中文摘要：

长链烯酮不饱和度（U37k？）作为定量反映古温度变化的重要替代指标, 已在海洋中得到广泛应用, 但在湖泊中长链烯酮不饱和度与温度的关系及其母源研究则很少。课题组研究了中国不同气候带、不同水化学环境湖泊表层沉积物中长链烯酮, 发现多数湖泊中存在2~4个不饱和键的长链烯酮, 首次报道硫酸盐型湖泊中存在长链烯酮, 总结了湖泊中长链烯酮的分布模式, 探讨了分布模式与环境、母源的关系。研究了湖泊长链烯酮不饱和度与温度的关系, 发现湖泊长链烯酮不饱和度与年均气温和春秋季节温度高度相关, 建立了中国湖泊表层沉积物中长链烯酮不饱和度与温度的经验函数关系, 结合文献中发表的数据, 建立了从热带的北缘湖光岩玛珥湖到北极的格陵兰的湖泊沉积物中长链烯酮不饱和度与温度的经验函数关系： U37k′ = 0.031× T ＋ 0.094 （n=76, r^2 = 0.67）。首次发现并成功分离出湖泊中长链烯酮母源等鞭金藻Chrysotila lamellosa, 通过单藻种控温培养, 建立长链烯酮不饱和度与水温关系方程, 实验室培养公式与经验公式斜率一致, 验证了长链烯酮不饱和度温标, 表明长链烯酮是可靠的陆地温标。

英文摘要：

The alkenone unsaturation paleothermometer has been successfully and widely applied to reconstructing SST in most oceanographic settings. The utility of the alkenone unsaturation index in the marine system has stirred the interest in the study of LCK in the limnic system, in the hope that it can also be used as a paleotemperature proxy in lacustrine sediments. A suite of long-chain di-, tri- and tetra-unsaturated ketones whose chain lengths range from C37 to C39 with variable patterns of LCK were detected in the lake sediment samples. The ratio of C37：4 methyl ketone to the sum of C37 alkenones observed in different lakes is highly variable, and higher than that seen in marine systems. Different distribution patterns of LCK were detected in the surface sediment samples. The very high ratio of C37 / C38 may imply that dominant LCK-producing algae are probably similar to the species C. lamellosa and I. galbana. The detection of C38：4-2 ethyl alkenones suggests that the precursor organism might be similar to E. huxleyi G. oceanica and some species of Isochrysis galbana. However, if only C38：4-2 ethyl alkenone was identified, the precursor organism may be or closely related species to Chrysotila lamellosa or some species of Isochrysis galbana. Empirical relationships between the alkenone unsaturation index U37k＇and different tempera-ture sets （mean annual air temperature, mean annual air temperature in different seasons, and lake surface water temperature of July） were tested. The better correlation between U37k＇and temperature was obtained using mean annual air temperature, mean air temperatures of spring and autumn. Based on the new data from the reference the authors fit a new global linear regression of U37k＇and MAAT can be expressed as U37k＇ = 0.031？ T ＋ 0.094 （n=76, r2 = 0.67）, it covers the lake system from the lakes in Greenland to the lakes in the northern part of tropical area in China. Although problems such as species-uncertainty and other unknown factors for U37k＇temperature d