Mercury on the horizon

An “EcoCELL” at the Desert Research Institute. Full size image available here

RENO, Nev.--Mercury gets around. A naturally occurring contaminant, mercury is found in water and soil but scientists are not exactly sure how mercury makes its way through the environment. Concerns over increasing levels of mercury contamination have sparked fish consumption advisories in certain areas.

Knowing how mercury ends up in these locations, however, is an area of concern for environmental scientists. Researchers at the University of Nevada, Reno recently discovered that plants play a significant role in how mercury travels.

"Based on previous studies, what we originally thought was that mercury in soil would be absorbed through a tree's roots, then released through the tree's leaves into the air," said Jody Ericksen, a Nevada graduate student who studied the contaminant for her master's degree in Environmental Science and Health. "We were wrong. What happened is that the plants absorbed the mercury from the air."

According to Nevada researchers, once a tree's leaves contain mercury, those leaves eventually fall off, decay and mercury goes back into the soil, air and, ultimately, water.

Research Associate Jody Ericksen Full size image available here

According to Mae Gustin, associate professor in the university's Department of Natural Resources and Environmental Science, the results of the study could have global implications.

Mercury from coal-fired power plants, or from areas such as Nevada that have high levels of naturally occurring mercury, can be in the air for six to 12 months and can cross continents.

"Researchers who model how mercury travels through the environment tell us that even if the United States turned off all of its coal-fired power plants, we would still have mercury being deposited here because of China's mercury emissions," Gustin said. "For mercury controls to make a difference there has to be a global effort."

The researchers' study was published in a recent issue of Environmental Science & Technology, one of the most prestigious environmental science journals.

The study was funded with a grant from the EPA Experimental Program to Stimulate Competitive Research. Collaborators on the project included: Dave Schorran and James Coleman of the Desert Research Institute; Dale Johnson, a professor of Natural Resources and Environmental Science at the University of Nevada, Reno; and Steven Lindberg of the Oak Ridge National Laboratory.

The College of Agriculture, Biotechnology and Natural Resources is a founding college of the University of Nevada, Reno, one of the top research universities in the country. The college, along with the federally established Nevada Agricultural Experiment Station, offers pioneering research and education in natural resource management, biotechnology, molecular biology, agricultural production, economic development, human/animal health and nutrition and environmental sciences.

CAPTION 1: An “EcoCELL” at the Desert Research Institute. Similar to a greenhouse, the two-story EcoCELL allows for environmentally-controlled conditions. The Nevada researchers measured conditions within the enclosed environment, including light and carbon dioxide levels as well as levels of mercury in the air and water. Highly accurate instruments took measurements every five minutes. Photo courtesy of Jody Ericksen.

CAPTION 2: Research Associate Jody Ericksen plants aspen trees in mercury-enriched soil at the Desert Research Institute. Contrary to expectations, rather than absorbing mercury from the soil into the trees' roots, mercury was assimilated through the trees' leaves from the atmosphere. With help from inmates at the Washoe County Sheriff's Department, 27 tons of gravel and mercury-enriched soil were used to plant 100 two-year-old aspen trees. Ericksen was a graduate student who helped conduct this research for her master's degree in Environmental Science and Health at the University of Nevada, Reno. Photo courtesy of Jody Ericksen.