Chemical Contamination in Arctic Linked to Bird Droppings
WASHINGTON A major source of chemical contamination in the Arctic turns out to be bird droppings.
Wind currents and human activities long have been blamed for fouling the pristine Arctic. But a study by a group of Canadian researchers found that the chemical pollution in areas frequented by seabirds can be many times higher than in nearby regions.
Researchers led by Jules Blais of the University of Ottawa studied several ponds below the cliffs at Cape Vera on Devon Island in the Canadian Arctic.
Scientists report in Friday's issue of the journal Science that the ponds, which receive falling guano from a colony of northern fulmars that nest on the cliffs, have highly elevated amounts of chemicals.
"If long-range transport was the only thing bringing these chemicals north, we would expect to see a very even distribution," Blais said in a telephone interview.
But the chemicals are concentrated in some places, he said, "and we have found a reason ... they can follow biological connections."
Blais calls it the boomerang effect.
"These contaminants had been washed into the ocean, where we generally assumed they were no longer affecting terrestrial ecosystems. 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 said.
The guano that falls into the ponds includes bits of fish, carrion, squid and other marine creatures eaten by the fulmars.
Research team member John Smol of Queen's University in Kingston, Ontario, said "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."
Todd O'Hara of the Institute of Arctic Biology at the University of Alaska in Fairbanks said the report adds new detail to "the role of biotransport in bringing contaminants to the Arctic with clear local impacts.
"Certainly, I believe biotransport is an underestimated process and for subsistence users it clearly indicates the need for local assessments of food sources and not to generalize about Arctic contamination," said O'Hara, who was not part of Blais team.
Chemicals such as PCB and DDT are no longer being released into the environment in North America, Blais noted, but were designed to last a long time and are doing so. In addition, he said, other chemicals still in use are toxic and also can last in the environment.
Perhaps the lessons learned from PCBs should be applied to other hazardous chemicals too, Blais said.
The area of the study is one of the most desolate on Earth, Blais said, and the local food chain is dependent on the guano from the seabirds.
Their droppings encourage the growth of mosses and plankton in the ponds, which feed lots of insects, which in turn support small birds called snow buntings, he said.
If the seabirds were to disappear the whole ecosystem would disappear, he said.
"If you fly overhead you can see green mosses growing under the cliffs," Blais said. "What is particularly striking is that these contaminants are getting concentrated at oases of biological productivity in the north."
The research was funded by Science and Engineering Research Canada, the EJLB Foundation, the Polar Continental Shelf Project and the Northern Scientific Training Program.
Source: Associated Press