全新世以来我国东部地区东亚夏季风降水区域差异的湖泊记录研究

It is difficult to discuss fully the asynchronous variations in precipitation between the northern and southern parts of eastern China on a millennial time scale because few continuous, high-resolution and well-dated Holocene precipitation/moisture records from southern China have been reported. On the basis of research work in Gonghai Lake in North China, this project proposes to collect another sediment core from Nanyi Lake located in South China. The high-precision chronology of sediment core will be established using 210Pb/137Cs dating of sediment and radiocarbon dating of well-preserved plant fragments. Based on a systematic study of modern process at this lake, a high-resolution well-dated Holocene record of precipitation or effective moisture from South China will be reconstructed by pollen analysis and diatom analysis combined with other proxy analysis such as carbonate content, grain size, TOC and environmental magnetic parameters. On the basis of this, the reconstructed precipitation or effective moisture record will be compared with precipitation record reconstructed from Gonghai Lake in North China in order to study the possible spatial difference of Holocene East Asia summer monsoon (EASM) precipitation in East China. In addition, controlling mechanisms for possible spatial difference of Holocene East Asia summer monsoon (EASM) precipitation in East China will be explored by comparison of these records with other internal forcing records or external forcing records.

由于缺少年代可靠的高分辨率全新世南方降水/湿度记录，千年尺度上我国东部地区东亚夏季风降水变化是否存在南北反相，其机制是什么？这一问题目前仍是古气候学界悬而未决的问题。在华北地区山西宁武公海湖泊研究工作的基础上，本项目选择位于南方的南漪湖作为研究对象，钻取沉积连续的全新世湖沼相岩芯，通过放射性核素测年建立精确的年代序列，以孢粉/硅藻为降水量/湿度变化指标，结合其它的常规理化指标，并在详细的湖泊流域现代环境过程研究基础上，高分辨率地定量重建年代可靠的全新世以来的湿度和降水变化历史。在此基础上，与公海定量重建的降水记录对比，研究全新世以来我国东部地区东亚夏季风降水的区域差异，如全新世最大降水期在南北是否存在反相的现象；进而将这种区域差异置于气候系统外部强迫和内部变率的框架之下，研究全新世以来我国东部地区东亚夏季风降水的区域差异可能的驱动因素，从而探讨我国东部地区东亚夏季风降水空间分异的控制机理。

在华北地区山西宁武公海湖泊研究工作的基础上，本项目选择位于我国南方的南漪湖作为研究对象，钻取沉积连续的全新世湖沼相岩芯，通过放射性核素测年建立精确的年代序列，以沉积物中的地球化学指标等为气候代用指标，在详细的湖泊流域现代环境过程研究基础上，高分辨率地定量重建年代可靠的全新世以来的湿度和降水变化历史。在此基础上，与公海定量重建的全新世降水记录进行对比，研究了全新世以来我国东部地区东亚夏季风降水的区域差异，并将这种区域差异与其它相关因素进行对比，研究了全新世以来我国东部地区东亚夏季风降水的区域差异可能的驱动因素，进而探讨了我国东部地区东亚夏季风降水空间分异的控制机理，从而为研究我国东部季风降水未来趋势变化及其影响提供了关键基础数据。发表SCI 检索论文4篇，包括以本项目为第一标注的Nature Climate Change、PNAS论文各1篇。培养博士1名，硕士3 名。并组织相关人员参加了国际国内学术会议，和同行广泛地交流了研究成果，取得了良好的效果。