Projects and People
happening in Phil Stevens lab?
The OH radical measurement project. The
OH radical is the Pac-Man of the atmosphere. It reacts with pollutants
in the air, transforming them into the more mundane water and
carbon dioxide. OH radicals are also a contributing factor in
the formation of smog and acid rain.
Because this radical is so unstable, it’s hard to know exactly
how much of it is in the atmosphere. Stevens’ goal is to
understand which factors determine how reactive the radicals are.
His findings will help refine government pollution regulation
What makes this project so unique to
Stevens has one of the few instruments designed to measure OH
radicals in the environment. There are only four in the country,
ten worldwide. Stevens actually built his himself, a handy skill
he acquired while doing post-doctoral work at Penn State University.
A half-million dollar National Science Foundation grant funded
the parts and Stevens took a sabbatical so he could build it.
The machine now tests atmospheric conditions in southern Indiana
as it sits at an open window in a SPEA lab.
So is the machine going to sit at SPEA?
Not always. First this device is making its way to Purdue, where
it will be paired with that school’s atmospheric simulator.
Stevens hopes that a controlled environment will yield new information
about the ways in which the OH radicals operate. He also plans
to set it up in forests in Indiana, Michigan, and California to
see how emissions from trees may be involved in pollution by reacting
to OH radicals.
Wait. Trees cause pollution?
In a way. President Ronald Reagan once said “Trees cause
more pollution than automobiles,” which isn’t totally
accurate, but trees are, in fact, more reactive than one might
think. Emissions from trees, known as isoprene emissions, are
eaten by the Pac-Man particles and could be one of the reasons
government models for estimated pollution standards may be different
from actual measurements. In fact, eastern states may have more
problems with smog than the West because of the larger amounts
of vegetation contributing to OH radical chemistry.
Why is this project good for SPEA students?
“They get to see a real measure of atmospheric chemistry,”
Stevens says. “It’s a real opportunity for them to
use state-of-the-art equipment.” It also gives students
the chance to work on a machine that very few others have access
to. In fact, some of the students helped build the machine and
calibrate it to make the measurements more accurate. Stevens even
believes they may know more about his creation now than he does.
So what’s going to become of all this?
As with most projects, Stevens hopes this one will be used to
solve real-life problems. “This will improve our understanding
of the chemical reactions in the atmosphere,” he says, noting
that it will hopefully lead to changes in our regulatory models
to make them more refined. Because we don’t fully understand
the extent of OH radicals and how they react, Stevens’ work
could lead to profound regulatory changes as he continues to unlock
more of the radicals’ secrets.
Stevens is an assistant professor at SPEA, IUB. His focus
is on the characterization of the chemical mechanisms that influence
regional air quality and global climate change. Professor Stevens
received his Ph.D. in chemistry from Harvard University in 1990.