POST-GLACIAL HISTORY AND MODERN ATMOSPHERIC LEAD DEPOSITION FROM THE SEDIMENTARY RECORD IN LOUISA POND, ESOPUS, NY

Louisa Pond is a small, eutrophic pond situated atop the Shaupeneak Ridge in the town of Esopus, New York. The pond sits in the nose of the Marlboro syncline and acts as an excellent sediment trap. Two sediment cores were collected in February, 2011. The first was obtained with a Russian peat borer to a depth of 4.5 m and the second using a vibracorer to a depth of 9.0 m. The stratigraphy of the sediments records a complete post-glacial history of the pond. The vibracore had fibrous organic sediments (peat bog) at the top with a total thickness of 7.17 m, and below them was 1.31 m of open lake silts and clays. The core reached glacial till at 8.48 m depth. Sub-samples were taken every 20 cm, and analyzed for carbon content using the loss on ignition procedure to quantify weight percent organic carbon and inorganic carbonate content. The increase in organic content up core demonstrates the eutrophication of the lake through time. The Russian core was entirely composed of organic fiber and was sub-sampled at 10 cm intervals. These samples were digested with the oxidizing agents hydrogen peroxide and nitric acid. The resulting supernatant liquid was analyzed for lead concentration using flame atomic absorption spectrometry. This information was used to demonstrate the record of atmospheric lead concentration. The rise in lead levels corresponds to the invention and increased use of automobiles, and the peak lead concentration in the core represents the mid-1970's when leaded gasoline was phased out in the United States. Discrete peaks in lead concentration during the 19^th Century can be related to local industry including a lead paint factory just north of Louisa Pond in Saugerties, NY.