HR: 1340h
AN: PP43B-1274    [Abstracts]
TI: Alkenone temperature and salinity: An evaluation of long chain C37 alkenone in Lake Qinghai, China
AU: * Liu, W
EM: liuwg@loess.llqg.ac.cn
AF: Weiguo Liu, Institute of Earth Environment, Xi'an, 710075, China
AU: Liu, Z
EM: zhonghui.liu@yale.edu
AF: Zhonghui Liu, Yale University, New Haven, CT 06520, United States
AU: Fu, M
EM: fmy@ieecas.cn
AF: Weiguo Liu, Institute of Earth Environment, Xi'an, 710075, China
AU: An, Z
EM: anzs@loess.llqg.ac.cn
AF: Weiguo Liu, Institute of Earth Environment, Xi'an, 710075, China
AB: In recently years, the alkenone unsaturation index (Uk'37=C37:.2/(C37:2+ C37:3)) has been used to reconstructed paleo-temperature for lacustrine sediments. However, few studies have addressed whether the relative abundance of the C37:4 alkenone to the total C37 production (C37:4 percent) can reflect surface salinity changes in lake systems. Here we present the distribution of C37 long chain alkenone of modern lake sediments in Qinghai Lake, Qing-Tibet Plateau, to evaluate significance of abundance change of long chain C37 alkenone as an indicator of lake paleo-enviromental evolution. A group of surface sediments from different locations in the lake have been analyzed in this study. The results of long chain C37 alkenone from 28 surface sediments analyses shown relative abundance of C37:4 alkenone to total C37 production (C37:4 percent) change from 14.5 to 48.6 percent and the abundance of C37:4 alkenone is increasing with decreasing salinity of lake water. For the salinity lake in land, we suggested the relative abundance of C37:4 alkenone in lake sediments may be a indicator of paleo-silinity; We have also found that Uk'37 values are weakly correlated with salinity and C37:4 percent changes, implying that potential minor contributions of temperature and salinity effects to C37:4 percent and Uk'37 respectively cannot be excluded in this study. However, since these contributions are weak, we suggest that the C37:4 percent proxy can be used to reconstruct paleo-salinity changes at a regional scale, especially in lake systems, while Uk'37 remains as a powerful tool for reconstructions of paleo-temperature changes in the lake systems.
DE: 1055 Organic and biogenic geochemistry
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting