 (corresponding osmotic pressure of 29.7 bar) and 50% water recovery (i.e., 50% of the feed stream becomes purified water and 50% becomes brine) requires at least 1.1 kWh per cubic meter of purified water. Regardless of the desalination technology, it is impossible to desalinate water using less energy than that determined by eq 12.
1.1 KWh per cubic meter is very much NOT a negligible amount, so the landauer analogy is incorrect.
Edit, found in another comment : For example, desalinating seawater with a typical seawater salt concentration of 35 g L–1 (corresponding osmotic pressure of 29.7 bar) and 50% water recovery (i.e., 50% of the feed stream becomes purified water and 50% becomes brine) requires at least 1.1 kWh per cubic meter of purified water. Regardless of the desalination technology, it is impossible to desalinate water using less energy than that determined by eq 12.
1.1 KWh per cubic meter is very much NOT a negligible amount, so the landauer analogy is incorrect.
Thanks for looking it up. Could you link to the sources? Thanks!
I stand corrected in that case.
I stand corrected in that case.
I wonder if we could use that as a building material.
Anything that is water soluble is going to be a pretty poor building material, unfortunately. The organics floating about (protozoa, algae, fish) also generally decompose, another undesirable property. The remainder- very very fine silt and microplastics- might be useful.
With all the chemical processing that would be needed to stabilize the salts, mechanical filtering and such, I think we're better off continuing to use bricks and ground sourced gravel and cement. At least the holes we dig can be repurposed into sanitary landfills.
With all the chemical processing that would be needed to stabilize the salts, mechanical filtering and such, I think we're better off continuing to use bricks and ground sourced gravel and cement. At least the holes we dig can be repurposed into sanitary landfills.
Corals manage it quite effectively
But not efficiently. Scientists think the polyps absorb bicarbonate and calcium ions and deposit calcium carbonate, but they're not really sure of the bio/chemical process involved.
Regardless, a polyp adds about 1mm to 1cm to the reef a year. You can get that right now just by throwing a shovel at the ground where I live.
Regardless, a polyp adds about 1mm to 1cm to the reef a year. You can get that right now just by throwing a shovel at the ground where I live.
Even if we split NaCl into its constituent parts -- sodium metal and chlorine gas -- there's not a whole lot that can be done with them.
Sodium is potentially useful towards two applications, off the top of my head. (1) Na2O is used in glassmaking, and it's possible that there are -- or that there can be discovered -- Na2O-enriched glasses that can be used in construction and as a filler substance, i.e. reduced to powder and added to cement. (2) Sodium-based zeolites can potentially be useful for carbon capture. Production of zeolites, however, also requires lots of alumina and silica.
I struggle to think of any large-scale application for all of that chlorine, though. Maybe vinyl chloride production? But the world doesn't need that much PVC...
Sodium is potentially useful towards two applications, off the top of my head. (1) Na2O is used in glassmaking, and it's possible that there are -- or that there can be discovered -- Na2O-enriched glasses that can be used in construction and as a filler substance, i.e. reduced to powder and added to cement. (2) Sodium-based zeolites can potentially be useful for carbon capture. Production of zeolites, however, also requires lots of alumina and silica.
I struggle to think of any large-scale application for all of that chlorine, though. Maybe vinyl chloride production? But the world doesn't need that much PVC...
I'm a proponent of just stockpiling it, spray it onto a large basin and form a salt lake, let it evaporate to a solid as deep or as high up as it needs to be. That's a stockpile that can eventually find a use. Or not, in which case it's harmless, assuming the salt doesn't go into the ground. Or does, if it's a desert or otherwise 'dead'.
Also in the production of Sodium batteries, which while significantly lower in energy density compared to Lithium, they have bigger cycle counts (and as such are/can be used to buffer grid based wind/solar generation)
Those leftovers are water soluble, so either you perform some interesting chemistry to convert them into something more durable or your buildings have to be in arid places (condominium in an old salt mine?)
Probably more practical to use more chemistry and find good uses for sodium and chlorine individually.
Desalination has become a lot better in the last decade or so.
Israel even turned into a water exported thanks to the technology.
See eg https://www.timesofisrael.com/how-israel-became-a-water-supe... and https://blogs.worldbank.org/water/israel-how-meeting-water-c...
Israel even turned into a water exported thanks to the technology.
See eg https://www.timesofisrael.com/how-israel-became-a-water-supe... and https://blogs.worldbank.org/water/israel-how-meeting-water-c...
>> if we can master desalination then humanity is in a great spot in regards to fresh water.
Don't forget that we actually mine salt, a lot of which ends up in the sea. A million years from now we might regret that ;-)
Don't forget that we actually mine salt, a lot of which ends up in the sea. A million years from now we might regret that ;-)
Further destroying the ocean's balance doesn't seem like the best idea. It literally drives life on Earth.
I've read that Israel has basically already solved this problem with their desalination tech.
Desalination is [responsible for] around 10% of the electricity consumed in Israel. [...] more than 90% of the country’s electricity comes from fossil fuels.
https://www.energymonitor.ai/tech/can-desalination-save-a-dr...
https://www.energymonitor.ai/tech/can-desalination-save-a-dr...
I'm surprised they haven't jumped the solar route. Seems like that area has nothing but sun.
Desalination is "solved". Main problem is the huge energy requiered.
So, not solved?
I'm not a physical chemist but there's probably a computable minimum energy necessary.
A quick search popped up https://pubs.acs.org/doi/10.1021/acs.jchemed.0c01194
A quick search popped up https://pubs.acs.org/doi/10.1021/acs.jchemed.0c01194
For example, desalinating seawater with a typical seawater salt concentration of 35 g L–1 (corresponding osmotic pressure of 29.7 bar) and 50% water recovery (i.e., 50% of the feed stream becomes purified water and 50% becomes brine)
requires at least 1.1 kWh per cubic meter of purified water.
Regardless of the desalination technology, it is impossible to desalinate water using less energy than that determined by eq 12.
With current membrane technology, yes.
There are so many examples in our collective technical history of overcoming these types of limitations not with brute force, but with finesse.
In this case, I expect it will be a combination of improved pumps, improved RO membrane technology, and finding synergies like making sea salt from the brine, collecting other useful minerals front the brine,etc. All of these things help to pay for the energy and development costs.
It's not a hard physics limit like the rule if squares or the speed of light. It's a complex engineering system that has may different dynamics and interactions between those dynamics, all opportunity for improvement.
There are so many examples in our collective technical history of overcoming these types of limitations not with brute force, but with finesse.
In this case, I expect it will be a combination of improved pumps, improved RO membrane technology, and finding synergies like making sea salt from the brine, collecting other useful minerals front the brine,etc. All of these things help to pay for the energy and development costs.
It's not a hard physics limit like the rule if squares or the speed of light. It's a complex engineering system that has may different dynamics and interactions between those dynamics, all opportunity for improvement.
> With current membrane technology, yes.
Equation 12 is the energy you need to counteract the effect of the entropy of the ions in solution and separate the initial solution into one that does not have the ions. It’s pretty much a thermodynamic limit and does not depend on process or technology.
They explicitly assume that they have a perfect membrane when they introduce the equation. The floor will never be zero, it is a physical limit.
Equation 12 is the energy you need to counteract the effect of the entropy of the ions in solution and separate the initial solution into one that does not have the ions. It’s pretty much a thermodynamic limit and does not depend on process or technology.
They explicitly assume that they have a perfect membrane when they introduce the equation. The floor will never be zero, it is a physical limit.
You can produce energy by disolving salt in fresh-water. That means there has to be a hard phyisical energy limit to desalinating water, otherwise you get a free energy producing machine.
The energy required happents to go into separating the bonds between the salt ions and the water molecules. Those bonds are quite strong, so it takes some energy to break them.
The engineering problem is more one about capital investment. The price of water, vs the price of electricity are not what block desalination. It is the cost (and maintenance) of the machines that you need to earn back. That cost is what tends to make desalination un-economical. And that is an area where engineering has a lot of space to improve.
The energy required happents to go into separating the bonds between the salt ions and the water molecules. Those bonds are quite strong, so it takes some energy to break them.
The engineering problem is more one about capital investment. The price of water, vs the price of electricity are not what block desalination. It is the cost (and maintenance) of the machines that you need to earn back. That cost is what tends to make desalination un-economical. And that is an area where engineering has a lot of space to improve.
Gibbs Free Energy is pretty much a hard physics limit.
Trying to pull gold out of the ocean to pay for pulling salt out of the ocean is --again not a chemist but-- probably thermodynamically worse.
Trying to pull gold out of the ocean to pay for pulling salt out of the ocean is --again not a chemist but-- probably thermodynamically worse.
That's my point. It's not a single thing, it's not about making it add up trying to do one thing, but if you batch them together and say, use thr waste heat from one process to power the next, etc. One can find new efficiencies.
Of course I'm not saying we need to break the laws of thermodynamics, in my house we obey the laws of thermodynamics.
In this case, the work needed is defined by the features of the RO membrane. It's conceivable that we could develop a RO membrane that requires less pressure or energy to operate. In fact they have been.
In that case, we would gain a more efficient process, while still obeying the laws of thermodynamics
Of course I'm not saying we need to break the laws of thermodynamics, in my house we obey the laws of thermodynamics.
In this case, the work needed is defined by the features of the RO membrane. It's conceivable that we could develop a RO membrane that requires less pressure or energy to operate. In fact they have been.
In that case, we would gain a more efficient process, while still obeying the laws of thermodynamics
I see this view a lot on HN, but this kind of wish for great new development can be unrealistic simple because there are no more low hanging fruit for these very physical processes.
It could easily be the case that RO is going to see only marginal improvements for the next decade or two (except perhaps some test membranes that are too expensive), and modern RO already uses energy recovery in the process.
It could easily be the case that RO is going to see only marginal improvements for the next decade or two (except perhaps some test membranes that are too expensive), and modern RO already uses energy recovery in the process.
This seems highly speculative
There is enough fresh water out there. The problem is that most countries are not building infrastructure to take advantage of it.
It is also mostly in "the wrong place". I keep reading about these fantasies of pumping water from large rivers in the MidWest (like the Missouri or Mississippi) to the deserts of Utah or Arizona. The altitude difference is enormous - every drop of water would have to be pumped uphill at least one mile in altitude to get it from, say Kansas City (which is about 800 feet above sea level) up over the Rockies into the places were people should not be living. And what makes it worse is that the majority of water used in those states goes towards agriculture (82% in the case of Utah), where farmers pay less than 1% of the cost of the water they use.
> It is also mostly in "the wrong place".
It's not the water that is in the wrong place. People are not supposed to live in places that can't sustain their numbers.
It's not the water that is in the wrong place. People are not supposed to live in places that can't sustain their numbers.
Cost / benefit, but also, reserves are running low. Worldwide there's news about how underground aquifers are emptying out faster than they naturally restore. That's relatively easy and low cost to acquire, once that is no longer an option, water will explode in price.
I'm confident that in our generation we'll see mass migrations due to water shortages in the west. California is already at risk, I gathered.
I'm confident that in our generation we'll see mass migrations due to water shortages in the west. California is already at risk, I gathered.
near infinite? there is literally a finite amount of water in this planet and it can be quantified objectively.
https://en.wikipedia.org/wiki/Water_distribution_on_Earth
https://en.wikipedia.org/wiki/Water_distribution_on_Earth
Something I heard a while ago:
The sea is salty because it
remembers the taste of the land.Two questions come to mind.
1) what would our world be like if the oceans were not salty? We could pump fresh water all over the globe, but are there other things that would happen at scale without the salt?
2) by the article it seems like the oceans will always increase in salinity. What is that rate of increase? Then run that model backwards was there a time when salt content was low enough for ocean water to be potable ?
Animals, and perhaps all life, would not exist. We carry the ocean around with us in our circulatory system, from a long ago bootstrap in which some creature needed to drag part of its "home" with it when it left home.
Why? Well fresh water is pretty boring. Seawater, with all those polar ions in it, enables and facilitates all sorts of interesting (i.e. useful) chemistry.
One of the reasons we can't drink seawater is that our body needs to maintain homeostasis on the blood so the chemistry continues to work properly. If you drink a lot of seawater the kidneys can't excrete the salt fast enough. For that matter, if you drink too much fresh water the opposite happens and you die too.
Why? Well fresh water is pretty boring. Seawater, with all those polar ions in it, enables and facilitates all sorts of interesting (i.e. useful) chemistry.
One of the reasons we can't drink seawater is that our body needs to maintain homeostasis on the blood so the chemistry continues to work properly. If you drink a lot of seawater the kidneys can't excrete the salt fast enough. For that matter, if you drink too much fresh water the opposite happens and you die too.
Exactly. We die if we don't get enough salt. There are all sorts of mechanisms in our body that rely on it. As an engineer, I like to think it's as simple as electricity not being nearly as conductive through pure water, various osmosis processes like happens in dialysis, etc.
If the ocean's hadn't been salty, we would likely have biochemistry that doesn't rely on salt so much.. instead of just keeling over.
Life finds a way
The chemical composition of the world ocean reflects the balance of inputs from the continents (as described, from riverine input as well groundwater), atmospheric cycling, and outputs: extraction via evaporite minerals in marginal environments, weathering at the seafloor, exchange over a range of temperatures with mid-ocean ridge basalt, and precipitation of minerals (mostly in the form of biogenic carbonates such as CaCO3, biogenic silica, etc.), as well as their subsequent dissolution, and lastly the biological processes of CO2 fixation and respiration of organic carbon (including electron acceptors other than O2, such as iron, sulfate, etc.).
It is the solubility of sparingly soluble phases such as CaCO3 that controls much of the seawater composition: surface seawater is close to saturation with respect to CaCO3 (calcite, aragonite). Because halite (rock salt, NaCl) is highly soluble, seawater is, conversely, fairly concentrated with respect to these ions. Seawater must be extensively evaporated to remove the far more soluble (evaporite) minerals. Over geologic time, the composition of seawater has changed, reflecting the relative pace of the various processes listed above that deliver and remove components from solution.
It is the solubility of sparingly soluble phases such as CaCO3 that controls much of the seawater composition: surface seawater is close to saturation with respect to CaCO3 (calcite, aragonite). Because halite (rock salt, NaCl) is highly soluble, seawater is, conversely, fairly concentrated with respect to these ions. Seawater must be extensively evaporated to remove the far more soluble (evaporite) minerals. Over geologic time, the composition of seawater has changed, reflecting the relative pace of the various processes listed above that deliver and remove components from solution.
Global climate would be pretty different without ocean currents driven by salinity gradients.
https://en.wikipedia.org/wiki/Thermohaline_circulation
https://en.wikipedia.org/wiki/Thermohaline_circulation
It would surely affect settlement not just in the positive sense (more potable water) but also in the negative (people need salt to live and it wasn’t always as abundant as it is now)
Just offhand thought is the earths geology over time tends to remove salt from the ocean. An example is the Messinian Salinity Crisis when the Mediterranean sea closed off and then mostly evaporated. The result was a huge layer of salt deposited under the seabed. And the rest of the earths oceans became much less salty. Would not surprise me if plate subduction doesn't sequester salts as well.
https://www2.atmos.umd.edu/~dankd/MessinianWeb/_private/HOME...
https://www2.atmos.umd.edu/~dankd/MessinianWeb/_private/HOME...
> And the rest of the earths oceans became much less salty.
Source for that claim?
Mediterranian is still more salty than oceans because of the high evaporation rate.
Source for that claim?
Mediterranian is still more salty than oceans because of the high evaporation rate.
I guess that at the time when ocean water would have been potable it would have had to wait millions of years for an animal to come along and drink. We don’t talk about air being potable ;)
Since salination is essentially driven by the CO2 in the air, does this imply the CO2 we add to the air increases the rate of salination (f' > 0, where f(t) is the salt content of the oceans)? If so, does this affect ocean currents?
Yes, increased CO2 probably contributes. I'm guessing it's a drop in the bucket for ocean currents though. Mining salt and dumping it on roads is probably an issue to, as it runs off and goes down rivers. Again, not doing much because the oceans are so big. But over a million years maybe not so great to do.
This doesn't explain why the water in springs, creeks, and rivers isn't salty.
There is much more water in an ocean for the salt to disperse than in a creek, somehow I can drink from it, but not from the ocean.
There is much more water in an ocean for the salt to disperse than in a creek, somehow I can drink from it, but not from the ocean.
I suspect it's because the erosion of the elements from land happens extremely slowly and barely detectable trace amounts, but the oceans is where they accumulate over the course of billions of years.
I think the real answer is that these elements (sodium and chloride) easily dissolve in water, and there's no process that removes them from the ocean, so they linger and accumulate.
I think the real answer is that these elements (sodium and chloride) easily dissolve in water, and there's no process that removes them from the ocean, so they linger and accumulate.
Because the water is flowing, in only one direction, with no feedback. So any salt is taken out and put into the ocean/sea it connects to.
In the early days of trying to determine the age of the Earth, one set of scientists were trying to determine from mineral flows from rivers into the oceans. Depending on which mineral was picked, the Earth was as young as 20,000,000 or as old as 10x that.
Water from springs (then creeks) comes out of the ground pre-filtered, some springs are salty, others are red from high concentrations of iron and so on. Second reason is because it's running water, so it doesn't stay in one place accumulating minerals.
There is a slight amount of salt in the rivers, but it is very low.
In the oceans, this accumulates, but the water evaporates. Hence the salt content goes up whilst the water volume remains constant (ignoring ice melt) which means the salt concentration goes up.
In the oceans, this accumulates, but the water evaporates. Hence the salt content goes up whilst the water volume remains constant (ignoring ice melt) which means the salt concentration goes up.
Those waters come from rain
> In a cubic mile of seawater, the weight of the salt (as sodium chloride) would be about 120 million tons. A cubic mile of seawater can also contain up to 25 pounds of gold and up to 45 pounds of silver!
Earth’s oceans contain a combined volume of 320 million cubic miles, according to Wikipedia.
Earth’s oceans contain a combined volume of 320 million cubic miles, according to Wikipedia.
TIL USGS has an FAQ
Makes you wonder how big the mountains were that dissolved into all that salt and other minerals…
I love facts like this, thanks!
Related:
Why is the ocean salty? - https://news.ycombinator.com/item?id=16129786 - Jan 2018 (90 comments)
Why is the ocean salty? - https://news.ycombinator.com/item?id=16129786 - Jan 2018 (90 comments)
I’ve googled this before and gotten a different answer- that it is the water going in and out of the seabed floor and dissolving all the salts in the rock.
And how does sea life filter out the ions? And can we acquire that gene, as it would solve a growing problem?
But why are the ions primarily Sodium and Chloride, why not like Lithium, Flouride, Magnesium, iron, etc?
Likely some combination of abundance and electronegativity. For instance, from your example - Sodium is about a zillion times more abundant than Lithium
https://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth...
https://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth...
Nice graph. But if I understand it correctly, Chloride is about as abundant as Lithium, and less abundant than its neighbours Sulfide, Phospor, Fluoride etc. So why is chloride so abundant in the ocean? Sodium makes sense, but chloride does not.
I'm also surprised to see that Nitrogen is relatively rare compared to its neighbours Carbon and Oxygen, despite making up 80% of the atmosphere. Or maybe that's why? Are we losing nitrogen to space?
I'm also surprised to see that Nitrogen is relatively rare compared to its neighbours Carbon and Oxygen, despite making up 80% of the atmosphere. Or maybe that's why? Are we losing nitrogen to space?
The 'electronagativity' was a handwave for 'the chemical and physical properties of the element'. E.g. the solubility of its salts or other compounds in water, processes that cycle or collect it elsewhere, etc.
Nitrogen is less reactive than Oxygen, doesn't form as many compounds as Carbon and has a molecule too fat to easily escape into space.
Nitrogen is less reactive than Oxygen, doesn't form as many compounds as Carbon and has a molecule too fat to easily escape into space.
Those ions can easily remain disolved, even in the presence of many other compouns. Many other ions are quite likely to bond to other ions, causing them to bind and fall out of solution.
Because cod made it that way.
>In a cubic mile of seawater, the weight of the salt (as sodium chloride) would be about 120 million tons. A cubic mile of seawater can also contain up to 25 pounds of gold and up to 45 pounds of silver! But before you go out and try alchemy on seawater, just think about how big a cubic mile is: 1 cubic mile contains 1,101,117,147,000 gallons of water!
This is one of the best sales pitches for the metric system that I've ever seen.
This is one of the best sales pitches for the metric system that I've ever seen.
To be honest, such numbers in the millions and trillions are totally incomprehensible to human experience regardless of which units are used.
It's equally silly to try to convey the size of a cubic mile of water in gallons, just as much as it is to convey the size of a cubic kilometer in liters. The numbers are just round in the latter case.
In other words, both:
It's equally silly to try to convey the size of a cubic mile of water in gallons, just as much as it is to convey the size of a cubic kilometer in liters. The numbers are just round in the latter case.
In other words, both:
1,101,117,147,000
1,000,000,000,000
> are equally meaninglessly
> large to any lay reader.
It contains however many liters of water are in that cubic kilometer after you subtract everything else in the ocean, it'll be close to a trillion liters, but not quite.
Of course the article may be using "water" in the loose sense.
But if it's not the metric version would implicitly provide you with an easily inferred percentage of how much of a cubic kilometer of ocean is made up of other stuff.
Whereas in imperial units you won't know that at a glance, you'll need to either repeat the calculation, or memorize various conversions.
A cubic km of sea water would weigh a bit north of a billion tonnes.
You're right that large numbers are hard to comprehend, but being able to summarise them and convert to other measures easily helps convey meaningful information.
Saying you want to process a billion tonnes of something is immediately grokable as vastly different to wanting to process a million tonnes.
Being able to immediately convert that into a conversation about processing a trillion litres vs a billion litres is similarly valuable.
If I can process 1 tonne of water per unit time, then I know that the cubic km will take 1000 times longer than a billion litres / million tonnes.
You're right that large numbers are hard to comprehend, but being able to summarise them and convert to other measures easily helps convey meaningful information.
Saying you want to process a billion tonnes of something is immediately grokable as vastly different to wanting to process a million tonnes.
Being able to immediately convert that into a conversation about processing a trillion litres vs a billion litres is similarly valuable.
If I can process 1 tonne of water per unit time, then I know that the cubic km will take 1000 times longer than a billion litres / million tonnes.
You can have an idea of orders of magnitude though, say a billion is a cube 1000 units on each side. That is, a meter cubed with units of 1mm. Actually you could have such a thing on the kitchen table.
Edit: now a trillion, that's getting beyond comprehension. Just multiply each side by 10.
Edit edit: that "1 billion" would make for a good conversation piece. Or, easier, a container with 1 billion small grains in it.
Edit: now a trillion, that's getting beyond comprehension. Just multiply each side by 10.
Edit edit: that "1 billion" would make for a good conversation piece. Or, easier, a container with 1 billion small grains in it.
Hard to understand unless it’s converted to football fields.
American or metric football fields?
[deleted]
VoodooJuJu(3)
Na CLue
The variants I've heard on this joke are:
Because the land didn't wave back
Because it's full of seamen
Because it's full of <name of game> players
Because the land didn't wave back
Because it's full of seamen
Because it's full of <name of game> players
[deleted]
The two ions that are present most often in seawater are chloride and sodium. These two make up over 90% of all dissolved ions in seawater.
The other ten percent are micronutrients that are also essential to life.
Most land animals have a skeleton not just to provide physical scaffolding to hang tissue on but because we need a store of calcium to mediate blood pH, something sea life doesn't require thanks to those minerals in the water. That's why you can have sharks which are mostly supported by cartilage with one set of bones: Their jaws.