Human body organs

Why is sea water salty and Why cant humans drink salt water

The water of the oceans is salty because the rivers dissolve salt minerals from the mountains and bring them into the sea.
When the water evaporates at the surface the salt remains.
Over millions of years, the amount of salt reached such a scale that the sea water has become undrinkable.

What is salinity?

The salt content in seawater, expressed in grams, is called salinity. The average ocean salinity is 35ppt, which means that in every kilogram (1000 grams) of seawater, 35 grams are salt.
The ocean water in estuaries is a mix of fresh and ocean water, so the salinity there is less than the open ocean. Also, bottom water almost always contains more salt than surface waters.

Why cant humans drink salt water?

The ocean animals have same salinity inside their bodies as the water outside, because the water likes a balance. If for example salt water animal is placed in fresh water, the fresh water will enter into the animal through its skin. Also, if fresh water animal found is placed into salty water, the water inside of it will rush out.  This process in which water flows from an area of high concentration (lots of water, little salt) to an area of low concentration (little water, lots of salt) is called osmosis.
This is the main reason why humans can’t drink salt water. 
When extra salts enter the body, it will try to expel them as quickly as possible. The kidneys will try to flush the salts out in the urine, and in the process, it will pump out large amount of water - more than taken.
This leads to dehydration, and the cells and organs will not be able to function properly.

The Dead Sea is the saltiest sea in the world, six times saltier from the water in the oceans!

The Dead Sea water has so many minerals, that the head and shoulders of the swimmers are always out.  

The Dead Sea is actually a large, narrow salt lake, which lies between the River Jordan and the State of Israel. It, has the lowest elevation in the world, about 400 meters below the surface of the Mediterranean Sea.


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