ASK JiMMY + ThE BuG?

Seawater contains lots of dissolved chemicals, including the one you shake over your fries. Sodium chloride-better known as table salt-is the most common of all the chemicals found in the ocean. There are about 35 pounds of it in every 1,000 pounds of seawater. That's enough to cover the entire planet with a layer of salt 500 feet high-as tall as a 50-story skyscraper.

Where does all the salt in the ocean come from? Nature "weathers" rocks and grinds down mountains, releasing locked-in mineral salts. Rain and melting snow carry these chemicals into rivers and out into the sea. Also, hot water (hydrothermal) vents on ridges in the ocean floor pump chemical-rich water into the sea. Even underwater volcanoes add salt to the ocean.

Freshwater in streams, rivers, and lakes contains salt, too-about one pound in a thousand pounds of water. It doesn't taste salty because the concentration, or amount, of dissolved salt is too low for the taste buds on your tongue to detect. In most lakes, water flows in one end and out the other, keeping the salt concentration low. But salt can build up in lakes if they have no outlets. The Great Salt Lake in Utah is 10 times saltier than the ocean. When water flows into the Great Salt Lake, it can't flow out. Some water escapes by evaporation, but the salt it contained is left behind.

Copyright Carus Publishing Company Apr 2004
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