横断山区贡卡湖记录的晚全新世区域水文变化及其与印度夏季风的联系  

Late Holocene hydrological variations recorded by sediments from Lake Gongka in the Hengduan Mountains and their linkage with the Indian summer monsoon

作　　者：邵帅 吴铎[2] 王涛 袁子杰 李友谟 冯小平 周爱锋[2] Shao Shuai;Wu Duo;Wang Tao;Yuan Zijie;Li Youmo;Feng Xiaoping;Zhou Aifeng(Group of Alpine Paleoecology and Human Adaptation(ALPHA),Institute of Tibetan Plateau Research,Chinese Academy of Sciences,Beijing 100101,P.R.China;College of Earth and Environmental Sciences,MOE Key Laboratory of Western China s Environmental Systems,Lanzhou University,Lanzhou 730000,P.R.China;University of Chinese Academy of Sciences,Beijing 100049,P.R.China;State Key Laboratory of Tibetan Plateau Earth System,Environment and Resources(TPESER),Institute of Tibetan Plateau Research,Chinese Academy of Sciences,Beijing 100101,P.R.China)

机构地区：[1]中国科学院青藏高原研究所古生态与人类适应团队,北京100101 [2]兰州大学资源环境学院,西部环境教育部重点实验室,兰州730000 [3]中国科学院大学,北京100049 [4]中国科学院青藏高原研究所,青藏高原地球系统与资源环境全国重点实验室,北京100101

出　　处：《湖泊科学》2023年第3期1126-1138,共13页Journal of Lake Sciences

基　　金：第二次青藏高原综合科学考察研究项目(2019QZKK0601);国家自然科学基金项目(42171150)联合资助。

摘　　要：印度夏季风(ISM)是全球季风系统的重要组成部分,其异常变化会对我国西南地区的生态环境和社会经济带来巨大影响。晚全新世是距离当下最近的地质历史时段,了解晚全新世以来ISM变化及其对区域水文的影响历史与规律,对预测我国西南地区未来的季风降水变化具有重要的参考价值。本文选择位于横断山区且对ISM变化响应敏感的高山湖泊贡卡湖(海拔3529 m)为研究对象,在湖泊中心获取204.5 cm的连续高质量沉积岩芯(GK20B钻孔),利用陆生植物残体AMS 14 C测年方法建立了过去3300年来可靠的地层年代序列。通过开展XRF元素扫描、烧失量、总有机碳氮(TOC、TN)及有机碳同位素(δ^(13)C_(org))等气候与环境代用指标的分析测试,重建了贡卡湖距今3300年以来的水文变化历史。研究结果显示,贡卡湖泥炭与湖相沉积互层的沉积结构与对应的代用指标变化共同揭示了湖泊水位波动,贡卡湖的水位自晚全新世以来整体呈现降低的趋势,响应了在北半球不断减弱的夏季太阳辐射驱动下ISM强度的衰退过程。同时湖泊水位指示的ISM强度存在着百年时间尺度的波动,这可能与地球气候系统内部的海气相互作用的影响有关。The Indian summer monsoon(ISM)is an important part of the global monsoon system.In southwestern China,the abnormal variations of the ISM not only cause abrupt changes of the climate and the ecological environment,but also bring huge economic losses to the society.The late Holocene is the most recent period in geological history.Therefore,understanding the history and mechanisms of the ISM and its influence on the regional hydrology during the late Holocene is important and helpful for predicting the future monsoon precipitation changes in southwestern China.Lake Gongka(3529 m above sea level)is an alpine lake with limited influence from human activities in the Hengduan Mountains and the climate in the region is mainly affected by the ISM.Lake Gongka is sensitive to climate change,making it an ideal region for paleoclimatic research.A 204.5-cm-long continuous and high-quality sediment core was drilled from the center of Lake Gongka(GK20B)by using a steel-barreled Livingstone square-rod piston corer in October,2020.Four samples of terrestrial plant materials and four total organic matter samples from the core were dated by using the AMS-14 C dating method.Based on the analysis of climatic and environmental proxies including XRF-based elements content,loss-on-ignition(LOI),total organic carbon and nitrogen(TOC,TN)contents and organic carbon isotope(δ^(13)C_(org)),we reconstructed the hydrological changes of the watershed since 3300 cal a BP.The sedimentary lithology which was the inter-bedding between peat and lacustrine sediments and the corresponding changes of climatic and environmental proxies revealed the huge fluctuations of the lake water level during the late Holocene.The results showed that the water level of Lake Gongka had been continuously decreasing in volatility during the late Holocene,which possibly reflected the decreasing trend of the ISM intensity.This trend most likely be associated with the decreasing summer solar insolation in the Northern Hemisphere.In addition,the lake level variations also

关 键 词：贡卡湖 水位 印度夏季风 气候变化 百年尺度 晚全新世 

分 类 号：P33[天文地球—水文科学] P532[水利工程—水文学及水资源] P534.632[天文地球—地球物理学]