An Unwanted Legacy: Mercury in the Connecticut River Watershed
May 2012—story by Jenny Morgan, photo courtesy of Anna Martini
Nearly ten years ago, Associate Professor of Geology Anna Martini took a group of students to the Connecticut River for what Martini thought would be a typical classroom assignment. They set out to investigate the deposition of inorganic mercury from Mount Tom, the coal-fired power plant situated between Holyoke and Easthampton, Massachusetts. After collecting both lichan from trees and sediment from a small lake along the river, the class analyzed their samples and found strikingly high amounts of mercury in both— and what began as a simple classroom experiment quickly became Martini’s newest area of research. Almost a decade later, the project has transformed into a multifaceted, interdisciplinary endeavor that involves both scholars and community stakeholders.
This year, Martini has continued the work— including a semester long lab, a senior thesis, and collaborative research— with support from the Engaged Scholarship Initiative.
As a hydrogeochemist, Martini focuses on the chemistry of surface and ground water in geological formations— or, as Martini describes, “I’m one of those rare geologists that doesn’t study rocks.” Her research has led her to study the paleohydrogeology of western Ireland, the geochemistry of hydrothermal springs in Saint Lucia, and microbial gas production in an ancient Devonian black shale in Michigan. A tenacious scientist, Martini is also somewhat of a historian: her research often addresses how hydrogeochemistry can be used to understand past geological eras and processes. Similar to her other projects, Martini’s study of mercury is also a historical investigation, with a slight variation: it traces a history of human activity, not geological. While there are naturally occurring sources of mercury, such as volcanoes, human activity— both past and present— has dramatically increased the presence of inorganic mercury in the environment. “There are lots of sources for inorganic mercury,” Martini explains, “and it’s a global contaminant. Today, coal-fired power plants are responsible for most of the atmospheric deposition.” She is quick to point out that mercury found locally is not simply from the nearby power plant. “Most of the inorganic mercury in the Pioneer Valley is from downwind, from the Midwest and the South. There’s just a lot of background mercury in the air.” It isn’t only the current practices of industry that are to blame, either. “During World War II, there was a large spike in mercury use. Along the Connecticut River, there were many industries that used mercury in their processing.” A significant aspect of Martini’s collaborative work is to more accurately understand how, and when, mercury enters and exits the Connecticut River system.
From the very first field trip to the Connecticut River, Martini has morphed a single study into a dynamic collaboration that spans multiple disciplines and includes significant student research. She has partnered with Karena McKinney, assistant professor of chemistry, to examine mercury in watersheds and the atmosphere near Mount Tom; she is also working in close cooperation with Jon Woodruff, assistant professor of sedimentology and coastal processes at the University of Massachusetts Amherst, to study how the sediment embayments “have filled up [with sediment] over time.” Martini is currently supervising the thesis research of Hanna Bouberhan ’12. Since this summer, Bouberhan has been immersed in nearly every aspect of the project. She has collected core and pore water samples from lakes, inlets, and embayments up and down the Connecticut River and has analyzed the effects of sulfate-reducing bacteria in sediment cores. Studying the sulfate-reducing bacteria is a key part of understanding the mercury cycle once it has been introduced in a river environment. “The mercury that accumulates in the ecological food chain is methylmercury,” Martini explains. The sulfate-reducing bacteria transform the inorganic mercury into methylmercury— which begins an irreversible process of bioaccumulation.
As the study continues to expand, Bouberhan and Martini have both worked alongside community and environmental organizations, including the Connecticut River Watch, the Nature Conservancy, and the Easthampton Gun and Rod Club. Martini continues to bring her classes to the river to help in the research, and this fall, she added a semester long lab to her Seminar in Biogeochemistry for exactly this purpose. She has also recently received funding from the National Science Foundation to continue the research. Even after ten years, Martini’s excitement for her work is palpable, and she especially likes how different this project is from her other research topics. “In some ways, [this] is very applied science…and it has true environmental impact, even from the simple things— like whether or not you want to dredge embayments to allow larger boats in and out, or just let them infill and not let those contaminated sediments reenter the environment.”
Jenny Morgan is a CCE staff writer. She enjoys springtime in New England and impromtu beach trips. She welcomes comments or questions at jmorgan[at]amherst[dot]edu.