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Research Magazine > ARCHIVE > Summer 01 > Article

Scientific Sleuthing
by Steve Koppes

If finding signs of extraterrestrial life in ancient meteorites seems like a challenge, you should see what Christopher Romanek can do with a little whale baleen and some wood stork feathers.

Just give Romanek a quarter of an inch of whale baleen — a tooth substitute — and he’ll conjure up thousands of miles of its owner’s travels and the contaminants it has picked up along the way. Likewise, from just a few feather clippings, he can unveil a list of where the bird came from and what it has been eating.

It’s all part of Romanek’s environmental research at the Savannah River Ecology Laboratory, which UGA operates for the U.S. Department of Energy. And it is made possible through the wonders of stable isotopic chemical analysis.

Stable isotopes are the nonradioactive siblings of the atomic world. They are varieties of an element, such as carbon, oxygen or nitrogen, that differ slightly in only one key characteristic: mass. Romanek uses the ecology lab’s high-precision isotope ratio mass spectrometer to learn how contaminants become incorporated into the food chain.

Essentially, he uses the same techniques that he first used on rocks as a geology student. Now he focuses some of his research on living things too.

“Rocks and minerals are very easy to work with because they’re just sitting there for you to pick up,” said Romanek, a UGA associate professor of geology and associate research scientist at SREL. “If you’re going to start collecting birds’ feathers or whale baleen and start analyzing them for their isotopic composition, it’s a much different proposition.”

Baleen whales are toothless. Instead of chewing food, they strain it through baleen, which are plates that grow from the roof of the mouth.

“They’re made out of the same type of tissue that our fingernails are made of, and they are very closely spaced,” Romanek said. “These whales actually filter-feed through the water to collect plankton for their food.”

Romanek conducts his whale baleen research in collaboration with Keith Hobson, a scientist at the Canadian Wildlife Service. They regard baleen like a sort of tape recorder. Baleen grows slowly, just like a fingernail grows from its base toward the fingertip. And as it grows, it records the animal’s experiences over time.

Just as scientists can analyze human hair samples for lead, arsenic and other toxins, Romanek and his colleagues can screen baleen for oceanic contaminants. Baleen whales migrate seasonally from the Arctic Ocean in the summer to the Bering Sea west of Alaska in winter. “We get this beautiful signature,” he said. “This fingerprint in stable isotopes and in trace-element content that tells us what those whales were eating and perhaps the kinds of waters they were living in during the period the baleen grew.”

Romanek’s research so far has proved that the Arctic whales have been exposed to mercury. He also has detected selenium, arsenic, cobalt, copper and zinc, though some of these may be from natural sources.

“We feel this is one of the few pristine environments left on Earth, and yet it is still showing the effects of humans,” Romanek said.

Much closer to home, the endangered wood stork breeds in the coastal regions of South Carolina, Georgia and Florida. The stork’s feeding grounds include the Savannah River Site, a 310-square-mile former nuclear weapons processing complex on the Georgia-South Carolina border.

Romanek and colleagues analyzed the feathers from inland and coastal breeding sites, including one near the Savannah River Site, and determined that the birds were being exposed to contaminants such as mercury. “We could tell where the mercury was coming from that these birds were exposed to,” Romanek said.

It turned out that all the birds with relatively high mercury concentrations received their mercury dose at inland sites. Parent wood storks on the coast, it seems, prefer to feed their young the prey plucked from freshwater sources, even though saltwater prey is easier to find.

Romanek’s study, published last year in the journal Oecologia, underscores the importance of preserving wetlands in their natural state if the wood stork is to thrive.

Using the same techniques, Romanek and his colleagues hope to find out why the inland Georgia food chains harbor more mercury than ones on the coast.


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Scientists can track a wood stork’s journey and diet just by examining — at an atomic level — a few of its feathers. Photo courtesy of I. Lehr Brisbin