STUDIES ON CLIMATIC CHANGE IN WESTERN DESERT AREAS IN CHINA AS DETERNINEDLONG CHAIN ALKENONE

Aim of this work is two-fold1)to identify long-chain alkenone in the saline lake sediments collected in the deep western desert area of China and 2)to clarify variability of lake water temperature after latest glacier maximum to present as calculated unsaturation index of long-chain alkenone which has been reported to exist in Coccolithophoride fossils of marine sediments。Following results were obtained：·A series of long-chan alkenones with carbon numbers of 37，38and39which have Several unsaturated C-C bonds were analyzed by retention time in gas Chromatography.·The long-chain alkenones were identified as di-，tri，tetra-unsaturated C_&lt；37&gt；alkenone by the combined gas chromatography-mass spectrometer.From the alkenone composition，we can calculated the unsaturate indices by which in situ temperature of lake water were determined as 4.8℃by using of Sawada-Handa Equation in the Lake Aibi.·Several spices of coccolithophoride including Gephaerocapsa sp.were identified as phytoplankton producing long-chain alkenone by both microscopy and scanning electron microscopy.·These data strongly suggest that long-chain alkenone analyses must be promising tool to explore paleoclimate change in the deep wester desert areas of China.

Aim of this work is two-fold 1) to identify long-chain alkenone in the saline lake sediments collected in the deep western desert area of China and 2) to clarify variability of lake water temperature after latest glacier maximum to present as calculated unsaturation index of long-chain alkenone which has been reported to exist in Coccolithophoride fossils of marine sediments.The saline lake sediments collected from Lake Aibi in Zhunger desert of the deep western China and analyzed for alkenones with carbon number of 37 to calculate unsaturation index of these compounds. Following results were obtained :・A series of long-chan alkenones with carbon numbers of 37,38 and 39 which have Several unsaturated C-C bonds were analyzed by retention time in gas Chromatography.・The long-chain alkenones were identified as di-, tri, tetra-unsaturated C_<37> alkenone by the combined gas chromatography-mass spectrometer. From the alkenone composition, we can calculated the unsaturate indices by which in situ temperature of lake water were determined as 4.8℃ by using of Sawada-Handa Equation in the Lake Aibi.・Several spices of coccolithophoride including Gephaerocapsa sp.were identified as phytoplankton producing long-chain alkenone by both microscopy and scanning electron microscopy.・These data strongly suggest that long-chain alkenone analyses must be promising tool to explore paleoclimate change in the deep wester desert areas of China.