Eastern Mineral and Environmental Resources Science Center
Overview of Lake Superior study
Accomplishments and Description of Field Work
Contact for further information
Geologists Connie Dicken, Laurel Woodruff, and Shana Pimley (l. to r.) preparing to sample soil, Voyageurs National Park.
Mercury as an environmental contaminant is a concern in the Lake Superior region including some National Parks where there are high levels of mercury in game fish in many Park lakes. This contamination can create health problems both for humans and wildlife that consume fish. A critical question for land and resource managers and regulators is whether this contamination is from local sources, including anthropogenic sources, vs. regional or global mercury emissions.
Our research in Isle Royale National Park, Michigan, and Voyageurs National Park, Minnesota, and in nearby Superior and Chequamegon National Forests, is helping to define the factors that control mercury accumulations in forests, and the relationship between mercury content in forest soils and mercury contamination of aquatic ecosystems.
In particular we have identified forest fires as a principal factor in the mercury cycle because of the ability of fire to volatilize mercury sequestered in forest floor organic material.
Working in conjunction with the National Park Service and the US Forest Service, we have been collecting soil samples in several studies areas in the Lake Superior region. Typically we collect three soil samples from a single site: O-, A-, and C-horizon soils. On Isle Royale we also collected paired lichen samples from soil sample sites. Samples are air dried and submitted for geochemical analysis to the USGS.
To study the effects of fire on soil geochemistry, we have sampled across the 1936 burn areas in Voyageurs and Isle Royale National Parks. The fires of 1936 were particularly severe in the Upper Midwest, killing large stands of timber and in many areas burning soils down to bare bedrock.
At Snowbank Lake in the Superior Forest, we sampled before a prescribed burn in 2000 and resampled the same sites 4 times in the following 3 years.
For 3 years we have been monitoring post-fire response in soils in a prescribed burn area in Superior National Forest near Snowbank Lake, Minnesota. Preliminary results are presented in a number of abstracts listed below (products section).
Cannon, W.F., and Woodruff, L.G., 2003, The geochemical landscape of northwestern
Wisconsin and adjacent parts of northern Michigan and Minnesota (geochemical
data files): U.S.
Geological Survey Open-File report 03- 259, onine only, version 1.0.
Cannon, W.F. and Woodruff, L.G., 2000, Some factors that control the distribution of mercury in surficial materials in Isle Royale National Park- earth, wind, and fire (abs): Institute on Lake Superior Geology, 46th Annual Meeting, Proceedings Volume 46, p. 8-9
Cannon, W.F., Dean, W.E., and Bullock, J.H., 2001, Eleven thousand years of mercury deposition in Elk Lake, Minnesota: effects of climate and vegetation change on the mercury cycle (abs): 2001, Geological Society of America, 2001 Annual Meeting, Abstracts with Program, v. 33, p. 186.
Cannon, W.F., Dean, W.E., and Bullock, J.H., 2001, Eolian deposition of mercury in Elk Lake, Minnesota - the impact of Holocene climate fluctuations on the mercury cycle (abs): International Association of Great Lakes Research, 45th Conference, p. 19.
Woodruff, L.G. and Cannon, W.F., 2002, Impact of fire on the forest floor and mineral soils, Snowbank Lake, Minnesota (abs): Institute on Lake Superior Geology, 48th Annual Meeting, Proceedings Volume 48, p. 54-55.
Woodruff, L.G., Cannon, W.F., Dicken, C.L., Bennett, J.P., and Nicholson, S.W., 2003, Bedrock, Soil, and Lichen Geochemistry from Isle Royale National Park, Michigan: U.S. Geological Survey Open-File Report 03-276, Version 1.0 .
Woodruff, L.G., Cannon, W.F., Dicken, C.L., and Pimley, S., 2002, Bedrock and Soil Geochemistry from Voyageurs National Park, Minnesota: U.S. Geological Survey Open-File Report 02-196, Online Only, Version 1.0.
Woodruff, L.G., and Cannon, W.F., 2001, The effect of fire on mercury and carbon in forest soils: results from northern Michigan and Minnesota (abs): Geological Society of America, 2001 Annual Meeting, Abstracts with Program, v. 33, p. 186.
Woodruff, L.W., Harden, J.W., Cannon, W.F., and Gough, L.P., 2001, Mercury loss from the forest floor during wildfire (abs): EOS Transactions of American Geophysical Union, 82(47), Fall Meeting Supplement, Abstract B32B-0017.
Woodruff, L.W., Cannon, W.F., and Dicken, C.L., Impact of fire on the geochemistry of forest soils: poster available on line at http://firescience.cr.usgs.gov/html/woodruff_abs02.html .
USGS Geologists William Cannon and Connie Dicken sampling soils in Isle Royale National Park. Samples are carefully collected according to soil horizon to determine soil mass per unit area.
William F. Cannon, Geologist
U.S. Geological Survey
Eastern Mineral Resources
954 National Center
Reston, VA 20192
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