Molecular and Isotopic Fate of Alkenones and Alkenes During Early Diagenesis

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9617892 Harvey The use of molecular organic markers has provided valuable information on a wide range of inputs and processes which occur in the worlds oceans and sediments. What is often absent from these observations, is quantitative information on the relationship of biological processing in the water column and sediments to the molecular signal which is ultimately preserved in the geological record. Such information may be particularly important for the long chain alkenones, a group of compounds present in several species of oceanic and coastal prymnesiophyte algae which are now being widely used to detail both recent and historical records of sea surface temperature. Recent disparities in temperature predictions and isotopic signature have been observed, yet no mechanistic information is available on the alkenones and related lipids after initial cellular biosynthesis to document diagenetic effects. This work will focus on the two major routes for the alteration of alkenones, alkenes and alkyl alkenoates in marine systems: zooplankton grazing and microbially mediated processes. The project will provide fundamental information on the synthesis and fate of the alkenones and related lipids in the marine water column and surface sediments and validate the potential for these compounds or their degradation products to provide a quantitative measure of sea surface temperature in present and past oceans. ***