Long-chain alkenones in Qinghai Lake sediments

Long-chain methyl and ethyl alkenones (C-37-C-40) containing two to four double bonds have been detected in sediments from Qinghai Lake, China. This is the first report of the alkenones in lake sediments, deposited under a variety of salinity conditions, where the lake has not encountered any marine incursions. The presence of the alkenones suggests the presence of Prymnesiophyceae in the lake which may have reached the lake via eolian transportation or seabirds. Sediment samples from the more saline areas of the lake contained higher concentrations of the more highly unsaturated compounds. Widespread use of these compounds as paleotemperature indicators in marine sediments introduces the possibility of extrapolating this approach to lacustrine environments if appropriate calibrations can be undertaken.