内蒙古高原湖泊铁的地球化学特征与环境意义

发布时间：2019-01-06 18:19

【摘要】：湖泊沉积物是铁等重要元素地球化学循环的重要环节和场所,是气候环境变迁的忠实记录者,储存着丰富的地球化学信息。铁作为沉积物中氧化还原敏感元素之一,在自然界元素循环当中扮演着重要的角色,不仅是早期成岩作用的重要参与者,对沉积物的氧化还原环境也具有重要的指示意义。本文以内蒙古高原四个湖泊——乌梁素海、呼伦湖、达里诺尔、岱海为研究对象,以沉积物中铁的形态提取为基础,以铁形态分布的影响因素及其与环境气候演化的相互关系为主线,系统开展了湖泊沉积物铁在水平和垂向上的分布特征研究,探讨了铁的存在形态与环境影响因素的相互关系,尝试性地讨论了铁形态与古气候古环境的响应关系,对理解不同形态铁的环境地球化学意义,深入探讨湖泊沉积物中Fe、P及重金属微量元素的界面循环与过程具有一定的资料价值。主要结果如下:1.对比总结了四个湖泊表层沉积物中铁形态分布的关键控制因子。研究发现,湖泊流域的自然地理条件、湖泊中不同铁形态赋存含量、有机质的矿化及受人为扰动程度等均是影响湖泊表层沉积物中铁形态地球化学特征的重要因素。2.给出四个湖泊柱芯沉积物中铁的主导形态,探讨了不同铁形态对湖泊生态系统铁的早期成岩作用的贡献及其差异性机制,了解了不同形态铁随沉积柱芯深度加深的变化规律,阐释了不同形态铁的相互转化规律。3.根据柱芯沉积物Fe_(mag)相与其他代用指标的一致性和同步性,尝试性地探讨了 Fe_(mag)形态铁分别与岱海、呼伦湖和达里诺尔湖环境气候演化的响应关系,揭示Fe_(mag)可敏感记录湖泊流域的环境气候变化。
[Abstract]:Lake sediment is an important link and place of geochemical cycle of iron and other important elements. It is a faithful recorder of climate and environmental change and stores abundant geochemical information. Iron, as one of the redox sensitive elements in sediments, plays an important role in the natural element cycle. It is not only an important participant in early diagenesis, but also an important indicator for the redox environment of sediments. In this paper, four lakes in Inner Mongolia plateau, Wuliangsuhai, Hulun Lake, Dalinole and Daihai, were used as research objects, and based on the form extraction of iron from sediments. Based on the influence factors of iron speciation distribution and their relationship with environmental climate evolution, the distribution characteristics of iron in lake sediments were systematically studied, and the relationship between iron forms and environmental factors was discussed. The response relationship between iron forms and paleoclimate is discussed tentatively, which is helpful to understand the environmental geochemical significance of different forms of iron, and to probe into Fe, in lake sediments. The interfacial circulation and process of P and heavy metal trace elements have certain data value. The main results are as follows: 1. The key controlling factors of iron speciation distribution in surface sediments of four lakes were compared and summarized. It is found that the physical and geographical conditions of the lake basin, the occurrence of different iron forms in the lake, the mineralization of organic matter and the degree of anthropogenic disturbance are the important factors affecting the geochemical characteristics of iron form in the surface sediments of the lake. The dominant forms of iron in the core sediments of four lakes are given. The contribution of different iron forms to the early diagenesis of iron in the lake ecosystem and its differential mechanism are discussed. The mutual transformation law of different forms of iron was explained. 3. According to the consistency and synchronism of Fe_ (mag) phase and other substitution indexes in core sediments, the response relationship between Fe_ (mag) iron form and the environmental climate evolution of Daihai, Hulun Lake and Dalinole Lake was probed into. It is revealed that Fe_ (mag) can sensitively record environmental climate change in lake basins.
【学位授予单位】：内蒙古大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P342

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