Rutgers begins five-year study of Hudson River contaminants and their fate in the Atlantic Ocean
May 07, 2003
NEW BRUNSWICK/PISCATAWAY , N.J. - Marine scientists from Rutgers, The State University of New Jersey, today embarked on a five-year National Science Foundation (NSF) -sponsored study to determine what happens to nutrients and contaminants that flow down the Hudson River and enter the Atlantic Ocean. The resulting numerical model of the river/ocean mixing process is expected to figure in New York City's future plans for sewage disposal.
Five times in the coming years, scientists will inject a harmless fluorescent dye into the plume of water flowing from the Hudson and follow the dye by boat as it moves along in the ocean, testing it all the way to learn the fate of the nutrients and contaminants in the plume.
An initial voyage today from Staten Island to Barnegat Inlet, N.J., is intended to survey the plume and test systems that will be used when dye is first injected in May 2004. Additional dye injections will take place in 2005 and 2006. Formulated with a red color, the dye will quickly disperse and become invisible to the eye, but the scientists' equipment is expected to detect it for up to 100 miles.
"Essentially we'll be tagging a piece of the ocean and following it," said Robert J. Chant, professor of physical oceanography with Rutgers' Institute of Marine and Coastal Sciences (IMCS). Chant is principal investigator on the study called "Lagrangian Transport and Transformation Experiment (LATTE)." He is working along with fellow IMCS scientists Scott M. Glenn, Oscar Schofield and John L. Wilkin, and John R. Reinfelder of Rutgers' environmental sciences department.
Rutgers is the lead research institution on the project and will receive $2.2 million of the total $4.2 million NSF grant. The remainder will be distributed equally among study collaborators at Columbia University, University of Massachusetts-Boston, University of Florida-Gainesville, California Polytechnic Institute and the Florida Environmental Research Institute.
Besides the shipboard LATTE studies, scientists will use components of IMCS's New Jersey Shelf Observing System, a satellite-networked system of submerged monitors, autonomous underwater vehicles and ocean radar systems that offers continuous real-time monitoring of ocean conditions.
Chant said New York City's 14 wastewater treatment plants currently process about 1.3 billion gallons of sewage per day, discharging most of it as inorganic nitrogen into the waters of the Hudson River plume. A long list of heavy metals and chemicals, most in trace amounts, are also moved along by the plume.
"While following the dye patches, we will use a wide variety of equipment and testing methods to determine how nitrogen, lead, cadmium, mercury and other substances are transported at different depths and under different conditions," Chant said. "We'll also study microscopic organisms called phytoplankton and zooplankton, and research how metals and nutrients enter the base of the food chain."
A large number of factors determine just where river water ends up and how fast it mixes with ocean water, said Chant. "Salt water is heavier than fresh water so the ocean tends to slump beneath the river and actually travel northward as the Hudson plume water flows south. This means heavier sediment may be less likely to move great distances into the ocean. Ocean currents, turbulence, tide temperature, wind and even the rotation of the earth all have an effect. In the end, we'll undoubtedly have the most sophisticated model of what the Hudson River really does as it mixes with the ocean."
Miscellaneous Facts About LATTE
The word "Lagrangian" in the title of the study comes from the name Joseph-Louis Lagrange, an 18th-century French mathematician who developed formulas for studying the motion of fluids while following their flow.
The LATTE acronym will have special meaning for coffee lovers, as well as scientists. One of the chemicals to be monitored in the Hudson River plume is caffeine -- it passes though sewage treatment plants unchanged, and because it has no oceanic source, it can be used as an additional tracer.
Shipboard testing will provide real-time results, allowing scientists to produce computer images of the Hudson River plume as they travel. The model will evolve as test cruises continue through 2006. Analysis of the comprehensive plume model is expected to be completed by 2008.
There are about 60 pounds of salt in every ton of sea water. Wherever salt water and fresh water meet, the heavier sea water sinks to the bottom and the lighter fresh water floats on top. Over time the two layers slowly mix.
Computer modeling in LATTE will tackle some complex issues, such as turbulent mixing and photosynthesis in microscopic ocean plants. The rotation of the earth will figure in the model because it causes ocean water in the northern hemisphere to turn to the right. This phenomenon, called the Coriolis effect, drives the plume up against the New Jersey coast.
In previous testing, water from the Hudson River plume has been detected in the ocean as far south as Cape May, N.J.
The dye to be used in the LATTE study is Rhodamine WT, a non-toxic liquid red dye commonly used in water-tracing studies. It is detected by using a submersible fluorometer, an instrument that flashes a light and measures the light reflected at a specific frequency. Rhodamine can be detected down to 10 parts per trillion-- or the equivalent of 1/50th of an ounce dropped in an Olympic-size swimming pool.
The meeting place of fresh water and salt water is called an estuary. The Hudson River and Atlantic Ocean region comprise the most densely populated estuary area in the United States.
In March 2003, Rutgers' Institute of Marine and Coastal Sciences, based in New Brunswick and with a field station in Tuckerton, celebrated its 10th anniversary and its entry into the national top 10 ocean study organizations in terms of NSF funding.
Contact: Bill Haduch
732/932-7084, ext. 633
Email: bhaduch@ur.rutgers.edu