HR: 1330h
AN: PP32B-0289    [PDF]
TI: Biomarker Records of Lake Albano (central Italy) and Lake Constance (southern Germany)- Implications for environmental change in the Holocene and Younger Dryas
AU: * Hanisch, S
EM: shanisch@awi-bremerhaven.de
AF: Alfred Wegener Institute for Polar and Marine Research, Columbusstrasse, Bremerhaven, D-27515 Germany
AU: * Hanisch, S
EM: shanisch@awi-bremerhaven.de
AF: Institut fuer Umweltgeologie, Technische Universitaet Braunschweig, Pockelsstrasse 3, Braunschweig, D-38106 Germany
AU: Schwalb, A
EM: antje.schwalb@tu-bs.de
AF: Institut fuer Umweltgeologie, Technische Universitaet Braunschweig, Pockelsstrasse 3, Braunschweig, D-38106 Germany
AU: Ariztegui, D
EM: daniel.ariztegui@terre.unige.ch
AF: Institute Forel and Department of Geology and Paleontology, University of Geneva, Rue des Maraicher 13, Geneva, 1205 Switzerland
AU: Wessels, M
EM: martin.wessels@lfula.lfu.bwl.de
AF: Institut fuer Seenforschung der Landesanstalt fuer Umweltschutz Baden-Wuerttemberg, Argenweg 50, Langenargen, D-88081 Germany
AU: Puettmann, W
EM: puettmann@kristall.uni-frankfurt.de
AF: Institut fuer Mineralogie-Umweltanalytik, Universitaet Frankfurt, Georg-Voigt-Str. 14, Frankfurt, D-60054 Germany
AB: Steroids, triterpenoids and n-alkanes from a 13 m Holocene sediment core from Lake Albano and a 7 m Late Pleistocene/Holocene core from Lake Constance (13,000 to 650 years BP) as well as pigments, pollen and stable isotopes from benthic ostracodes, are used to reconstruct climatic changes and human impact on the lake systems and their catchments. Dinosterol, isoarborinol, hopanoids, and tetrahymanol in Lake Albano sediments indicate changes in the biological assemblages and enhanced lake mixing and thus stronger wind activity at around 6,500 and 3,800 years BP. A development from forest to a more open landscape in the Lake Albano catchment from 5,000 years BP is suggested by a decrease of n-alkanes derived from deciduous trees (C27 and C29). N-alkanes, friedelin and amyrenones show a close correspondence with the percentage of broadleaf-tree pollen, indicating deforestation after 5,000 and 6,500 years BP,. High concentrations of land-plant derived $\beta$-sitosterol in Lake Constance sediments during the Younger Dryas indicate erosive input due to sparse vegetation. The increase of $\beta$-sitosterol after 7,000 years BP suggests terrigenous input as a result of enhanced precipitation. Dinosterol distribution traces a period of high productivity between 11,600 and 7,000 years BP. Tetrahymanol, a biomarker for ciliates and possibly an indicator for water column stratification, shows relatively high concentrations at approximately 9,000 years BP. This coincides with a 4 $\permil$ shift to more negative values of $\delta$ 13C in the ostracode L. mirabilis, suggesting hydromechanic changes in Lake Constance.
DE: 1055 Organic geochemistry
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting