Jul 3 2013
More frequent sweltering summers, droughts, flooding and extreme weather across the country are expected with our changing global climate. The problem is so severe that the Obama Administration is taking new steps to cut greenhouse gas emissions to help the nation manage the effects of climate change and to lead international climate efforts.
Brent Williams
The climate changes are clear. Since 1901, the average surface temperature across the continental United States has risen at an average rate of 0.13 degrees Fahrenheit per decade. However, the southeastern United States is one of the few places on Earth that has had an overall cooling trend over the last century.
Brent Williams, PhD, in the School of Engineering & Applied Science at Washington University in St. Louis, has received a nearly $300,000 Early Career grant from the U.S. Environmental Protection Agency (EPA) to bring his expertise in measuring particles in the atmosphere to a national study of the climate trend in the southeastern United States as well as to the St. Louis area.
The three-year grant was one of 13 awarded by the EPA totaling more than $4.3 million to study and improve the understanding of how certain organic particles form in the atmosphere and how they impact regional climate.
The research, also funded in partnership with the National Science Foundation (NSF), the National Oceanic and Atmospheric Association and private industry, will help the federal government improve its air-quality management systems and climate change models and to protect the health of citizens and the environment.
Williams, the Raymond R. Tucker Distinguished I-CARES Career Development Assistant Professor in the Department of Energy, Environmental & Chemical Engineering, will use the funding to take part in two field studies: the Southern Oxidant and Aerosol Study (SOAS), and one in East St. Louis, Ill. He also will conduct studies in his laboratory using a wide range of chemical and physical measurement systems to characterize controlled atmospheric processes.
SOAS is one of five collaborative projects addressing various components of air quality, chemistry and aerosols over the southeastern United States that fall under the larger Southeast Atmosphere Study, a joint project among the NSF, the EPA, Washington University in St. Louis, and more than 60 other international research institutions, with more than $20 million invested to answer some of the most pressing issues in air quality and climate change.
Williams has two students working this summer on the SOAS study in Alabama using an instrument he created to measure the chemistry of atmospheric particles. Their measurements will contribute to determining why the southeastern United States has cooled over the last 100 years.
“We believe this region has cooled because of the large amount of naturally occurring emissions from the dense forests in the southeastern United States mixed with man-made pollution, lots of sunlight and high humidity, and you have the perfect ingredients for particle formation, which results in cooling as a result of reflected sunlight,” Williams says. “We are there to figure out which specific key ingredients are driving this chemistry and enhanced particle formation.”
In the local study, a group of scientists from other universities will come to the area to measure similar particles at the EPA’s St. Louis-Midwest Fine Particulate Matter Supersite in East St. Louis, Ill., a long-time project of Jay Turner, PhD, associate professor of energy, environmental and chemical engineering. As part of the St. Louis regional study, researchers will use an ultraviolet reaction chamber to accelerate the “aging” of local air to determine within minutes how the molecules found in St. Louis air may form particles up to two weeks downwind of St. Louis.
“This study will help us to understand how the St. Louis region may contribute to, or be affected by, similar particle impacts seen in the southeastern U.S.,” Williams says.
Williams, an expert in organic particle chemistry, is interested in determining the origin of particles in the air and what chemical reactions have taken place within the particles.
“It gets complex because there are tens of thousands of individual compounds in every sample we analyze,” he says. “And the majority of the particles in the atmosphere weren’t emitted as particles, but as a gas from trees, vehicles or industry, for example. Once in the atmosphere, the sunlight-driven chemistry makes reaction products that have a lower volatility and will force them to condense into particles.”
The particles Williams studies are regulated as PM2.5, particulate matter smaller than 2.5 micrometers in diameter, or 1/30th the diameter of a human hair. Particles are a mixture of microscopic solids and liquid droplets suspended in air and made up of different components, including acids, organic chemicals, metals, soil or dust particles and allergens, such as pollen or mold spores.
“From a health perspective, atmospheric particles are things you don’t want to breathe,” Williams says. “But from a climate perspective, certain types of particles, such as many of those found in the southeastern United States, can actually counter greenhouse gas warming to provide a cooling effect for that region. So some particles are bad for health, but help to counter regional warming. That’s why the EPA is interested in understanding this complex process that has complex implications.”
Engineers at Washington University in St. Louis have a long history of working to improve air quality. Raymond Tucker, mayor of the City of St. Louis from 1953-1965, was chair of the school’s Department of Mechanical Engineering from 1921-1951 and a vocal advocate for clean air. In the 1940s, he worked with the City of Los Angeles to recommend ways to correct its smog problem. His work also helped to create the first unified air pollution agency with powers to adopt and enforce air pollution regulations.