Reading Selection, Lesson 15
Separating Solutions and the Salty Sea
Salt is a valuable commodity that has been traded for thousands of years. It is used in food, providing flavor and acting as a food preservative . It is also used to make a wide variety of chemicals. These chemicals are used in many industrial processes, including making glass, soap, and chlorine.
Today, most salt comes from mines, although a lot is also extracted from the sea or salty lake water. Salt has been extracted from salty bodies of water throughout history. One common method of extraction is to let the heat from the sun completely evaporate seawater that is trapped in pools or small lagoons.
In some desert areas, water is very scarce. But many of these deserts are near seas (or salt lakes), and salt can be removed from seawater to get fresh water. This process is called desalination. Seawater that is desalinated is fresh enough to drink and to grow crops. In some desalination plants, the saltwater is heated. The water evaporates away from the salt, as steam. The steam then condenses to form fresh water. This process requires a lot of energy, so it is very expensive. Other desalination plants remove salt from water by a process called reverse osmosis.
1. Use library or Internet resources to find information on the locations of the Salton and Aral Seas. Answer the following questions: What do the Salton and Aral Seas have in common? What environmental problems do they have?
2. It is widely believed that the term "salary" was derived from the Latin word for salt. Based on what you read in this article, why might this be true?