稳定同位素连续测量技术及其在青藏高原冰芯高分辨率气候记录重建中的应用

Tibetan Plateau ice core is an important archive for high resolution past climate reconstruction. However, traditional discrete measurement technique hinders the retrieval of high resolution records from the middle and lower parts of the ice core, also limits high resolution dating of these parts. This project will establish stable isotope continuous-flow analysis technique suitable for Tibetan Plateau ice cores to achieve high resolution continuous observation of stable isotopes. The high resolution stable isotope data series of Qiangtang No.1 ice core which drilled to bedrock with the depth of 109m in central Tibetan Plateau will be established by this technique. On this basis, high resolution seasonal signals of stable isotopes and other methods will be used to determine the precise year of the ice core. Finally, the high resolution time series of the ice core will be studied, especially for the recovery of high frequency fluctuation signals of stable isotopes in the lower part of the ice core, and the recovery of longer time scale ENSO cycle information. The study will provide a new solution for the ice core stable isotope measurement technology, high precision dating, and high resolution past climate change information, which will further expand the depth of ice core paleoclimatic record research.

青藏高原冰芯是过去高分辨率气候环境记录的良好载体。但由于测量技术的限制，目前仍然缺乏针对冰芯中下部冰芯高分辨率信息的提取，也影响了冰芯底部高分辨率定年。本项目将从技术上建立一套适合青藏高原冰川的稳定同位素连续测量方法，实现冰芯稳定同位素高分辨率连续观测。并通过该技术建立青藏高原中部羌塘1号冰川109 m透底冰芯的高分辨率稳定同位素数据序列；在此基础上，通过稳定同位素的高分辨率季节信号，结合其它方法，完成该冰芯高分辨率精确定年。最后，研究该冰芯高分辨率时间序列，特别是恢复冰芯中下部的稳定同位素高频波动信号，并力图恢复更长时间尺度ENSO循环信息。该研究将为青藏高原冰芯稳定同位素测量技术、高精度定年、以及高分辨率过去气候变化信息的提取提供一套新的解决方案，将进一步拓展冰芯古气候记录研究的深度。

青藏高原冰芯是记录过去高分辨率气候环境信息的良好载体。但由于测量技术的限制，目前仍然缺乏针对冰芯中下部冰芯高分辨率信息的提取，也影响了冰芯底部高分辨率定年。本项目1）综合具有季节变化的化学指标利用数年层的方法、冰芯年层厚度与深度拟合的方法建立了一套青藏高原中部冰芯的定年方法。2）结合有气象记录时段（1948-2011）的气象资料分析了冰芯中δ18O及过量氘的主要影响因素。3）对过去千年的稳定同位素记录进行分析。研究结果表明羌塘1号冰芯整支冰芯的年层共包含1343年，时间尺度为669AD±66年。大尺度大气环流通过影响对流过程影响羌塘1号冰芯δ18O的年际变化；大尺度大气环流通过影响水汽源区相对湿度影响羌塘1号冰芯过量氘的年际变化，在千年尺度上冰芯δ18O和过量氘仍保留着ENSO信号。本项目的研究成果可为稳定同位素古气候记录研究提供参考。