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青藏高原纳木错湖泊沉积物正构烷烃与环境变化研究
林晓
Subtype博士
Thesis Advisor朱立平
2008-07
Degree Grantor中国科学院研究生院
Place of Conferral北京
Degree Name博士
Degree Discipline自然地理学
Keyword青藏高原  湖泊沉积  纳木错  正构烷烃  环境变化
Call NumberB000008
Abstract

青藏高原是全球地学界瞩目的焦点,常被科学家们称为地球的第三极。青藏高原的湖泊面积占全国的50%左右,而纳木错作为青藏高原的第二大湖泊,具有非常重要的地位。本论文利用纳木错深水湖芯的正构烷烃重建了该区域8.4kaBP以来的气候环境变化历史,是973项目“青藏高原环境变化及其对全球变化的响应与适应对策”之子课题“青藏高原过去环境变化的时空特征(2005CB422002)”的研究内容之一。生物标志物在高原湖泊沉积与环境变化中的应用还不多见,本研究选取了结构简单、具有饱和性和稳定性的正构烷烃作为研究对象。首先利用GC/MS测试了纳木错周边植物及表层沉积物所含烷烃的组成与含量。测试结果表明:沉水植物主要含有C21、C23、C25等中等链长烷烃;陆生高等植物主要含有C27、C29、C31、C33等长链烷烃,其中C29多来自于木本植物,C31多来自于草本植物,C33则专属于香柏。据此,可推断纳木错表层沉积物中正构烷烃的来源以陆生植被输入为主,沉水草本植物输入次之,低等藻类输入最少。并且这些烷烃在空间分布上有所差异:长链烷烃由陆生高等植物输入,因而从湖岸到湖中心,其相对丰度会逐渐降低;而中等链长烷烃由沉水植物输入,这种空间变化并不明显;短链烷烃则完全没有空间差异。然后利用GC/MS进一步测试了纳木错深水湖芯NMLC-1孔沉积物中的烷烃组分及含量。分析结果表明其来源仍以高等植物输入为主,与表层沉积物有所不同的是,在1.4kaBP以前,沉水植物输入的烷烃明显超过陆生植物。各类烷烃具有不同的环境意义,陆生植物输入的长链烷烃能反映温度和降水强度的变化,沉水植物输入的中等链长烷烃能反映温度和湖面波动的变化。而整个序列中短链烷烃始终较少,并且由于“优先”降解作用和湖泊营养条件的限制,它们保存的环境变化信息相当少,没有明确的环境意义。在此基础上,根据该孔烷烃含量变化重建了纳木错8.4kaBP以来的环境变化序列:约8.4~6.7kaBP期间,气候温干,湖面较低,降水强度变化易引起湖面波动。约6.7~2.9kaBP期间,早期温暖湿润,陆生和沉水植物繁盛;晚期降温,逐渐干旱,以冷干事件结束。约2.9kaBP~现在,冷暖交替,中期出现冰川融水的大量补给,1.4ka以来趋于干旱。将烷烃与其它成熟的环境代用指标进行比较和验证,确定中长链烷烃比较真实地反映了过去环境变化,在湖泊沉积环境重建研究中具有实际应用的意义。与其它湖泊环境变化序列的对比的结果表明:纳木错的暖期环境主要受季风增强的影响,冷期环境主要受西风环流的影响;有时也受到冰川作用的影响。同时也说明纳木错区域的环境变化特征具有明显的过渡性。

Other Abstract

Tibetan Plateau is always focused by geoscientists and often called “The Third Pole” of the earth. The area of lakes on Tibetan Plateau is about 50% of whole country’s. As the second largest lake on Tibetan Plateau, Nam Co is very important to research in the field of past global changes. In this thesis, the environmental changes of Nam Co region since 8.4kaB.P. were reconstructed by n-alkanes in lake sediments and other environmental indicators. These research are supported by project of “Spatial and Temporal Characteristics of Past Environmental Changes on Tibetan Plateau (No. 2005CB422002)”, which is the sub-project of National Basic Research Program of China (Responses of Environmental Changes on the Tibetan Plateau and adaptations under the Global Changes). Applications of biomarkers in plateau lake sediments to palaeoenvironmental reconstruction is not abroad now. Because n-alkane has a simple carbon skeleton with saturation and stability, it was looked as a research object. Based on the measure of n-alkanes extracted from plants, it has been known that the n-alkane distribution of submerged aquatic plants commonly maximize at n-C21, C23, and C25 alkanes. Land vascular plants contain large proportions of n-C27, C29, C31and C33 alkanes in their epicuticular wax. In addition, n- C29 and n-C31 alkanes come mainly from woody plants and herbaceous plants, respectively. n-C31 alkanes come mainly from Sabina pingii. According to this result, the main resources of n-alkanes in Nam Co surface sediments are not phytoplankton but land plants and submerged aquatic plants. Furthermore, abundance of long chain length n-alkanes come from land vascular plants decreased gradually from lakeshore to center. But difference of spatial distribution of mid chain length n-alkanes come from submerged aquatic plants is not obvious enough. Especially the short chain length n-alkanes come from phytoplankton distribute evenly in the lake. Based on the measure of n-alkanes extracted from NMLC-1 core sediments of Nam Co, it can be decided that main resource of them is still higher plant vascular plants. But mid chain length n-alkanes are more abundant than long chain length n-alkanes before 1.4kaB.P.. Different kind of n-alkane has different environmental significance. Temperature fluctuation and precipitation intensity can be reflected by concentration changes of long chain length n-alkanes, while temperature fluctuation and water level changes can be reflected by mid chain length n-alkanes. But short chain length n-alkanes are not suitable for environment reconstruction because they are easily degenerated by bacteria and forbidden by TN. Then palaeoenvironmental changes of Nam Co region was reconstructed by n-alkanes in core sediments. The results indicated that in the period of 8.4~6.7 kaB.P., it was warm and the precipitation slightly increased. This stage was ended by an obvious cold/dry event. During 6.7~5.8 kaB.P., temperature increased rapidly. At about 6.0 kaB.P., it was again in the condition of warm and wet and very optimum to the growth of land plants and submerged hydrophytes. After that, temperature decreased smoothly. The environmental conditions of Nam Co shifted back to cold and dry at 3.0 kaB.P.. From 2.9 kaB.P. to now, it was fluctuated between warm and cool, and became arid after 1.4 kaB.P.. It can be proved that environmental changes reflected by n-alkane is credible through comparison with other well-known environment indicators. N-alkanes has application significance in the field of research on environment reconstruction by lake sediments. Based on the comparison of environment sequences between Nam Co and other lakes on Tibetan Plateau, Nam Co would influenced by strong monsoon and westerly circulation in warm stage and cold stage, respectively. So the environmental change in the region of Nam Co has a transitional character.

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

第一章 绪论.................................................................................................................................................1
1.1 青藏高原湖泊沉积研究与全球变化..............................................................................................2
1.1.1 长尺度湖泊沉积研究........................................................................................................... 2
1.1.2 万年尺度湖泊沉积研究....................................................................................................... 4
1.1.3 进展与不足........................................................................................................................... 8
1.2 生物标志物研究概况....................................................................................................................10
1.2.1 有机地球化学简史............................................................................................................. 10
1.2.2 生物标志物的研究对象..................................................................................................... 10
1.2.3 生物标志物在全球变化中的应用..................................................................................... 11
1.3 类脂分子的研究与进展................................................................................................................15
1.3.1 研究方法与手段................................................................................................................. 15
1.3.2 不同载体中的类脂研究进展............................................................................................. 17
1.4 分子地层学....................................................................................................................................21
1.4.1 分子地层学的基本概念..................................................................................................... 21
1.4.2 分子地层学的原理与方法................................................................................................. 22
1.5 本文研究思路................................................................................................................................23
1.6 小结................................................................................................................................................24
第二章 纳木错自然地理与研究概况.......................................................................................................25
2.1 自然地理概况................................................................................................................................25
2.2 研究历史........................................................................................................................................26
2.3 湖泊调查进展................................................................................................................................26
2.3.1 湖泊水下地形..................................................................................................................... 26
2.3.2 水质参数调查..................................................................................................................... 27
第三章 表层沉积物的烷烃含量及来源...................................................................................................31
3.1 样品采集与实验方法....................................................................................................................31
3.1.1 样品采集及预处理............................................................................................................. 31
3.1.2 植物鉴定.............................................................................................................................32
3.1.3 有机前处理实验与测试..................................................................................................... 34
3.1.4 定性定量分析..................................................................................................................... 35
3.2 高等植物的烷烃含量....................................................................................................................36
3.2.1 草本植物叶片的烷烃含量................................................................................................. 36
3.2.2 木本植物叶片的烷烃含量................................................................................................. 37
3.3 纳木错表层沉积物的烷烃............................................................................................................38
3.3.1 表层沉积物的烷烃含量..................................................................................................... 38
3.3.2 主成分分析......................................................................................................................... 40
3.4 表层沉积物的烷烃来源................................................................................................................43
3.5 小结................................................................................................................................................46
第四章 NMLC-1 孔湖芯的烷烃及环境意义..........................................................................................47
4.1 样品与测试....................................................................................................................................47
4.2 NMLC-1 孔的深度-年代模式.......................................................................................................49
4.3 NMLC-1 孔沉积物的烷烃组分及来源........................................................................................50
4.3.1 烷烃组分与含量................................................................................................................. 50
4.3.2 烷烃的来源......................................................................................................................... 52
4.4 烷烃及其特征参数的环境意义....................................................................................................53
4.4.1 长链烷烃的环境意义......................................................................................................... 53
4.4.2 中等链长烷烃的环境意义................................................................................................. 56
4.4.3 短链烷烃的环境意义......................................................................................................... 57
4.5 NMLC-1 孔中烷烃所反映的环境变化........................................................................................58
4.6 小结................................................................................................................................................60
第五章 纳木错8.4kaBP 以来的环境变化..............................................................................................61
5.1 烷烃与其它环境代用指标的对比................................................................................................61
5.1.1 长链烷烃与TOC 的对比................................................................................................... 61
5.1.2 中等链长烷烃与碳酸钙、Sr/Ba 的对比........................................................................... 63
5.1.3 短链烷烃与TN 的对比...................................................................................................... 65
5.2 纳木错8.4kaBP 以来的环境变化序列........................................................................................66
5.3 纳木错与其它湖泊研究的对比....................................................................................................67
5.3.1 与邻近湖泊的比较............................................................................................................. 67
5.3.2 与西部湖泊的比较............................................................................................................. 71
5.3.3 与南部湖泊的比较............................................................................................................. 72
5.4 小结................................................................................................................................................73
第六章 结论...............................................................................................................................................75
6.1 主要结论........................................................................................................................................75
6.2 主要不足........................................................................................................................................76
6.3 对未来工作的展望........................................................................................................................77
参考文献.......................................................................................................................................................79
图版Ⅰ...........................................................................................................................................................89
图版Ⅱ...........................................................................................................................................................90
图版Ⅲ...........................................................................................................................................................91
附录...............................................................................................................................................................92
致谢...............................................................................................................................................................93

图片目录
图1-1 青藏高原典型湖泊沉积研究示意图......................................................................................... 3
图1-2 深海沉积的U37
k’与δ18O 及海水表面温度变化的对比(据Brassell et al.,1986) .......... 13
图1-3 本文研究思路简图................................................................................................................... 23
图2-1 纳木错流域位置图................................................................................................................... 25
图2-2 纳木错水下等深线图............................................................................................................... 27
图2-3 纳木错水质参数测量典型剖面............................................................................................... 28
图3-1 纳木错表层沉积物与植物采样点位置图............................................................................... 32
图3-2 样品前处理实验与测试过程................................................................................................... 34
图3-3 正构烷烃标样的总离子流图与质谱图(以50ppm 为例).................................................. 35
图3-4 纳木错草本植物样品中的烷烃含量(单位:μg/g)............................................................ 36
图3-5 藏东南地区木本植物叶片中烷烃的相对含量(单位:ppm)............................................ 38
图3-6 纳木错表层沉积物的烷烃含量(单位:μg/g).................................................................... 40
图3-7 主成分因子载荷图................................................................................................................... 42
图3-8 藻类输入到纳木错表层沉积物中的短链烷烃含量............................................................... 44
图3-9 沉水植物输入到表层沉积物中的中等链长烷烃含量........................................................... 44
图3-10 陆生高等植物输入到表层沉积物中的长链烷烃含量......................................................... 45
图3-11 纳木错表层沉积物中3 类烷烃的空间分布图..................................................................... 45
图4-1 纳木错NMLC-1 孔位置图...................................................................................................... 47
图4-2 纳木错NMLC-1 孔深度-年代模式图..................................................................................50
图4-3 纳木错NMLC-1 孔正构烷烃的质量色谱图示例(m/z=85)…………………………………50
图4-4 NMLC-1 孔沉积物的烷烃含量与CPI.................................................................................... 52
图4-5 长链烷烃的三角投影图........................................................................................................... 55
图4-6 NMLC-1 孔的烷烃含量及特征组成指数............................................................................... 59
图5-1 NMLC-1 孔沉积物的TOC 和TN 含量.................................................................................. 61
图5-2 长链烷烃与TOC 指标的对比................................................................................................. 62
图5-3 中等链长烷烃与CaCO3 指标的对比...................................................................................... 64
图5-4 短链烷烃与TN,C/N 指标的对比......................................................................................... 65
图5-5 纳木错NMLC-1 孔多指标综合所反映的环境变化.............................................................. 67
图5-6 青藏高原湖泊分布示意图....................................................................................................... 68

列表目录
表1-1 主要天然载体可提取的古气候古环境信息(据张兰生等,2000 修改) ............................ 1
表1-2 青海湖湖泊沉积环境序列研究示例......................................................................................... 5
表1-3 高原西部湖泊沉积环境序列研究............................................................................................. 6
表1-4 高原南部和东南部湖泊沉积环境序列研究............................................................................. 7
表1-5 高原中部湖泊沉积环境序列研究............................................................................................. 8
表1-6 海洋、湖泊沉积物中用于古环境重建的有机指标和生物标志物....................................... 11
表1-7 类脂所反映的一些环境事件(据谢树成等,2007 修改).................................................. 15
表3-1 纳木错陆生植物与沉水植物的鉴定与分类........................................................................... 33
表3-2 文献中沉水植物的烷烃含量................................................................................................... 37
表3-3 藏东南地区木本植物叶片的烷烃含量................................................................................... 37
表3-4 纳木错表层沉积物的粒度、总有机碳与烷烃含量............................................................... 39
表3-5 特征值与方差贡献率............................................................................................................... 41
表3-6 主成分因子载荷与得分........................................................................................................... 42
表3-7 海洋藻类的正构烷烃含量(据Youngblood et al.,1971 修改) ........................................ 43
表4-1 有机前处理实验编号及对应的原始样品............................................................................... 48
表4-2 纳木错NMLC-1 孔AMS14C 测年与日历年龄校正及其“碳库”效应估算...................... 49
表4-3 NMLC-1 孔沉积物的烷烃含量............................................................................................... 51
表5-1 青藏高原中部湖泊的基本信息............................................................................................... 69

Pages94页
URL查看原文
Language中文
Document Type学位论文
Identifierhttp://ir.itpcas.ac.cn/handle/131C11/1258
Collection图书馆
Recommended Citation
GB/T 7714
林晓. 青藏高原纳木错湖泊沉积物正构烷烃与环境变化研究[D]. 北京. 中国科学院研究生院,2008.
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