ELEMENTAL MERCURY CONCENTRATION AND 40-ELEMENT ICP ANALYSES FOR LAST 70 KY: LAKE TULANE, FL

An 18-m-long sediment core taken from Lake Tulane, Florida, was analyzed at 10-cm intervals for 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 6-, 10-, 13-, and 18-ky (calendar years, BP). Concentrations of mercury between 18- and 28 ky are at about background levels (30-40 ug/kg dry weight), but there are peaks of less magnitude than the four cited above at 28-, 35-, 50-, and 60 ky. There is a general correlation between high mercury concentrations with 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. ICP analyses are being studied for correlation of elements with mercury levels and possible relation to dust as a transporting agent. The source of the mercury remains unknown.