Water
River in a Pot

When lakes and rivers get hurt by acid rain, they can sometimes be healed by adding stuff to the river that takes away the acid. This stuff is a "base," the opposite of an acid. When you mix red paint with white paint, you get pink, a color in between red and white. The same sort of thing happens when a base is added to an acid. The acid and base combine to form something in between that is neither an acid nor a base. This process is called "buffering," and it has been used to help lots of acid lakes and rivers so that they can once again support life.

The acid in any liquid can be measured by something called pH. The most acid materials have a pH of 0; the least acid would rate 14. Neutral is 7, and clean rainwater should measure 6 or so. Lakes and rivers filled with acid rain can dip as low as pH4 -- a disaster for the animals and plants living there. (For more on pH see The pH Factor.)

Are you ready to create your own mini acid river and then buffer it?

To make the acid detector:
knife
red cabbage
blender
small glasses for water testing

To make the acid river:
Water
vinegar or lemon juice
cooking pot
dishwasher detergent
acid detector mixture

To make the acid detector mixture:

1. Use the knife to cut up the red cabbage in small pieces.

2. Place in the blender and blend until it is mush.

To make and test the acid river:

1. Put an equal mixture of water and vinegar (or lemon juice) into the pot.

2. Check the mixture with your acid detector. To do this, pour a bit of your acid water into the acid detector. The darker the color the more acid. (At this point you want it dark, because you want your river to be acid).

3. Mix a couple of spoonfuls of dishwasher detergent with water in a cup. This is your base. Pour this base into your acid pond and stir.

4. Use some acid detector mixture to test how the pond is now. Is it still acid?

One of the most common bases is limestone. Some parts of the world have limestone already in the rocks under lakes, rivers and soil. This gives those lakes, rivers and lands a natural ability to buffer acid rain. For this reason, the same amount of acid rain can fall on two bodies of water, and one can end up dead and acidic, while the other, on limestone bedrock, can flourish. Lakes and rivers found in areas with no limestone in the rocks under them are especially endangered by acid rain. Are your local lakes and rivers in trouble? Is there limestone in your area?

In the role of an environmentalist in your community, write about two pages describing a program you will design to make sure that the pH, in the water around you, is kept at a safe level. Describe who will be involved in order for the program to be successful. Also, how will your program ensure all citizens that their water is safe?

For more information and experiments related to acids and bases, see The pH Factor.

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