[HN Gopher] Why is the ocean salty? (2022)
___________________________________________________________________
Why is the ocean salty? (2022)
Author : thunderbong
Score : 91 points
Date : 2023-09-10 19:56 UTC (3 hours ago)
(HTM) web link (www.usgs.gov)
(TXT) w3m dump (www.usgs.gov)
| leetharris wrote:
| 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.
| phkahler wrote:
| >> 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 ;-)
| CapitalistCartr wrote:
| I wonder if we could use that as a building material.
| A_D_E_P_T wrote:
| 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...
| thombat wrote:
| 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?)
| zdragnar wrote:
| 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.
| Blahah wrote:
| Corals manage it quite effectively
| acidburnNSA wrote:
| Probably more practical to use more chemistry and find good
| uses for sodium and chlorine individually.
| riffic wrote:
| 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
| bee_rider wrote:
| If we must do pedantry, technically the original comment
| didn't specify "on Earth."
| riffic wrote:
| words have meaning
| bedobi wrote:
| Applause nitpicking the nitpickers, love it
| anon____ wrote:
| The volume of the Pacific Ocean is 1.583x10^8 cubic miles. (htt
| ps://www.wolframalpha.com/input?i=volume+of+pacific+ocean...)
|
| The world's freshwater need is about 950 cubic miles a year. (h
| ttps://www.wolframalpha.com/input?i=worldwide+water+use+in+...)
|
| You can just put the leftovers back without worrying much about
| it.
| Obscurity4340 wrote:
| I've read that Israel has basically already solved this problem
| with their desalination tech.
| gsich wrote:
| Desalination is "solved". Main problem is the huge energy
| requiered.
| iancmceachern wrote:
| So, not solved?
| dang wrote:
| Related:
|
| _Why is the ocean salty?_ -
| https://news.ycombinator.com/item?id=16129786 - Jan 2018 (90
| comments)
| kbrisso wrote:
| I love facts like this, thanks!
| johncole wrote:
| TIL USGS has an FAQ
| pcurve wrote:
| I wish more scientific explanation were this concise and to the
| point. Basically in just one short paragraph.
| [deleted]
| pcthrowaway wrote:
| ... because the shore never waves back.
| [deleted]
| barrkel wrote:
| 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?
| actionfromafar wrote:
| 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.
| aquafox wrote:
| 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?
| phkahler wrote:
| 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.
| supportengineer wrote:
| Na CLue
| politelemon wrote:
| 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
| [deleted]
| asimpleusecase wrote:
| 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 ?
| emodendroket wrote:
| 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)
| rsa4046 wrote:
| 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.
| gumby wrote:
| 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.
| iancmceachern wrote:
| 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.
| perihelions wrote:
| Global climate would be pretty different without ocean currents
| driven by salinity gradients.
|
| https://en.wikipedia.org/wiki/Thermohaline_circulation
| eep_social wrote:
| 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 ;)
| Gibbon1 wrote:
| 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...
| DoreenMichele wrote:
| _Many of the dissolved ions are used by organisms in the ocean
| and are removed from the water...
|
| 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.
| Blahah wrote:
| 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?
| DoreenMichele wrote:
| 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.
| hn_throwaway_99 wrote:
| No. The human nose is mostly cartilage and it's hard.
| edgyquant wrote:
| It's pretty soft compared to bone. I can push mine half way
| down to the skin.
| DoreenMichele wrote:
| I imagine the hardness of cartilage varies depending on a
| variety of factors, such as body chemistry, so it's
| possible the squishiness varies some from person to
| person and from one species to another.
|
| Searching on "is cartilage in sea life squishier than in
| humans" gets me nothing especially useful. Trivia that
| came up in my search: the skeleton of human babies is
| mostly cartilage.
| skymast wrote:
| [dead]
| helf wrote:
| [dead]
| ColinWright wrote:
| Something I heard a while ago: The sea is salty
| because it remembers the taste of the land.
| ThePowerOfFuet wrote:
| >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.
| swampthinker wrote:
| Hard to understand unless it's converted to football fields.
| VoodooJuJu wrote:
| [flagged]
| crtified wrote:
| Any system of regular measurement can be adapted to various
| real world equivalences.
|
| The argument that one division system is inherently superior
| to the other would be a long one indeed.
| emodendroket wrote:
| Yet regimes all over Europe adapted it anyway. The reason the
| US retained its system has less to do with the units being so
| intuitive and more to do with having industrialized early
| enough that switching would have been expensive.
| spookie wrote:
| The metric system came about around the same time as the
| U.S. Either way, that intuitive understanding of the
| imperial system may just come about due to one's growing up
| with it.
|
| I have the same (I assume), innate understanding of the
| various metric units, given that I was exposed to it all my
| life. It's easy for me to glance at something and know if
| it's as big as a centimeter, a couple, perhaps a decimeter
| or even a meter. The same goes for the volume of something.
| I think it has more to do with your education, and
| experience in life, than it's with... the arbitrary way
| someone came about with those units.
|
| Nothing against the imperial system, I understand how
| difficult it is to leave it now, and no-one could predict
| if the metric system were to take off at the time. I wish
| all of us would use only one though.
| emodendroket wrote:
| It seems likely, yeah. Also, these customary units had
| all kinds of variations (technically they still do in
| countries using the UK-derived units though in practice
| the US ones are the ones people care about).
| CapitalistCartr wrote:
| Western Europe was more industrialized than we were at the
| creation of the Metric System, yet they managed. The longer
| we waited, the more expensive it got. Now here we are, the
| last holdout.
| avar wrote:
| > Western Europe was more > industrialized than
| we were[...]
|
| One reason for this is that weights and measures in
| Europe were less standardized at the time.
|
| While the US (mostly) used a consistent system, different
| countries, or even different cities and towns in Europe
| had incompatible systems when metric was introduced.
| > Now here we are, the last > holdout.
|
| Don't forget Liberia and Myanmar!
| [deleted]
| emodendroket wrote:
| Still, industrialization happened before serious
| metrification drives and that's what caused the problem.
| This video discusses it.
| https://m.youtube.com/watch?v=1OeoBbjwEFg
|
| In practice though it's not as though metric is not used
| to a significant extent in some contexts even in the US.
| Your medications do not list the contents of their active
| ingredients in drams.
| zzzoom wrote:
| I live in a country that uses the metric system. Water and
| gas pipe diameters are in inches. Nothing breaks because
| there aren't any competing standards.
| avar wrote:
| What country is that? Here in The Netherlands there's at
| least 3 entirely different standards for household water
| and gas pipes (and I know Germany's much the same).
|
| There's BSP (imperial), but be careful, it's not the
| diameter that's in inches, it's the _inner_ diameter.
|
| Then there's the common 15mm and 22mm copper water and
| gas pipes, and Alpex 16mm and 20mm.
| zzzoom wrote:
| Argentina. I'm pretty sure that gas installations
| wouldn't pass inspection with non-standard pipes. You
| could probably use whatever you want for water pipes.
| avar wrote:
| I hate to be the bearer of bad news, but some quick
| searching seems to suggest that it's just as much of mess
| in Argentina as here ;-)
|
| https://www.totaline.com.ar/wp-
| content/uploads/2016/08/17-Ca...
|
| My Spanish is rather bad, but I think this:
|
| > Los tubos son producidos segun los estandares
| establecidos por la norma internacional ASTM B88 y B88M.
|
| Says that ASTM B88 and it's metric equivalent are
| accepted. As you'll see from the listed dimensions the
| latter is truly metric, while the former is imperial.
| emodendroket wrote:
| The huge size of the US market has led to
| internationalization of the inch to some extent. In Japan
| televisions are sold with a size in inches even though
| inches aren't really used for anything else I'm aware of.
| mardifoufs wrote:
| Europe adopting something does not mean it's good or
| intuitive. I like metric but that's just a non argument.
| It's just like saying the US manages to uses imperial just
| fine, so imperial is just fine too
| emodendroket wrote:
| It is an argument against the idea that it's an insane
| idea from socialists gone mad since conservative regimes
| found it equally useful.
| vhcr wrote:
| "just fine",
| https://en.wikipedia.org/wiki/Mars_Climate_Orbiter
| kibwen wrote:
| While I could talk at length about the intuitive advantages
| of customary units (and how that alone isn't enough to
| outweigh the advantages of the metric system), pounds aren't
| intuitive (humans are pretty bad at intuiting weight in
| general) and neither are miles (humans are decent at
| intuiting human-scale lengths, but miles are just too long).
| emodendroket wrote:
| Once we start getting into large units the argument seems
| ridiculous. Especially with stuff like a hogshead that is a
| slightly different amount depending on what is being
| measured.
| [deleted]
| crazygringo wrote:
| 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: 1,101,117,147,000
|
| and liters in 1 km^3: 1,000,000,000,000
|
| are equally meaninglessly large to any lay reader.
| HPsquared wrote:
| 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.
| verve_rat wrote:
| 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.
| avar wrote:
| > are equally meaninglessly > large to any lay
| reader.
|
| No, because a cubic kilometer of ocean does _not_ contain a
| nice round number of liters of water.
|
| 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.
___________________________________________________________________
(page generated 2023-09-10 23:00 UTC)