LONG-CHAIN ALKENONES IN QINGHAI LAKE-SEDIMENTS

Long-chain methyl and ethyl alkenones (C-37-C-40) containing two to fo ur double bonds have been detected in sediments from Qinghai Lake, Chi na. This is the first report of the alkenones in lake sediments, depos ited under a variety of salinity conditions, where the lake has not en countered any marine incursions. The presence of the alkenones suggest s 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 t he more highly unsaturated compounds. Widespread use of these compound s as paleotemperature indicators in marine sediments introduces the po ssibility of extrapolating this approach to lacustrine environments if appropriate calibrations can be undertaken.