Knowledge Resource Center for Ecological Environment in Arid Area
| 慕士塔格冰芯与东绒布冰芯的气候环境记录 | |
| 其他题名 | Climatic and environmental records in Muztagata and East Rongbuk ice/firn cores |
| 赵华标 | |
| 出版年 | 2008 |
| 学位类型 | 博士 |
| 导师 | 姚檀栋 |
| 学位授予单位 | 中国科学院寒区旱区环境与工程研究所 |
| 中文摘要 | 世界大多数人口生活在中、低纬度地区，中、低纬地区冰川不仅记录了气候环境的自然变化，也记载了人类活动对气候环境变化所附加的影响。高亚洲地区拥有大量的冰川，是除极地以外冰川分布最密集地区，因而借助于冰川记录研究该地区人类活动与气候环境变化的关系显得更为重要。本论文以青藏高原西部边缘54.6 m长的慕士塔格冰芯和南缘22.5 m长的东绒布粒雪芯为研究对象，分析冰芯/粒雪芯所记录的气候环境变化及其可能影响因素。\n慕士塔格冰芯的δ18O记录反映了温度的变化，不仅与当地气温记录一致，更与青藏高原其它冰芯记录所代表的气温变化及北半球升温趋势相似。冰芯的化学记录受粉尘影响较大，可溶离子中粉尘源组分占绝大部分，主要离子浓度的EOF分析也表明了粉尘源离子占主导地位。以Ca2+为代表的粉尘源离子的浓度变化与西风环流指数呈正相关关系，指示了西风环流的动力作用对粉尘输送的影响。根据Ca2+的季节变化特征，认为慕士塔格冰芯所记录的粉尘事件主要源于上风向的中亚及伊朗―阿富汗地区。冰芯中人类活动排放所产生的次生气溶胶组分SO42−和NO3−在1970s中期前基本为粉尘信号所掩盖，但其后SO42−和NO3−浓度的变化趋势明显超过粉尘的影响，凸显出中亚地区人类活动排放的增强。慕士塔格冰芯的NH4+浓度变化具有独特性，未受粉尘输入的影响，1940s以来NH4+浓度增长揭示了中亚地区人为活动排放的增强及NH3排放对气温升高的响应。\n慕士塔格大气气溶胶的主要元素组成为典型的地壳类来源如Al、Ca、Fe、K、Mg和Na，同样表明该地区大气环境受粉尘影响较大。粉尘源元素的夏高冬低的季节变化特征印证了冰芯中粉尘源离子的季节变化，进一步论证慕士塔格地区的粉尘来源并非来自我国西北干旱区。上风向中亚地区的冬季燃煤取暖导致慕士塔格大气气溶胶元素Cr、Ni、Cu和Zn在冬季具有较高的富集因子，而稳定的工业活动排放使得Cd、As、Pb和Bi常年表现为高富集因子。冰芯中Pb的人类活动影响的减弱在大气气溶胶中也得到了体现。\n东绒布粒雪芯的δ18O变化与印度夏季风指数呈负相关关系，体现珠峰地区季风降水中δ18O的“降水量效应”。粒雪芯中非季风期间的可溶性Ca2+浓度序列与北非及中东地区10~5月份的地表气压呈正相关关系。粒雪芯的NH4+浓度尽管存在后沉积效应的影响，但其变化过程在1990s初期降低后又呈现出明显的升高趋势，表明全球增温对陆地与海洋源的NH3排放强度的影响。 |
| 英文摘要 | The majority of the world's population lives at mid- and low-latitudes. Ice cores collected from mid- and low-latitude glaciers archive not only natural variations in climate and environment but anthropogenic influences as well. Central Asian mountain ranges contain a large number of glaciers, the highest concentration of glaciers outside of Polar Regions. It is vital, therefore, to understand how the climate and the environment are changing and that the impacts we as people are having on them by ice cores records. In this sense, a 54.6 m-long ice core and a 22.5 m-long firn core, which were collected from Mt. Muztagata on the western Tibetan Plateau in 2003 and Mt. Qomolangma on the southern Tibetan Plateau in 2005, respectively, are involved in this thesis to discuss the climatic and environmental changes recorded in them and their possible impacting factors.\nThe annual fluctuations of δ18O in Muztagata ice core are in good agreement not only with the annual air temperature changes at the nearby meteorological station, but also with the annual variations of the “δ18O mean temperature on the Tibetan Plateau” and Northern Hemisphere temperature anomalies, indicating that the isotopic record from this ice core is a reliable temperature indicator. The water-soluble species in this ice core are controlled predominantly by the influx of dust because of its site in the vicinity of arid and semi-arid regions in Central Asia, which is further verified by EOF (empirical orthogonal function) analysis for all-ion concentrations. The 3-year running average of Ca2+ concentrations, which is a representative ion of dust-related species, is significantly positive correlated with that of zonal index, showing the close relationship between westerly circulation pattern and dust transport strength. According to the seasonal fluctuations of Ca2+ concentrations with high values in summer and low values in winter, it can be concluded that dust events recorded in the Muztagata ice core are originated from Central Asia, Iran and Afghanistan regions. Anthropogenic impacts on atmospheric SO42− and NO3− can not be distinguished in this core because of the masking effect from large terrestrial dust inputs before mid-1970s. However, the increasing trends of anthropogenic species are sufficiently differentiated from that of dust-related species by the naked eyes after mid-1970s, which means that anthropogenic emissions of SO2 and NOx in Central Asia are mostly strengthened from then on. Differing from other ions, the profile of NH4+ concentrations has shown a distinct trend. The substantial increase of NH4+ concentrations after 1940s may reflect the stronger NH3 emissions from human activities in the surrounding areas and its response to global warming.\nThe major species of atmospheric aerosol in Mt. Muztagata are mostly composed of typical crust elements such as Al, Ca, Fe, K, Mg and Na. The seasonal fluctuations of crust elements content of aerosol also show high concentrations in summer and low in winter, further suggesting that mineral dust deposited in Mt. Muztagata is not transported from arid area in western China. High values of EF (enrichment factor) for Cr, Ni, Cu and Zn in winter and that for Cd, As, Pb and Bi during the whole year are caused by domestic heating by coal combustion and stable emissions from industrial activities in upwind areas, respectively. In addition, the decreased influence of anthropogenic emissions on Pb concentrations in Muztagata ice core is shown in atmospheric aerosol samples as well.\nThat two time series of δ18O in East Rongbuk firn core and Indian summer monsoon index are negative correlated suggests the “amount effect” as being the dominant influence on the isotopic fractionation in summer monsoon precipitation in Mt. Qomolangma region. The time series of non-monsoon Ca2+ concentrations in the firn core is positively correlated with that of October-May surface pressure from NCEP/NCAR reanalysis data over North Africa and the Middle East regions. Despite of post-depositional effects, NH4+ concentrations still have shown a general increase till now after a drop in the early 1990s. Its rising trend indicates the significant impacts on the emission strength of NH3 sources from landmass and ocean resulted by persistent global warming. |
| 中文关键词 | 慕士塔格 ; 东绒布 ; 冰芯 ; 气溶胶 ; 粉尘 ; 人类排放 |
| 英文关键词 | Muztagata East Rongbuk ice core aerosol dust anthropogenic emission |
| 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/2XILL650/286661 |
| 推荐引用方式 GB/T 7714 | 赵华标. 慕士塔格冰芯与东绒布冰芯的气候环境记录[D]. 中国科学院寒区旱区环境与工程研究所,2008. |
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