New Delhi: There is a famous line from Samuel Taylor Coleridge’s poem, ‘The Rime of the Ancient Mariner’: ‘Water, water everywhere and not a drop to drink’. The line denotes that the water in the sea or ocean is so salty that it is not clean or safe enough to drink. But why is the water in the ocean so salty?
Why is ocean water salty?
As we read in our geography books in school, 70 per cent of the surface of the Earth is covered by ocean and about 97 per cent of all water on and in the Earth is saline. Some studies have estimated that if we remove the ocean’s salt and spread it evenly over the land surface of this planet, it would form a layer more than 500 feet thick, the same as the height of an office building of around 40 storeys.
The cause behind the saltiness
The water cycle brings rain, which brings with it some dissolved carbon dioxide from the surrounding air when it falls on the ground. The carbonic acid makes the rainwater slightly acidic. The rainwater leads to the erosion of the rocks and then they are chemically broken down by the acids. After that, the water carries salts and minerals along with it, dissolving them as ions which are ultimately deposited in the streams and rivers and finally in the ocean. There are several organisms in the ocean which use the dissolved ions, greatly removing them from the water. The ions which are not used and are left for a long time where, over a considerable period, their concentrations increase.
The ocean water gets salt from another source: The hydrothermal fluids from the seafloor’s vents. Ocean water gets into the seafloor cracks and then the magma from the Earth’s core heats the water. It leads to chemical reactions and oxygen, sulfates and magnesium go out of the water. Then, the water gets filled with zinc, copper and iron from surrounding rocks and then the vents in the seafloor release the heated water with metals in it. Also, underwater volcanic eruptions release minerals into the ocean which makes the water salty.
Also, there are salt domes which makes the ocean water salty. The domes have a vast amount of salt formed over geological timescales and are present underground and under the ocean. They are common across the continental shelf of the northwestern Gulf of Mexico. So, if you were wondering why the ocean water is salty, then you have found the answer.
The water cycle brings rain, which brings with it some dissolved carbon dioxide from the surrounding air when it falls on the ground. The carbonic acid makes the rainwater slightly acidic. knowledge Knowledge News, Photos and Videos on General Knowledge
