Science Wednesday: Into the Woods, Exploring Mercury in Northeastern Forests

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About the author: Jason Townsend is a Ph.D. student in Conservation Biology at the State University of New York College of Environmental Science and Forestry. His work is funded by an EPA Science to Achieve Results (STAR) Graduate Research Fellowship.

Scientists have known for some time that mercury is accumulating in America’s waterways and the ocean. Emissions from coal-fired power plants contribute significant amounts of mercury to the atmosphere. Mercury-laden precipitation is especially severe in parts of the northeastern U.S. directly in the line of prevailing winds from Midwestern, coal-powered power plants.

Accumulation of this potent neuro-toxin poses a threat to wildlife and people through consumption of contaminated fish.

We do not know, however, the extent to which mercury is accumulating in non-aquatic environments—forested areas of the Northeast, for example. It is possible that mercury-laden precipitation is accumulating in leaves, soils, and leaf-litter on the forest floor. This could lead to contamination of land-bound wildlife with unknown effects on their reproduction.

Accumulation of mercury in forested areas might also contribute to waterways for many years to come because the mercury might slowly run off the land and leach into watersheds.

My study is designed to compare mercury accumulation in several forest types in New York’s Catskill Mountains. The study takes place in the heavily forested Ashokan Reservoir watershed, an area that provides drinking water to approximately nine million people in and around New York City.

Image of man entering data into laptop in the woodsI am currently collecting samples of soils, leaves, leaf litter, insects that live in the leaf litter, salamanders that eat the insects of the leaf litter, and blood samples from birds that consume both insects and salamanders. In this way I will be able to identify the amount of “biomagnification” in the forest – the extent to which any mercury that is deposited by rainfall is increasingly concentrated in organisms higher and higher up the food chain. The study takes place at multiple elevations, from the banks of the Ashokan Reservoir at 600’ elevation to the headwater streams at the top of the Catskill’s highest peaks at over 4000 feet.

This information will be critical for identifying “biological hotspots” – areas that exceed the mercury levels deemed safe for human and wildlife populations. It will also provide monitoring information to help regulators determine the magnitude of mercury emissions reductions that will be necessary in the coming decades.