Why is the sea salty?

(ORDO NEWS) — Have you ever wondered why the ocean is salty? Have you ever wondered why lakes might not be salty? Here we look at what makes the ocean salty and why other bodies of water have different chemistry.

Key takeaways: Why is the sea salty?

The world’s oceans have a fairly stable salinity of about 35 parts per thousand. Basic salts include dissolved sodium chloride, magnesium sulfate, potassium nitrate and sodium bicarbonate. In water, these are sodium, magnesium and potassium cations, as well as chloride, sulfate, nitrate and carbonate anions.

The reason for the salinity of the sea is that it is very old. The gases emitted by volcanoes dissolved in the water, making it acidic. The acid dissolved the minerals from the lava, forming ions. More recently, ions from igneous rocks entered the ocean as rivers flowed into the sea.

Although some lakes are very salty (high salinity), some do not taste salty because they contain low amounts of sodium and chloride ions (common salt). Other lakes are more dilute simply because the water drains into the sea and is replaced by fresh rainwater or other precipitation.

Why is the sea salty

The oceans have existed for a very long time, so some salts were added to the water at a time when gases and lava erupted as a result of increased volcanic activity. Carbon dioxide dissolved in water from the atmosphere forms weak carbonic acid, which dissolves minerals.

When these minerals dissolve, they form ions that make the water salty. When water evaporates from the ocean, salt remains. In addition, rivers empty into the oceans, bringing with them additional ions from rocks that have been washed away by rainwater and streams.

The salinity of the ocean, or its salinity, is fairly stable at about 35 parts per thousand. To give you an idea of ​​how much salt that is, it is calculated that if you take all the salt from the ocean and spread it over land, the salt forms a layer over 500 feet (166 m) deep.

You might think that the ocean gets saltier over time, but this is partly because many of the ions in the ocean are taken up by the organisms that live in the ocean. Another factor may be the formation of new minerals.

Why is the sea salty 2

Salinity of lakes

Lakes receive their water from streams and rivers. Lakes are in contact with the ground. Why aren’t they salty? Well, some of them are salty! Remember the Great Salt Lake and the Dead Sea. Other lakes, such as the Great Lakes, are filled with water that contains many minerals but does not taste salty. Why is it so?

Partly because water tastes salty when it contains sodium and chloride ions. If the minerals associated with the lake do not contain much sodium, the water will not be very salty. Another reason why lakes are usually not saline is that the water often leaves the lakes and continues on its way to the sea.

According to an article in Science Daily, a drop of water and its associated ions remain in one of the Great Lakes for about 200 years. On the other hand, a drop of water and its salts can remain in the ocean for 100-200 million years.

The most dilute lake in the world is Lae Notasha, located at the crest of the Oregon Cascade in Oregon, USA. Its electrical conductivity is between 1.3 and 1.6 µS-1, and the predominant anion is bicarbonate. Although the lake is surrounded by forest, the watershed does not appear to contribute significantly to the ionic composition of the water. Because the water is so dilute, the lake is ideal for monitoring atmospheric pollutants.


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