Salt
of the Earth
Warm
and salty, the lagoons of Baja California Mexico are not just ideal nurseries
for gray whale babies. These lagoons also offer ideal conditions
for producing solar-evaporated salt. They are apart from the sea. They
receive very little rainfall and almost no freshwater runoff. The
winds are brisk and persistent.
Laguna Ojo de Liebre's 75,000 acres of
evaporating salt ponds are home to the world's largest solar saltworks.
The salt is produced by Exportadora de Sal, S.A. de C.V. (ESSA for short).
With headquarters in the town of Guerrero Negro, the company is jointly
owned by Japan's Mitsubishi Corporation and the government of Mexico.
About half the salt exported from the Guerrero Negro saltworks is
used
in Japan's industries to help produce PVC plastics, bleach, chlorine
gas, road salt, and glass.
The photos below show some steps in salt
production.
Does any of this salt end up in your salt shakers or on your icy streets
in winter? In the activity that follows, discover how salt
beds
are formed and relate your results to the photos below.
Try
This!
Create Mini-Saltbeds
Materials
Needed
Table
salt
Water
Glass bowl, 2 qt. (2 liter)
Measuring spoon for a tablespoon (15 ml)
Measuring cup, 1 cup (250 ml)
- Decide
whether students will work in pairs, small groups, or individually,
or whether this will be a class demonstration.
- Stir together
in the bowl 1 cup of water and 4 tablespoons salt.
- Allow
the bowl to sit undisturbed until all the water evaporates. This may
take 3 to 4 weeks.
- Make predictions
in science journals before and during the process about what will happen.
- What can
you see in the photos above that corresponds to what happened in your
experiment? (For example, which photo shows where climbing clumps of
frosty salt were formed as water rose up the sides of the pond and the
salt in the water crystallized as the water quickly evaporated?)
Try
This! Discussion or Journaling Questions
- Why do
you think crystals line the bottom of the bowl, while white frosty deposits
appear on the inner sides of the bowl?
- How could
you find out where the salt in your kitchen come from?
- How do
you think each of these factors helps make the Baja lagoons so ideal
for solar salt production?: The lagoons are isolated from the sea, they
receive very little rainfall and almost no freshwater runoff, and the
winds are brisk and persistent.
- What effects
might the saltmaking operation have upon the whales and the sea birds
that come to winter in the lagoons each year?
- If you
lived in Guerrero Negro, you would probably work for the saltworks or
make your living fishing. How might various groups feel about the preservation
of wildlife habitat and the Baja ecosystem?
National
Science Education Standards
- Materials
can exist in different states?solid, liquid, and gas.
National
Geography Standards
- The physical
and human characteristics of places.
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