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题名: 青藏高原汞的污染特征及环境行为研究
作者: 邵俊娟
学位类别: 博士
答辩日期: 2016-05
授予单位: 中国科学院研究生院
授予地点: 北京
导师: 江桂斌 ; 史建波
关键词: 汞,青藏高原,同位素,来源,重金属 ; mercury, the Tibetan Plateau, isotope, source, heavy metals
其他题名: Contamination characteristics and environmental behaviors of mercury in the Tibetan Plateau
学位专业: 分析化学
中文摘要:       汞是一种有毒的全球污染物,具有持久性、生物累积及生物放大的特点。汞在大气中的寿命较长,从污染源排放到大气中的汞,可以经过长距离的大气迁移,经干、湿沉降,到达偏远地区的河流和湖泊,给当地环境带来严重的污染。青藏高原作为世界上海拔最高的高原,具有人口少、工业少的特点,对于研究汞的长距离传输具有重要的意义。
    本文研究了青藏高原河流野生鱼体中总汞和甲基汞的累积、放大及摄入风险。以苔藓和松萝作为汞的生物指示物,研究了汞在青藏高原的污染特征,并根据汞同位素的分馏效应,对青藏高原色季拉山土壤中汞的来源进行了分析。最后,使用苔藓和松萝作为重金属(铬、锰、钴、镍、铜、砷、镉、铅)的生物指示物,研究了重金属在青藏高原的空间分布规律。
    对采自青藏高原四条河流的 60条鱼体中的总汞、甲基汞含量进行了分析,研究了汞在青藏高原野生鱼体内的累积、放大及摄入风险。青藏高原鱼体中总汞和甲基汞的浓度范围分别为 11– 2097 ng/g(平均值:819 ng/g)和 14 – 1960 ng/g(平均值:756 ng/g)。拉萨河鱼体内总汞和甲基汞的浓度与其所处的营养级成显著正相关(p < 0.01,n = 36)。此外,鱼体内总汞的浓度与鱼的体长、体重间也存在显著的正相关(p < 0.05,n = 60)。食用白鱼、胡子鱼、尖嘴鱼和土鱼会带来高的甲基汞暴露。
    对采自青藏高原的 130个苔藓、52个松萝和    146个土壤样品中汞的含量与形态进行了研究。结果表明,青藏高原苔藓和松萝中总汞和甲基汞的浓度与文献报道的南极、北极样品浓度处于同一数量级。苔藓中总汞、甲基汞和无机汞的浓度呈现出从西到东的下降趋势。苔藓中总汞、甲基汞和无机汞的浓度随着采样点海拔的升高而增高,表明青藏高原对汞具有潜在的冷凝效应。
    通过分析色季拉山苔藓、松萝和土壤样品中汞的同位素组成,对色季拉山土壤中汞的来源进行了研究。结果显示,苔藓、松萝和土壤样品中的汞均发生了显著的质量分馏和非质量分馏。苔藓、松萝和土壤样品中 Δ199Hg与  Δ201Hg的比值接近于 1,表明汞在进入这些环境介质前,经历了二价汞的光还原过程。二元混合模型的计算结果表明,色季拉山土壤样品中 67.7%的汞来源于大气沉降,32.3%的汞来源于地质成因。
    对青藏高原苔藓和松萝样品中的重金属含量和空间分布特征进行了研究。结果表明,苔藓中铬、锰、钴、镍、铜、砷、铅的浓度显著高于同一采样点松萝中的浓度,表明苔藓和松萝对这些元素的富集能力存在显著差异。相关性分析和主成分分析的结果表明,苔藓和松萝中重金属的分布规律相同。苔藓和松萝中的大部分重金属含量都呈现出从南到北,从西到东的下降趋势。与汞的分布规律类似,苔藓中锰、钴、镍、铜、砷、镉、铅的浓度随着采样点海拔的升高而增高,表明青藏高原对这些元素的分布具有一定的影响。
英文摘要:     Mercury  (Hg)   is  a   toxic  and   global  pollutant,   with  the   characteristics  of persistence, bioaccumulation and  biomagnification. Due to the long  lifetime of Hg in the atmosphere and  the ability of long range  transport, Hg emitted from the pollution sources can be deposited into remote rivers  and lakes, resulting in serious pollution in local aquatic  system. The  Tibetan Plateau  is the highest  plateau, with  sparse human population and almost  no industry. It is  important to study the  role Tibet plays in  the long range transport of Hg.
    In  this study,  the bioaccumulation,  biomagnification  and risk  of  total mercury (THg) and methylmercury (MeHg) in fish collected from rivers in the Tibet have been studied. Mosses and lichens were used as  the bioindicators to study the contamination characteristics of Hg  in the Tibet.  The Hg isotopic  fractionation was applied  to trace the sources of Hg in soil from the  Shergyla Mountain in the Tibet. The concentrations and  distribution patterns  of  trace  metals (Cr,  Mn,  Co,  Ni,  Cu, As,  Cd  and  Pb) in mosses and lichens collected from the Tibet were also investigated.
    A total  of  60 fish  samples  were collected  from  four rivers  across  the Tibetan Plateau  to study  the  accumulation of  Hg  in  Tibet. The  concentrations of  THg  and MeHg in  fish ranged  from 11  to 2097  ng/g dry  weight (average:  819 ng/g  dw) and from 14 to  1960 ng/g dw  (average: 756 ng/g  dw), respectively. The contents  of THg and MeHg  had significantly  positive correlation with  the trophic  levels of fish  from Lhasa River  (p <  0.05,n = 36).  Moreover, the  THg levels in  fish had  significantly positive  correlations with  the  length  and weight  of  fish  (p <  0.05,n  =  60). Risk assessment revealed that the  consumption of some of  fish from Tibet would lead to  a high exposure to MeHg.
    The  accumulation and  species of  Hg  in 130  mosses, 52  lichens  and 146  soils collected from high-altitude Tibetan Plateau  were studied. The concentrations of THg and MeHg in mosses and lichens collected from Tibet were compared with those from Arctic  and Antarctic.  The THg,  MeHg  and inorganic  Hg (IHg)  contents  in mosses decreased form  west to  east. The  concentrations of  THg, MeHg  and IHg  in mosses increased with  the increasing  altitudes of  the sampling  sites indicating  the potential mountain trapping of Hg in the Tibetan Plateau.
    The  isotopic  compositions of  Hg  in  mosses,  lichens and  soils  from  Shergyla Mountain   were    studied   to    trace   the    sources   of    Hg   in    soils.    Significant mass-independent  fractionation   (MIF,   Δ199Hg)  and   mass-dependent  fractionation (MDF,  δ202Hg) were  observed  in moss,  lichen  and soil  samples  from the  Shergyla Mountain.  The  ratios  of   Δ199Hg/Δ201Hg  were  close  to   1  indicating  the  possible
photoreduction processes of  Hg2+ prior to  entering the environmental matrices  of the Shergyla Mountain. The result  of binary mixing-model indicated that  67.7% of Hg in soils  from the  Shergyla  Mountain came  from  the atmospheric  deposition  and only 32.3% of Hg was geogenic.
    The patterns and concentrations of heavy metals (Cr, Mn, Co, Ni, Cu, As, Cd and Pb) in moss  and lichen samples  were studied. The concentrations  of Cr, Mn,  Co, Ni,Cu,  As and  Pb in  mosses  were significantly  higher  than those  in  lichens collected from the same  sites, indicating that mosses  and lichens from  the Tibetan Plateau had different abilities  for accumulating  these metals.  The results of  correlations analysis and  principal   component  analysis  indicated  that   the  trace  metals   had  a  similar distribution   patterns   in  mosses   and   lichens.   The   spatial   distribution  of   most determined metals  in mosses and  lichens displayed a  decreasing trend from  south to north and from west to east. The contents of Mn, Co, Ni, Cu, As, Cd and Pb in mosses increased with  the  ascending altitudes  of the  sampling  sites, implying  the potential influence of the Tibetan Plateau on the distribution of these trace metals.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/36951
Appears in Collections:环境化学与生态毒理学国家重点实验室_学位论文

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Recommended Citation:
邵俊娟. 青藏高原汞的污染特征及环境行为研究[D]. 北京. 中国科学院研究生院. 2016.
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