DOE Pulse
  • Number 368  |
  • July 30, 2012

Teresa Mathews combats historical contamination with modern science

Teresa Mathews

Teresa Mathews.

She is a biologist who has studied coastal contamination in New York and radioactive contamination in France. Teresa Mathews, a researcher at DOE’s Oak Ridge National Laboratory, now finds herself monitoring mercury contamination in creeks that run through DOE's Oak Ridge Reservation.

Mercury discharged into streams that ran through the federal site came mostly as a result of Cold War-era nuclear weapons production and research. Fast-forward to today, and researchers like Mathews are monitoring levels of mercury contamination in an attempt to reduce the effects of this toxic metal on the environment, including fish and humans.

Although she has numerous research interests, Mathews focuses on mercury because it can accumulate in the food chain, which translates to fish, which ultimately translates to humans. Another concern on her radar is methyl mercury, a particularly toxic form of the element produced from sediments and bacteria.

Monitoring the bioaccumulation of mercury and methyl mercury presents many challenges.

"Units of mercury in water do not easily translate to units of mercury in fish," Mathews said. "There's not an obvious correlation. While mercury in the water may decrease dramatically, it may only decrease slightly in fish."

That's why biologists and toxicologists are working to answer a critical question: Is there a level of mercury in water that will lower the levels of mercury in fish? Depending on the contamination levels, that answer can be yes and no.

In just three years of working at ORNL, she and her colleagues have seen mercury levels decrease dramatically in water and fish in White Oak Creek, a stream that runs through Oak Ridge National Laboratory.

However, another stream, East Fork Poplar Creek, which runs through the Y-12 weapons plant situated across a ridge and in a separate watershed from ORNL, has seen a similar drop in mercury levels that has not correspondingly dropped in that stream's fish.

Mercury levels in in East Fork Poplar Creek were much higher than White Oak Creek. Mathews predicts mercury levels in East Fork Poplar Creek's waters and sediment may have to be reduced more dramatically to see a change in mercury in its fish.

As an added twist to the equation, ORNL researchers have discovered that organic matter can stimulate methyl mercury production.

In laboratory tests that simulate streams and creeks, Mathews added contaminated sediments from East Fork Poplar Creek to clean water, and then added mercury at the "head" of the stream. Within two days, she measured significant levels of methyl mercury in the stream.

"There's no way to turn off bacteria in water," Mathews said. "So we have to figure out what the conditions are that make methyl mercury."

Mathews received her doctorate in coastal oceanography from Stony Brook in New York. She conducted her post-doctoral research at Cadarache University in France where she studied radioactive contaminants.

When she's not knee deep in contaminant research, Mathews, the New York native, enjoys riding her Kawasaki W650 motorcycle. – by Emma Macmillan

Submitted by DOE's Oak Ridge National Laboratory