salinity of oceans and seas

[jackson6612]

I'm not a science student, so please keep your replies simple and straightforward. Thanks.


Is the salinity of seas and oceans always increasing, if not, then what factors are responsible to control it? Rivers carry their dissolved salt content into seas which are themselves parts of oceans, and from oceans water evaporates to form clouds to feed the cycle of water circulation around the world. Please guide me. Thanks.

[Andre]

You may notice that there is a 'salt cycle' (http://www.es.flinders.edu.au/~mattom/IntroOc/intro2.html)

The salt cycle involves the ocean, the geosphere and to a very minor extent the atmosphere.
Minerals are leached from rocks through flowing groundwater and surface erosion. They enter the rivers and from there the ocean where they accumulate, making sea water salty. They are removed from the water and enter the sediment by chemical action.

But it is assumed that when life was formed, the salinity of the oceans was in the order of magnitude to the normal saline (0.91% NaCl) (http://en.wikipedia.org/wiki/Saline_(medicine)), which seems to be common for all biota.