 |
NADP/National
Trans Network site at Walker Branch
Watershed at Oak Ridge National
Laboratory.
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| Estimated
sulfate ion deposition, 1999.
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Acid rain is created when sulfur
and nitrogen emissions from industrial
processes and cars dissolve in water
droplets in clouds and form sulfuric
and nitric acids. Scientists at several
national laboratories were the first
to uncover the detailed chemical and
atmospheric processes that convert
these emissions to acids, which then
are deposited on the ground in both
dry and wet forms. They established
that inorganic sulfur and nitrogen
species are the major anthropogenic
contributors to acid deposition and
that dry deposition can account for
a third to a half of the total input,
depending on location. They also documented
the importance of adsorption-desorption
properties in soils, especially the
role of hydrous oxide coatings on
soil particles, as a buffering mechanism
that reduces the transport of sulfate
deposited from the atmosphere into
surface waters. These discoveries
led to the development of models that
provide realistic simulations of acid
deposition scenarios. The work was
performed at Argonne, Brookhaven,
Oak Ridge, and Pacific Northwest national
laboratories.
Scientific Impact:
This research contributed to understanding
of the processes that both generate
acidic deposition and determine the
extent of its effects on terrestrial
and aquatic ecosystems. Before this
work began in the late 1970s, very
little was known about the mechanisms
producing acid rain; by the early
1990s, the scientific questions were
resolved sufficiently that the processes
could be modeled.
Social Impact: The
acid deposition models enabled by
these discoveries were essential for
the development of pollution control
measures and pollution prevention
strategies. The scientific and modeling
advances also led to a political consensus
on the actions needed; releases of
sulfur dioxide and nitrogen oxides
have been cut drastically in recent
decades because of new laws.
Reference: Hales,
J.M., Fundamentals of the theory of
gas scavenging by rain," Atmos.
Environ. 6: 635-659 (1972).
Hicks, B.B., T. P. Meyers, C. W. Fairall,
V. A. Mohnen, and S. A. Dohlske, "Ratios
of dry to wet deposition of sulfur
as derived from preliminary field
data," Global Biogeochemical Cycles,
3: 155-162 (1989).
Johnson, D. W. and D. W. Cole, "Anion
mobility: relevance to nutrient transport
from forest ecosystems," Environ.
Internat. 3:79-90 (1980).
Johnson, D.W., and S.E Lindberg (Eds.),
"Atmospheric Deposition and Forest
Nutrient Cycling," Ecological
Studies, Vol. 91, pp. 707, Springer-Verlag,
New York (1992).
Lindberg, S.E., G.M. Lovett, D.R.
Richter, and D.W. Johnson, "Atmospheric
deposition and canopy interaction
of major ions in a forest," Science
231:141-145 (1986).
Lindberg, S.E., and C.T. Garten, Jr.
"Sources of sulfur in forest canopy
throughfall," Nature 336:148-151
(1988).
Newman, L., "Atmospheric oxidation
of sulfur dioxide: a review as viewed
from power plant and smelter plume
studies," Atmos. Environ.
15: 2231-2239.
URL: http://nadp.sws.uiuc.edu/
Technical Contact:
Dr. Ari Patrinos, Associate Director
for Biological and Environmental Research,
301-903-3251
Press Contact: Jeff
Sherwood, DOE Office of Public Affairs,
202-586-5806
SC-Funding Office:
Office of Biological and Environmental
Research |
