The salts originate in weathering of the lithosphere, accelerated by the functioning of the biosphere [plant growth].
The supply of sodium chloride and calcium chloride produced by weathering far exceeds their demand
by the biosphere.
The surplus is wasted as excess salinity which drains to the sea.
The salinity of typical fresh waters is about 300 ppm.
In contrast, the salinity of the seas is 34,500 ppm [of which 85% is sodium and chloride ions].
