posted 10/08/01

Surface to Depth: Hudson River Research at the Columbia Earth Institute
Columbia University’s Commitment to the Hudson Supports Dozens of Researchers Working to Unravel the Mysteries of This Complex River

By Abigail Beshkin

The Hudson River is not the gangster graveyard it is often portrayed as being. Nor is it merely a toxic wasteland, saturated with PCB’s. The Hudson is a dynamic river where remnants of a glacial past, invasive zebra mussels and underwater dunes more reminiscent of the Sahara Desert, come together. It’s the stage on which an ecological drama unfolds.

In recent years, the Columbia Earth Institute has been the leader in New York State for the study of the Hudson River. Dozens of researchers devote their time to the Hudson, scrutinizing it from surface to depth. Columbia’s researchers study everything from the river’s mud to its marshes. They look at the contaminants within it and the wildlife around it. Columbia’s Hudson River Research is a comprehensive and concerted effort by the Institute’s leading experts who are committed to the Hudson’s future health and habitability.

Mapping the Hudson

At the helm of this research is Dr. Robin Bell. A passionate guru of the Hudson, Bell is the first person to map the Hudson since 1930. From 1998 until 2000, Bell led the Hudson River Estuary Project team, which mapped 40 miles of the river. The team, made up of scientists from the State University of New York at Stony Brook and Queens College, uncovered a dynamic riverbed, with large dunes of sand and gravel, banks of oysters and archaeological artifacts. This study identified places where recent mud has settled — contaminants like PCB’s tend to be found in recent mud. Researchers also found that sediment movement affects the movement of pollutants such as PCBs. Based on the success of the first phase of their project, the New York State Department of Environmental Conservation Hudson Action Program recently renewed a $1.5 million grant for Bell to map the river from the Battery to Troy, New York. Early results from the new program include the first mapping of landslides that were triggered by the torrential rains from Hurricane Floyd and left scars far into the river.

In September, as part of the New York state funded program Dr. Steven Chillrud led a team of 15 Lamont scientists to collect over 150 new samples from Palisades north to Cold Spring. This sampling program collected 120 two-meter cores, which are like tape-recorders, capturing the river’s history. The sampling recovered material as young as last week and as old as several thousand years. "World’s End," so-named because it is the Hudson’s deepest point, is more than 200 feet deep. Until the team recovered cores of fluffy mud it had been assumed that World’s End was a rocky conduit through which the river flowed, leaving little sediment trace. Identifying new sediment deposits is important for understanding the accumulation of sediments within the Harbor of New York and the plan for dredging this material.

In June, Dr. Suzanne Carbotte, working closely with other Lamont scientists sited and recovered the new deep samples from the ancient glacial lake that once flooded the Hudson Valley. When the ice sheet retreated 14,000 years ago it acted as a bulldozer, pushing forward mud and debris and creating a natural dam, which blocked the flow of the Hudson into the ocean and caused a giant lake to form in the valley. Carbotte identified the distinctive signature of the glacial deposits in the seismic data acquired in the spring. With assistance from a local utility company, samples from the glacial lake were recovered, and these are now being analyzed at Lamont’s Core Laboratory for evidence of climatic cycles and the river’s response to changing climate.

How Contaminants Move Through the Hudson

In July, Dr. Peter Schlosser and his team injected a harmless gas into the Hudson to see how quickly it would spread through the water. Surprisingly, the highest concentration of gas did not move from Newburgh, New York, the site where it was first injected into the river. The experiment showed that the decrease in concentration of the gas is caused not by the flow of the river but instead by the churning of the river. This has tremendous implications for our understanding of how contaminants move through the river and how to follow and remove them from the river.

Another team, led by Dr. Robert Houghton, used dye tracers to measure the flow of the Hudson River tides that run east and west, as opposed to the more easily-measured tides running north to south. The scientists injected Fluorescein near the bottom of the deepest portion of the river, the navigation channel on the east side, just north of Spuyten Duyvil. Within hours the tracer moved across the river channel to shallow water on the west side. This indicates that the effect of mixing in the Hudson is significantly higher than had originally been believed, and that any pollutant injected in the river will spread throughout the Hudson at a high speed.

For 25 years, Lamont scientists, led by Dr. James Simpson, have been reconstructing how contaminant levels at different locations in the river have changed over the last several decades. Such contaminants as heavy metals and PCB’s tend to accumulate in the Hudson’s fine-grained sediments. By collecting these sediments, the researchers are able to learn about the geochemical behavior of the contaminants, and how the contaminants are transported around the Hudson River basin.

Hudson History

Dr. Dorothy Peteet is an expert on the origin and history of the Hudson River’s marshes. The marshes are among the most crucial places in the Hudson, as they form the base of the food chain, protect young plants and animals and protect the shoreline. Recently, Peteet and her researchers have examined the salt and charcoal content of the marshes, and found that over the last 4,000 years, the marshes have been strongly affected by drought, as indicated by high salt and charcoal content. The Hudson’s marshes are repositories of historic information about the regional New York climate, and are especially valuable because they have a high sedimentation rate, and detailed sampling is possible.

One research team, led by Dr. Cecilia McHugh and Dr. Stephen Pekar searches for paleoclimate signals in Hudson River sediment cores, particularly from the lower Hudson. This work is part of a larger effort at the Lamont-Doherty Earth Observatory to understand the evolution of the Hudson Estuary and the regional climate since the last glacial retreat some 24,000 years ago. The oxygen isotopes found in the shell material retrieved from the Hudson’s sediment indicate whether the shells grew during a period in which the Hudson had a higher salt content, or was filled with fresher water. Preliminary results from the cores indicate periods of cooler and/or drier climate prior to about 4000 years before present. Some data suggest multiple cycles of wetter/drier climate conditions early in this time period.

Jamaica Bay

In a recent project, one team, led by Dr. Arnold Gordon, brought together researchers to make baseline measurements within Jamaica Bay. Working with the National Park Service, they measured physical properties of Jamaica Bay, including its circulation and mixing patterns and its chemical properties. They found that the flushing rate of Jamaica Bay — the length of time it takes for a chemical to be completely diluted from part of the Bay — is much faster than had been thought originally.

About The Earth Institute
The Earth Institute at Columbia University is the world's leading academic center for the integrated study of Earth, its environment and society. The Earth Institute builds upon excellence in the core disciplines — earth sciences, biological sciences, engineering sciences, social sciences and health sciences — and stresses cross-disciplinary approaches to complex problems. Through research, training and global partnerships, it mobilizes science and technology to advance sustainable development, while placing special emphasis on the needs of the world's poor. For more information, visit www.earth.columbia.edu.