Soils are extremely important parts of every ecosystem. They are a home to many microbes and provide vital nutrients to the plants that live in them. pH is the measure of acidity or alkalinity of a solution, and most organisms have a very small range of pH values in which they can survive. 7 is considered neutral, lower than 7 is acidic (lemon juice, rain water) and above 7 is basic (bleach, soap).
Lots of urban areas are dependent on car transportation, and at the present time, most of our cars run on gasoline. It has already been documented that burning gasoline produces greenhouse gases that contribute to warming in our atmosphere, and byproducts have been linked to asthma and cancer. Do gas stations also pollute the soil around them?
Problem: Do gas stations affect the pH of surrounding soil?
Form a hypothesis on whether or not the presence of gas stations in your area affects the soil by observing plant life.
Materials
Tablespoon
Sterile lab dishes, small
Labeling tape
Marker
Universal pH indicator and color table
Plastic zip-top bags
Water
Plastic dropper
Procedure
1. Collect 1-tablespoon soil samples from the immediate area surrounding 4 different gas stations. Store the samples in separate plastic bags and label the location where you collected them.
2. Collect 1-tablespoon soil samples from areas away from gas stations. Try to get soil samples from urban, suburban and rural areas. For this experiment, the more samples, the better.
3. Put a pea-sized portion of each sample into a separate lab dish. Label the samples carefully.
4. Use the plastic dropper to add drops of water until the sample is barely covered.
5. Add 2 to 3 drops of universal pH indicator to each sample.
6. Observe your samples and use the color table that comes with the indicator to record the pH of each sample.
Results
The results of your test will depend on the environmental regulations of your state, city or town, and on how