HR: 08:15h
AN: B41A-02    [PDF]
TI: Oxygen, Carbon, and Nitrogen Isotopic Evidence of Environmental Changes in Eastern Lake Erie Over the Past Century
AU: Knowlton, C K
EM: knowltck@hotmail.com
AF: Department of Geological Sciences, The University of Michigan, 425 East University Avenue, Ann Arbor, MI 48109-1063 United States
AU: * Meyers, P A
EM: pameyers@umich.edu
AF: Department of Geological Sciences, The University of Michigan, 425 East University Avenue, Ann Arbor, MI 48109-1063 United States
AU: Eadie, B J
AF: Great Lakes Environmental Research Laboratory (NOAA), 2205 Commonwealth Boulevard, Ann Arbor, MI 48105-2945 United States
AU: Robbins, J A
AF: Great Lakes Environmental Research Laboratory (NOAA), 2205 Commonwealth Boulevard, Ann Arbor, MI 48105-2945 United States
AB: The oxygen isotopic composition of calcium carbonate that precipitates in hardwater lakes is affected by meteorologic factors whereas the inorganic and organic carbon and nitrogen isotopic compositions lake sediments are influenced by biological productivity within the lake. We have measured the isotopic compositions at 1-cm intervals in three cores of Lake Erie sediment that span the period 1895 to 1991, and we have compared these parameters to meteorological records and to mass accumulation rates of the aquatic productivity proxies, organic carbon and calcium carbonate. Calcite d18O values that become smaller from 1980 to 1991 in the absence of evidence of a summer temperature change suggest a decadal change in air mass trajectories. In contrast, a shift to larger d18O values from 1905 to 1910 that is accompanied by diminished calcite precipitation and higher lake levels suggests a period of cooler summer temperatures. Increases in inorganic and organic d13C values, d15N values, and organic carbon accumulation starting in 1960 reflect the heightened productivity caused by anthropogenic nutrient increases to Lake Erie.
DE: 1803 Anthropogenic effects
DE: 1833 Hydroclimatology
DE: 1845 Limnology
DE: 4870 Stable isotopes
SC: Biogeosciences [B]
MN: 2003 Fall Meeting