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过去温度变化的定量记录对于深入探讨气候变化机制非常重要,不仅有助于检验并改善气候模式模拟的准确性,也可以为全球变化背景下的气候变化幅度提供参考.青藏高原由于其特殊的地理位置影响着大气环流格局,研究青藏高原气候变化有助于理解高原对全球气候变化的响应及其与全球气候系统之间的关系.生物标志化合物代用指标在气候变化研究中的应用为定量重建高原过去温度变化提供了可能.湖泊沉积物中甘油二烷基甘油四醚类化合物(GDGTs)来源相对复杂,其分布特征受多种气候与环境因素影响.本文对青藏高原27个湖泊表层沉积物及部分湖泊流域表土样品GDGTs进行分析,探讨湖泊表层沉积物中GDGTs分布特征的影响因素,并建立其与气候要素的定量关系.结果显示:(1)绝大多数湖泊表层沉积物GDGTs以b GDGTs为主,crenarchaeol和GDGT-0含量较低;(2)高原多数湖泊表层沉积物与表土GDGTs分布没有显著差异,表明i GDGTs可能同时来源于湖泊环境和陆源输入;(3)湖泊表层沉积物i GDGTs分布主要受湖水水化学要素(p H和盐度)及近地表大气年均温的影响,对于青藏高原小型湖泊,TEX86可能反映湖水p H的变化;(4)湖泊表层沉积物b GDGTs分布主要受气候要素(温度和降水)控制;(5)利用已发表的转换方程重建高原同一地区温度差异明显,因此利用GDGTs定量重建青藏高原过去气候前必须开展GDGTs的现代过程调查.本研究基于湖泊表层沉积物b GDGTs分布,分别利用代用指标(MBT,CBT)及不同b GDGTs化合物组分丰度(fabun)与湖泊所在地的年均气温(MAAT)建立了适用于青藏高原湖泊古气候研究的转换方程,为高原古气候定量重建提供研究基础.
Quantitative records of past temperature changes are very important for further research on climate change mechanisms, which not only help to test and improve the accuracy of climate model simulations, but also provide references for the magnitude of climate change in the context of global change. Because of its special geography The location influences the general circulation pattern and studying the climate change in the Tibetan Plateau helps to understand the response of plateau to global climate change and its relationship with the global climate system.The application of biomarker substitution index in climate change research In order to quantitatively reconstruct the plateau In the past, the source of glycerol dialkylglycerol tetraethers (GDGTs) in lacustrine sediments was relatively complicated and the distribution characteristics were affected by many climatic and environmental factors.In this paper, GDGTs were analyzed in some lake basin topsoil samples to investigate the influencing factors of GDGTs distribution in surface sediments of lake and to establish their quantitative relationship with climatic elements.The results showed that: (1) The GDGTs of surface sediments of most lakes are b GDGTs Main, crenarchaeol and GDGT-0 content is low; (2) most plateaus lake surface sedimentation There is no significant difference in the distribution of GDGTs between surface and topsoil, indicating that i GDGTs may be derived from both lake environment and terrestrial input. (3) The distribution of i GDGTs in lake surface sediments is mainly affected by the chemical composition of lake water (p H and salinity) and near-surface atmospheric years (4) The distribution of b GDGTs in lake surface sediment is mainly controlled by climatic elements (temperature and precipitation); (5) By using the published transformation equation Therefore, it is necessary to carry out the GDGTs modern process investigation before GDQTs quantitatively reconstruct the past climate of the Qinghai-Tibet Plateau.Based on the distribution of b GDGTs in the surface sediments of the lake, we use the proxy index (MBT, CBT) and b GDGTs The compound equation of abundance (fabun) and the mean annual temperature (MAAT) of the lake locality are established for the study of paleoclimate in the Qinghai-Tibet Plateau, and provide the basis for the quantitative reconstruction of paleoclimate in the plateau.