Though caspian sea is enclosed its salinity is just 14 to 17 parts per thousand why is it so
Answers
Caspian sea which is actually considered as a lake is the biggest in the world is surrounded on the south by Persia.
Seas are usually determined by association to the ocean or different sea through salt water, which the Caspian Sea is not. Seas are normally or partly enclosed by land, according to the National Oceanic and Atmospheric Administration, but the Caspian Sea is completely enclosed by land. Seas commonly consist of salty water. While the Caspian Sea is not fresh water, its salty water is diluted by the inflow of fresh water, especially in the north which reduces its salinity.
As Caspian sea, is part of an internal drainage system due to this the Caspian lake is slightly saline although it is enclosed. Ordinary salinity ranges between 12.80 and 12.85 percent but its sharply drops to less than 1 % across the delta of the Volga river. However, it extends usually from north to south and from west to east. Hence average salinity is thus only 9.28 percent in the northern basin, 13 percent in the central basin, and 13.1 percent in the southern basin.
The salinity of Caspian Sea depends on the salinity of the tributaries flowing into it.
Thus, the salinity of this water body decreases near the mouth of River Volga. As there is no circulation of the water on the surface and deep within the lake, the salinity differs at different parts of the water.
When the tributaries bring in more water during the spring and summer, the salinity level of Caspian Sea drops even more.