青藏高原湖泊表层沉积物GDGTs分布特征及其影响因素

发布时间：2018-01-20 12:15

本文关键词： 青藏高原湖泊沉积物表土 GDGTs转换方程定量重建　出处：《中国科学:地球科学》2016年02期 　论文类型：期刊论文

【摘要】：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.
[Abstract]:The quantitative recording of past temperature changes is very important for the in-depth study of climate change mechanism, which is not only helpful to test and improve the accuracy of climate model simulation. It can also provide a reference for the extent of climate change in the context of global change. The Qinghai-Xizang Plateau affects the general circulation pattern because of its special geographical location. The study of climate change in the Qinghai-Xizang Plateau is helpful to understand the response of the plateau to global climate change and its relationship with the global climate system. Changes in temperature in the past provide the possibility. Dialkylglycerol tetraether compounds in lake sediments. The source of GDGTs is relatively complex. The distribution characteristics are influenced by many climatic and environmental factors. The GDGTs of surface sediments of 27 lakes in the Qinghai-Xizang Plateau and the surface soil samples of some lake basins are analyzed in this paper. The factors influencing the distribution of GDGTs in the surface sediments of lakes were discussed. The quantitative relationship between GDGTs and climatic elements is established. The results show that the GDGTs of most of the lake surface sediments is b GDGTs. The contents of crenarchaeol and GDGT-0 were low. (2) there is no significant difference in the distribution of GDGTs between surface sediments and topsoil in most lakes in the plateau, indicating that I GDGTs may originate from both lake environment and terrestrial input; (3) the distribution of I GDGTs in the surface sediments of the lakes is mainly affected by the chemical elements of lake water, pH and salinity) and the annual mean temperature of the atmosphere near the surface, for the small lakes in the Qinghai-Xizang Plateau. TEX86 may reflect the change of pH in lake water. (4) the distribution of b GDGTs in the surface sediments of lakes is mainly controlled by climatic factors (temperature and precipitation). 5) the difference of temperature in the same region of the plateau is obvious by using the published transformation equation. Therefore, before using GDGTs to quantitatively reconstruct the past climate of Qinghai-Xizang Plateau, a modern process investigation of GDGTs should be carried out. This study is based on the distribution of b GDGTs in lake surface sediments. MBT was used as substitute index. The conversion equations for paleoclimate study of lakes over the Qinghai-Xizang Plateau have been established by using CBT), the abundance of different b GDGTs compounds and the average annual temperature of the lake site. It provides a basis for quantitative reconstruction of paleoclimate in the plateau.
【作者单位】：中国科学院青藏高原研究所环境变化与地表过程重点实验室;中国科学院大学地球科学学院;中国地质大学(武汉)地球科学学院;
【基金】：国家自然科学基金项目(批准号:41072120,41321061)资助
【分类号】：P343.3;P532
【正文快照】： 1引言新生代以来青藏高原的隆升对亚洲气候格局具有显著影响(Raymo和Ruddiman,1992;Kutzbach等,1993;An等,2001),不仅改变了大气环流格局,也与季风的起源及中亚地区干旱化密切相关(刘东生等,1998),因此青藏高原气候变化一直受到广泛关注(Liu和Chen,2000;Yao等,2012).近年来,基

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