Soil Pollution Experiments

History of the Soil

• Know the history of the soil you are working with. Find out what the land was used for. If there was an orchard on it before 1947, there is a good chance that arsenic-based pesticides were used, which may be at toxic levels in the soil. If the area where the soil is used to be a parking lot, cars may have leaked leaded gas into it. If the soil you are working with is near a busy road, lead my have built up from the high concentrations in the exhaust of cars when gas was leaded. The same goes for if your soil was near a service station or if it is (or was) downwind from heavy industry, such as smelters. Arsenic can also come from oil, coal and leaching from wood treated with arsenic.

Exposure to Soil Pollutants

• Exposure to toxic lead and arsenic can occur whenever direct contact with the polluted soil happens, such as with skin contact and breathing in dust. Children are the most likely to become exposed to soil pollution since they are on the ground and are typically less protected. Working without gloves in your garden is probably the most likely way to be exposed to lead and arsenic. Digging to plant a tree stirs up dust, which when breathed in can cause poisoning from polluted soils. Likewise, dust from polluted soil being carried into the home can become airborne and harm those who breathe in the particles. Minimize exposure by wearing protective clothing when working with the soil, particularly gloves and shoes. Moisten the soil to keep the dust down and make sure children do not go barefoot, eat the soil or play in it. Make sure to wash your hands after being in contact with the soil.

Testing for Arsenic and Lead

• Contact your local university extension office for details on how to collect samples to be tested for soil pollutants. In general, use a plastic trowel to collect several samples from the top 8 inches of soil that you suspect may have arsenic or lead in it. Place all of the samples in a bucket and mix them together. Take a cup-sized composite sample from the mixture and put it in a sealable plastic bag. Write your name, date, location and the depth of sample on the bag. Request that the testing laboratory give total lead and total arsenic concentrations.

Experiments

• Pin white sheets of paper to the ground in your lawn or garden at several locations. Monitor how much dust has blown onto the paper from potentially contaminated areas for certain periods of time, such as one hour, 12 hours and one day. This experiment may also be used to determine whether dust is settling out of the atmosphere from a nearby factory. The darker the paper, the more dust has accumulated. Use several locations and test where the least amount of dust lands to determine roughly where working in the soil would be the safest. You may also test how much arsenic and lead are getting into your garden plants. To conduct this experiment, take leaf samples from the same type of plant, such as radishes, at different locations in your garden. Place each sample in a separate labeled containers. Send the plant material to a testing lab at your state's land grant university. Compare the levels of arsenic and lead in the leaf samples with the location of the tested plants to determine the best place to continue growing food.