UD researchers sort air pollutants

Murray Johnston (left), professor of chemistry and biochemistry, and research assistants Melissa Reinard and Matthew Dreyfus check an air-pollution monitoring station in Wilmington.

4:10 p.m., May 25, 2005--Inside a cramped trailer on Martin Luther King Boulevard in Wilmington, a specially built mass spectrometer sorts through one liter of air every minute, particle by particle.

As expertly as the sorting hat from the Harry Potter books, the spectrometer designed by University of Delaware scientists determines whether iron, carbons or other pollutants may be hitching a ride on any of the millions of minute, separate particles that comprise Wilmington air.

The scientists aim to identify the pollutants that keep Delaware from meeting the federal standards for clean air. The state, under pressure to implement a plan to clean the air or lose transportation funds, has funneled Environmental Protection Agency (EPA) money to fund their research.

That funding allows scientists and students to operate two sampling stations--the one on Martin Luther King Boulevard and another at the Lammot du Pont Laboratory on UD’s Newark campus. At each, the spectrometers separate the chemical components of the air we breathe.

“We’d like to know where the airborne particles come from so that we can control emissions,’’ Murray V. Johnston, professor of chemistry and biochemistry, said.

Johnston said the scientists, graduate students and postdoctoral students researching the air particles can track the pollutants back to the source because different chemical components are the results of different processes. They begin by separating the chemical components into those that are generated outside the area and those that are locally generated.

“We can see a certain signature of metals,’’ Johnston said. “For instance, emissions taken at du Pont Laboratory, which is near the physical plant where UD generates its heat, show iron because iron escapes from our emission stacks. Wherever you have diesel or gas vehicles, such as Martin Luther King Boulevard, you’ll see particles with a lot of carbon in them.”

Once researchers determine a pollutant is locally generated, they can use exacting hand-held equipment to take a sample at the suspect site, or they can employ a specially equipped mobile research van from Duke University in North Carolina. The van, currently in Delaware for the research, is equipped to detect chemical molecules in the air.

Their work focuses on identifying the problems and their sources to pave the way for mitigation. Johnston and other researchers have experience at EPA sites in Pittsburgh and Baltimore, where they identified the chemical composition of the matter on each particle of air, quantified the sources of the pollution and developed advanced monitoring techniques.

“I’m just really thrilled to be doing measurements in Wilmington because, as we were driving to the other communities, we were thinking, ‘It would be nice if we could do this in Wilmington.’ It’s very nice to finally have the funding and the ability to make measurements here,” Johnston said.

Article by Kathy Canavan
Photo by Kathy F. Atkinson

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