Alexandra Ponette-Gonzalez

Alexandra Ponette-Gonzalez

DENTON (UNT), Texas -- Post oak and blackjack oak trees in full foliage may provide more benefits for humans than blocking winds and casting shade to cool the ground on hot days. The trees may also improve air quality when air pollutants fall onto their branches and leaves and are eventually washed to the ground by rain or fall to the ground with the leaves, according to Alexandra Ponette-González, University of North Texas assistant professor of geography.

Ponette-González recently received a $475,167 National Science Foundation CAREER award for a five-year analysis of the effectiveness of blackjack oaks and post oaks in capturing black carbon -- commonly emitted by diesel engines -- in urban areas.

The CAREER awards, the most prestigious awards offered by the NSF for young investigators, support early career development activities of teacher-scholars who effectively integrate research and education within the context of the mission of their organization. Ponette-González is the eleventh UNT researcher to earn an NSF CAREER award, and the first from UNT's Department of Geography and the Environment.

"Trees in urban areas may work as urban air filters. Tree canopies are more effective than other vegetation types, and building materials such as glass, in scrubbing pollutants from the air," she said. "Many urban planners think about the benefits of planting trees in cities, but more research is needed on how the trees improve air quality."

Ponette-González grew up in Mexico City, where she regularly experienced ozone action days because of high levels of air pollution in the city. Before joining the UNT faculty in 2011, she was a National Science Foundation Minority Postdoctoral Research Fellow at the University of Texas at Austin, conducting research in Peru on the impacts of past fires and grazing on vegetation and soil dynamics at treelines. She also went to Brazil, Indonesia and Mexico for research, focusing on substances discharged into the atmosphere in urban areas, and the substances' impact on tropical forests.

When Ponette-González came to UNT, she expanded her research to focus on the impact of air pollutants on urban areas. With the NSF Career Award, she and her research team will measure how much black carbon is filtered from the air by 30 trees in the city of Denton, and determine how the buildings, highways and green spaces that surround the trees affect this process.

She noted that black carbon particles absorb solar radiation and have adverse effects on human health when inhaled.

"Understanding the factors that contribute to black carbon removal in urban areas could help mitigate climate change while improving air quality for urban residents. Tree crowns, in particular, are efficient at intercepting particulates," she said.

Ponette-González is also the recipient of a National Science Foundation grant to study the effect of Texas' 2012 dust storms on the atmosphere and ecosystems. She received her bachelor's degree from United States International University in Mexico City, master's degree from the University of Texas at Austin and doctoral degree from Yale University's School of Forestry and Environmental Studies.