re: Why is the sea salty? - The Straight Dope
How much of an impact do dead bodies contribute to the sea’s salt?
Creatures have been dying and falling to the bottom of the ocean for billions of years.
Surely the salt from their decaying bodies has some effect on salinity (?).
Where are those creatures getting their salt? From the sea. The same sea they die in.
Furthermore, the total accumulation would be small compared to all the salt in the oceans. Finally, the ocean floor is constantly being subducted and regenerated.
Pardon me for not doing the math here, to support my point. But I’d need to know the average lifetime of sea floor, and average amount of deadkill … and since most of the deadkill is already covered above … why bother?
Life in the ocean comes from in the ocean. Ergo, the salt in their bodies is pulled from the ocean, and returns to the ocean. (Do fish piss?) There may be a state of flux, but it is an equilibrium. If the amount of sea life fluctuates significantly, then the balance in salt trapped in their bodies might be different than the salt free in the ocean. But how much fluctuation is there before it becomes significant enough to measure?
I suppose there is some balance difference for birds or other land-based life eating sea life. Those would be removing salt. And there might be some increase from land-based life falling into the ocean, like birds dying or something.
Most life is likely long decayed before subducted. I guess you get calcium concentrates like limestone built up from ocean floors not getting sucked under and churned into the mantle, but upthrust again.
Fish have kidneys, and some have bladders connected to the anus, but a much larger % of water, electrolyte, and urine exchange goes on directly across the gill membrane (exact amount varies a lot by species and salt content of the water). The systems are very diverse as they have to cope with balancing the plasma ion concentrations with continual direct membrane exposure and fluid exchange.
If I read Cecil’s reply correctly, he states that the sodium arrived from continental weathering and the chlorine from oceanic outgassing…
How did the sodium arrive by river unaccompanied by chlorine?
Dissolved ions from other compounds?
Interesting article on this concept of sea salinity: