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“… and due to the interactions of nitrogen and
carbon, makes the challenge of providing food and
energy to the world’s peoples without harming the
global environment a tremendous challenge,”….
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Web address:
http://www.sciencedaily.com/releases/2008/05/080515145419.htm
Excessive Reactive Nitrogen in Environment Alarms Environmental Scientists
ScienceDaily (May 18, 2008) – While human-caused
global climate change has long been a concern for
environmental scientists and is a well-known
public policy issue, the problem of excessive
reactive nitrogen in the environment is
little-known beyond a growing circle of
environmental scientists who study how the
element cycles through the environment and
negatively alters local and global ecosystems and
potentially harms human health.
Two new papers by leading environmental
scientists bring the problem to the forefront in
the May 16 issue of the journal Science. The
researchers discuss how food and energy
production are causing reactive nitrogen to
accumulate in soil, water, the atmosphere and
coastal oceanic waters, contributing to the
greenhouse effect, smog, haze, acid rain, coastal
“dead zones” and stratospheric ozone depletion.
“The public does not yet know much about
nitrogen, but in many ways it is as big an issue
as carbon, and due to the interactions of
nitrogen and carbon, makes the challenge of
providing food and energy to the world’s peoples
without harming the global environment a
tremendous challenge,” said University of
Virginia environmental sciences professor James
Galloway, the lead author of one of the Science
papers and a co-author on the other. “We are
accumulating reactive nitrogen in the environment
at alarming rates, and this may prove to be as
serious as putting carbon dioxide in the
atmosphere.”
Galloway, the founding chair of the International
Nitrogen Initiative, and a co-winner of the 2008
Tyler Prize for environmental science, is a
longtime contributor to the growing understanding
of how nitrogen cycles endlessly through the
environment. In numerous studies over the years
he has come to the realization of the “nitrogen
cascade.”
In its inert form, nitrogen is harmless and
abundant, making up 78 percent of the Earth’s
atmosphere. But in the past century, with the
mass production of nitrogen-based fertilizers and
the large-scale burning of fossil fuels, massive
amounts of reactive nitrogen compounds, such as
ammonia, have entered the environment.
“A unique and troublesome aspect of nitrogen is
that a single atom released to the environment
can cause a cascading sequence of events,
resulting ultimately in harm to the natural
balance of our ecosystems and to our very
health,” Galloway said.
A nitrogen atom that starts out as part of a
smog-forming compound may be deposited in lakes
and forests as nitric acid, which can kill fish
and insects. Carried out to the coast, the same
nitrogen atom may contribute to red tides and
dead zones. Finally, the nitrogen will be put
back into the atmosphere as part of the
greenhouse gas nitrous oxide, which destroys
atmospheric ozone.
Galloway and his colleagues suggest possible
approaches to minimizing nitrogen use, such as
optimizing its uptake by plants and animals,
recovering and reusing nitrogen from manure and
sewage, and decreasing nitrogen emissions from
fossil fuel combustion.
“Nitrogen is needed to grow food,” Galloway says,
“but because of the inefficiencies of nitrogen
uptake by plants and animals, only about 10 to 15
percent of reactive nitrogen ever enters a human
mouth as food. The rest is lost to the
environment and injected into the atmosphere by
combustion.
“We must soon begin to manage nitrogen use in an
integrated manner by decreasing our rate of
creation of reactive nitrogen while continuing to
produce enough food and energy to sustain a
growing world population.”
Galloway’s next effort is to create a “nitrogen
footprint” calculator that people can access on
the Internet, very similar to current “carbon
footprint” calculators.
He says people can reduce their nitrogen
footprints by reducing energy consumption at
home, traveling less, and changing diet to
locally grown vegetables (preferably organic) and
fish and consuming less meat.
Galloway is quick to point out that along with
the problems of excess reactive nitrogen in many
areas of the world, there also are large regions,
such as Africa, with too little nitrogen to grow
enough food for rapidly growing populations. In
those regions, the challenge is find ways to
increase the availability of nitrogen while
minimizing the negative environmental effects of
too much nitrogen.
Adapted from materials provided by University of Virginia. (2008, May 18).
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