高浊度河流生物地球化学过程对渤海GDGTs指标影响的研究

近年来，基于微生物标志物GDGTs的分子代用指标在重建海洋(湖泊)表层水温度和陆地气温以及指示有机碳来源等方面展现出了巨大的潜力，成为古海洋学、古湖泊学和生物地球化学关注的热点。在我国陆架边缘海，由于受到长江、黄河、珠江等大河的强烈影响，GDGTs指标与环境因子之间的关系远比陆地和大洋复杂，因此有必要研究河流控制陆架边缘海的现代过程，以评估TEX86、MBT/CBT和BIT作为古环境和古气候指标的区域可靠性。本项目拟分析黄河-渤海悬浮颗粒物、沉积物及土壤中的极性和核心GDGTs，结合其他地球化学参数和分子生物学数据，评估高浊度河流中GDGTs的原位生产效应及控制因素，揭示长距离河流搬运中支链和类异戊二烯GDGTs的环境稳定性，并探讨河流生物地球化学过程对渤海GDGTs来源、组成和指标的影响。在此基础上，利用渤海沉积物重建全新世海水温度和陆地气温的变化，揭示黄河流域全新世季风的演化。

Recently,a series of molecular proxies based on microbial biomarkers, so-called Glycerol Dialkyl Glycerol Tetraethers (GDGTs) have been proposed and used for the reconstruction of sea(lake) surface temperature, continental air temperature and organic matter sources. These GDGTs-based proxies such as TEX86, MBT/CBT and BIT index have become a hot topic in Paleoceanography, Paleolimnology and Biogeochemistry. In the China continental margins, due to intense influences of large rivers such as Yangtze River, Yellow River and Pearl River，the relationship between the GDGTs-proxies and environmental factors is much more complex than in land and open ocean. Consequently, the global temperature calibration equations of TEX86 and MBT/CBT can not be directly applied in these regions without local calibration. Here, we choose the Yellow River-Bohai Sea as our study area, and examine intact polar GDGTs and core GDGTs in suspended particles, sediments and soils. By combining GDGTs,bulk geochemical parameters and molecular microbiology data, we attempt to evaluate the in-situ production of GDGTs in this high turbid river and its controlling factors, relative stability of isoprenoid and branched GDGTs during long-range transport from the mid-Yellow River to Bohai Sea, as well as the influence of the biogeochemical processes in the Yellow River on the source, composition and proxy reliability of GDGTs in the Bohai Sea. Based on these results, we will analyze GDGTs in sediment cores from certain areas of the Bohai Sea, which are suitable for application of MBT/CBT and TEX86, and reconstruct Holocene variability in sea surface temperature and continental air temperature, thereby understanding the Holocene evolution of East Asian Monsoon in the Yellow River basin.