Device Could Lead to Better Understanding of Smog Formation
at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory
have developed a new tool for quantitatively measuring elusive
atmospheric chemicals that play a key role in the formation of
Better measurements will improve scientists' understanding of the
mechanisms of smog formation and their ability to select and predict
the effectiveness of various mitigation strategies. The Brookhaven
scientists have been issued a U.S. patent for their apparatus, which is
available for licensing, officials announced on Nov. 19.
The device measures atmospheric hydroperoxyl radicals --
short-lived, highly reactive intermediates involved in the formation of
ozone, a component of photochemical smog -- in the lowest layer of
Earth's atmosphere. The levels of these radicals can indicate which of
a variety of chemical pathways is predominant in converting basic
starting ingredients -- hydrocarbons, nitrogen oxides and water vapor
-- into smog in the presence of sunlight.
"Understanding the relative importance of the various pathways can
help you tailor your mitigation strategies," said Brookhaven
atmospheric chemist Stephen Springston, one of the inventors. "For
example, are you better off spending your money reducing hydrocarbon
emissions or nitrogen oxide emissions?"
"Our measurements will help predict which strategy would be most
successful for a particular set of atmospheric conditions -- and make
modifications to the strategy as those conditions change," said
co-inventor Judy Lloyd of the State University of New York at Old
Westbury, who holds a guest appointment at Brookhaven Lab.
Because hydroperoxyl radicals are so reactive, getting accurate
measurements is not easy. "These chemicals are so fragile you cannot
take a bottle home with you," Springston said. "You have to measure
them where they form, in the atmosphere, before they react and
Various groups have developed detectors for hydroperoxyl radicals,
but these have been cumbersome and costly. Officials said the new
device is comparatively small, lightweight and inexpensive, has low
power requirements and gives a sensitive, fast response. It works by
detecting a "glowing" signal from a chemiluminescent compound --
similar to the compound that makes fireflies glow -- when it reacts
with the hydroperoxyl radicals in atmospheric samples fed into the
device during flight.
"The chemiluminescence produced in solution creates a strong and
readily detectable signal without the need for complex amplification
procedures," Lloyd said.
The device has been tested in a mountaintop setting but has not yet
been deployed on an aircraft for a sampling mission. It is designed to
be flown on atmospheric sampling aircraft, such as DOE's Gulfstream 1,
which has been used by Brookhaven and other national laboratory
scientists for a variety of atmospheric studies.
This work was funded by the Office of Biological and Environmental
Research within DOE's Office of Science and by the National Science
For more information, contact Brookhaven at http://www.bnl.gov.