ANN ARBOR—Measuring additional volatile gases emitted by forests could help researchers better understand how the atmosphere cleans itself and help them predict the life span of air pollutants, according to a new study.

Results of the study appear in the April 30 issue of the journal Science. Researchers from the University of Michigan, Pennsylvania State University, Universitá di L’Aquila, Ohio University, Purdue University, the University of Miami, and the National Center for Atmospheric Research made the discovery while measuring atmospheric gases as part of the Program for Research on Oxidants: Photochemistry, Emissions, and Transport (PROPHET) at the U-M Biological Station in northern Michigan.

One of those gases measured is the hydroxyl radical, (OH), a very volatile compound that reacts strongly with other compounds, said Mary Anne Carroll, a U-M professor in the atmospheric, oceanic and space sciences department and PROPHET director, who participated in the research. It’s important that scientists are able to predict OH reactivity, because understanding its reactivity—the cause and effect relationship of OH with other compounds—is crucial to understanding atmospheric behavior.

“OH is like the PacMan of the atmosphere; it controls the lifetime and abundance of most pollutants,” Carroll said.

In the Science paper, scientists discovered that OH reactivity was higher than expected, based on compounds present. This led them to conclude that unidentified compounds were present in the atmosphere that heightened OH reactivity.

Because OH formation in the atmosphere has long been thought to occur during daylight hours, the findings of OH at night at this site by the Pennsylvania State University researchers led scientists to speculate that forest emissions of additional, unmeasured reactive gases play a role in the generation of OH at night, Carroll said.

“The conclusion is, it appears that unmeasured hydrocarbons are being emitted from the forest that could play an important role in (creating) OH,” Carroll said. “These findings underline the importance of identifying and measuring these compounds because we must have a full understanding of OH levels and behavior in order to develop a predictive capability for the fate of pollutants and long term effects on the chemical composition of the atmosphere.”

The University of Michigan College of Engineering is celebrating its 150th anniversary this year, and is consistently ranked among the top engineering schools in the world. The College is composed of 11 academic departments: aerospace engineering; atmospheric, oceanic and space sciences; biomedical engineering; chemical engineering; civil and environmental engineering; electrical engineering and computer science; industrial and operations engineering; materials science and engineering; mechanical engineering; naval architecture and marine engineering; and nuclear engineering and radiological sciences. Each year the college enrolls over 7,000 undergraduate and graduate students and grants about 1,200 undergraduate degrees and 800 masters and doctoral degrees. To learn more, visit: www.engin.umich.edu.

For more information see: http://aoss.engin.umich.edu/PROPHET/

Nehls-Frumkin, (734) 763-7305, Maryln@umich.edu

www.engin.umich.eduhttp://aoss.engin.umich.edu/PROPHET/Maryln@umich.edumcarroll@umich.edu