University of Michigan
Department of Ecology and Evolutionary Biology

For the first time, the chemical "fingerprints" of the element mercury have been used by UM researchers to directly link environmental pollution to a specific coal-burning power plant.

The primary source of mercury pollution in the atmosphere is coal combustion. The U-M mercury-fingerprinting technique – which has been under development for a decade – provides a tool that will enable researchers to identify specific sources of mercury pollution and determine how much of it is being deposited locally.

"We see a specific, distinct signature to the mercury that's downwind of the power plant, and we can clearly conclude that mercury from that power plant is being deposited locally," said Joel Blum, the John D. MacArthur Professor of Earth and Environmental Sciences who is also a professor of ecology and evolutionary biology.

Blum is co-author of a paper published online Dec. 13, 2011 in the journal Environmental Science & Technology. The lead author of the paper is U-M doctoral candidate Laura Sherman, who works with Blum.

"This allows us to directly fingerprint and track the mercury that's coming from a power plant, going into a local lake, and potentially impacting the fish that people are eating," said Sherman, who has worked on the project for four years.

Mercury is a naturally occurring element, but some 2,000 tons are emitted to the atmosphere each year from human-generated sources such as incinerators, chlorine-producing plants and coal-fired power plants.

But results from the latest study by Sherman and her colleagues prove that mercury is deposited locally near coal-fired power plants and doesn't simply vanish into a global pool high in the sky. "It makes it hard to argue that there's no local deposition when we're seeing such unique signatures like this," Sherman said.

"This study represents the first use of stable mercury ratios to investigate the near-source mercury deposition resulting from coal combustion," Blum said. "We're very excited about this result, in part because it is technically difficult, and also because we've been told for years that it couldn't be done."

Image: Sampling tripod with funnels to collect precipitation. This study site was located on the Gulf of Mexico coast near Crystal River, Florida. Photo by Laura Sherman

U-M News Service press release