共和盆地末次冰期以来地下水中的惰性气体古气候记录研究

青海共和盆地位于东亚季风、印度季风和西风环流的交汇地带，区域生态环境对由季风变换引起的温度和湿度变化十分敏感。以往在该区利用湖相沉积、黄土和泥炭等开展的古气候研究，仅能间接、定性地反映古气候的冷暖干湿状态变化。地下水中的惰性气体，相比而言，具有直接和定量恢复古气候信息的独特优势，尤其是识别末次盛冰期与全新世平均气温的差异，这对于校正和验证全球及区域大气环流模型具有重要意义。本项目拟以共和盆地为典型研究区，在多种环境示踪剂（3H、3H-3He、14C、4He）联合定年的基础上，利用地下水中的惰性气体重建该区末次冰期以来的古气候变化记录，并通过与地下水中的18O和13C记录以及该区及其周边其它地质载体气候变化记录的对比分析，进而揭示我国季风交汇带末次冰期以来的古气候变化特征。项目成果对于深入认识区域大气环流模式以及我国西北干旱地区的水资源管理具有重要的科学意义。

The Gonghe basin in Qinghai is located in the convergence zone of East Asian monsoon, Indian monsoon and Westerly Circulation, where the regional ecosystem is extremely sensitive to the temperature and humidity change caused by monsoon variation. The previous paleoclimate records deduced from lacustrine sediments, loess and peat were only able to indirectly reflect the qualitative climate variation. In contrast, the noble gas has the advantage of quantitatively acquiring the paleotemperature during recharging, and especially in quantifying the temperature change between the Last Glacial Maximum and Holocene, which is quite helpful and meaningful for the calibration and certification of general and regional circulation models. In this study, the paleoclimate records were quantitatively and directly derived from the noble gases on the basis of environmental isotopes (3H, 3H-3He, 14C, and 4He) age dating in Gonghe basin, China. By comparing with the records of stable isotopes 18O and 13C in groundwater and some other paleoclimate proxies surrounding the region, and thus to reveal the paleoclimate change since the last glacial period at the convergence zone of monsoons in China. This conclusion is significant for better understanding the regional atmospheric circulation patterns and valuable for water resources management in the arid regions of western China.