G6 – Why is the Ocean Salty? 600-700l – 02

Are you, “worth your weight in salt?” Perhaps you have been told you are the “salt of the earth?” Don’t be insulted; both can be complimentary statements about your character. Both terms come as a result of salt’s importance throughout history.

We are very lucky to live on planet Earth. It is the only planet in the solar system where water exists in all three states of matter. In fact, over two-thirds of Earth’s surface is covered by water. Even with all that water, there are some people that do not have enough. Do you know why?

Most of Earth’s water is in the form of salt water. All that water in the ocean is water that humans cannot drink. The oceans of Earth are filled with salt water. Humans require fresh water to survive. Only three percent of Earth’s water is fresh. Fresh water is water that contains little or no dissolved salt. Of that fresh water, most of it is locked up in Earth’s ice caps. These ice caps are located in Greenland and Antarctica. Less than a percent of Earth’s water is available in a form we can use.

It all comes back to Earth’s water cycle. If not for it, we would not have salt. We would also not have the fresh water we need to survive. Why do you think the majority of water on Earth is salt water?

The answer is simple. The salt in the ocean comes from rocks on land. When it rains, raindrops pick up small amounts of carbon dioxide gas as they fall. The carbon dioxide makes the rain slightly acidic. You may have heard of carbonic acid. It’s the same type of acid in soda. Though acid in rain is not nearly as strong as that in soda, given enough time, it can dissolve rocks.

With each rainfall, the rock is slowly weathered. This means the slightly acidic water breaks it down. The salts contained in the rocks are eroded and are carried away as runoff. This runoff makes its way to the oceans via streams and rivers. Over time, the salts build up, making the ocean even more salty.