You'd think one of the benefits of living in frigid Antarctica would be putting some distance between you and your warm-weather neighbors. But at least for Adelie penguins, the world seems to be a smaller place than that.
Enthusiastic use of potent insecticides became the ecological nightmare of the mid-20th century. And ever-increasing accumulation of greenhouse gases in the atmosphere promises to be the ecological problem of the mid-21st century. Adelie penguins may be dealing with both at the same time, according to a study reported this week in Environmental Science and Technology.
Along the Antarctic Peninsula, one of the most rapidly warming places on the globe, glaciers are melting. Mixed in with the torrents of meltwater are unusually high levels of organic pollutants. The alphabet soup of toxic compounds includes the infamous, long-lived insecticide DDT--the compound that helped curb malaria, but that also built up to poisonous levels in the food chain, putting predators like bald eagles, peregrine falcons, and ospreys on the endangered species list.
How does DDT wind up in a pristine glacier? As New Scientist explains, the pollutant molecules adhere to airborne particles and are carried around the globe on the wind. Over the poles, they come back down to Earth in blizzards and join the ice pack. There they sit, frozen in place, until the ice warms up.
According to the article, the Antarctic Peninsula's glaciers could be releasing up to 4 kilograms of accumulated DDT per year. The steady trickle may explain why the study found that DDT levels in Adelie penguins hadn't declined in the last 40 years despite major drops in worldwide use of the pesticide. (In 1959, the U.S. alone used 40,000 tons of DDT according to the EPA. Today, world usage is about 1,000 tons per year.)
(Image: Cape Royds, Ross Island, Antarctica, by H. Powell. Hat tip: sitta)