Ninety-one percent of the mercury entering the ocean is deposited from the atmosphere to the sea surface in rain, snow, fog and particles. (COURTESY)
Dartmouth study follows mercury pollution path
HANOVER - A new Dartmouth-led study into mercury in the environment from the source of contamination to the seafood people eat is the first comprehensive study of its kind and was compiled to guide global policy-makers who are finalizing the first global treaty to regulate mercury contamination early next year, said Celia Y. Chen, Ph.D., research professor of biological sciences at Dartmouth College.
The comprehensive research combines three studies to which more than 70 scientists contributed and is a first to pinpoint mercury pollution at its source to where it ends up, Chen said.
Science literature hasn't fully addressed this connection between the sources of mercury to the fish that we're eating, Chen said.
"I talk to my mom and I talk to my friends and they all know about mercury in seafood, but they don't know where it comes from," she said. "Where does it come from and how does it get into fish and what are the fish that people should and shouldn't eat?"
The issue is vital, because while people should avoid fish high in mercury because of the neurological and developmental problems it could cause, the same health problems become an issue for people who do not get the important omega-3 oils found in fish. So eating fish low in mercury is important, as is finding ways to reduce mercury pollution, Chen said.
More than 40 percent of the mercury released into the atmosphere is released from coal-burning power plants, Chen said.
The technology to remove mercury during the coal-burning process is available, Chen said, though it may not be financially feasible for the coal-burning plants in developing countries.
"Mercury is just a natural element and we are basically taking it out of the ground and releasing it so there is a lot more mercury in the atmosphere," Chen said. In fact there is two times the amount of mercury in the atmosphere than there was 100 years ago.
Mining also causes mercury contamination.
Part of the study shows how historic small-scale mining on the West Coast has led to a high level of mercury contamination in San Francisco Bay.
In this case the source is not the atmosphere, but the mercury left in the river sediment that flow into the bay.
Last week, Chen and her colleagues, Charles T. Driscoll, Ph.D., professor of environmental systems engineering at Syracuse University, and Robert P. Mason, Ph.D., professor of marine sciences at the University of Connecticut, presented the research to lawmakers as well as national and international policy makers in Washington, including to members of the State Department and the Environmental Protection Agency.
The research findings are especially timely since the U.S. and other nations are preparing for the fifth session of the United Nations Environment Program's Intergovernmental Negotiating Committee January in Geneva, Switzerland, to create a legally binding agreement to control mercury releases into the environment.
After years of work on the issue, Chen said it is likely the language of the treaty will be nearly complete at this fifth session. She hopes the scientific data she helped to collect and compile helps the global policy-makers shape the agreement and leads to the eventual reduction of mercury in the environment.
The new research was published in a special issue of the journal Environmental Research last week.
The research can be found at www.sciencedirect.com/science/journal/00139351/119.
A companion report by the Dartmouth-led Coastal and Marine Mercury Ecosystem Research Collaborative, Sources to Seafood: Mercury Pollution in the Marine Environment was also released. The study - found at www.dartmouth.edu/~toxmetal/C-MERC/index.html - reports that mercury released into the air and then deposited into oceans contaminates seafood commonly eaten by people in the U.S. and globally.