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Why Sea Water is salty and River Water not?

Geography | 7-14 yrs | Reading Pod

When we go to a beach often the sea water gets into our mouth and it tastes salty. On the other hand when we visit a river or a waterfall the water is clear and unsalted.

Difference between Fresh Water and Salt Water

  • River water is mostly rain water that is always running or soaked by the soil. Rainwater is not salty. Clouds bring rain with the help of vapour which is unsalted. Rivers are constantly running. They pick up minerals and salt from the rocks they pass by. Rivers run towards the ocean and when river water mixes with the ocean water, the salt mixes along with it.
  • River waters are constantly being restocked by fresh water from rain and springs, thus they do not taste salty. But the ocean collects all of the river water salt and minerals. The ocean floor also contains minerals which get dissolved in the water, adding to the salinity of the sea.
  • The process of evaporation starts when the heat from the sun evaporates water from the ocean and produces vapour. When sea water evaporates the salt is left behind because salt is too heavy to become vapour. Thus ocean water remains salty. Millions of years have passed and with constant evaporation and inflow of river water, our oceans have reached a stagnant point of salinity.
  • Now, there are certain lakes too which are saline. That is because such lakes do not have escapes to rivers or sea. Rivers carried water to these lakes, the water in the lakes evaporated but left the salt behind.
  • Another reason why ocean water is salty is submarine volcanism or the eruption of volcanoes under the ocean. Here sea water reacts with the hot rocks erupted by the volcanoes and dissolves the mineral constituents. This also adds to the salt content of the ocean.

Little known Facts about Fresh Water and Salt Water

  1. 96% of the earth’s water is sea water.
  2. Sodium chloride or common table salt is the most prevalent salt in the oceans.
  3. 1 gallon of sea water = ½ cup of salt
  4. The Ganges, Yangtze and Indus are the most polluted rivers on Earth.
  5. 65% of drinking water comes from rivers and streams.