GEOC 1 |
| The hydrogen isotopic composition (D/H) of of aquatic and terrestrial derived lipid biomarkers is increasingly used to reconstruct paleohydrological changes throughout the geological time. A number of calibrations are now available and have shown that algal lipids record the isotopic composition of the water source used. Lipid D/H values from lake surface sediments along a climatic gradient through Europe record the source water D/H ratios. However, culture studies have shown that variable fractionation factors exist among different species. We examined how salinity affects the lipid isotopic composition of cyanobacteria and found a decreasing fractionation with increasing salinity. The isotopic composition of terrestrial lipids is influenced by even more variables as a number of plant physiological processes such as evapotranspiration influence the lipid D/H signal. We further show that significant seasonal variations in the isotopic composition of leaf waxes exist. Accumulation of terrestrial and aquatic lipids in sediments integrates these influences over spatial as well as temporal scales. We show that a thorough understanding of these processes affecting the D/H ratio of lipids is essential when using them for paleoclimate reconstruction. |
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Modern Calibrations and Terrestrial Applications of Stable Isotope Paleo Proxies
9:00 AM-12:10 PM, Sunday, August 19, 2007 Boston Park Plaza -- St. James Rm, Oral
Division of Geochemistry |