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引用本文:张润,金章东,张飞,张小龙,李良波,徐阳,徐柏青.藏南冰前湖枪勇错近百年沉积速率变化及冰川进退反演.湖泊科学,2021,33(5):1584-1594. DOI:10.18307/2021.0525
Zhang Run,Jin Zhangdong,Zhang Fei,Zhang Xiaolong,Li Liangbo,Xu Yang,Xu Baiqing.Sedimentation rate variations of the proglacial lake (Qiangyong Co) and its implications for glacial fluctuations over the past century, southern Tibet, China*. J. Lake Sci.2021,33(5):1584-1594. DOI:10.18307/2021.0525
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藏南冰前湖枪勇错近百年沉积速率变化及冰川进退反演
张润1,2, 金章东1,3, 张飞1,3, 张小龙4, 李良波1,2, 徐阳1,2, 徐柏青4,5
1.中国科学院地球环境研究所, 黄土与第四纪地质国家重点实验室, 西安 710061;2.中国科学院大学, 北京 100049;3.中国科学院第四纪科学与全球变化卓越创新中心, 西安 710061;4.中国科学院青藏高原研究所, 青藏高原环境变化与地表过程重点实验室, 北京 100101;5.中国科学院青藏高原地球科学卓越创新中心, 北京 100101
摘要:
青藏高原上分布着大量的大陆性冰川,其对区域及全球气候变化响应极其敏感.工业革命以来,随着全球升温速率加快(特别是北半球),青藏高原部分地区的冰川在近百年显著退缩.冰前湖沉积物是最直接的冰川变化记录载体之一,但其沉积速率如何响应冰川及气候变化,能否反演冰川进退过程却知之甚少.本文依据210Pb和137Cs限定藏南冰前湖枪勇错QY5沉积岩芯的年龄,计算出不同深度沉积物的沉积速率,且与前人(QY-3)的沉积速率进行对比,揭示了近百年来枪勇错流域冰川变化历史及其与气温之间的关系.结果表明,枪勇错QY5近百年来的平均沉积速率为0.21 cm/a,比湖心(QY-3)快2倍左右,但两者的变化基本同步,高沉积速率对应温度上升期,是冰川退缩的直接响应:(1)1900-1960年,枪勇错沉积速率整体增加且变幅较大,与1890-1950年之间西藏温度波动式升高相对应,反映枪勇冰川总体处于退缩状态;(2)1960-1985年,沉积速率低且变幅较小,同期气温下降,枪勇冰川退缩程度相对较低且保持平稳;(3)1985年以来,枪勇错沉积速率呈上升趋势,是全球增暖下冰川显著退缩的直接响应.在短时间尺度内冰前湖沉积速率所揭示的枪勇冰川变化主要受控于温度,降水量对冰川变化的影响较小,但冰川对温度变化的响应滞后5~10 a.由于全球变暖和冰川对温度响应的滞后,在未来几十年高原冰川的融化速率可能会加快,亚洲水塔将面临着新的挑战.
关键词:  沉积速率  210Pb和137Cs测年  冰川变化  全球变暖  冰前湖  枪勇错
DOI:10.18307/2021.0525
分类号:
基金项目:中国科学院战略性先导科技专项(XDA2007010202,XDB40020100)资助.
Sedimentation rate variations of the proglacial lake (Qiangyong Co) and its implications for glacial fluctuations over the past century, southern Tibet, China*
Zhang Run1,2, Jin Zhangdong1,3, Zhang Fei1,3, Zhang Xiaolong4, Li Liangbo1,2, Xu Yang1,2, Xu Baiqing4,5
1.State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, P. R. China;2.University of Chinese Academy of Sciences, Beijing 100049, P. R. China;3.CAS Center for Excellence in Quaternary Science and Global Change, Xi'an 710061, P. R. China;4.Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, P. R. China;5.CAS Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing 100101, P. R. China
Abstract:
Continental glaciers on the Tibetan Plateau are sensitive to regional and global climate change. Since the industrial revolution, with the acceleration of global warming (especially in the Northern Hemisphere), glaciers in most parts of the Tibetan Plateau have shrunk significantly over the past century. The sediments in proglacial lakes are one of the direct record carriers of glacial fluctuations, but little is known about how their sedimentation rate (SR) responds to glacier and climate changes, particularly under the background of global warming. In this study, the 210Pb and 137Cs activities were used to constrain the age of a core (QY5) from Qiangyong Co in southern Tibet and to calculate the SRs of the core sediments at different depths. By comparing the SRs of the core (QY5) with those of the QY-3 core from central Qiangyong Co, the history of glacial fluctuations and its relationship with air temperature during the last century were revealed. The results show that the average SR of upstream of Qiangyong Co (QY5) is 0.21 cm/a, about double of the centre of the lake (QY-3), but with the same patterns. High SRs are corresponded to warm temperatures, as a direct response to the glacial retreat within the Qiangyong catchment: (1) from 1900s to 1960s, the SR of Qiangyong Co increased and fluctuated greatly as a result of the glacial retreat, corresponding to increased temperature in Tibet between 1890s and 1950s; (2) during 1960s-1985 when temperature decreased, the SR was low and stable, indicating stable Qiangyong glacier; (3) since 1985, the SR in Qiangyong Co increased gradually, as a direct response to glacier retreat under the acceleration of the global warming. Over a short time scale, the change of the Qiangyong glacier revealed by the SR in the proglacial lake is mainly controlled by air temperature, rather than by precipitation. However, there is a 5 to 10 years delay of glacier retreat to increased temperature. Due to global warming and the delayed response of glacier retreat to temperature, the melting rate of the Qiangyong glacier may accelerate in the next decades, and the Asian water tower will face a new challenge.
Key words:  Sedimentation rate  210Pb and 137Cs dating  glacial fluctuations  global warming  proglacial lake  Qiangyong Co
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