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青藏高原湖泊沉积正构烷烃单体氢同位素比值的气候意义
夏忠欢
Subtype博士
Thesis Advisor徐柏青
2008-07
Degree Grantor中国科学院研究生院
Place of Conferral北京
Degree Name博士研究生
Degree Discipline自然地理学
Keyword正构烷烃  湖泊沉积  氢同位素比值  气候  青藏高原
Call NumberB000011
Abstract

本文分别在青藏高原南部的大枪勇错、空姆错,中部的纳木错以及东北部的克鲁克湖和小柴达木湖钻取了浅岩芯,通过对沉积物中正构烷烃的提取分析和单体氢同位素比值的测定来探讨该类生物标志物单体δD值的气候指示意义。 通过将青藏高原南北断面湖泊表层沉积物中陆源正构烷烃 (n-C25、n-C27、n-C29、n-C31)的δD 值与当地生长季节大气降水的δD 值进行比较,发现两者有很好的相关性,说明陆源沉积正构烷烃主要记录了生长季节降水的同位素信号。正构烷烃n-C25、n-C27与大气降水间氢同位素表观分馏在-45‰ 至-70‰之间,平均分馏值是-57‰;正构烷烃n-C29、n-C31与大气降水间氢同位素表观分馏在-70‰ 至 -95‰之间,平均分馏值是-82‰。这四种陆源生物标志物与降水间的氢同位素表观分馏沿断面都稳定。通过对比欧洲南北断面的-130‰表观分馏值,可以看出青藏高原南北断面陆源沉积正构烷烃与大气降水间的表观氢同位素分馏小很多。 通过将青藏高原南北断面湖泊表层沉积物中水生生物来源的正构烷烃 (n-C17、n-C19、n-C21、n-C23) 的δD 值与当地湖水的δD 值进行比较,发现两者不具有相关性,说明沉积物中水生生物来源的正构烷烃没有记录源水的同位素信号。藻类来源的正构烷烃n-C17、n-C19与湖水间的氢同位素分馏在-30‰ 至-170‰之间,沉水/浮游植物来源的正构烷烃n-C21、n-C23与湖水间的氢同位素分馏在-40‰ 至 -160‰之间,沿断面分馏均不稳定。通过对比欧洲南北断面稳定的-157‰分馏值,可以看出不同地区源水与沉积物中水生生物来源的正构烷烃间的氢同位素分馏可能不一定稳定在-157‰。 通过将青藏高原南部空姆错的时间跨度约50年、7年间隔的岩芯剖面中陆源正构烷烃 (n-C25、n-C27、n-C29、n-C31) 的δD 值与当地浪卡子气象站和拉萨气象站的气候要素进行比较,发现这些生物标志物单体的δD 值与年平均气温相关,与生长季节平均气温显著相关,说明陆源沉积正构烷烃单体dD 值主要记录了生长季节的气温信号,具有作为古温度代用指标的潜力。

Other Abstract

To explore the climatic implication of compound-specific hydrogen isotope ratios of sedimentary n-alkanes, the author sampled shallow sediment cores respectively from the climatically and environmentally distinct basins Qiangyong Glacier Lake,Kongmu Co Lake,Nam Co Lake, Keluke Lake and Xiao Qaidam Lake along a S-N transect on the Tibetan Plateau for the extraction and analysis of these biomarkers. δD values of terrigenous n-alkanes (n-C25, n-C27, n-C29 and n-C31) extracted from recent lake surface sediments from the five lakes along the S-N transect are compared to that of precipitation spanning a wide range from -167‰ to -51‰ and clearly correlate with δD values of meteoric water during the growth, indicating that terrigenous n-alkanes record the precipitation signal during the growth. The fractionation between precipitation and alkanes of n-C25 and n-C27 cover a range from -45‰ to -70‰ whilst that between precipitation and alkanes of n-C29 and n-C31 vary from -70‰ to -95‰, both being fairly constant along the S–N Tibetan transect with the mean at -57‰ and -82‰, respectively. By comparison with the fractionation of -130‰ along the S–N European transect, it implies that the hydrogen isotopic fractionation between meteoric water and terrestrial n-alkanes along the Tibetan transect represent distinct character. δD values of aquatic derived n-alkanes (n-C17, n-C19, n-C21 and n-C23) extracted from recent lake surface sediments from the five lakes along the S-N transect are compared to that of lake water spanning a wide range from -135‰ to -22‰ and the results show that these biomarkers do not record lake water signal. The fractionation between lake water and algae derived alkanes of n-C17 and n-C19 cover a range from -30‰ to -170‰ whereas that between lake water and submerged/floating plants derived alkanes of n-C21 and n-C23 varies from -40‰ to -160‰, both covering a wide range along the S–N Tibetan transect with the mean at -94‰ and -93‰, respectively. By comparison with the constant fractionation of -157‰ along the S–N European transect, it implies that the hydrogen isotope fractionation between source water and sedimentary aquatic n-alkanes may not be necessarily constant at -157‰ in different regions. δD values of terrigenous n-alkanes (n-C25, n-C27, n-C29 and n-C31) extracted from a short sediment profile spanning the past near-50 years at 7-year resolution from Kongmu Co Lake on the southern Tibetan Plateau are compared to the climate elements of Langkazi and Lhasa weather stations and clearly correlate with mean annual air temperature and significantly correlate with mean growing season air temperature, indicating that these biomarkers record the air temperature signal during the growth and have the potential to be used as a paleotemperature proxy.

Department环境变化与地表过程重点实验室
Subject Area自然地理学
MOST Discipline Catalogue理学::地理学
Table of Contents

摘要 ............................................................................................................................................ I
ABSTRACT .............................................................................................................................. II
第一章 绪论 ........................................................................................................................... 1
1.1 过去全球变化研究的目标和内容 ................................................................................. 1
1.2 湖泊沉积记录在过去全球变化研究中的地位 ............................................................ 1
1.3 生物标志化合物正构烷烃在过去全球变化研究中的应用 ........................................ 2
1.3.1 生物标志化合物的定义 ........................................................................................ 2
1.3.2 生物标志化合物在过去全球变化研究中的应用概述 ....................................... 2
1.3.3 正构烷烃在过去全球变化研究中的主要应用 .................................................... 3
1.3.3.1 生物输入源的识别 .................................................................................... 3
1.3.3.2 古植被演化序列的重建 ............................................................................ 4
1.3.3.3 源区气候变化的响应 ................................................................................ 4
1.3.3.4 古季风变化的指示 .................................................................................... 5
1.3.3.5 古CO2 浓度的指示 ................................................................................... 5
1.3.3.6 古温度的指示 ............................................................................................ 5
1.4 问题的提出及本研究的目的和内容 ............................................................................ 6
第二章 研究区气候环境概况 ............................................................................................. 14
第三章 样品采集和实验分析 ............................................................................................. 20
3.1 湖泊沉积样和水样采集 ............................................................................................... 20
3.2 210PB 和137CS 定年 ...................................................................................................... 20
3.3 沉积物中有机物的提取与分离 ................................................................................... 21
3.4 正构烷烃单体浓度测定 ............................................................................................... 21
3.5 正构烷烃单体δD 值测定 ............................................................................................ 21
3.6 水样δD 值测定 ............................................................................................................ 22
第四章 青藏高原湖泊表层沉积中陆源正构烷烃单体δD 值的气候意义 ........................ 23
4.1 沉积物中陆源正构烷烃的分子特征 ........................................................................... 23
4.2 沉积物中陆源正构烷烃单体的δD 值 ........................................................................ 23
4.3 沉积物中陆源正构烷烃与大气降水间的氢同位素分馏 ........................................... 27
4.4 小结 ............................................................................................................................... 30
第五章 青藏高原湖泊表层沉积中水生来源正构烷烃单体δD 值的特征 ........................ 31
5.1 沉积物中水生来源正构烷烃的分子特征 ................................................................... 31
5.2 水样的δD 值 ................................................................................................................ 31
5.3 沉积物中水生来源正构烷烃单体的δD 值 ................................................................ 32
5.4 沉积物中水生来源正构烷烃与湖水间的氢同位素分馏 ........................................... 34
5.5 小结 ............................................................................................................................... 36
第六章 空姆错岩芯中陆源正构烷烃单体δD 值的气候意义 ............................................ 37
6.1 定年结果 ....................................................................................................................... 37
6.2 岩芯中陆源正构烷烃的分子特征 ............................................................................... 37
6.3 岩芯中陆源正构烷烃单体的δD 值 ............................................................................ 39
6.4 岩芯中陆源正构烷烃单体的δD 值与气候要素之间的相关性 ................................ 40
6.5 小结 ............................................................................................................................... 50
第七章 结语 ........................................................................................................................... 51
参考文献 ................................................................................................................................. 54
个人简历 ................................................................................................................................. 63
附录 ......................................................................................................................................... 64
致谢 ......................................................................................................................................... 65

Pages66页
URL查看原文
Language中文
Document Type学位论文
Identifierhttp://ir.itpcas.ac.cn/handle/131C11/1228
Collection图书馆
Recommended Citation
GB/T 7714
夏忠欢. 青藏高原湖泊沉积正构烷烃单体氢同位素比值的气候意义[D]. 北京. 中国科学院研究生院,2008.
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