Inland seas and lakes
In such lakes which have got an inland location and in which there is no outlet i.e. no rivers originate from them, the salinity is bound to be higher. Rivers that discharge their water into them bring salt in solution.
Since there is no escape for salts in the absence of an outlet, the salinity gradually grows more and more. Absence of an outlet means that evaporation in such lakes equals the supply of fresh water.
The amount of salinity in such lakes will depend on the age of the lake. On the contrary, a lake with an outlet or a river draining out its water is not very saline.
However, in a certain large inland lake such as the Caspian Sea, there are marked variations in salinity in its different parts. For example, salinity is less than 14%o in its northern part because of the inflow of fresh water brought by the Volga and Ural rivers.
But in the Gulf of Karabugas which is shallow and is connected with the rest of the sea only by a restricted opening, the salinity touches a higher value of 170%. A high degree of salinity (237.5%) is found in the Dead Sea, where the evaporation is high and there is complete absence of an outlet.
Even higher salinity found in some of the lakes situated in the dry parts of the world. The Lake Van in Turkey is the saltiest of all the inland lakes, and the salinity of the surface water touches a higher value of 330%.
