地理学报 ›› 2020, Vol. 75 ›› Issue (1): 68-81.doi: 10.11821/dlxb202001006

• 地表过程 • 上一篇    下一篇

1899—2011年青藏高原南部枪勇错沉积物磁性矿物的环境意义

高星1, 康世昌2, 刘青松3, 陈鹏飞2, 段宗奇1,4()   

  1. 1. 中国科学院地理科学与资源研究所 资源与环境信息系统国家重点实验室,北京 100101
    2. 中国科学院西北生态环境资源研究院 冰冻圈与全球变化研究室,兰州 730000
    3. 南方科技大学海洋科学与工程系,深圳 518055
    4. 中国地理学会,北京 100101
  • 收稿日期:2019-09-25 修回日期:2019-11-13 出版日期:2020-01-25 发布日期:2020-03-25
  • 通讯作者: 段宗奇 E-mail:duanzq@igsnrr.ac.cn
  • 作者简介:高星(1966-), 男, 山东济南人, 研究员, 博导, 主要从事地震地质灾害及环境磁学方面研究。E-mail: gxing@igsnrr.ac.cn
  • 基金资助:
    国家自然科学基金项目(41506075);国家自然科学基金项目(41430962);国家自然科学基金项目(41574036);国家自然科学基金项目(41705132)

Magnetic characteristics of Qiangyong Co Lake sediments, southern Tibetan Plateau and its environmental significance during 1899-2011

GAO Xing1, KANG Shichang2, LIU Qingsong3, CHEN Pengfei2, DUAN Zongqi1,4()   

  1. 1. State Key Laboratory of Resources and Environmental Information System, Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China
    2. State Key Laboratory of Cryospheric Science, Institute of Eco-Environment and Resources, CAS, Lanzhou 730000, China
    3. Department of Marine Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, Guangdong, China
    4. The Geographical Society of China, Beijing 100101, China
  • Received:2019-09-25 Revised:2019-11-13 Online:2020-01-25 Published:2020-03-25
  • Contact: DUAN Zongqi E-mail:duanzq@igsnrr.ac.cn
  • Supported by:
    National Natural Science Foundation of China(41506075);National Natural Science Foundation of China(41430962);National Natural Science Foundation of China(41574036);National Natural Science Foundation of China(41705132)

摘要:

重金属污染物因具有持久性和难降解性,严重影响生态系统健康。青藏高原湖泊远离人类污染区,是研究人类污染物远端效应的理想区域。基于定年数据,湖泊沉积物可以追踪近百年内的人类污染物变化趋势。环境磁学具有经济、快捷和无损耗的特点,被广泛证实可以有效指示重金属污染;但目前还缺乏对青藏高原湖泊沉积物中的相关环境磁学研究。为此,选取青藏高原南部枪勇错1899—2011年的沉积物,进行系统的环境磁学分析,探讨磁性矿物与重金属Hg的相关关系及环境指示意义。结果表明:1899—2011年磁性矿物的类型没有发生变化,可分为4类组分,其中:组分C1(赤铁矿)占比不断增多,C2(针铁矿)占比相应减少,C3和C4(磁铁矿)的占比基本保持不变。样品的饱和等温剩磁和低频磁化率与Hg含量相关性较低。然而C1组分与Hg含量呈现良好的正相关关系。本文认为在近百年全球和青藏高原气温不断增高的趋势下,枪勇错的主要补给——枪勇冰川融化加速,导致原来被冰川或冰尘封存的人类污染产生的Hg重新释放。在这个过程中,C1(赤铁矿)组分因表面积大而易于富集Hg,最终二者一同随融水进入到枪勇错。本研究表明,环境磁学可以应用于青藏高原南部湖泊的重金属研究,并为揭示Hg在青藏高原南部湖泊中的富集过程提供新的视角。

关键词: 青藏高原南部, 枪勇错, 湖泊沉积, 环境磁学, 环境变化

Abstract:

Far from major zones of human pollution, the widely developed lakes on the Tibetan Plateau are ideal regions to evaluate global and regional impacts caused by human activities. Based on the reliable dating, they can provide historical records of human pollution. Heavy metal is one of the most harmful pollutants, and is harmful to biological environment and people's health due to its degradation-resistancy. Environmental magnetism characterized by its sensitivity, facility and non-destructiveness, has been applied widely in estimating increased heavy metal pollution in different environmental systems. However, there lacks the relevant research in lake sediments on the Tibetan Plateau. Thus, we conducted a systematic environmental magnetic investigation of lake sediments in the Qiangyong Co Lake, southern Tibetan Plateau to explore the relevance between magnetic minerals and heavy metal (Hg). Results indicate that magnetic mineral species constituted by four different components (C1, C2, C3, C4) remain stable during 1899-2011 AD, but the component C1 (hematite) increased continuously with the corresponding decrease of component C2 (goethite). In contrast, components C3 and C4 (magnetite) have no significant changes. The correlation between SIRM and Hg differs from that between χlf and Hg, probably because SIRM and χlf are affected by different factors of complex magnetic mineral species (four different components). But the component C1 is correlated well with both Hg content and climate warming of the Tibetan Plateau. This indicates that Qiangyong glacier (the main recharge source of Qiangyong Co Lake) melt faster upon the Tibetan Plateau warming, and the accumulated Hg in glacier and cryoconite were released again. During the processes, C1 (hematite) with large specific surface area absorbs Hg, and is transported to the Qiangyong Co Lake. This research indicates that the magnetic properties of the Qiangyong Co Lake are excellent environmental proxies, which can provide a new method to study the process of Hg deposition in lakes on the southern Tibetan Plateau.

Key words: southern Tibetan Plateau, Qiangyong Co Lake, lake sediments, environmental magnetism, environmental changes