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?
