<p>My 13 yr old kid is studying the water cycle and has raised me some question I  don't have answers to regarding how the salinity levels of the oceans are kept constant (over very long period of time)</p>
<p>Q1: How is salinity maintained constant in the oceans?</p>
<p>His reasoning is as follow:</p>
<p>(1) salts stays in the oceans while water evaporates
(2) fresh waters transport salts from the rocks</p>
<p>If (2) adds more salts, and (1) doesn't remove salts, shouldn't salinity increase over time? (even if it's a very long period of time)</p>
<p>Q2:  is there not a (very long) time when there won't be anymore salts to &quot;take&quot; from the rocks and the ground?</p>
<p>How is that supply renewed over time?</p>
<p>Is there some sort of a salts cycle that somehow takes away salts from the oceans and adds them back into the ground/rocks?</p>
<p>I was thinking aquatic organisms take salts into their body, we eat them, we die, our body goes back into the ground... But, to mean, that does sound really convincing. Also living things decomposition maybe?</p>

CC BY-SA 4.0
2021-11-29T02:24:43.500Z
A little of info on paleo-salinity: https://alioshabielenberg.com/how-salty-has-the-sea-been-over-the-past-541-million-years/
arkaia
CC BY-SA 4.0
2021-11-29T02:42:19.847Z
A good explanation on salinity and its changes comes from Herbert Swenson (USGS): https://www2.palomar.edu/users/lyon/Assignments/7-%20Why%20is%20the%20Ocean%20Salty.pdf
arkaia
CC BY-SA 4.0
2021-11-30T19:58:59.360Z
[The "Global Salt Cycle": Formation of Giant Salt Accumulations, a Result of Subduction, Mantle Upwelling, and Rifting](https://www.preprints.org/manuscript/202107.0377/v1) [This version has pictures](https://www.researchgate.net/publication/353336542_The_Global_Salt_Cycle_Formation_of_Giant_Salt_Accumulations_a_Result_of_Subduction_Mantle_Upwelling_and_Rifting)
Keith McClary
CC BY-SA 4.0
2021-12-01T13:05:05.623Z
Thanks, very interesting links. I think that serves well as answers.
Alexandre Dumont
<oceanography><water><rivers><salinity>
Salinity balance in the oceans, is it increasing over time?
Alexandre Dumont
# Salinity balance in the oceans, is it increasing over time?

(Asked by: username_0 on 2021-11-28)

My 13 yr old kid is studying the water cycle and has raised me some question I don't have answers to regarding how the salinity levels of the oceans are kept constant (over very long period of time)

Q1: How is salinity maintained constant in the oceans?

His reasoning is as follow:

(1) salts stays in the oceans while water evaporates
(2) fresh waters transport salts from the rocks

If (2) adds more salts, and (1) doesn't remove salts, shouldn't salinity increase over time? (even if it's a very long period of time)

Q2: is there not a (very long) time when there won't be anymore salts to "take" from the rocks and the ground?

How is that supply renewed over time?

Is there some sort of a salts cycle that somehow takes away salts from the oceans and adds them back into the ground/rocks?

I was thinking aquatic organisms take salts into their body, we eat them, we die, our body goes back into the ground... But, to mean, that does sound really convincing. Also living things decomposition maybe?

**Tags:** oceanography, water, rivers, salinity

> **Comments:**
> **username_1**: A little of info on paleo-salinity: https://alioshabielenberg.com/how-salty-has-the-sea-been-over-the-past-541-million-years/  
> **username_1**: A good explanation on salinity and its changes comes from Herbert Swenson (USGS): https://www2.palomar.edu/users/lyon/Assignments/7-%20Why%20is%20the%20Ocean%20Salty.pdf  
> **username_2**: [The "Global Salt Cycle": Formation of Giant Salt Accumulations, a Result of Subduction, Mantle Upwelling, and Rifting](https://www.preprints.org/manuscript/202107.0377/v1) [This version has pictures](https://www.researchgate.net/publication/353336542_The_Global_Salt_Cycle_Formation_of_Giant_Salt_Accumulations_a_Result_of_Subduction_Mantle_Upwelling_and_Rifting)  
> **username_0**: Thanks, very interesting links. I think that serves well as answers.  

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## 0 answers

