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青藏高原中部唐古拉冰芯气候环境记录研究
郑伟
Subtype博士
Thesis Advisor姚檀栋
2008-07
Degree Grantor中国科学院青藏高原研究所
Place of Conferral北京
Degree Name博士
Degree Discipline自然地理学
Keyword青藏高原 唐古拉冰芯 雪冰化学 气候环境 生态破坏
Call Number无纸质版
Abstract

唐古拉山脉地处高亚洲中部,是干旱半干旱的大陆性气候和温湿的海洋性气候的过渡带。同时,唐古拉山口区作为长江源头又是气候变化的敏感区,脆弱的生态环境面临着人类活动的干扰,水土流失状况严重。因此,该地区冰芯研究不仅对大气化学和水汽来源的认识有着特殊的意义,同时对长江源头乃至整个流域的气候和生态环境变化有一定的预警作用。本文根据青藏高原中部唐古拉冰川32.4m的冰芯完成了冰芯定年和冰芯记录的分析,探讨了唐古拉冰芯揭示的青藏高原中部气候和环境的变化过程及可能机制,主要研究结论如下:
实验数据和气象记录分析表明唐古拉冰川净积累量自19世纪中期以来有逐渐增大的趋势,尤其是20世纪60年代以后增长趋势极为显著。但从20世纪90年代开始,净积累量有轻微的下降趋势。在冰芯记录的150年的冰川净积累量变化中,较小的时期分别是:1860年以前,1880~1910年和1950~1965年。唐古拉冰芯净积累量近50年的变化趋势和唐古拉山以北的沱沱河气象台站的降水记录基本一致,说明冰川净积累量基本能反映唐古拉冰川附近的大气降水历史,尤其是对于唐古拉山以北相同的水汽循环区域;然而,由于地形、气温、降水强度等的影响,冰川净积累量可能和历史实际降水量存在一定的差异。
唐古拉冰芯的主要离子特征显示,Ca2+、HCO3-分别是最主要的阳离子和阴离子,二者占整个离子组成的73.4%。唐古拉冰川离子和青藏高原其它地区冰芯离子存在差异,从离子浓度的数量级来看,唐古拉冰川的离子浓度和高原南部冰川离子浓度更为接近,但从离子成分的构成来看,唐古拉冰川离子组成又表现出与高原北部冰川相同。唐古拉冰芯离子统计分析(相关分析及EOF分析)表明唐古拉冰芯离子来源可分为三类:粉尘源,代表性离子为Mg2+、Ca2+和HCO3-;盐湖矿物源:代表性离子为SO42-、Na+、K+、Cl-;人类活动及生物源:代表性离子为NH4+、NO3-。在离子构成上,主要化合物种类有:Ca(HCO3)2、Mg(HCO3)2、Na2SO4、NaCl、(NH4)2SO4及NH4NO3。
不同来源的离子在唐古拉冰川的沉降方式存在差异。陆源的Ca2+、Mg2+、Cl-、Na+以干沉降为主,Cl-、Na+的干沉降过程表现的更为突出是因为唐古拉山以北区域海盐的输送已经很不明显,盐湖蒸发可能是Cl-、Na+的又一重要来源。NO3-、NH4+湿沉降过程明显强于干沉降过程,两者更多的是以NH4NO3伴随着降水过程沉降在冰面,NO3-的湿沉降不如NH4+表现显著,说明部分NO3-可能以硝酸盐(如NaNO3)的形式存在于气溶胶中。
唐古拉冰芯150年以来的主要离子记录显示19世纪相对于20世纪明显是高粉尘期,粉尘强度要比20世纪高1倍以上,属于小冰期的最后一次冷期。而冰芯记录显示在20世纪,青藏高原中部分别于20年代有一次气候转型,在60~70年代有一次小的冷事件发生。该区域粉尘在70年代末以后有增加的趋势,但这种增加不同于19世纪表现为气候作用的产物,而是由于原本的自然环境受到了人类活动的干预,导致局地源区生态景观的破坏。
唐古拉冰芯中的SO42- 记录显示,该区域的SO42-主要以粉尘和盐湖蒸发为主,但近50年来的因人类活动导致的SO42-浓度的增长表明人类活动对大气环境的影响已扩散到青藏高原内陆大气“洁净”区;NO3-、NH4+和北半球气温表现出一致的变化,近几十年NO3-、NH4+ 浓度的显著上升表明大气沉降中NH4+、NO3-变化的温度效应,与此同时该区域的人工耕作面积的扩大、草甸短期的增加也可能是NH4+、NO3-浓度升高的重要原因。

Other Abstract

Mt. Tanggula locates in the middle of High Asia, which belongs to the transition zone from arid and semi-arid continental climate to warm and moist marine climate. At the same time, as the source of Changjiang River, the gap region of Mt.Tanggula also is the sensitive area of climate variation. In those areas, the fragile ecosyetem is facing the interference from artificial environment, and the situation of soil and water loss begins to exacerbation. Based on present state, the study of ice core in this area has special significance on understanding of atmospheric chemistry and moist source. Moreover, this study also can perform a forewarning function for the changes of climate and ecological environment at the source of Changjiang River, even the whole river basin. In this paper, the dating and analysis about 32.4m Tanggula ice core from Middle Tibetan Plateau have been completed, then the process and possible mechanisms about changes of climate and environment in Middle Tibetan Plateau, which are revealed by Tanggula ice core are investigated. And the following conclusions can be achieved:
After analyzing the experimental data and the meteorological record, a raising trend about glacial net accumulation recorded in Tanggula ice core since the half past 19 century is found. In especial, this trend is shown obviously after 1960s. But the net accumulation has a slight decrease since the previous years of 1990s. In the 150 years records about glacial net accumulation, the low accumulation periods are before 1860 A.D, 1880~1910 A.D and 1950~1965 A. D, respectively. A same tendency is present between the 50 years variations in net accumulation recorded by Tanggula ice core and precipitation recorded by Tuotuohe Station, which lies at the north of M.t Tanggula. This shows glacial net accumulation can reveal the history of atmospheric precipitation near the Tanggula glacier. Otherwise, concerned topography, temperature, precipitation intensity and other factors, maybe there are some differences in net accumulation and actual precipitation in history.
The characteristics of major ions in Tanggula ice core show Ca2+ and HCO3- are the primary cation and anion, respectively. They account for 73.4% of the total mass. Ion concentration has some differences between in Tanggula and in other areas in Tibetan Plateau. the order of magnitude of ion concentration shows the concentration in Tanggula near this in ice core from South Tibetan, at the same time, the ion composition presents the similar form between Tanggula glacier and glacier in North Tibetan. The statistical analysis ( correlation analysis and EOF analysis) indicates ion species in Tanggula ice core can be classified 3 species: dust source ions ( Mg2+, Ca2+ and HCO3- ), salt lake and mineral source ions (SO42-, Na+, K+, Cl- ), anthropogenic and biogenic source ions (NH4+, NO3-). These ions most likely form compound including: Ca(HCO3)2, Mg(HCO3)2, Na2SO4, NaCl, (NH4)2SO4 and NH4NO3.
Different source ions have different ion deposition modes. Land source ions show dry deposition mode. Remarkable dry deposition in Cl- and Na+ shows sea salt transport is rather weak and evaporation from salt lake maybe is the important source for Cl- and Na+. Wet deposition process in NO3- and NH4+ exceed obviously dry deposition process, and the two ion combines likely into NH4NO3 , then deposition with precipitation process. Compared with NH4+, NO3- has a weak wet deposition, which shows part of NO3- maybe exist in aerosol in form of nitrate (such as NaNO3).
The ions concentration record in Tanggula ice core for 150 years shows 19 century is a higher dust period and the intensity of dust over one time than 20 century, so this period is looked as the last cold stage in Little Ice Age. At the same time, this core has record a climatic shift in 1920s and a cold event in1960s~1970s. Ice core reveals dust began to increase in this area since 1970s, but this case is different from 19 century, which is the result of climatic effect. In fact , the increased dust is result from natural environment interfered by human activity, which leads to destructive ecological landscape in source region.
SO42- concentration recorded by Tanggula ice core reveals most of sulfate in this area come from dust transport and salt lake evaporation. But in recent 50 years human activity lead to a increase in SO42- concentration. That means anthropogenic influence on atmospheric environment has extended to inner land of Tibetan Plateau. Both concentration of NH4+ and that of NO3- are showed to have a remarkable correlation with north-hemisphere air temperature. In recently decades, a higher concentration for NO3- and NH4+, respectively, indicates a temperature effect. At the same time, expansion of farmland and increased grassland in short term maybe is a important factor for increased NH4+ and NO3-.

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..............................................................................................................................................................III
第一章 绪论................................................................................................................................................................1
1.1研究问题的提出和本研究的科学意义..................................................-1 -
1.2国内外雪冰化学研究的历史和现状.......................................................6
1.2.1极地冰盖冰雪化学研究进展.........................................................7
1.2.2中低纬度高海拔区冰雪化学研究进展................................................10
第二章 唐古拉山地区自然地理特征和气候环境特征...........................................................................................25
2.1唐古拉山地区自然地理和地质特征......................................................25
2.2唐古拉地区气候环境特征..............................................................26
2.3唐古拉地区现代冰川的主要特征........................................................28
第三章 唐古拉冰芯样品处理及冰芯定年...............................................................................................................33
3.1唐古拉冰芯样品处理和实验分析........................................................33
3.2唐古拉冰芯定年和冰芯降水量的重建....................................................35
3.2.1冰芯定年........................................................................35
3.2.2冰芯降水量的重建................................................................38
第四章 唐古拉冰芯记录...........................................................................................................................................41
4.1唐古拉冰芯净积累量变化..............................................................41
4.2唐古拉冰芯可溶性离子化学特征........................................................44
4.2.1 离子平衡.......................................................................47
4.2.2唐古拉冰芯离子组成..............................................................48
4.2.3冰芯中主要阴、阳离子同青藏高原其它地区的比较....................................49
4.2.4唐古拉冰芯离子浓度相关分析......................................................50
4.2.5唐古拉冰芯化学成分时间变化的EOF分析.............................................53
4.3小结................................................................................54
第五章 唐古拉冰芯揭示的气候环境变化...............................................................................................................56
5.1唐古拉冰芯离子沉降模式..............................................................57
5.2唐古拉冰芯反映的近150年来青藏高原中部气候环境变化..................................60
5.3近50年来唐古拉冰芯对气候环境变化的响应.............................................63
5.3.1冰芯记录的自然环境的变化........................................................63
5.3.2 冰芯记录对近50年来人类活动和生态环境变化的响应.................................63
5.4小结................................................................................67
第六章 结语..............................................................................................................................................................68
参考文献....................................................................................................................................................................71
个人简历....................................................................................................................................................................83
致谢............................................................................................................................................................................84

Pages84页
URL查看原文
Language中文
Document Type学位论文
Identifierhttp://ir.itpcas.ac.cn/handle/131C11/8459
Collection图书馆
Recommended Citation
GB/T 7714
郑伟. 青藏高原中部唐古拉冰芯气候环境记录研究[D]. 北京. 中国科学院青藏高原研究所,2008.
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