One of the best ways to track the history of air pollution is to find the harmful substances that were brought to the earth by rainwater. That’s why assistant chemistry prof. Alison Spodek Keimowitz and two of her students spent part of the summer hiking to some bogs at the tops of six peaks in the nearby Catskill Mountains. These bogs form peat, and the Vassar team sampled the peat and brought it back to Vassar for chemical analysis.
The bogs Keimowitz and her students, Hailey Steichen ’17 and Natasha Vargo ’17, used for their study were ombrotrophic, meaning all of the water came from rainfall, not from streams or underground springs. “Sphagnum moss grows on top of the bedrock on these peaks and forms layers of peat, and the metals and other substances from the rainwater are captured in the moss as it becomes peat,” Keimowitz explains. “The data we gather tells us about the history of the release of these elements into the atmosphere.”
Steichen and Vargo focused their research on finding out how much lead and mercury, two elements known to be harmful to humans, were in their peat samples. Mercury is commonly found in gases released by coal-fired power plants and other factories; lead comes from the same sources and was also used as an additive in gasoline. The students were conducting the research under the auspices of the college’s Undergraduate Research Summer Institute (URSI).
“We know these minerals are harmful, but our study wasn’t about what happens when they interact with living organisms,” Steichen says. “We’re trying to find out how much of these deposits there are and when they were made.”
Steichen and Vargo used a large cylindrical tube with a sharp cutting edge (called a Russian Peat Borer) to extract columns, or cores, of peat from the bogs. By keeping the cylindrical samples intact until they returned to the lab at the Mudd Chemistry building, they were able to analyze the makeup of the more recent peat deposits near the surface and compare it to the older deposits taken from the same column several feet below.
Keimowitz says analyses of these samples are expected to demonstrate the positive effect of the federal Clean Air Act and other environmental laws enacted since the 1970s. Some of these laws required coal-fired plants to be equipped with scrubbers to minimize environmental harm, while another banned the use of leaded gasoline in automobiles in 1996. “Finding less of these minerals near the surface of these bogs is a validation of the Clean Air Act,” she says.
When Steichen, a biology major from Albuquerque, NM, and Vargo, a chemistry and geography double major from Washington, D.C., brought their soil samples to the lab, they dissolved them in a solution that enabled them to analyze their chemical composition. They used an atomic absorption spectrometer to measure the mercury and an X-ray fluorescence spectrometer to measure the content of lead.
Steichen and Vargo both say the research project taught them many new skills. “I was intrigued with the project because I knew we’d be out in the field a lot,” Steichen says. “I’m particularly interested in studying the effects of environmental toxicology, and lead and mercury are a big part of that.”
Steichen says that while she’d never worked with the spectrometer before, her previous lab courses at Vassar had prepared her for the summer research project. “At Vassar, we’re taught to be flexible and absorb information quickly,” she says, “so once you acquire the methodology, you’re not hesitant to take on new lab work.”
Vargo says her summer research furthered her studies of geography and chemistry. “I loved the idea of doing work outside, and this project, studying what’s happening to the land, is a perfect combination of my interest in both fields,” she says.
“Everything I did this summer was brand new to me,” Vargo adds. “URSI has been a great experience because it’s a blend of guidance by a professor while you’re learning new things for yourself. It’s a completely different experience from classroom learning.”
Video by Richard Le ‘17