"We can watch the wind pick up soil, carry
it in clouds miles above the ground, and then deposit dust over urban areas
where it can cause respiratory problems," says
ARS agricultural engineer Keith E.
Saxton.
Saxton is speaking about a new computer prediction model for the Pacific
Northwest's Columbia Plateau region. The model simulates dust storms from
beginning to end by linking smaller models for wind erosion and dust emissions.
Saxton and about 15 colleagues developed the model as part of the Northwest
Columbia Plateau Wind Erosion/Air Quality Project.
The scientists are with ARS and Washington State University in Pullman and the
University of Idaho at Moscow. They tested the model on a 50,000-square-mile
section of the Columbia Plateau, using several previously recorded dust storms.
For those studies, "dust" was defined as particulate matter less than
10 micrometers in diameter—or PM-10. These particles are small enough to
be drawn into the lungs. But more recent concerns about health problems have
put the greatest focus on particles smaller than 2.5 micrometers—PM-2.5.
Often, about a third of the windblown soil particles caught in samplers are
PM-2.5 in size. Other PM-2.5 sources include smoke from fireplaces,
smokestacks, and fields that farmers burn to stop soilborne crop diseases.
"The Columbia Plateau is one of the world's largest areas of wind-blown
volcanic soils," Saxton says. "These soils are extremely light and
prone to forming dust clouds."
Farmers on the plateau typically grow winter wheat every other year. In the
"off" year they leave the land bare to save soil moisture. But ARS
agronomist Frank L. Young and several ARS and state scientists are developing
crop rotations to keep land covered as much of the year as possible.
Saxton serves on the National Agricultural Air Quality Task Force charged with
advising the Secretary of Agriculture on all aspects of air quality related to
agriculture. This task force was formed in 1996 as ARS was beginning to expand
its research on how agriculture affects air quality. Targets include not only
dust but also odors, ozone, pesticides, and ammonia emissions from animal
operations.
Following the task force's recommendations, the U.S. Environmental Protection
Agency has formally agreed to work closely with USDA when air quality issues
involve agriculture. This will help both agencies face the environmental
challenges of the new century.—By
Don Comis,
Agricultural Research Service Information Staff.
Keith E. Saxton and
Frank L. Young are in the
USDA-ARS Land Management and Water
Conservation Research Unit, 215 Johnson Hall, Washington State University,
Pullman, WA 99164-6421; phone (509) 335-1552, fax (509) 335-3842.
"Curbing Wind-Blown Dust" was published in the
March 2000
issue of Agricultural Research magazine.
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