Are the oceans getting saltier?

Question

Discounting "temporary" effects of ice caps forming and melting through the ice ages and warmer periods, why aren't oceans getting saltier? Is there a meganism that takes salt from the ocean and return it to land? Or are the oceans getting saltier in the long term?

Answer 1

this puzzled scientist for a long time. Then they found the deep ocean vents and rifts in the ocean crust for the plate tectonics and that is where fresh unsalty water comes back after it seeps thru the rock on land.

Also the mineral accumulation from rivers and erosion are not collecting on the ocean floor as one would expect - and elevate the mineral and salt content of the ocean - they get turned under the plates when the plates move. The ocean bottom has a very thing crust rather than huge layers of sediment.

The water cycle also helps to keep the oceans from getting to salty. Water evaporates and insalty rain comes down on ground. Some flow nback out thry lakes and rivers and run off, some ends up getting soaked thru the crust and purified.

Also glaciers on the poles collect ice which melts (now faster than we want)

Scientist estimate the salinity level has been stable of the last 100 million years

Answer 2

Ocean salinity changes depending of the output of magma upwelling from the mantle. For example, during the Paleozoic there was an increase in magnesium in ocean water that resulted in the formation of of dolostone (dolomitic limestone) at the expense of (calcitic) limestone. Hypersaline environments precipitate salts onto basin floors and a certain amount of salt (and water) is subducted under continents along with ocean floors. One cannot speak of "the long term" in Geology without realizing that several factors influence these processes, and that these processes are subject to change over geologic timescales.