Cleaning up soiled sites: two middle school students plant a future for land tainted by oil pollution.

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It's a sight you might see in any urban landscape: closed gas stations, crumbling industrial buildings, and old shuttered factories. These abandoned commercial sites, called brownfields, are more than just eyesores. "Brownfields can contain contaminants that can be harmful to people who live nearby," says 12-year-old Rani Iyer. "An abandoned gas station, for example, may have a leaking underground storage tank. The chemicals seeping out can pollute the soil and drinking water," adds 13-year-old Arthi Puri.

Arthi and Rani live in West Lafayette, Indiana. They became interested in brownfields when they noticed green spaces in their hometown giving way to new construction while abandoned commercial sites sat untouched. Arthi and Rani decided to come up with a science project that could help clean up brownfields so the land could be transformed into parks, housing developments, or business districts.

The girls teamed up with Paul Schwab, director of the Natural Resources and Environmental Science Program at Purdue University. Together they launched an investigation to learn whether plants could help remove oil pollution from soil. "Petroleum is probably the most common contaminant around," says Schwab. Arthi and Rani's work was selected out of thousands to be one of 22 finalists in the Siemens We Can Change the World Challenge, a science contest in which middle school students develop an environmentally friendly project for their communities.

SPROUTING A PLAN

Arthi and Rani's project could have been tricky if they hadn't stuck to the scientific method. Scientists use this process to design and perform experiments. The scientific method helped keep their project on track. "Staying organized was important so the girls could make sure their results were accurate and reproducible," says Schwab.

Like all science projects, Arthi and Rani's began with an observation. They had learned about phytoremediation, or the use of plants to remove toxins from the environment, from Schwab, who studies agronomy (branch of agriculture dealing with soil and crops). Arthi and Rani wondered if this process could be applied to polluted areas like brownfields.

Cleaning up these sites usually requires removing all of the contaminated soil and taking it to a toxic waste facility. Phytoremediation, on the other hand, offers a low-cost and green alternative. Knowing what they wanted to study, the team could state the purpose of their project in the form of a research question. Arthi and Rani wanted to know: Could common grasses remove oil from soft?

DIGGING IN

Next, the girls set about conducting background research on their topic. First, they visited Indiana's Department of Environmental Management's Web site to find out about brownfields in their area. Next, the girls looked into the benefits of phytoremediation. They found that growing plants at industrial sites helps keep toxic dirt in place so the contamination can't spread into the surrounding environment. The plants can also remove chemicals, such as dangerous heavy metals, from the environment by absorbing them. Additionally, bacteria that live on plants' roots can break down organic (carbon-based) pollutants like oil.

Based on this information, Arthi and Rani had a possible answer to their research question. Their hypothesis was that grasses can get rid of oil pollution. To test their hypothesis, Arthi and Rani needed to conduct an experiment. They devised a detailed procedure containing clear instructions to test the effect of one variable, or characteristic, on another.

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The girls' independent variable, or factor they would change on purpose during the experiment, would be grass type. To discover how well the different grasses worked at cleaning up contamination, Arthi and Rani decided to measure the amount of oil the plants removed from the soil. This would be their dependent variable, or the factor that responds to a change in the independent variable.

CROP TESTING

Arthi and Rani started their experiment by spraying diluted motor oil onto scoops of soil collected from a farm field. This simulated the contaminated ground at a brownfield. Then they placed the scoops of "contaminated" soil into eight separate pots. The girls set aside samples of the soil mixture from the pots so they'd know the original amount of oil in each.

The girls next planted rye grass seeds in half of their pots and tall fescue grass seeds in the other half. These two grass varieties are commonly found in lawns. They left the plants to grow in a greenhouse for six weeks and the girls again took soil samples from each pot. They mixed the collected samples with a chemical that dissolves oil, then filtered the mixture to remove the dirt. They then compared the amount of oil extracted from the samples before and after phytoremediation.

Arthi and Rani now had the data, or collected information, they needed to answer their research question. This was their conclusion, or summary of their results: Both types of grasses removed a significant amount of oil from the soil. They found that tall fescue grass on average removed 33 percent of oil, while rye grass on average removed 46 percent. Their hypothesis was correct.

SOWING SEEDS

The girls wanted to spread the word about applying this simple yet effective cleanup technique to brownfields. They were motivated by the fact that northern Indiana is part of the nation's Rust Belt. This section of the United States was once the center of the steel industry, but now its many steel manufacturing plants sit idle. Turning these once-toxic spaces into usable land could help revitalize communities by curbing urban sprawl, protecting public health, and the economy.

The girls took action by discussing their project with student groups at their local high school and meeting with their city's Go Greener Commission. "Kids are important because they can get the word out about environmental issues and talk to the government to change legislation," says Arthi. Arthi and Rani are also working with Schwab to set up a phytoremediation pilot project at an actual industrial site. The girls hope their grassroots efforts will turn their community's brownfields green.

web extra

There are more than 450,000 brownfields across the U.S. For a link to redevelopment efforts in your area, visit: www.scholastic.com/scienceworld

nuts & bolts

What are the steps to the Scientific Method?

SCIENTIFIC-METHOD CHECKLIST

-- 1. Base your idea for an experiment on an observation.

-- 2. State your purpose. Usually the purpose of an experiment is stated in the form of a research question: What is the effect of your independent variable on your dependent variable?

-- 3. Perform background research to find out what is already known about your topic.

-- 4. State your hypothesis, a possible answer to a research question.

-- 5. Design a detailed procedure, or list of steps (see p.12).

-- 6. Carry out your experiment and collect data.

-- 7. Record your results. In many cases, you can present your results in charts, pictures, or graphs (see p. 15).

-- 8. Draw a conclusion from your results, Was your hypothesis correct?

SCIENTIFIC METHOD: WORDS TO KNOW

* VARIABLES: Characteristics in an experiment that change or could be changed.

* INDEPENDENT VARIABLE: Factor that you change on purpose; also called manipulated variable.

* DEPENDENT VARIABLE: Factor that you observe or measure in response to a change in the independent variable; also called responding variable.

* HYPOTHESIS: Possible explanation for a set of observations or an answer to a scientific question; must be testable.

* CONSTANTS: Characteristics in an experiment that are kept unchanged in all trials.

* CONTROL: Standards to which you will compare your results.

* TRIALS: Number of times an experiment is repeated for each level, or value, of the independent variable. The more trials, the more reliable your results.