July 14, 2005

Birds spread pollution in Arctic, study finds

By Maggie Fox, Health and Science Correspondent

WASHINGTON (Reuters) - Sea birds can spread pollutants such
as mercury and pesticides across the Arctic in their droppings,
Canadian researchers reported Thursday.

The finding, published in the journal Science, surprised
experts, who had presumed that the chemicals were being spread
only by atmospheric winds.

It could help explain the high levels of such pollutants
found in the bodies of people living in and near the Arctic
region, far from the industries that produce them.

The birds eat fish, squid and other animals that
concentrate the chemicals in their bodies. The chemicals are
concentrated even more in the bodies of the birds.

The birds, some of which range for thousands of miles
(kilometer), then rain polluted guano onto once-pristine
environments, Jules Blais of the University of Ottawa and
colleagues found.

"The effect is to elevate concentrations of pollutants such
as mercury and DDT to as much as 60 times that of areas not
influenced by seabird populations," said John Smol, a biology
professor at Queen's University in Kingston, Ontario.

"Our study shows that sea birds, which feed in the ocean
but then come back to land, are returning not only with food
for their young but with contaminants as well. The contaminants
accumulate in their bodies and are released on land."

Blais and colleagues studied ponds below cliffs on Canada's
Devon Island near Greenland, where a large colony of petrels
called northern fulmars live.

The ponds right underneath where the birds roost contained
higher levels than nearby sites of DDT, mercury and
hexachlorobenzene, used in pesticides.

Fulmars range as far as 250 miles. But other species of
birds are known to range much farther -- terns, for instance,
fly back and forth from the Arctic to the Antarctic.

Bird droppings end up on the land and back in the sea,
where they join the food web. Pollutants in them could be taken
up by plants and animals that are eaten by larger animals such
as seals, polar bears, fish and whales.

Some of these animals in turn are eaten by people.

"Some chemicals will build up in the food webs that
comprise northern traditional diets," Linda Kimpe of the
University of Ottawa said in a statement.

"As a result, some of our northern Canadian populations are
among the most mercury and PCB-exposed people on the globe."

Mercury, released by coal-burning power plants, and PCBs,
which were once produced by industry, build up in body fat and
thus are found at especially high levels in fatty animals such
as whales and seals and fish such as tuna and salmon.

"Most of Canada's coastline is at our northern fringe, and
northern aboriginal communities rely on these ecosystems as a
source of nutrition, economic development, traditional customs,
and culture," Blais said in a statement.

"We now have evidence that seabirds can concentrate
industrial contaminants in coastal areas to levels that can be
affecting those ecosystems."