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Transpacific Pollution Leaves Thicker and Thicker Trail


Environmental News Network
August 1, 2000


In China, urban areas such as Nanning, pictured here, are
becoming more heavily traveled by cars and trucks rather than bicycles

Rising industrialization in Asia is discharging millions of tons of
previously undetected contaminants annually into the winds that travel
across the Pacific Ocean, researchers say.

The aerosols are killing crops and spreading illness in Asia. They're
probably polluting waters in America. And they could dramatically alter
global climate.

"Previous research has shown that every spring there are massive dust
storms in Asia that transport soil eastward to Japan and across the
Pacific to the United States. Now we've found that sulfate and organic
aerosols are also present, and in roughly the same amounts," said Thomas
Cahill, a professor emeritus of physics and atmospheric science at the
University of California at Davis and an international authority on the
atmospheric transport of pollutants.

Asia is the largest source of aerosols in the world, said Cahill, who
presented new data at a conference in Seattle with colleagues from UC
Davis. Asia burns millions of tons of coal annually from abundant coal deposits.

Aerosols are generated from coal-burning power plants and coal-fired
locomotives; heavy industry such as metals production; automobile and
truck exhaust; home heating; and overtilling of dry-area farmland.
The new findings are crucial for several reasons, Cahill said.

"First, the northern Pacific Ocean is one of the last really clean areas
of the Northern Hemisphere. If we start to pollute the air above that
ocean, we'll change the balance of heating and cooling of the ocean and
that will produce changes in the weather.

"Second, there are increasing numbers of reports of what appear to be
toxic Asian pollutants in the lakes and streams of North America.
"Finally, and perhaps most important, there is an established link between
aerosol levels and rates of illness and death in people."

While releases of one key type of aerosol, sulfur dioxide, have been
decreasing in the United States and Europe since tough air-pollution rules
were enacted, the releases are increasing in Asia. Between 1990 and 2000,
annual releases of sulfur dioxide into the atmosphere in the United States
dropped from about 20 million tons to 13 million tons, but in Asia they
climbed to about 45 million tons.

Once released into the air, aerosols ride the wind over land and sea,
rising to altitudes of several miles, where their travel is sped by the
dry atmosphere and swift winds.

Wherever they go, they retain a unique signature of their origins in their
composition of trace elements, such as nickel, copper, zinc, arsenic and
lead. Aerosols with these unique signatures from Asia have been detected
all the way to the Rocky Mountains in the United States, Cahill said.

Tom Cahill, an atmospheric scientist at the University of
California at Davis, holds two filters, one clean (right) and
one exposed to air pollution in Kyoto, Japan

The new data is the result of a research project called the University of
California Pacific Rim Aerosol Network. The project was started in 1998
with $67,000 from the university system.

Besides releasing results of the project, the researchers also described
their role in the forthcoming ACE-Asia project. ACE-Asia, or Aerosol
Characterization Experiment, will be the world's largest attempt to
identify the exact sources and destinations of those tiny particles of
dust, sulfate and organic matter.

Cahill outlined the strategy of the multimillion-dollar research project.
In ACE-Asia, existing air samplers and some additions will gather data for
six weeks in spring 2001. New samplers will be installed at sites in five
Asian countries (China, Taiwan, the Philippines, South Korea and Japan),
Mexico and the United States.

The heart of the network is the newly designed International Aerosol
Sampler designed and built at UC Davis. It is inexpensive, lightweight and
low-tech for producing reliable data in undeveloped regions with
unreliable power supplies. It collects air samples that can be chemically
checked for unique signatures and tracked as they move around the globe.

This method of developing chemical signatures has been put to intensive
use at UC Davis since the early 1970s, when Cahill and colleagues
conducted the first studies to identify the origins of view-blocking haze
in U.S. national parks.

"Working with our Asian colleagues, we hope to help them efficiently
address the causes of these aerosols and aid in developing mitigation. The
findings may prompt Asian policymakers to restructure developmental
mandates to take into account the devastating air-quality problem they
have," Cahill said.

"The relationship between a smelter in Manchuria and aerosol pollution in
Japan is not obvious. That's the understanding we're trying to achieve,"
he added.

 

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