长江中下游典型红土剖面微生物类脂分子特征及其气候环境意义

The red earth in southern China is distributed to the north till the south of the Qinling Mountain -Huaihe River line and to the west till the east of Tibet.It has the widest distribution in the form of Quaternary earthy deposits in China. Abundant in formation about geology,envrionment,climate and Paleolithic culture has been available on it.Its significance can be compared favourably with loess deposits in North China. However,owing to the intensive pedogenesis in the tropical-subtropical area,the Vermicular rubified paleosol is proposed to be incapable of containing the original information about the past clomate and envrionment.Therefore, Previous studies on bio-climatic approaches including pollen and spore fossils and phytoliths are also believed not suitable for such kind of stratigraphy. It is necessary to introduce some new means to extract the detailed biological information in the red earth. Microbial lipid biomarkers,based on the powerful analysis of gas chromatography (GC) and GC-mass spectrometry (MS), enable a potential molecular record to trace the past changing climate.Some initial studies showed the significant microbial molecular fossil have the effectiveness in recording the paleoenvironment and related climate variation,but its implications in red earth need to be tapped and confirmed further. The Xuancheng profile of the red earth in Anhui Province ,located in Middle-Lower Yangtze River Region ,with sensitive change in climate and enough chronosequence will be studied in detail in this project.This project will develop field survey detailedly and collect sample systematically, employ the alkaline hydrolytic method to extract lipids from the red earth, study on the characteristic of the micobial lipids by simulation experiment and systematical analysis and Comprehensive research and comparative confirmation. Based on accurate evaluation on the pedogenesis of the later period of the red earth formation,we will reveal the potential implications of paleoclimate and environment further. Especially ,we hope to verify the validity of temperature index based on MBT/CBT from bGDGTs in top red earth and develop it the application in Pleistocene vermicular red earth in south China. Determination and application of implications of the microbial lipids in the red earth will develop a new breakthrough point for obtaining a more intensive paleoclimate evolution information.

中国南方更新世红土是古气候环境变化研究非常重要的载体之一，红土微生物类脂分子是其古气候环境研究的更有效指标，但其在红土中的古气候意义需要更进一步的挖掘和明确。本项目拟在几个典型红土层现代过程研究的基础上，以红土微生物类脂分子为红土更精细的古气候演化信息新的切入点，对处于气候变化敏感地带、已有很好年代学基础的安徽宣城剖面，进行详细的野外地质调查和样品采集，利用改善后的碱式水解法提取红土类脂分子，通过模拟实验、对比分析、比较印证等方法对其微生物类脂分子特征进行系统研究，正确评估其受后期影响程度，更进一步明确红土微生物类脂分子的古气候环境意义，特别是以期验证基于细菌bGDGTs的古温度指标MBT/CBT在中国南方表层红土中的适用性，拓展其在更新世红土中的应用。

为了进一步挖掘和明确中国南方更新世红土中微生物类脂分子的古气候环境意义，项目重点选取处于气候变化敏感地带、已有很好年代学基础的安徽宣城红土剖面，进行详细的野外地质调查和样品采集；运用改善后的碱式水解法提取红土微生物类脂分子，使用液相色谱—质谱联用仪对其进行分析测试，通过对比分析、比较印证等方法对其GDGTs特征进行系统研究。样品的GDGTs分布特征显示：剖面下部各环境指标波动较大，而上部成土环境相对稳定；土壤pH大致在7.0～8.0之间变化，推测最初成土环境为中性到弱碱性；从陆源输入指数BIT来看，宣城红土的BIT值并不都接近于1。表明红土中微生物类脂物GDGTs亦能够定量、高分辨率地重建安徽宣城的古气候环境，具有重要研究意义。