Mercury in Soils, Lakes, and Fish in Voyageurs National Park (Minnesota):? Importance of Atmospheric Deposition and Ecosystem Factors

Mercury in Soils, Lakes, and Fish in Voyageurs National Park (Minnesota):? Importance of Atmospheric Deposition and Ecosystem Factors

2006

Concentrations of methylmercury in game fish from many interior lakes in Voyageurs National Park (MN, U.S.A.) substantially exceed criteria for the protection of human health. We assessed the importance of atmospheric and geologic sources of mercury to interior lakes and watersheds within the Park and identified ecosystem factors associated with variation in methylmercury contamination of lacustrine food webs. Geologic sources of mercury were small, based on analyses of underlying bedrock and C-horizon soils, and nearly all mercury in the O- and A-horizon soils was derived from atmospheric deposition. Analyses of dated sediment cores from five lakes showed that most (63% ± 13%) of the mercury accumulated in lake sediments during the 1900s was from anthropogenic sources. Contamination of food webs was assessed by analysis of whole, 1-year-old yellow perch (Perca flavescens), a regionally important prey fish. The concentrations of total mercury in yellow perch and of methylmercury in lake water varied substantially among lakes, reflecting the influence of ecosystem processes and variables that affect the microbial production and abundance of methylmercury. Models developed with the information-theoretic approach (Akaike Information Criteria) identified lake water pH, dissolved sulfate, and total organic carbon (an indicator of wetland influence) as factors influencing methylmercury concentrations in lake water and fish. We conclude that nearly all of the mercury in fish in this seemingly pristine landscape was derived from atmospheric deposition, that most of this bioaccumulated mercury was from anthropogenic sources, and that both watershed and lacustrine factors exert important controls on the bioaccumulation of methylmercury.

Wiener, James G
Knights, B. C.
Sandheinrich, Mark B
Jeremiason, J. D.
Brigham, Mark E.
Engstrom, Daniel R.
Woodruff, Laurel G

USGS, La Crosse
Gustavus Adolphus College
St. Croix Watershed Research Station: Science Museum of MN

8

Surface Water
Water Conveyance & Hydraulics
Water Education, Outreach & Community Capacity

surface water
surface waters
surface-water
surface-waters
surfacewater
surfacewaters
ecosystem
ecosystems
fish health
water quality & pollutants
water quality and pollutants
water biology & aquatic habitat
water biology and aquatic habitat
water biology & aquatic habitats
water biology and aquatic habitats
mercury
methyl-mercury
methylmercury
MeHg
methyl mercury

2000-2009

Yes

Do Not Have Copyright Permission

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