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Historical deposition of mercury and selected trace elements to high-elevation National Parks in the Western U.S. inferred from lake-sediment cores

January 1, 2010

Atmospheric deposition of Hg and selected trace elements was reconstructed over the past 150 years using sediment cores collected from nine remote, high-elevation lakes in Rocky Mountain National Park in Colorado and Glacier National Park in Montana. Cores were age dated by 210Pb, and sedimentation rates were determined using the constant rate of supply model. Hg concentrations in most of the cores began to increase around 1900, reaching a peak sometime after 1980. Other trace elements, particularly Pb and Cd, showed similar post-industrial increases in lake sediments, confirming that anthropogenic contaminants are reaching remote areas of the Rocky Mountains via atmospheric transport and deposition. Preindustrial (pre-1875) Hg fluxes in the sediment ranged from 5.7 to 42 μg m−2 yr−1 and modern (post-1985) fluxes ranged from 17.7 to 141 μg m−2 yr−1. The average ratio of modern to preindustrial fluxes was 3.2, which is similar to remote lakes elsewhere in North America. Estimates of net atmospheric deposition based on the cores were 3.1 μg m−2 yr−1 for preindustrial and 11.7 μg m−2 yr−1for modern times. Current-day measurements of wet deposition range from 5.0 to 8.6 μg m−2 yr−1, which are lower than the modern sediment-based estimate of 11.7 μg m−2 yr−1, perhaps owing to inputs of dry-deposited Hg to the lakes.

Citation Information

Publication Year 2010
Title Historical deposition of mercury and selected trace elements to high-elevation National Parks in the Western U.S. inferred from lake-sediment cores
DOI 10.1016/j.atmosenv.2010.04.024
Authors Alisa Mast, David J. Manthorne, David A. Roth
Publication Type Article
Publication Subtype Journal Article
Series Title Atmospheric Environment
Series Number
Index ID 70179813
Record Source USGS Publications Warehouse
USGS Organization Colorado Water Science Center