SS3.17 Global Mercury Cycling: From Natural to Anthropogenic Sources
Date: Tuesday, June 11, 2002
Time: 10:00:00 AM
Location: Carson C
 
EdgarNT, U.S. Geological Survey, St.Petersburg, USA, tedgar@usgs.gov
Jacobson, G, L, University of Maine, Orono, USA, jacobson@maine.edu
Holmes, C, W, U.S. Geological Survey, St. Petersburg, USA, cholmes@usgs.gov
Swarzenski, P, W, U.S. Geological Survey, St. Petersburg, USA, pswarzen@usgs.gov
McNeal, J, M, U.S. Geological Survey, Reston, USA, jmcneal@usgs.gov
 
PREHISTORIC ELEMENTAL MERCURY CONCENTRATION FOR THE LAST 70,000 YEARS: LAKE TULANE, FLORIDA
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An 18-m-long sediment core taken from Lake Tulane, Florida, was analyzed at 10-cm intervals for total mercury variability over the late Quaternary. The core was dated to 31 ka by 14 C and extrapolated to 70 ka by correlating to Heinrich events. Results of analyses for elemental mercury concentrations identified four major peaks since the last glacial maximum. These peaks are at about 18, 13, 10, and 6 ka, (calendar years, BP). Concentrations of mercury between 28 and 18 ka are at about background levels (30-40 ug/kg dry weight), but there are peaks of less magnitude than the four cited above at 60, 50, 35, and 28 ka. There is a general correlation between high mercury concentrations and dry periods in central Florida as determined by oak and pine pollen. This correlation suggests that atmospheric mercury in Florida is concentrated during dry periods but is removed from the atmosphere and deposited by precipitation from local storms. The source of the mercury remains unknown.