Vendée Globe 2008: Water, Water, Everywhere, Nor Any Drop To Drink

It’s hard to imagine, but did you know it’s possible to die of thirst at sea?

A desalinator. Photo courtesy of sitesALIVE!The reason for that is that the ocean is made up of saltwater, which can be poisonous to the human body if you drink it in any but the smallest quantities. Salt is processed in your body by your kidneys and is perfectly healthy in small amounts. Normally, if you have a little too much salt in your food, your kidneys use the liquid you drink to help flush the salt of your body when you urinate. When your body has more salt in the bloodstream than it can handle, it starts pumping water out of your other cells to help flush the salt out of your system. Seawater, however, has a lot of salt in it — way too much for your kidneys to handle. If you don’t drink more freshwater to help replenish the water that comes out of your cells, eventually your kidneys can’t handle it anymore and shut down, and your body’s cells start to die.

Because you need water to live, Skipper Wilson and other sailors use what’s known as a desalinator, a tool that removes the salt from sea water, making it safe to drink. He uses this tool to change seawater into drinking water, which he then stores in the Great American III’s 88-liter freshwater tank. You can read more about it here and here.

People have been interested in removing salt from seawater for a long time. In fact, Thomas Jefferson wrote a report about desalination back in 1791!

Sailors use this technology so they don’t need to haul lots of water with them on their voyages, but some places remove the salt from seawater for drinking water for their land-based populations, too. The Middle East, which is made up of lots of deserts bordering the sea, has a lot of desalination plants that produce close to 9 million gallons of drinking water from seawater a day!

(The title of this post comes from “The Rime of the Ancient Mariner” by Samuel Taylor Coleridge.)

Ecosystem Services: Water Purification (6-8)
This Science NetLinks lesson uses the example of natural water purification to show students that healthy ecosystems provide services to people that are essential to life as we know it.


Water Treatment Cycle (3-5)
This Science NetLinks tool allows students to follow a drop of water from the source (in this case a lake) through the treatment process.

How Does the Ocean Get Its Salt? (3-12)
This resource, which is part of the Miami Museum of Science Web site, provides an experiment that demonstrates how the ocean get its salt. Included are a list of all the materials needed, the procedure, and an explanation of the results.

Salt: Up Close and Personal (3-5)
This lesson from Science NetLinks lets students view salt under varied magnifications so they can begin to construct the understanding that materials may be composed of parts that are too small to be seen without magnification.

Earth’s Ocean (3-12)
This resource, from Windows to the Universe, is part of a larger resource on the water cycle and is available in three reading levels for students. This resource explains ocean tides, currents, and deep circulation. This resource also details the ocean’s role in the water cycle.


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