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对比研究青藏高原5条冰川中痕量元素记录的环境信息
其他题名Comparative study on environmental information recorded by trace elements in snow and ice from the Tibetan Plateau
黄菊
出版年2018
学位类型硕士
导师李月芳
学位授予单位中国科学院大学
中文摘要大气中自然来源和人为来源的痕量元素可以被传输到中低纬度高山或两极地区的雪冰中，因此雪冰记载了气候变化信息和人类活动的影响。目前，青藏高原周边地区正在经历快速的经济增长和工业化进程，不可避免地向青藏高原周边大气中排放了大量污染物。同时，自20世纪80年代以来，气候变暖直接导致青藏高原地区冰川快速消融，会促进一些具有潜在毒性的元素例如Sb、Pb、As、Cd的释放。虽然之前在青藏高原地区已经开展很多关于痕量元素的研究，并揭示了人类排放活动对青藏高原环境造成了一定的影响，但是这些研究大都基于传统的酸化方法而开展的。为了进一步深入研究采用不同前处理方法对于雪冰样品中痕量元素溶解效率的差异和影响，本研究对2016年5月采自七一冰川（QY）、煤矿冰川（MK）、玉珠峰冰川（YZF）、小冬克玛底冰川（XDKMD）、哈日钦冰川（HRQ）的雪坑样分别进行酸化处理和消解处理，并用高分辨电感耦合等离子体质谱仪（ICP-MS）测试了样品中13种痕量元素（Al、Ba、Cd、Co、Cr、Cu、Fe、Li、Pb、Sb、Sr、U、Zn）的酸化浓度和总浓度。结果表明：Al和Cr的质量分数最低（在煤矿冰川、玉珠峰冰川和哈日钦冰川中的质量分数≤40%），Cd、U、Pb、Sr和Zn的质量分数较高（>3 Almass fraction），Ba、Co、Cu、Fe、Li的质量分数介于前二者之间（Almass fraction 0.05）。进一步利用Mann-Whitney U检验发现，青藏高原北部的七一、煤矿、玉珠峰冰川中的Cd和Ba的总浓度高于中部地区的小冬克玛底和哈日钦冰川（P <0.05）。对比以Fe作为参考元素计算的酸化浓度的富集系数（EFacid）和总浓度的富集系数（EFtotal），发现Cr的EFacid< EFtotal；Li、Ba、Co、Cu、Sb在5条冰川上EFacid/EFtotal的平均值介于70~157%之间；Sr、Cd、Pb、U、Zn的EFacid >EFtotal，可见基于酸化浓度计算而得的这5种的痕量元素的富集系数会高估除粉尘外其它来源的贡献，特别是高估人类活动的影响。以Fe为参考元素计算的总浓度EF中（EFtotal），5条冰川上粉尘来源占主导（大部分痕量元素的EF<5），5条冰川一些样品中Cd、Sr、Cu、Ba、Pb、Zn、Sb的EF值>5（其中Sb>10），说明冰川在这些样品对应的雪坑积累时间段内，也受到了人为活动的影响。进一步利用Kruskal-Wallis H检验和单因素方差检验分析，发现哈日钦冰川和小冬克玛底冰川的EFtotal（Sb）明显大于煤矿冰川和玉珠峰冰川的EFtotal（Sb）（P<0.05）。这是因为虽然煤矿冰川、玉珠峰冰川、小冬克玛底冰川、哈日钦冰川都距离青藏铁路和青藏公路较近，但是煤矿冰川和玉珠峰冰川受到粉尘源贡献大于交通排放源。利用主成分分析的方法进一步识别痕量元素的潜在来源，结果表明：除了受到粉尘源的影响外，这5条冰川还受到了交通排放、化石燃料燃烧、有色金属冶炼和其它工业活动等人类活动的影响。利用后向轨迹模型进行聚类分析，进一步表明在雪坑积累过程对应的时间内，这5条冰川都受到西风环流的影响。其中，七一冰川地区大气中气团的输送路径主要是中亚、塔克拉玛干沙漠。煤矿、玉珠峰、小冬克玛底和哈日钦冰川地区大气中的气团主要来自塔克拉玛干沙漠、青藏高原西部和西南部、中东、中亚地区。此外，这些气团经过一些工业发达和人口众多的城市（例如乌鲁木齐、喀布尔、新德里等），也会把污染物传输至这5条冰川地区。
英文摘要Trace elements (TEs) mainly derive from natural processes and human activities and can be transported to the snow and ice of alpine and polar glaciers. Thus information about the climate change and effects of human activities can be recorded by the snow and ice. At present, the surrounding areas of Tibetan Plateau (TP) are experiencing rapid economic growth and industrialization. Inevitably, a lot of pollutants were emitted to the atmosphere around the TP. Since 1980s, climate warming has directly resulted in the melting and shrinking of glaciers in the TP, which will accelerate the release of potentially toxic elements such as Sb, Pb, As, and Cd. Although previous investigations of the TEs in snow and ice from the TP obtained interesting information about pollution from human activities, most were based on traditional acidification methods. In order to further investigate the influence of different sample-preparation methods on the records of TEs，snow pit samples were collected from the Qiyi (QY), Meikuang (MK), Yuzhufeng (YZF), Xiaodongkemadi (XDKMD), and Hariqin (HRQ) glaciers on the TP and prepared using two methods: traditional acidification and full digestion. Concentrations of 13 TEs (Al, Ba, Cd, Co, Cr, Cu, Fe, Li, Pb, Sb, Sr, U, and Zn）in acid-leached and digested samples were measured by using the high resolution inductively coupled plasma mass spectrometry (ICP-MS). Results showed mass fractions of Al and Cr were the lowest, which were no more than 40% in the MK, YZF, and HRQ glaciers. Mass fractions of Cd, U, Pb, Sr, and Zn were higher than other TEs (>3Almass fraction), whereas mass fractions of Ba, Co, Cu, Fe, and Li varied from 1 to 3 times of those of Al. Compared with previous study, it was showed that mass fractions of TEs increased as the acidification time increased from 11/2 months to 91/2 months and the acidification strength increased from 1% HNO3(V/V) to 2% HNO3(V/V). Although mass fractions of Al and Cr in the MK and YZF glaciers increased by about 50%, mass fractions of the two TEs were still very low in our study (≤40%). Mass fractions of Fe, Ba, and Sb increased by 22~30%, 45~81%, and 17~61% among the MK, YZF, and XDKMD glaciers and mass fractions of the three TEs were about 80% in our study. Moreover, acid-leached concentrations of Cu and Pb in the MK and YZF glaciers had reached a maximum value after 11/2 months of acid-leaching.The Kruskal-Wallis H test was used to test the spatial distribution of TEs among the five studied glaciers. All data statistical analysis was performed using SPSS 19.0 for Windows (SPSS Inc.,Chicago, USA).The statistical analysis results showed no significant differences in total concentrations of most TEs (except Cd and Ba) among the five glaciers (P>0.05). Used the Mann-Whitney U test to further investigate the differences, results showed that the total concentrations of Ba and Cd in the QY, MK, and YZF glaciers from the northern TP were higher than those in the XDKMD and HRQ glacier from the central TP (P<0.05).Compared EFacid values (EF values calculated by using acid-leached concentrations) with EFtotal values (EF values calculated by using total concentrations) which were calculated by using Fe as crustal reference elements，it was showed that for Cr, EFacid values were lower than EFtotal values. The ratios of EFacid values to EFtotal values of Li, Ba, Co, Cu, and Sb varied from 70% to 157% among the five glaciers. While for Sr, Cd, Pb, U, and Zn, EFacid values were generally higher than EFtotal values, which indicated that relatively high EFacid values would lead to a greater contribution of other sources expect dust, especially for human activities. Based on EFtotal values which were calculated by using Fe as crustal reference elements, most TEs were originated from dust sources. In addition, EFtotal values of Cd, Sr, Cu, Ba, Pb, Zn, and Sb in some samples of the five glaciers were higher than 5 (EFtotal values of Sb >10)，which indicated that the glaciers might be affected by human activities during the period of these samples covering. The statistical analysis results showed EFtotal (Sb) of the XDKMD and HRQ glaciers were higher than those in the MK and YZF glaciers (Kruskal-Wallis H test and ANOVA test, P >0.05). Although the MK, YZF, XDKMD, and HRQ glaciers are close to the railway, the contribution of dust was higher than traffic emission in the MK and YZF glaciers. Moreover，principal component analysis (PCA) was also performed to further identify the possible sources of TEs. Results showed that besides dust sources, the five glaciers were affected by human activities such as traffic emission, nonferrous metals smelting, fossil fuel combustion, and other industrial activities.Evidences from air mass back trajectories showed that during the period of these samples covering, the five glaciers were generally dominated by the westerlies. The QY glacier might receive significant TEs inputs which came from Taklimakan desert, Central Asia. Moreover, the MK, YZF, XDKMD, and HRQ glaciers might be closely associated with the air masses that originated from Taklimakan desert, the arid western TP, the southwestern TP, Central Asia, and Middle East. In addition, these air masses passed through some big cities with developed industry and large population such as Urumqi, Kabul, and New Delihi might also bring pollutants to the five glaciers.
中文关键词青藏高原 ; 痕量元素 ; 质量分数 ; 空间分布 ; 来源评估
英文关键词Tibetan Plateau Trace elements Mass fraction Spatial distribution Sources identification
语种中文
国家中国
来源学科分类环境工程
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/2XILL650/288141
推荐引用方式
GB/T 7714		 黄菊. 对比研究青藏高原5条冰川中痕量元素记录的环境信息[D]. 中国科学院大学,2018.
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