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Researchers Win EPA Grant
to Study Mercury
in Long Island Sound
November 8, 1999

The next time you see a plume of smoke coming from a coal-burning plant or an incinerator, think about Long Island Sound. And think about the fish you eat. It doesn't matter what community you're in at the time or even which continent you're on, any mercury emitted in that plume could end up in the sound or in the fish you eat.

William Fitzgerald, a professor of marine sciences, has spent more than 25 years researching the life and travels of mercury, and has become a world-renowned authority on the metal. In fact, he is referred to by fellow scientists around the country as the "father of mercury research."

Recently, he and a colleague at the Avery Point campus, microbiologist Pieter Visscher, have been awarded a three-year, $592,000 grant by the Environmental Protection Agency, to study mercury and its methods of cycling through Long Island Sound.

"Far more is known about mercury's influence on freshwater lakes than its effect on marine environments," says Fitzgerald. Yet we know that the ocean is the principal means by which humans are exposed to the metal, he says, "so what we discover about mercury's behavior once it reaches the sound is critical."

Mercury varies in form and toxicity, and much of it is emitted during the burning of fossil fuels. Forty to 70 percent of the mercury emitted is in its elemental form, which can stay in the atmosphere for up to a year and can be deposited anywhere in the world. Ionic mercury accounts for the remaining portion emitted and is highly reactive, so it is quickly removed from the atmosphere through precipitation and deposited near to the source of the pollution.

Whether or not it was locally deposited or traveled from another continent, eventually mercury works its way into freshwater lakes and streams and to the rivers that feed the ocean. Fitzgerald and Visscher will study that process, along with what happens to the mercury once it reaches coastal areas, either through freshwater or from wastewater treatment plants.

The researchers are also in hot pursuit of two particular mercury mysteries they hope to solve. The first is, what causes a small amount of the mercury that has been deposited in the ocean to methylate and become toxic? Methylmercury poses a serious health threat to humans because it moves through the food chain and into the fish we consume. Researchers know that micro-organisms convert the inorganic mercury to methyl mercury, but what conditions lead to it?

"Most people believe that methylmercury is most prominent in the western sound, which is polluted by New York's sewage treatment plants. But we believe what we'll discover is that methylmercury production occurs at variable rates and in variable amounts throughout the sound," Fitzgerald says.

And while some of the mercury deposited in the ocean turns into the toxic form, a large portion of it does not. That's the second enigma Fitzgerald is pursuing. Based on his earlier research, he believes a lot of elemental mercury is being produced in the sound and is vaporizing back into the atmosphere. He now wants to find out how it is being produced and in what amounts, and what conditions are most favorable to its production.

The research project consists of a series of field experiments and lab studies that are expected to take place during the next three years, from the spring until fall. The focus sites chosen are the mouth of the Connecticut River and where the East River meets the western sound. Those areas are particularly important because preliminary work suggests that the interactions between freshwater and sea water, and between wastewater and sea water, are key to determining the amounts of methylmercury or elemental mercury produced.

The researchers' long-term goal is to turn the research into a predictive model that can be applied to other coastal areas, including Puget Sound and Chesapeake Bay.

Fitzgerald says the project was one of nearly 60 proposals presented to the EPA for funding; only 15 percent received approval. "It's an honor to be among the 15 percent. You're competing with your peers, some of whom have excellent research projects that didn't get funded," he says. "It validates that our research proposal was well-structured and based on sound science."

Janice Palmer