东南极冰芯中汞高分辨率时空变化记录及其影响机制研究

Mercury (Hg) is a toxic metal and can be transported globally. By now it has attracted the worldwide attention. As an import part of the earth system, the cryosphere played an important role in the biogeochemical cycle of the Hg. Antarctic ice sheet lies far from other continents and was surrounded by vast oceans and polar vortex and it is an ideal place for the historical research on Hg records and the relevant influencing factors. Antarctic ice core offer us the opportunity to rebuild the historic records of Hg deposited in Antarctica. Three shallow firn cores with the duration between 150-500 years were captured in three different places of the Lambert Glacier Basin (LGB) and they were designed for Hg analysis. Four main subjects of the research are listed below: 1) High-resolution history of deposited Hg during the past 5 centuries will be rebuilt; 2) Different sources, transporting and depositing mechanisms influencing the Hg records in different locations of Lambert Glacier Basin will be compared with the aid of other environmental records; 3) Mercury isotopes will be used to monitor the source regions of the mercury and quantitatively evaluate the influence from human activities in the surrounded areas, and 4) The post-depositional effects (physical transformation of the snow layers and chemical reactions) and their influences on the deposited Hg records will be tentatively studied. This project would promote our understandings on the biogeochemical cycles of Hg in Antarctica; provide basic data to the modeling research on global transport of Hg; and give our proof on the control of global Hg contaminants discharge.

汞是具有生物毒性并可全球大气传输的重金属，已经受到世界各国的广泛关注。冰冻圈作为地球系统的重要组成部分，在全球汞循环中扮演了重要角色。南极冰盖独特的地理位置及沉积环境使其成为研究全球汞传输及其沉积记录的理想之地。南极冰芯作为汞的理想载体，为我们系统认识历史时期汞的沉积序列及影响机制提供了良好契机。本项目拟通过对在东南极Lambert冰川流域获取的三支浅冰芯中不同形态汞的研究，高分辨率地重建过去500年以来东南极汞的沉积历史记录；结合冰芯中其他环境参数，对比分析东南极不同沉积环境中不同来源和沉积机制对冰芯中汞记录的影响；利用汞同位素技术确定南极汞的贡献源区，量化人类活动对南极汞的贡献；并探索各种物理化学过程对汞沉积后过程的影响。本研究将会有效提升对南极汞生物地球化学循环的认知水平，为系统模拟汞的全球传输提供基础数据，并为全球汞污染排放控制提供重要参考依据。

汞是具有生物毒性并可全球大气传输的重金属，已经受到世界各国的广泛关注。冰冻圈作为地球系统的重要组成部分，在全球汞循环中扮演了重要角色。南极冰盖独特的地理位置及沉积环境使其成为研究全球汞传输及其沉积记录的理想之地。南极冰芯作为汞的理想载体，为我们系统认识历史时期汞的沉积序列及影响机制提供了良好契机。本项目通过对在东南极中山站获取的超过两年的连续气溶胶样品，结合汞同位素技术研究了近岸带大气颗粒态汞的季节变化并探讨了其影响机理。本项目还对中山站——Dome A考察断面获取的一系列雪冰样品中痕量金属汞的时空变化格局进行了探讨，发现东南极内陆地区是大气汞重要的汇区，且夏季受地形下降风携带的二价汞是近岸带颗粒态汞的重要贡献源。另外，通过对不同区域冰芯记录的过去不同时段内气候变化信息的解译，本研究还重建了过去2680年以来东南极气候环境变化的历史，为进一步研究不同贡献源（自然源及人类活动）及沉积后过程对东南极近岸带和内陆地区汞的沉积的影响奠定了基础。依托于本项目，共发表了研究论文7篇，其中SCI论文3篇；积累了东南极气溶胶、雪冰等样品中汞及同位素数据3000余份。本研究有效的提升了对南极汞生物地球化学循环的认知水平，为系统模拟汞的全球传输提供了基础数据，并将会为全球汞污染排放控制提供重要参考依据。