Teresa Mathews: Tackling mercury pollution for healthier aquatic ecosystems

Moving to landlocked Tennessee isn’t an obvious choice for most scientists with new doctorate degrees in coastal oceanography.

But for environmental scientist Teresa Mathews, making that move launched a rewarding career at the Department of Energy’s Oak Ridge National Laboratory, where she leads the Biodiversity and Ecosystem Health Group. As group leader, Mathews oversees diverse projects with a common theme: Understanding how different energy strategies impact the natural world – especially water.

Sources of energy generation from fossil fuels to hydropower can affect water resources in numerous ways, from influencing water flow and temperature to affecting water quality. Mathews’ group works to better understand and minimize these environmental impacts.

Mathews’ research specifically focuses on how nutrients and contaminants move through aquatic ecosystems. She studies how organisms from microbes to fish influence both the forms in which these chemicals exist in the environment and the ways they move between parts of the ecosystem. She also examines how these chemicals can, in turn, impact biodiversity.

At ORNL, much of her research has centered on mercury, a challenging metal contaminant. Mercury pollution is a growing problem across the world, but it’s especially relevant in Oak Ridge, where  the metal was released into local waterways during the 1950s and ’60s.

Scientists are still addressing legacy mercury contamination, a task complicated by microbes. Through a process called methylation, bacteria transform inorganic mercury into methylmercury. The latter is far more toxic, and it builds up in biological tissues, working its way up the food chain.

“We can do things to control inorganic mercury concentrations, but the microbial transformation of mercury into methylmercury is much more challenging to understand and control,” Mathews said. “These questions drive a lot of my research: What are the factors that affect mercury methylation? Are there best management practices or other technologies that we can use to control the factors driving mercury methylation?”