Knowledge Resource Center for Ecological Environment in Arid Area
| 新疆天山雪冰中粉尘的时空变化特征研究 | |
| 其他题名 | Temporal and Spatial Change of Atmospheric Dust Deposition in Snow and Ice on Glaciers in Tianshan Mountains, central Asia |
| 董志文 | |
| 出版年 | 2012 |
| 学位类型 | 博士 |
| 导师 | 李忠勤 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 全球和区域气候变化是当前众所关注的重大问题之一。作为影响气候变化的一个重要因子，大气粉尘及其对气候环境的影响亟待深入研究。源自于地壳表面的气溶胶矿物粉尘是重要的大气组成部分，能够影响地球表面的辐射平衡，中和降水中的酸性物质，作为地球气候系统的辐射强迫因子，同温室气体一道扮演着改变地球系统能量收支平衡的重要角色。高寒地区的冰川雪冰中沉降的大气粉尘微粒研究有着更为重要的意义，如冰芯微粒研究对于冰芯定年、气候环境变化的纪录恢复方面起了重要作用；而冰川积雪中的不溶粉尘微粒则用来研究近期气候环境变化。粉尘气溶胶可以改变冰川反照率进而影响能量平衡、加速冰川消融，因而对冰川区粉尘沉降的特征及其时空变化观测研究已是目前亟待解决的科学问题。天山地区位于中亚干旱区的核心区域，周边被广袤的大沙漠所包围，气候环境极端干旱，而天山之巅发育的冰川是重要的水资源，对该区冰川区粉尘沉降的研究很有科学和现实意义。大气粉尘浓度和粒径分布等特征的变化由于受到风力、搬运距离、沉降过程等因素影响，从中亚粉尘源区开始搬运、传输，经过距离远近不同地区时表现出不同特征。因此，在亚洲粉尘源区研究雪冰中微粒沉积的特征，并与北半球其他地区已有的相关研究结果进行比较，对于完善全球大气粉尘循环和沉降机制的认识也显得尤为重要。基于此，对天山地区冰川上的粉尘特征进行研究显得十分必要，是对全球大气粉尘循环研究的重要补充和完善。\n本研究主要对我国境内天山不同区域的典型冰川积雪中粉尘沉降的特征进行研究。雪冰中粉尘微粒特征分析表明，自西向东随着研究点地理环境的变化，除了青冰滩72号冰川外，积雪中不溶微粒的质量浓度、沉积通量和体积粒径分布的众数都表现增加的趋势：奎屯哈希勒根51号冰川和48号冰川最小，乌鲁木齐河源1号冰川、博格达峰四工河4号冰川次之，托木尔峰青冰滩72号冰川其次，哈密庙尔沟平顶冰川最大。研究表明，哈密庙儿沟和托木尔峰冰川区受粉尘源影响较大，而乌鲁木齐河源区、博格达峰地区与奎屯河源冰川区受影响则相对较小，说明了天山冰川中粉尘沉降存在很大的空间差异性。雪坑微粒浓度剖面和离子相关性分析表明，天山冰川积雪中的污化层富含亚洲粉尘的富Ca2+、Mg2+、Na+矿物；微粒体积—粒径分布众数介于3~22 μm，粒径分布显示了单结构模式。冰川积雪的污化层剖面揭示了春季零星的粉尘浓度峰值以及沉积数量上较大的年际变化，意味着天山东部雪冰中粉尘沉积对大气环境变化的敏感性。与全球其他区域相比，天山冰川区粉尘特征反映了中亚粉尘源区沙尘活动的明显影响。\n同时，通过冰川表层雪样的采集和连续密集的观测，对位于中亚粉尘活动源区的天山乌鲁木齐河源1号冰川积雪中沉积的大气粉尘微粒的数量浓度及其季节粒径分布特征等进行了观测研究。结果表明，表层雪中不溶粉尘数量浓度在沙尘活动的4~6月份非常高，推测可能是由于亚洲春季发生的沙尘暴事件影响造成的；将4~8月积雪表面不溶粉尘粒径分布进行了比较，粉尘微粒质量粒径分布表现出分布模式由沙尘活动前的单一模式 (3~21 μm)，到沙尘活动期间的双峰分布模式 (3~21 μm和20~80 μm组成)，再到非沙尘季节的单一模式 (3~21 μm)的变化规律；粉尘化学离子组成，尤其是主要代表矿物颗粒的Ca2＋，在4~6月份浓度很高，另一方面，NH4＋和SO42-等作为可溶部分其浓度变化存在差异。同时，用后向气团轨迹分析模型（HYSPLIT）验证了该区大气粉尘的传输路径, 发现沙尘与非沙尘季节大气粉尘来源不同：分别来源于西北和西南方向，这对大气粉尘的传输和沉降造成很大影响。\n此外，以天山乌鲁木齐河流域为例，对高山冰川区和郊区降水中粉尘沉降随时间变化特征及其差异进行研究。结果表明，降水中粉尘颗粒物的浓度、粒径分布及化学要素组成在两个取样点都具有明显的季节变化。粉尘颗粒浓度表现为冬-春季节升高而夏-秋季节降低，与降水量成反向变化，反映了降水受中亚沙尘活动的影响明显。粉尘颗粒在冬-春季节的粒径分布众数较大，而在夏-秋季节相对较小；且这种变化在高山区和郊区存在差异，可能是局地环境影响造成。粉尘颗粒的化学特征的季节差异反映了区域自然环境和人为活动对降水的共同影响。与其它区域降雪中粉尘和化学特征进行了比较。并结合HYSPLIT 模型对大气降水和粉尘颗粒的来源进行验证。天山高山冰川区和低山区的明显差异也反映了冰川区的粉尘沉降的特殊性。总体上，新疆天山冰川区雪冰中沉降的粉尘表现强烈的季节性、空间性和以及较为明显的区域和局地差异性，反映了中亚干旱区粉尘源区对天山高海拔冰川区的不同程度的强烈影响，对区域大气环境的演化产生了重要的作用，并有可能加速山岳冰川的快速消融。尽管如此，对于其影响机制需要进行更深入研究。 |
| 英文摘要 | Windblown mineral dust derived from the crustal surface is an important atmospheric component affecting the Earth's radiation budget. Mineral aerosol dust is an important indicator of changes in the atmosphere associated with changes in temperature, precipitation, and atmospheric circulation. Ice core records show that high dust concentration corresponds with cold and dry climate conditions, while low dust concentration corresponds with warm and wet conditions. Aerosol dust information can be recorded and stored in the snow and ice of high mountains and of the Polar Regions. Much research has been carried out concerning dust records in ice cores, to understand climate change in ancient times. Other research has measured dust deposition in recent snow to understand recent climate and environment conditions. Atmospheric transport processes and transformation processes of the dust particles have also been studied to characterize the geochemical role of aeolian dust events in the Asia region. These dust events have been observed frequently in spring over the Asia-Pacific region because of the strengthened wind speed in springtime. \nDeposition of atmospheric dust was measured in snow deposited on Glacier No.1 at the headwater of Urumqi River, Sigonghe Glacier No.4 in Mt Bogeda, Haxilegen Glacier No.51 and Glacier No.48 in Kuitun, Qingbintan Glacier No.72 in Mt Tuomuer, and Miaoergou Glaicer in Hami in Tianshan Mountains, western China. An analysis of horizontal distribution of dust layers, snow height and concentration of dust in the snow cover suggests that deposition of dust in Tianshan is different from each other. The characteristics of modern atmospheric dust deposition in snow are different between six research sites in Tianshan Mountains, as the environment changes from west to east. Dust layers in the snow cover contain Ca-rich materials typically found in Asian dust particles. Vertical profile of Na+ concentration in the snowpack is also very similar with duat’s. Volume size distributions of dust particles in the snow showed single–modal structures having volume median diameters from 3~22 μm. Dust profiles in snow cover over the last 4 yr reveal frequent sporadic high dust concentrations and large year-to-year variations in the amount deposited, implying that dust deposition in Tianshan Mountains is very sensitive to atmospheric environment change. \nDeposition of atmospheric dust was measured in the snow on Glacier No.1 at the headwater of Urumqi River in eastern Tianshan Mountains, central Asia. An analysis of seasonal change of concentration of dust particles in the snow cover suggests that number concentration of dust particle is significantly high from April to June (439×103 /ml), which may be caused by Asian dust storm in spring. The comparison of mass-size distribution of dust particles between April to August shows an obvious change trend. The distribution of particles changes from single model (3~21 μm) in non-dust period before April, to bio-model (3~21 μm and 20~80 μm) during Asian dust period, and to single model (3~21 μm) after June in non-dust period again. Ca2+concentration in the snow is also very high from April to June, while NH4＋and SO42-, as water-soluble constituents the concentration change is different from each other. Backward trajectory was also employed to examine the transport process of air mass in this region.\nChemistry and environmental significance of insoluble dust particles in precipitation at alpine and rural sites were determined in the Urumqi river valley in Tianshan Mountains. Results showed that the concentration, size distribution and chemical constitutes of dust particles in precipitation varied seasonally in both two sites. Dust concentration increased during winter and springtime but decreased during summer and autumn period, which is negative correlation with the seasonal change of precipitation, which reflect the significant influence of Asian dust storm. Volume-size distribution of particles showed larger size in winter-spring, but relatively smaller in summer-autumn period. Chemical constitutes of precipitation indicated that precipitation is affected by both regional atmospheric environment and human activity in central Asia. HYSPLIT Model is also employed to examine the transport process of air mass and insoluble dust particles in this region. \nDust deposition shows obvious spatial and seasonal vaitation on the glaciers in Tianshan Mountains, China, also showing obvious regional and local differences. Dust may originate from dufferent source of dust basins in central Asia. The transport of dust particles need to be understanded. The use of Sr and Nd isotopes would be a fruitful method to apply in future studies to test the interpretations made in this study, as these methods have been used to identify source regions of dust particles in ice cores of the Tibetan Plateau and the East Antarctica. Moreover, the process of aerosol dust deposition in the snow on the glaciers of the Tianshan Mountains is still unclear and further research is needed. |
| 中文关键词 | 中亚天山 ; 气溶胶粉尘 ; 山岳冰川 ; 区域差异 ; 沙尘活动 |
| 英文关键词 | Tianshan Mountains Aerosol dust Alpine glaciers Seasonal and spatial variation Dust activity |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 自然地理学 |
| 来源机构 | 中国科学院西北生态环境资源研究院 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287034 |
| 推荐引用方式 GB/T 7714 | 董志文. 新疆天山雪冰中粉尘的时空变化特征研究[D]. 中国科学院大学,2012. |
| 条目包含的文件 | 条目无相关文件。 | |||||
| 个性服务 |
| 推荐该条目 |
| 保存到收藏夹 |
| 导出为Endnote文件 |
| 谷歌学术 |
| 谷歌学术中相似的文章 |
| [董志文]的文章 |
| 百度学术 |
| 百度学术中相似的文章 |
| [董志文]的文章 |
| 必应学术 |
| 必应学术中相似的文章 |
| [董志文]的文章 |
| 相关权益政策 |
| 暂无数据 |
| 收藏/分享 |
除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。
