Knowledge Resource Center for Ecological Environment in Arid Area
| 青藏高原典型冰川中类脂物的组成特征及其环境意义研究 | |
| 其他题名 | Distribution Characteristics and Environmental significances study of lipid biomarkers in typical glaciers over the Tibetan Plateau |
| 李全莲 | |
| 出版年 | 2009 |
| 学位类型 | 博士 |
| 导师 | 王宁练 |
| 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 | 冰芯作为气候环境信息的良好载体已经得到广泛认同，冰芯中不仅记录着自然变化信息，而且记录着过去人类活动对气候环境的影响。大气中自然来源和人为来源的有机化合物及其大气光化学反应的最终产物在大气环流和降水等因素的作用下以干、湿沉降的方式降落到冰川上，随着雪的老化和变质作用以及冰川的发育过程进入冰川内部，使得冰川成为研究生物地球化学循环的良好载体。青藏高原素有“世界屋脊”和“地球第三极”之称，其特有的海拔高度和广阔的冰川覆盖面积确保了各种环境信息能够被完整、准确得记录下来。为了充分认识高原不同地区雪冰中有机物组成和含量的区域特征，我们在念青唐古拉山羊八井地区古仁河口冰川、唐古拉山小冬克玛底冰川、东昆仑山玉珠峰冰川以及祁连山七一冰川采集雪坑、冰川融水和冰川末端冰样，对七一冰川还采集了冰雪不溶微粒、冰面污化物（冰尘）以及七一冰川周围表层土壤样品，对这些介质中自然来源和人类活动排放产生的类脂物进行了系统研究。研究结果如下：\n1.\t所研究冰川雪冰中正构烷烃的含量从青藏高原东北部到中南部依次减小，并且其含量状况与高原南部的达索普冰川、俄国阿尔泰山的Belukha冰川和Sofiyskiy冰川没有数量级上的差别，但是都高于格陵兰冰芯记录，表明亚洲大陆冰川雪冰中人为来源和自然来源的正构烷烃具有比格陵兰冰芯中较高的负载量。正构烷烃的分布特征表明，它们主要来自高等植物蜡和化石燃料燃烧的产物，低等生物贡献很小。生物来源的正构烷烃在总正构烷烃中的百份含量低于人类活动排放来源, 表明快速的工业化发展已经影响到青藏高原冰川中有机污染物的组成变化。从青藏高原南部到东北部，∑nC21-/∑nC22+ 和（nC15+nC17+nC19）/（nC27+nC29+nC31)的比值依次降低，正构烷烃的碳优势指数（Carbon Preference Index, CPI）值逐渐升高（玉珠峰受人为影响严重除外），说明从高原中部到东北部，高等植物和陆生植物的贡献增大，海洋中的菌藻类低等生物和水生生物贡献减小。\n2.\t所研究冰川雪冰中多环芳烃的含量在玉珠峰冰川中最高，小冬克玛底冰川中最低。多环芳烃主要以2~4环低分子量的化合物为主，而且都以菲的含量最高。结合因子分析和多环芳烃的相关参数分析结果，说明青藏高原地区冰川中的多环芳烃主要来自煤和生物质的低温燃烧。\n3.\t玉珠峰冰川和小冬克玛底冰川中正构烷烃的含量在冰川融水中最高，冰川末端冰中最低，雪坑介于二者之间。而七一冰川和古仁河口冰川中正构烷烃的含量在雪坑中最高，冰川融水中次之，冰川末端冰中最低。七一冰川，玉珠峰冰川以及古仁河口冰川中多环芳烃的含量在雪坑中最高，冰川冰中最低，冰川融水介于二者之间。小冬克玛底冰川与这三条冰川不同，多环芳烃的含量在冰川冰、雪坑和冰川融水中相差不大。\n4.\tCa2+含量、δ18O 和总正构烷烃的含量（T-HCs）及其相关参数表明，古仁河口冰川和七一冰川雪坑样品代表了2008年的春季和夏季的部分降雪。而小冬克玛底冰川和玉珠峰冰川的雪坑样品也许只是春季几次降雪事件的综合。气团反向轨迹分析表明，这4条冰川在雪坑样品所代表时段内的水汽主要来自西风环流所携带的中亚及我国西北干旱区粉尘，由季风带来的水汽较少。\n5.\t七一冰川雪冰和冰川融水中PAHs的组成相似，主要以3~4环的PAHs为主，以菲的含量最高，没有检测到6环化合物。冰雪不溶微粒和冰川周围表层土壤以及冰川冰面污化物（冰尘）中的PAHs以4~5环为主，这两种介质以苯并萤蒽的含量最高，冰尘以萤蒽的含量最高。冰雪不溶微粒和七一冰川附近表层土壤中生物标志化合物的组成类似。主要包括nC16-nC33正构烷烃，C14-C26一元饱和正脂肪酸，C19-C31三环二萜烷、C27-C34β藿烷系列化合物、C27-C29甾烷、2-7环的母核多环芳烃。甾萜烷的成熟度参数分布特征表明，它们可能主要来源于化石燃料的燃烧产物并叠加有部分机车尾气。\n6.\t七一冰川冰尘中正构烷烃分别以nC29为主峰，nC17为次主峰, 并且在nC17至nC20烷烃之前检测到相同碳数的烯烃。藿烷以C30和C31藿烯为主，甾烷也表现出未成熟特征，脂肪酸以C18:3为主峰，表明冰尘中的有机质主要来自高等植物与细菌和藻类的混合贡献。冰尘中还检测到C14~C31的正脂族-2-酮系列化合物、C14-C26一元正脂肪酸甲脂以及长链脂，其中脂肪酸甲脂只有在中性环境下才能存在，表明冰尘介质偏中性。冰尘中有机污染物的种类多于冰雪不溶微粒和冰川周围的表层土壤，说明冰尘与冰雪不溶微粒和七一冰川周围表层土壤的生物化学环境的差异。 |
| 英文摘要 | Ice cores, known as the “natural achieves”, provide the information about the past climatic and environmental changes as well as past anthropogenic activities. Specifically, organic compounds that emitted directly to the atmosphere from both biogenic and anthropogenic sources along with the photooxidation products formed in the atmosphere can be transported by wind and scavenged from the air by snowfall and dry fallout. Particularly, during snow pack ageing and metamorphism, the organic compounds can be deposited into the interior of glaciers. Therefore, glaciers can be considered as good matrices for the study of biogeochemical cycle. The Tibetan Plateau is known as “the roof of the world” and the “third pole of the earth”. The vast area of the Tibetan Plateau has been covered by the glaciers, which have recorded detailed environmental and climatic information.\nIn order to study the composition and concentration of lipids biomarkers in the glaciers of the Tibetan Plateau as well as their regional variation. The snow samples, glacier meltwater and glacier bottom ice from the Gurenhekou glacier(GRHK) in Nyainqêntanardsha Range, the Xiaodongkemadi(XDKMD) glacier in Tangkula Mountains, the Yuzhufeng(YZF) glacier in eastern Kunlun Mountains and the Qiyi(QY) glacier in Qilian Mountains, ice snow insoluble particles, cryoconite and surface soil from QY glacier were also collected to study systematically organic pollutants from natural and anthropogenic origins in these mediums. The major results were obtained as follows:\nThe results indicate a decrease in the total n-alkane concentration (T-HCs) from the northeast to the south over the Tibetan Plateau. The T-HCs in these studied areas were close to those in the Belukha and Sofiyskiy glacier, Russian Alati Mountains and the Dasuopu glacier in the Himalaya but were much higher than that in the Greenland ice sheet, suggesting that the mountain glaciers in the Asian continent may receive a higher loading of n-alkanes than the Greenland ice core. Moreover, the compositional characteristics of n-alkanes indicated that the n-alkanes in the studied areas were probably originated from the plant waxes as well as the fossil-fuel combustion exhaust, whereas the contribution from the lower organisms was small. In addition, the plant wax (WaxCn) and anthropogenic(non-WaxCn) contributions revealed that fast industrialization may have significant effects on the organic pollutant composition in glacier over the Tibetan Plateau and its circumference environment. Particularly, except for the YZF glacier, the ∑nC21-/∑nC22+ and （nC15+nC17+nC19）/（nC27+nC29+nC31) ratio decreased from the QY glacier to the GRHK glacier over the Tibetan Plateau, while the carbon preference index(CPI) values increased. These results indicate a decrease in terrigenous input while an increase in marine input from the northeast to the south over the Tibetan Plateau. These two ratios can be used as the climatic and environmental change indicators.\nAverage concentration of 16 U.S. EPA priority controlled PAHs was highest in YZF glacier and lowest in XDKMD glacier. PAHs from snow and ice in these glaciers were dominated by 2~4 ring and Phenanthrene was the most abundance compound. Factor analysis and isomer pair ratios suggest that PAHs of glaciers over the Tibetan Plateau were derived from low temperature combustion of coal and biomass, Vehicle emission may be also contribute to some PAHs.\nThe concentration of n-alkanes in glacier melt water from YZF and XDKMD glacier were highest and glacier bottom ice lowest, snow between them. Whereas the concentration of n-alkanes in snow from QY and GRHK glacier were highest and glacier bottom ice lowest, glacier melt water between them. The PAHs concentration in snow from QY, YZF and GRHK glacier were highest and lowest in glacier bottom ice, glacial melt water between them. Whereas XDKMD glacier was different from these three glaciers, the content of PAHs in glacier bottom ice was highest, snow and glacier melt water showed little difference.\nIn accordance with the change of Ca2+，δ18O，n-alkanes and their parameters with the increase of snow depth in snowpit from each glacier, we can’t confirm the seasonal changes of chemical compostions in snowpits from YZF and XDKMD glacier, probably they were only comprehensive results of a few snowfall incidents in spring,2008. Whereas GRHK and QY glacier represented snow accumulation from spring to summer in 2008. Air mass back trajectory indicated that the vapor in the period of time represented by the snowpit in these four glaciers mainly come from dust derived from centra asia and arid area of Northwest China because of westerly wind circulation. Whereas the vapor derived from monsoon is little.\nPAHs in snow ice and glacier meltwater from QY glacier were dominated by three-ring and four-ring. However, PAHs in snow ice insoluble particulates and surface soil around QY glacier were dominated by four to six rings. The contents of benzofluoranthene were highest in these two mediums and fluoranthene were highest in cryoconite.Snow ice insoluble particulates and surface soil around QY glacier have similar composition, including normal alkanes of nC16-nC33, normal fatty acids of C14-C26, extended tricyclic terpanes of C19-C31, C24 tetracyclic terpane, hopanes of C27-C34, steranes of C27-C29, PAHs of 2~7 rings. Maturity parameters of the steranes and terpanes indicated that they may derive from fossil fuels and exhaust of traffic vehicles.\nIn cryoconite, n-alkanes had two main peaks at nC17 and nC29, the same carbon number alkenes were identified before alkanes of nC17-nC20. Moreover, hopene of C30 and C31 were the major hopane components. In addition, steranes showed the characteristics of immaturity. Finally, C18:3 was the maximum peak value in fatty acids. Indicating that organic matters in cryoconite mainly derived from the mixtures of higher plants and microorganism, this distribution pattern also suggested that evolution degree of organic matter was low in QY glacier because of the semi-arid and cold environment. C14-C31 n-alkan-2-one and C14-C26 long chain fatty acid methyl esters were also identified in cryoconite. Fatty acid methyl ester only exists in neutral environment, suggesting cryoconite are belong to neutral. The species of organic matters in snow ice insoluble particulates and surface soil around QY glacier were more than that of cryoconite. This showed that there had different environment in cryoconite and its circumference environment. |
| 中文关键词 | 青藏高原 ; 古仁河口冰川 ; 小冬克玛底冰川 ; 玉珠峰冰川 ; 七一冰川 ; 冰川融水 ; 冰川末端冰 ; 雪坑 ; 冰雪不溶微粒 ; 冰尘 ; 类脂化合物 |
| 英文关键词 | Qinghai-Tibetan plateau Gurenhekou glacier Xiaodongkemadi glacier Yuzhufeng glacier Qiyi glacier Gla |
| 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/2XILL650/286769 |
| 推荐引用方式 GB/T 7714 | 李全莲. 青藏高原典型冰川中类脂物的组成特征及其环境意义研究[D]. 中国科学院寒区旱区环境与工程研究所,2009. |
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