DDT levels in Antarctic penguins present a complex mystery
HEIDI GEISZ
The use of DDT peaked several from two different populations. problematic, she adds. decades ago at more than 36,000 They measured total DDT in the The team also suggests that climetric tons (t) per year. Today, less breastplate fat sac of each bird mate change could accelerate the than 1000 t of the organochlorine as well as in the addled or frozen release of these chemicals into the pesticide—banned in most couneggs. The researchers compared environment. However, says David tries since the 1980s—is applied their findings with past measureVaughan of the British Antarctic annually for mosquito control and ments reported in the literature as Survey, climate change on the Antfarming, mainly in the Southern far back as 1964. They found that arctic Peninsula “is only increasing Hemisphere. Despite this drop, the ratio of p,p′-DDT to p,p′-DDE the melt by a relatively small perAdélie penguins in the Antcentage,” about 10% during arctic continue to have the the past decade. “I’d be sursame levels of total DDT prised if climate change can in their bodies as they did be blamed for a wholesale 30 years ago. New research change in the mechanism published in ES&T (pp of DDT transfer,” he says. 3958–3962) identifies AntNevertheless, “the release arctic meltwater as the conof this stored DDT into the tinued source of total DDT, marine environment is inand possibly other pollutevitable as glaciers go about ants, in the southern contitheir normal business of nent’s ecosystems. producing icebergs.” DDT and other perThe team has “develDDT metabolites continue to accumulate in the fatty desistent organic pollutants oped a strong case” for posits of Adélie penguins in the Antarctic. Researchers (POPs) follow atmospheric steady and even increasing say melting snow and ice could be releasing decades-old paths to the Antarctic and total DDT concentrations DDT and its derivatives into South Pole ecosystems. the Arctic and eventually in Adélie penguins, notes are deposited there in snow Derek Muir of Environand ice. Animals at both poles sedeclined over time; this shift indiment Canada. “The authors have quester the derivatives p,p′-DDT cates that the birds are exposed to gone to a lot of effort to examine and p,p′-DDE in their fat. But while the remnants of older DDT deposithe reliability of the older data,” Arctic-dwelling creatures such tion, not new sources. he comments, some of which were as birds, whales, and seals have To pinpoint where the older based on packed-column gas chroshown a dramatic drop in total DDT might be coming from, the matography. That method could be DDT levels during the past decade, researchers used measurements of confounded by PCBs, but the DDT levels in Adélie penguins in the glacial outwash taken in the past measurements remain more reliAntarctic have remained steady, few years. (Directly measuring ice able over time. according to the new results. and snow remains technically difThe “remarkable” differencAdélie penguins, which are proficult.) From those data, they eses between Arctic and Antarctic tected under international contimated that melted snow and ice trends for DDT in seabirds, ringed servation rules, live across the could be providing about 1–4 kiloseals, and other animals present a continent and overwinter there. grams per year of DDT to offshore complex mystery, Muir suggests. The birds’ stationary behavior Antarctic ecosystems. The Arctic ice holds more DDT bemakes them apt subjects for studyThe short food chain in the Antcause of its past use in the Northing Antarctic sources of DDT and arctic, from krill to penguins, for ern Hemisphere, but declining possibly other POPs; migratory example, means that glacial meltlevels in animals there “suggest it birds such as skuas, which winter water is an almost direct delivery is not having a large impact,” he in South America or closer to the system of DDT to birds and other says. The new results “point [out] equator, could pick up these chemlarge animals, says Geisz. The the need to examine this in more icals on their travels. measured DDT burdens are too detail,” particularly in the Arctic, Heidi Geisz of the Virginia Inlow to be harmful to the animals, where researchers have collected stitute of Marine Science and her but continued exposure to mixmore high-resolution data over colleagues sampled dead Adélie tures of persistent pollutants at low time on DDT in animals. penguins and abandoned eggs levels could eventually prove to be —NAOMI LUBICK June 1, 2008 / Environmental Science & Technology ■ 3909
