If water flowing over continents in rivers is what concentrates salt in our ocean, would a planet that has always been covered in water just be freshwater? The water is just sitting there, not eroding through salts.
If water flowing over continents in rivers is what concentrates salt in our ocean, would a planet that has always been covered in water just be freshwater? The water is just sitting there, not eroding through salts.
probably not.
unless the planet is water all the way down, I don’t think it’s possible to have life or even submerged landmasses that don’t have the chemical elements that can create salts. dead things would dissolve in the water and chemicals in rocks will leach into water over time.
now if this water planet is far enough away from the sun to freeze, sure. the frozen ice should be all fresh. I’m not aware of any salts that stay in frozen water ice. the stuff underneath the frozen stuff most definitely will be salty.
not a chemist or chemistry major but I’m using the word “salts” deliberately. there’s more types of salt than NaCl.
If salts were present when the water froze, the salts would still be there. If the ice is pure water but you can’t microscopically brush away all the salts during thawing, can fresh water be extracted?
In freeze desalination, the initial ice crystals before it freezes solid are pure water; you mostly freeze a volume of saltwater into slush, strain out the ice, and discard the liquid (which will be brine; higher in salt than your initial water).
Probably not super efficient, and probably needs multiple steps, but I dunno. Somewhere where the ambient temperature is below freezing, but geothermal is available, it could work at scale, but if you have to refrigerate, you’re probably better off with regular distillation