山西阳城岩溶湖泊年分辨率类脂生物标志物气候环境意义研究

Lipid biomarkers in lake sediments contain a wealth of climatic and environmental information, which have been widely used in paleoclimate and paleoenvironment reconstructions. The significances of the biomarker indicators, however, still have multiple solutions and uncertainties, which need further investigation. By many field surveys, we found that the sediments of the karst lakes in the Xicheng Mountain of Yangcheng, Shanxi Province have clear varves which were preliminarily identified as annual layers by using 210Pb and 137Cs dating and lamina counts methods. In this study, representative karst lake sediments in Yangcheng area of Shanxi Province were selected as the research objects. Sediment traps were used to obtain deposit samples in freezeup period and non-freezeup period to analyze the distribution differences of lipid biomarkers in different depositional environments. Lipid biomarkers were also extracted from laminated clay to establish lipid biomarker records with annual resolution. By using daily meteorological data from Yangcheng meteorological station and RClimDex software to calculate extreme climate indices, and combined with the XRF elemental abundance, organic carbon and nitrogen isotope value, carbonate content, magnetic susceptibility and particle size to explore the refined climatic information of lipid biomarkers in karst lakes. This study will provides a new method for the climatic and environmental reconstruction by using lipid biomarkers in lake sediments.

湖泊沉积物类脂生物标志物蕴含了丰富的气候环境信息，已广泛应用于第四纪古气候、古环境重建，但其代用指标的指示意义尚存在多解性，亟需进一步精细化。申请者通过前期野外调查探明山西阳城地区岩溶湖泊沉积物保存有清晰的层理，采用210Pb和137Cs测年结合纹层计数初步确定其为年纹层。在此基础上拟利用沉积物捕获器获取非冰封期与冰封期沉积样品，分析不同沉积条件下类脂生物标志物分布特征的异同，查究不同沉积阶段生标指标的指代性；并根据湖泊沉积纹层提取类脂生物标志物，尝试建立年分辨率的类脂生物标志物变化序列。进而利用阳城台站近60年以来逐日气象资料以及RClimDex程序计算极端气候指数，结合XRF元素丰度、有机碳氮含量及同位素值、碳酸盐含量、磁化率、粒度等常规理化指标，探索岩溶湖泊中类脂生物标志物指标精细化的气候/环境意义。本次研究将为今后选用湖泊沉积物类脂生物标志物开展气候/环境重建工作提供新的思路。

岩溶湖是喀斯特地区常见的一类湖泊，我国存在大量因岩溶作用而形成的山地岩溶湖泊。此类湖泊的沉积物记录了丰富的气候、环境变化信息，是我们评价喀斯特地区气候状况和预测未来环境演变趋势的珍贵资料。本项目选择位于山西太行山南部圣王坪娘娘湖作为研究对象，钻取连续的沉积物岩芯，通过放射性核素测年(210Pb和137Cs)及纹层计数建立精确的年代序列，进而确定山西阳城圣王坪岩溶湖沉积纹层为年纹层。同时以沉积物中的地球化学指标(生物标志化合物、有机碳氮同位素、元素含量等)为气候代用指标，在详细的湖泊流域现代环境过程研究基础上，定量重建了近60年以来的气候环境变化。在此基础上，将各类指标变化与南方涛动指数(SOI)以及北大西洋涛动指数(NAO)进行对比，探索了山西南部降水以及气温变化与ENSO现象之间的联系。查明了山西南部地区气候变化的机制，推进了我国岩溶湖泊沉积物研究在古气候、古环境演变中的作用，为今后相关研究提供了关键参考资料。项目已发表SCI检索论文3篇，核心期刊论文1篇，培养硕士研究生3名。并组织课题组人员参加了国内学术会议并做相关学术报告，取得了良好的交流成效。其研究结论可应用于我国喀斯特地区古气候重建以及岩溶环境评价中，相关成果转化及应用工作正在逐步推进中。