Embargoed until 1 p.m. EST
NSF PR 01-22 - April 5, 2001
Media contact:
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Peter West
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(703) 292-8070
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pwest@nsf.gov
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Small Streams Contribute Far More Than Previously
Thought to Cleaning Waterways
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A typical small tundra stream in the Arctic
Tundra Long-Term Ecological Research site
near Toolik Lake, Alaska. The Brooks mountain
range is in the background.
Photo credit: Bruce
Peterson, Marine Biological Laboratory,
Woods Hole, Massachusetts.
A
larger version is here.
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Small streams remove more nutrients such as nitrogen
from water than do their larger counterparts, according
to researchers who have applied sampling methods developed
in a National Science Foundation (NSF) Arctic area
ecological study to waterways across the nation. The
finding could have important implications for land-use
policies in watersheds from the Chesapeake Bay on
the East Coast to Puget Sound in the West.
The findings, to be published in the April 6 edition
of Science, are based on data collected initially
from streams in NSF's Arctic Tundra Long-Term Ecological
Research (LTER) site in Alaska. Excess nitrogen can
cause ecologically damaging effects in large waterways,
include algeal blooms, because the nutrients are transported
downstream and collect there.
"There's a very strong relationship between the size
of a stream and how rapidly that stream removes nutrients,"
said Bruce Peterson of the Ecosystems Center at the
Marine Biological Laboratory in Woods Hole, Mass.
"The smaller the stream, the more quickly nitrogen
can be removed and the less distance it will be transported
down the stream."
Peterson is one of more than a dozen researchers who
contributed to the Science paper.
He noted that the findings are unique because they
were produced by research teams working in a coordinated
and identical fashion nationwide under the same research
protocol.
"In terms of ecosystems studies it's very rare to get
people from this many sites to agree to do this kind
of controlled experiment," Peterson said. "Many people
study nitrogen cycling, but they all tend to do their
own experiments. Collaboration is the key to developing
a general understanding of ecosystems."
Peterson notes that, collectively, the new studies
provide a radically different picture of the role
of small streams in contributing to existing nutrient
loading. "Traditionally streams have been thought
of as transport system moving substances from catchments
to downstream points," he said. "It's been difficult
to understand how dynamic the stream system itself
is."
By placing tracers in smaller streams, the researchers
discovered how quickly nutrients were assimilated
and processed by organisms that live on the streambeds.
Peterson argues that the finding could have important
implications for land use policies. In many agricultural
areas, for example, small streams are often covered
to allow ease of access for tilling and working fields.
The covering, in effect, creates a dark pipe that
inhibits the stream's ability to scrub excess nutrients.
While excess nitrogen has many sources, including runoff
from residential lawns and byproducts of automobile
combustion, taking greater care to insure that small
streams can work effectively to clean the water will
reduce the overall nitrogen load that makes its way
into larger bodies of water.
"It doesn't mean that you can ignore your sewage treatment
plants, but if we can do better with our small streams
and do some restoration activities, it's going to
have some benefits," he said. "What it means is that
you have to take care of the streams on the landscape."
For more information about the Arctic Tundra LTER,
see: http://lternet.edu/sites/arc/
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