Ocean salinity has been constant at about 3.5% for a very long time. Salinity stability in oceanic environments is important as most cells require a rather constant salinity and do not generally tolerate values above 5%. The constant ocean salinity was a long-standing mystery, because no process counterbalancing the salt influx from rivers was known. Recently it was suggested that salinity may also be strongly influenced by seawater circulation through hot basaltic rocks, and emerging as hot water vents on mid-ocean ridges. However, the composition of seawater is far from equilibrium, and it is difficult to explain this fact without the influence of organic processes. One suggested explanation lies in the formation of salt plains throughout Earth's history. It is hypothesized that these are created by bacterial colonies that fix ions and heavy metals during their life processes.
In the biogeochemical processes of the earth, sources and sinks are the movement of elements. The composition of salt ions within our oceans and seas are: sodium (Na+), chlorine (Cl−), sulfate (SO42-), Magnesium (Mg2+), calcium (Ca2+) and potassium (K+). The elements that comprise salinity do not readily change and are a conservative property of seawater.There are many mechanisms that change salinity from a particulate form to a dissolved form and back. The known sources of sodium i.e. salts is when weathering, erosion, and dissolution of rocks transport into rivers and deposit into the oceans. When the earth's crust (primarily igneous rocks) degas and become differentiated. The mainstream, non-Gaian interpretation of the thermohaline circulation (The Gulf Stream) for salinity in the oceans is needed on the salinity page.
The Mediterranean Sea as being Gaia's kidney is found (here) by Kenneth J. Hsue a correspondence author in 2001. The "desiccation" of the Mediterranean is the evidence of a functioning kidney. Earlier "kidney functions" were performed during the "deposition of the Cretaceous (South Atlantic), Jurassic (Gulf of Mexico), Permo-Triassic (Europe), Devonian (Canada),Cambrian/Precambrian (Gondwana) saline giants,