两种温度指标(Uk'37和TEX86) 的现代水体调查和沉积记录整合研究

Paleothermometer-TEX86 displayed great potential application in the past climate research since its establishment 10 years ago.However, notable discrapacy were found between TEX86 and other paleotemperature proxies in variable areas and different geology periods, And more research is forcusd on the paleorecord and seldom on the modern observation. Thus,in ththe present proposal, two organic paleothermomters: UK' 37 and TEX86 will be investigated through the integration of the past and present. Alkenones and Archaeal tetraethers will be detected in the typical oceanic region with different depth, to understand the modern seasonal and special distribution of the corresponding organisms (Coccolithophore and Archaeota, respectively) and their influence on the corresponding organic paleothermomters. Meanwhile, comparison between these two organic paleotemperature proxies since the last glaciation in the deep sea sediment will promote our understanding on the mechanism and implication of the two proxies on the glacial/interglacial climate change. This work will improve our knowledge about the real indication of the organic temperature proxies by combining the modern observation and paleorecord reconstruction, furthermore, will provid basic data bases for the reliable reconstruction of the past climate change by these proxies.

TEX86海水古温度指标自十年前发现以来显示出巨大的应用潜力，针对近年的多指标重建记录显示不同区域，和地质时期该指标指示意义的显著差异，以及偏沉积记录少现代观测的实情，本项目拟利用两个有机地球化学海水温度重建指标UK' 37和TEX86，结合现代观测和地质记录，通过测定热带典型海域不同水层中烯酮和古菌四醚脂类，了解现代南海及西太平洋热带海域两种古温度指标母源生物(颗石藻和古菌) 季节性和空间分布特征，及其与两种有机温度指标的关系，同时通过末次冰期以来两种指标的对比，探讨气候、环境的重大变化过程中古温度指标的变化机制及其意义。本申请通过古今结合研究，将明确不同古温度指标的实际指代意义，为该指标在热带海域古气候重建中的正确应用提供基本的数据依据。

本项研究通过对表层海水及不同深度水体中悬浮颗粒物的现代调研，分析讨论了两种温度重建有机指标的母源有机质在海水中分布情况，研究结果显示Uk'37所对应的长链烯酮物质在水体的分布随水深的增加，其含量呈降低趋势，但变化幅度不大，说明水体中烯酮的抗降解特征，TEX86所对应的四醚膜脂GDGTs类物质的高值出现在次表层水体，表层水体中含量非常低，随水深的增加，含量迅速降低。两种物质在南海表层水体中的含量都非常低，烯酮呈现在近岸低而远洋高的特征，GDGTs在北部低而西部高的特征可能与营养物质的供应及水体环境相关。总体而言，烯酮指标（Uk‘37）主要反映了表层水体温度，四醚指标（TEX86）代表次表层水体温度。.二种有机指标的古温度重建在不同尺度地质历史时期都呈现出明显的冰期低而间冰期高的特征，二者的温差反映了南海上层水体的变化：过去3万年来的记录显示了南海的三段式变化模式，进一步比较GDGT分布模式，我们发现TEX86H信号还受到奇古菌群落结构变化的影响；该群落结构的转变发生在~15 ka。南海南部45万年来的记录显示了更长时间尺度的海气相互作用，暖期温跃层浅，冰期温跃层深的基本规律。