南极两站地区湖泊沉积物分子化石记录及其古环境意义

Global change is a significant theme for human sustainability in 21 century. Antarctic, as the last "pure land" , has been a natural laboratory to carry out scientific research of global change studies, especially the Antarctic lake which is rarely impacted by people activities. The biomarkers in Antarctic lake sediments contain a large number of paleoenvironmental information and can be a ideal carrier to restore the ancient environment. Biomarkers，the remnant of organisms formed in the stratum in the geological period after the lengthy geological reformation，could still remain their original C-structure to a varying extent．Based on sampling with high resolution，the biomarkers can reveal paleo-biological and paleo-environmental changes of ten years period，hundreds years period or thousands years period．Studies about Antarctic environment evolution in the past mainly focus on Antarctic ice cores, penguins, seals and giant petrels' remains, excrements, and relics. The related study of biomarkers in lake sediments is relatively weak..In this study, lake sediments of Changhu Lake near GreatWall station and Heart Lake near Zhongshan station will be used to research. Using organic geochemical methods identify biomarkers, analysis its characteristics and the original biological source, establish the relationship between the biomarkers and the palaeoenvironment, then discuss the application of the sedimentary environment through biomarker characteristics. Furthermore, by comparing the respective biomarkers characteristics of two lakes, research the evolution trends of paleoenvironment in the Antarctic region since Holocene..This research will provide more available information for us as biomarkers (molecular fossils) and the global change research.

全球变化是当前国际地学界关注的热点问题。南极作为人类"最后的净土"， 是开展全球变化科学研究的特殊天然试验场地，尤其是南极内陆湖泊系统的演化甚少受到人类活动的影响，湖泊沉积物中的生物标志化合物包含了众多古环境信息，因而是恢复古环境演变的理想地质载体。以往对南极环境演变的研究主要以南极冰芯或如企鹅、海豹、巨海燕等的遗体、排泄物、遗迹等作为主要研究载体，对湖泊沉积物的研究还相对薄弱。本研究以南极中国长城站区长湖和中山站团结湖湖相沉积物岩芯柱为主要研究载体，采用有机地球化学方法，分析对比两湖沉积物中生物标志化合物的类型、特征及原始生物来源，建立生物标志化合物指标与古环境的关系，反演全新世以来南极地区古环境演变，进而探讨全球变化在南极地区的响应，同时也为生物标志化合物（分子化石）与全球变化的关系研究提供更多可供利用的信息。

项目对南极长城站西北部的海豹滩沉积物和动物粪土样品中有机碳、碳、氮同维斯、氯仿沥青“A”和萜烷、甾烷等饱和烃、以及铜同位素等进行检测分析，研究了海豹滩沉积物中有机地球化学特征，取得了如下认识：（1）海豹滩沉积物中有机碳含量较低，平均值为0.34%，海豹粪便样品的有机碳含量较高接近2%；（2）TOC/TN值显示有机质主要来源于陆生植物，δ13C值均在-25‰左右，也说明其沉积物中的有机质来源于陆生植物；（3）沥青“A”的含量与TOC的含量之间并无特征的相关关系，沉积柱中表层与深层相比，沥青“A”的含量较深部明显偏低；（4）沉积物中均检测到C19~C29的三环萜烷，以C23为主峰，在C26-三环萜烷前，均检测到明显的C24-四环萜烷，显示高等植物来源特征；（5）甾烷显示了较丰富的陆源母质输入和水生生物混合为主要特征。以上研究发现南极地区由于天气寒冷，沉积物中有机碳含量较少，但是生物标志化合物还是具有明显的特征，这也为下一步更深入的研究提供了依据。在接下来的工作中，将对极地环境和中国内陆环境进行比对研究，深化全球变化研究。