Characterisation of alkenone temperature indicators in sediments and organisms

Abstract

Recent literature reports have suggested the use of long chain ( n-C 37) alken-2-ones in Quaternary marine sediments as a palaeoclimate indicator. They occur as di-, tri- and tetra-unsaturated components whose relative abundances are measured as an internal ratio (U 37 k). Since the precise structures of the compounds were unknown, both the all- Z and all- E isomers of the gross structures assigned previously have been synthesised. GC coinjection studies indicate that the natural components in the alga Emiliania huxleyi and in marine sediments have the unusual and unexpected E configuration. The synthesised compounds offer promise as standards for the development of more sensitive and specific methods for measurement of U 37 k ratios.