Why isn’t the ocean fresh water?
In: Chemistry
As others have mentioned, the main input of salts into the ocean is from rivers which run off the continents and carry with them dissolved ions from the minerals in continental rocks.
Another input is the mineral constituents pumped into the deep oceans at hydrothermal vents.
However, no other responses here have yet mentioned the *removal* of salts from the oceans. Salts are removed through sedimentation onto the seafloor (either directly or via dying micro-organisms which make it to the seafloor sediments), or directly into the oceanic crust when seawater is moving through it before it comes out at hydrothermal vents with a completely different mineral profile. That is to say, hydrothermal vent systems both remove and add various different chemical species to and from the oceans.
This is summarised succinctly in an old r/askscience post to a similar question [here](https://reddit.com/r/askscience/comments/3c9u7f/since_evaporating_ocean_water_is_pure_does_this/cstrbso), and a few more details on the subject gone through in a slightly less old r/askscience post [here.](https://reddit.com/r/askscience/comments/7o1hf2/are_oceans_becoming_increasingly_saltier/ds6fiyk)
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