We present a case study comparing metrics of methylmercury (MeHg) contamination for four undeveloped lakes in Voyageurs National Park to wet atmospheric deposition of mercury (Hg), sulfate (SO4-2), and hydrogen ion (H+) in northern Minnesota. Annual wet Hg, SO 4-2, and H+ deposition rates at two nearby precipitation monitoring sites indicate considerable decreases from 1998 to 2012 (mean decreases of 32, 48, and 66%, respectively). Consistent with decreases in the atmospheric pollutants, epilimnetic aqueous methylmercury (MeHg aq) and mercury in small yellow perch (Hgfish) decreased in two of four lakes (mean decreases of 46.5% and 34.5%, respectively, between 2001 and 2012). Counter to decreases in the atmospheric pollutants, MeHg aq increased by 85% in a third lake, whereas Hgfish increased by 80%. The fourth lake had two disturbances in its watershed during the study period (forest fire; changes in shoreline inundation due to beaver activity); this lake lacked overall trends in MeHgaq and Hg fish. The diverging responses among the study lakes exemplify the complexity of ecosystem responses to decreased loads of atmospheric pollutants. © 2014 American Chemical Society.
CITATION STYLE
Brigham, M. E., Sandheinrich, M. B., Gay, D. A., Maki, R. P., Krabbenhoft, D. P., & Wiener, J. G. (2014). Lacustrine responses to decreasing wet mercury deposition rates-results from a case study in northern Minnesota. Environmental Science and Technology, 48(11), 6115–6123. https://doi.org/10.1021/es500301a
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