南黄海中部泥质区高分辨率全新世孢粉记录的环境变化

The South Yellow Sea (SYS) is a shallow, semiclosed and epicontinental sea between China and Korea, where the high rate deposits in the central area provide detailed information about the paleo-ocean and terrestrial provenance variations. The rich fossil pollen in the marine mud sediments transported from land could record the past vegetation and climate changes of the pollen source areas. Till now, few high resolution palynological records have been conducted to reconstruct the past changes in the pollen source region of the SYS, and the transporting path and pattern of pollen in the SYS are still not clear. Therefore, pollen analysis will be carried out on the samples from atomospheric, surface seawater and surface sediments in the midwestern SYS, which will help to deeply understand the pollen terrestrial provenance and transporting process in the SYS. At the same time, based on the CSDP-1 core obtained from the mud area in the central SYS, high resolution chronology and pollen analysis will be carried out on the top 25 meters long sediments continuously deposited during the Holocene. We aim to explore the paleo-ocean environment changes, the ecosystem and climate changes in the pollen source areas, and to discuss the possible abrupt events. For deep explanation of pollen data, we will try to use quantitatively reconstruction method for tracing the pollen provenance,ocean currents and climate changes, which would provide new high resolution data for studying regional response to the global changes.

南黄海属西太平洋边缘的半封闭陆架浅海，该区中部的高速率沉积保存了丰富的古海洋和陆源物质变化的记录，其中，来自陆区丰富的孢粉化石，是记录泥质堆积的物源区陆地植被和气候变化细节的重要载体。目前，利用高分辨率孢粉分析方法探讨南黄海陆源区全新世古生态和古气候变化的记录相当缺乏，且对该海区孢粉的传播路径和方式也缺乏深入了解。本课题拟通过对南黄海中西部表层沉积物，表层海水及空气样品的立体孢粉分析，深入探讨南黄海沉积物孢粉的来源区和入海后的传播过程。同时，借助大陆架科学钻探项目在南黄海中部泥质区获取的CSDP-01孔上部25米全新世连续沉积，进行高分辨率测年和孢粉分析，揭示南黄海全新世古海洋学和陆源区沿岸生态系统变化及其反应的气候变化，并探讨可能存在的气候突变事件。在孢粉解释方面，尝试利用定量化方法探索孢粉物质来源区及海洋环流变化，为全球变化的区域响应研究提供新的高分辨率古环境替代性资料。

依托国家自然科学青年基金项目‘南黄海中部泥质区高分辨率全新世孢粉记录的环境变化’和海洋区域调查项目，通过对我国黄渤海海域（表层沉积物、水体和空气样品，以及钻孔沉积）及其入海海流冲积物的孢粉分析，探讨南黄海沉积物孢粉的来源区和入海后的传播过程，并揭示黄海海域晚更新世以来的海平面变化和陆源区植被及其反应的气候变化。研究结果表明，海区沉积物孢粉以松为主的木本花粉占主导，草本中藜科和蒿含量较高。孢粉浓度与表层沉积物粒度密切相关，细粒沉积物（粘土及细粉砂）中孢粉浓度较高，粗粒沉积物（砂）孢粉浓度低。孢粉在近岸海域以水流携带为主，草本浓度较高。随着离岸距离的增加，风力携带的花粉浓度（如松属花粉）显著增加。同时，海区与河流样品孢粉组合的非相似度分析还表明，海域不同区块孢粉组合特征的差异与陆源区植被分布有关，尤其是入海河流沿岸的植被特征。黄渤海钻孔（DLC70-3，CSDP-01，TJC-01）孢粉记录揭示出该研究区晚更新世以来孢粉组合特征变化显著，间冰期阶段阔叶组分和蒿比例较高，气候偏暖，属沉积动力相对稳定地浅海或滨海环境，而冰期或亚冰阶，针叶组分或冷杉含量增加，中生-水生草本含量相对较高，气候偏冷，属沉积动力相对复杂的滨岸湖泊或沼泽等陆相环境。综合对比周边区域其他孢粉记录，认为在冰期-间冰期旋回过程中孢粉组合中针叶与阔叶组分此消彼长，草本含量的相对变化可指示滨岸局域植被的演替，一定程度上可反映海平面的升降。