呼伦湖沉积物中金属元素的沉积记录及其污染评估

发布时间：2018-11-06 14:27

【摘要】：呼伦湖是大洋洲及东北亚候鸟迁徙的驿站,也是调节我国北方气候的"草原明珠"。然而,随着人类社会和经济水平的高速发展,呼伦湖水环境的日益恶化,已经影响到湖泊生态系统的健康。沉积物作为湖泊中污染物的重要载体,可以记录较长时间序列的湖泊环境变迁,对湖泊污染历史研究具有深刻意义。本文选择呼伦湖沉积物作为研究内容,对表层沉积物中重金属的空间分布特征进行分析,确定性的地累积指数与潜在生态风险方法、基于地球化学基线值和基于盲数理论的地累积指数的方法结合,对重金属环境风险进行评价,利用放射性核素14C计年法设定沉积物年代序列,分析了湖泊的沉积速率变化状况,结合年代序列对金属元素垂向分布趋势进行分析,对不同历史阶段的重金属污染程度进行了探讨。主要研究结果如下:1.呼伦湖表层沉积物中Cu、Cd、Mn、Zn、Fe、Pb浓度空间分布规律基本相似,西南岸和北岸的旅游景区处重金属含量明显偏高,呼伦湖东岸的入湖河流处重金属含量明显偏低。Cd处于轻微污染～偏中污染状态,Cu、Zn、Mn、Fe、Pb为清洁～轻微污染状态,整体已经属于中等污染。2.本文重建立了沉积物3063BP的重金属沉积记录,主要包括3个阶段,阶段三:3063-1375 cal.a.BP,Zn、Pb、Cd的EF值波动剧烈但是变化较少,主要是受当时的全球气候变化影响;阶段二:1258-274 cal.a.BP,EF值变化较小有微弱的变化趋势,这一阶段呼伦湖周围开始有人类的生活,但是影响很小整体较为平稳;阶段一:259-51cal.a.BP,EF值在波动中明显减少,沉积记录显现出人类活动的影响。3.通过对表层沉积物中Cu、Zn、Mn、Fe、Pb、Cd做相关性分析和主成分分析,结果显示,表层重金属可以分为两类,第一类为Cu、Pb、Cd、Zn,第二类为Fe和Mn元素。由此可以推断,呼伦湖表层沉积物中重金属分别来自包括沉积母质的自然来源和包括大气沉降和地表径流等输入导致重金属含量增加的人类活动。
[Abstract]:Hulun Lake is a post station for migratory birds in Oceania and Northeast Asia, and also a "prairie pearl" regulating the climate of northern China. However, with the rapid development of human society and economy, the water environment of Hulun Lake is deteriorating day by day, which has affected the health of lake ecosystem. As an important carrier of pollutants in lakes, sediment can record the changes of lake environment in a long time series, which is of great significance to the study of lake pollution history. In this paper, the spatial distribution characteristics of heavy metals in surface sediments are analyzed, and the deterministic land accumulation index and potential ecological risk method are used to study the sediments of Hulun Lake. The environmental risk of heavy metals is evaluated based on geochemical baseline value and geoaccumulation index based on blind number theory. The sediment age series is established by radionuclide 14C dating method, and the variation of deposition rate in lakes is analyzed. The vertical distribution trend of metal elements was analyzed with age series, and the pollution degree of heavy metals in different historical stages was discussed. The main results are as follows: 1. The spatial distribution of Cu,Cd,Mn,Zn,Fe,Pb concentration in the surface sediments of Hulun Lake was similar, and the heavy metal content in the tourist spots on the southwest coast and the north coast was obviously higher. The contents of heavy metals in the rivers entering the lake on the east shore of Hulun Lake are obviously low. Cd is in the condition of slight pollution to moderate pollution, Cu,Zn,Mn,Fe,Pb is clean to slight pollution, and the whole is a moderate pollution. 2. In this paper, the heavy metal deposition record of sediment 3063BP is established, which includes three stages: stage 3: 3063-1375 cal.a.BP,Zn,Pb,Cd EF fluctuates sharply but changes little, which is mainly affected by the global climate change at that time. Stage two: the change of 1258-274 cal.a.BP,EF value is small and the change trend is weak. In this stage, the human life begins to exist around Hulun Lake, but the influence is very small as a whole. Stage I: 259-51cal.a.BPNEF value decreases obviously in the fluctuation, the sedimentary record shows the influence of human activities. 3. Through the correlation analysis and principal component analysis of Cu,Zn,Mn,Fe,Pb,Cd in surface sediments, the results show that the heavy metals in the surface layer can be divided into two categories, the first is Cu,Pb,Cd,Zn, the second is Fe and the other is Mn. It can be concluded that the heavy metals in the surface sediments of Hulun Lake are derived from the natural sources of sediment parent material and human activities which include atmospheric subsidence and surface runoff which lead to the increase of heavy metals content.
【学位授予单位】：内蒙古农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X524

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