Mary Tobin

Mud Yields Ghosts of Hudson River's Past

By Kirk Johnson, New York Times aboard the R. IAN FLETCHER, off Nyack, N.Y.
Hannah Fairfield / The New York Times

About a thousand years ago, a hurricane of cataclysmic proportions swept up the Hudson River.

Or perhaps it was the mother of all northeasters. No one knows. What is clear, however, is that the force of the storm was beyond any recorded or remembered human experience. Great swaths of the river bottom were scraped up and moved about in one ferocious flood.

Robin E. Bell, a senior research scientist at Columbia University, has seen the storm in her imagination, and touched with her fingers the dense, black-earth core drilling samples that reveal, in their banded marks, the river's ancient trauma.

From the deck of the Fletcher, a 36-foot-long work boat that sails out of Nyack, laden with computers and mini-cameras, sonar fish and salinity meters, Dr. Bell and other scientists at Columbia and the State University of New York at Stony Brook are mapping the Hudson from the bottom up, trying to understand how the ghosts of the river's past, like the perfect storm of A.D. 1000, might give clues about its future.

"It's about trying to find out these secrets, these time markers, so that you can put everything together," she said on a recent cold, gray day, as the boat bobbed gently on a slack tide just north of the Tappan Zee Bridge.

Dr. Bell's mission, which is to build a complete model of the Hudson's bottom using every high- tech tool of the information age, is revealing things about the river that its murky waters have long kept veiled.

Huge natural reefs, made entirely of oyster shells, have been found for the first time. The reefs, built by hundreds of generations of oysters growing and dying and crumbling upon one another's backs, are at least 6,000 years old, predating the Great Pyramids. Sunken ships, one more than 150 feet long, that were long rumored or vaguely placed on shipping charts have been pinpointed.

But perhaps the most startling findings are coming from the most humble of sources: the river-bottom mud itself, which is giving up the secrets of how, why and where it is deposited.

In December, the federal Environmental Protection Agency, citing its own research about the properties of Hudson River mud, said that the General Electric Company, which dumped toxic PCB's into the river from its factories 150 miles north of here, should be required to clean up the chemicals that have become embedded in the sediment. It would be one of the largest and most complex river cleanups in American history, with a price tag of $460 million in dredging costs alone.

General Electric's research, however, suggests that the PCB's are best left where they are, entombed by successive layers of mud. The natural containment of the chemicals, G.E. officials say, grows more secure with every year and every new layer of silt.

Dr. Bell cautions that while her mapping project did not focus on the areas proposed for dredging, the portrait of the river that is emerging from her work suggests that both the government and the company are partly right. Changes to the river bottom happen slowly, as G.E.'s research concludes, with gradual and predictable new sediment layers piling one on top of another in a layer cake effect. But that pattern can be suddenly torn apart by an earthquake, a flood or some other environmental upheaval.

The evidence of such upheavals, Dr. Bell said, supports the E.P.A.'s position that while the PCB's may be buried now, their escape into the water will always be possible unless the chemicals are removed from the sediment. PCB's, polychlorinated biphenyls, which were widely used as insulating materials in electrical products until they were banned in the 1970's, have been linked to cancer in humans and to other problems in wildlife.

to Part 2

Robin E. Bell, right, a scientist at Columbia University, examining Hudson River temperature and salinity data collected by Lamont engineer, Jay Ardai, left.

Norman Y. Lono for The New York Times

Related Articles:

E.P.A. Gives Its Plan on Hudson River PCB's, but a Fight Lies Ahead (Dec. 7, 2000)

Dredging PCB's Could Be a Cure Worse Than the Disease, G.E. Insists
(Dec. 7, 2000)

U.S. to Order $490 Million River Cleanup by G.E. (Dec. 6, 2000)

On Hudson, Cleanup Idea Stirs Emotions
(Dec. 2, 2000)

In War Over PCB's in Hudson, the E.P.A. Nears Its Rubicon
(June 5, 2000)

The Natural World: The Environment

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EPA Announces Its Preferred Cleanup Plan

Map Core Sample Sources on the Hudson

Columbia Hudson Research
More about Hudson River Research at Columbia's Lamont-Doherty Earth Observatory



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