| |
January
22, 2007
SCIENTISTS
ANALYZE CORN TO MAP NORTH AMERICAN
CARBON DIOXIDE
Scientists have
developed a novel way of mapping carbon dioxide levels in various parts
of North America,
by analyzing corn grown in those regions.
Diana Hsueh at the University
of California,
Irvine,
and colleagues collected corn from nearly 70 locations in the United States and Canada.
They found that the Ohio
Valley
and California
had the most fossil-fuel-emitted
carbon dioxide, while the Colorado
region had the least.
This method of measuring carbon dioxide produced by burning fossil
fuels, such
as coal, oil, and natural gas, can help atmospheric scientists better
understand where carbon dioxide, a greenhouse gas, is located and how
it mixes
and moves in the air. Plants, the researchers say, provide a
cost-effective way
to record average daytime conditions over several months, as they take
in
carbon dioxide gas during photosynthesis, and it becomes part of the
plant
tissue. Their report will be published January 23 in Geophysical
Research Letters, a journal of the American Geophysical
Union.
The scientists chose corn, because it is widely grown and, as an annual
plant,
all of its carbon is derived from a single growing season. They avoided
pollution point sources, such as highways and power plants, to allow
for
mapping of regional patterns across various states and provinces. In
the
laboratory, they dried samples of corn leaves and husks and chemically
converted
them into graphite. They then analyzed the graphite in a mass
spectrometer,
which measured levels of radiocarbon, a rare isotope of carbon.
Carbon dioxide derived from fossil fuels contains no radiocarbon, so it
is
easily distinguishable from other sources. With measurements from the
mass
spectrometer, the scientists calculated overall levels of carbon
dioxide
produced by fossil fuels at the locations where the corn samples were
collected.
The scientists had expected carbon dioxide from California
and other western coastal states to drift eastward, but they found that
the Rocky Mountains
appeared to provide a barrier. Air in the
Mountain West, including Colorado, Idaho, and New Mexico, had the
lowest carbon
dioxide, about 370 parts per million. Air in the Eastern United States,
which
includes Massachusetts,
New Hampshire, and New York,
contained an additional 2.7 parts per million of carbon dioxide from
fossil
fuel sources. Air in Maryland, Ohio, Pennsylvania, and West Virginia
had nearly
twice as much additional carbon dioxide from fossil fuels, 4.3 parts
per
million.
"Many nations are facing increasing pressure to monitor and regulate
the
release of carbon dioxide from fossil fuel sources to limit greenhouse
gas
warming," said James Randerson, a co-author of the study. "This
method can help determine how much fossil fuel carbon dioxide is coming
from
different regions."
"We have to better understand emission patterns and changes in the
atmosphere in order to better regulate fossil fuels," said Susan
Trumbore,
another co-author of the study. "This is a direct way to measure the
release of carbon dioxide emissions that are contributing to climate
warming."
The research was funded by the National Science Foundation and NASA.
##
Contact:
Peter
Weiss
American
Geophysical Union
202-777-7507
pweiss@agu.org
This text derived from:
http://www.agu.org
Recommend this Article to a Friend
Back to: News |
