Briny sea

Why is the sea salty?

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Publication Date: 16 May 2014
Asked By: Delese Brewster
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Answer by teachersupport on question Briny sea

Expert Answer

 Salt in the ocean comes from rocks on land. When rain falls on the Earth’s surface it contains some dissolved carbon dioxide which makes it very slightly acidic. This acidic water erodes (chemically breaks down) the rocks as it travels to streams, rivers and eventually the ocean.  But why is the ocean salty when the rivers running into it are not? The dissolved salts (ions) are carried with the water.  Many of the ions are used up by organisms in the ocean, but others are not, and their concentration builds up over time making the ocean salty.

See http://oceanservice.noaa.gov/facts/whysalty.html for a very good explanation and some good experiments to do with students here: http://marinewaters.fish.wa.gov.au/resources/salty-seas/#.U3v68PmSz50 .

Answer by sinh_test on question Briny sea

The oceans are salty because small amounts of salt from the land areas dissolve in the waters of streams and rivers, and are carried to the sea.

When water evaporates from the oceans into the atmosphere, the salt is left behind. The amount of salt dissolved in the oceans is, on average 3.5 % by weight.

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