热点大瓜

Chemicals that haven’t been manufactured in the U.S. for years or even decades are turning up in the bodies of migratory terns in the Great Lakes region, a new study finds.

Researchers discovered the chemicals in the organs of more than two dozen common terns in breeding grounds along the Niagara River and the Lake Erie shore. The harmful compounds—PBDEs (a class of flame retardants), PCBs (used as a coolant or insulating fluid), and metabolites of DDT (an insecticide)—were found in terns of all life stages as well as in emerald shiners, a small fish that is the birds’ primary food source in the area, suggesting that pollution in the Great Lakes region is the source of at least some of this contamination.

The findings illustrate how household and industrial chemicals have become ubiquitous in the environment, where they can endure for many years, posing risks to wildlife.

“These chemicals are still there. They don’t just go away,” says University at Buffalo chemist , an author on the study. “With PCBs, for example, they haven’t been produced in the U.S. for a long time now, but you can still find them in the environment. The fish eat organisms that accumulate them, and then the birds eat the fish.”

The findings highlight the urgency of protecting the environment as new issues surrounding other classes of persistent chemicals, such as per- and polyfluoroalkyl substances (PFAS), emerge. Aga, who remembers eating the fish from the river near the small Philippine village where she grew up, and later watching the river turn black with pollution, feels this urgency especially acutely. “The more we understand about the fate and transport of the chemicals in the environment,” she says, “the better we can prevent their detrimental effects in the future.” &/home/how/articlehost.host.html/content/shared/www/eub/here-is-how/8203;

For terns, the threat from legacy pollutants starts before they even hatch, says Stephen Travis, the study’s first author, who successfully defended his PhD thesis at UB last fall.  “We see these really high concentrations in the smaller chicks, which indicates that there is maternal transfer of contaminants into the eggs,” he says. Since pollutants accumulate in terns’ bodies faster than the liver can filter them out, a portion of those chemicals is passed on to the next generation, potentially affecting development and causing deformities, cancers and behavioral impairment.

However, he adds, “One positive outcome of the study is that we only see the metabolite of DDT, called ‘DDE,’ in the fish. This likely indicates that there aren’t new sources of DDT being introduced to Lake Erie and the Niagara River, and that the DDT that was there is breaking down.”